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1. 286 Appendix F Model Files and Keywords and so on When the vehicle file is read the program finds more references to other PARSFILEs with data for suspensions tires and various vehicle properties The LOG file is a list of every PARSFILE that was referenced starting with the file named in the SIMFILE Listing F 3 shows the top portion of a LOG file Listing F 3 Example LOG File nclude PARSFILE C CARSIMED UNS 603 PAR nclude PARSFILE C CARSIMED EFHICLES VEHICLES 58 par nclude PARSFILE C CARSIMED EHICLES AERO 34 par Example aero data full nclude PARSFILE C CARSIMED EFHICLES STEER STRS_CAR 40 par nclude PARSFILE C CARSIMED EHICLES STEER STR_4W 12 par Front Wheel Steer Viewing Keywords The files read by the solver programs in CarSimEd are scanned for input data Parameters are identified by keywords Viewing a Complete List of Parameters The list of parameters in the next section was created from within the software for a particular run To create a similar list for other runs do the following 1 Go to the Runs library and find a run involving the vehicle of interest 2 If the run has not already been made click the Run button 3 Click the View All Parameters button to view the file in a text editor Alternatively look at the ID number in the upper right corner of the Runs screen e g 430 Then use a file browser such as Windows
2. B 46 par parsfile C CARSIMED 45 VEHICLES CARS_ED 53 par P parsfile C CARSIMED 45 INPUTSROAD E60 par 3 H 225 par parsfile C CARSIMED 45 comp_par 40 par E 222 par stopt 13 E 363 par speed 72 B 364 par mu 0 75 E 365 par E 366 par testid 640 E 367 par used by animator program E 368 par PARSFILE C CARSIMED 45 4NIMATESCAMERAS4235 par B 39 used by plotting programs E pa PARSFILE C CARSIMED 45 RUNS_2D 640 plt par E 371 par title Sine Sweep H 365 par E 366 par END E 367 par E 372 par EJ 373 par E 368 par E 369 par if E 370 par E 374 par Parsfile path and filename amp E 226 par C CARSIMED 45 RUNS_2D 640 par B 375 par d Q File can t be found Keyword error Create LpiFile Reload File Load New File Exit a Figure 5 4 An example Parstree for a Runs data set LPO and LPF Echo Files When a solver program runs it creates summary files that list each and every parameter value One of these files is created before the run LPO and the other is created at the end of the run LPF Both files contain all parameter values for a simulation In addition the LPO file contains the initial conditions for the state variables in the simulation The information in the LPO file is sufficient to exactly repeat a run The difference between the PAR and LPO files is that the LPO file contains every parameter value in one file see Appendix F for an example whereas the PAR file con
3. User Settings Note User settings that are common for all tabular data screens are described in Chapter 7 in the section Tabular Data O Table field for cornering stiffness keyword KFY_TABLE Each line should have a value of cornering stiffness N followed by a corresponding value of trail N deg Although lateral force and side slip have opposite signs cornering stiffness is typically defined as a positive quantity and therefore all numbers in the table should be positive The solver program uses linear interpolation and flat line extrapolation with this table For values of load that are less than the range covered in the table the first value of cornering stiffness is used For values of load larger than the range covered the last value of cornering stiffness is used The table needs at least two lines of data or else an error message is generated Location in CarSimEd CarSimEd Startup Runs Vehicles Car Tires CarSimEd Tires Cornering Stiffness Kfy 213 Chapter 9 Alphabetical Library Reference File Location Vehicles Tires Kfy Kfy tbk Tires Pneumatic Trail Use this screen to specify pneumatic trail as a function of vertical load Discussion The line of action for the shear force produced by a tire is generally not exactly through the center of tire contact For small lateral slip angles the shear force usually acts behind the center This distance acts as a moment arm producing a torque t
4. 168 Chapter 9 Alphabetical Library Reference If the vehicle station is less than zero the line connecting the first two points in the table is extended in a straight line If the vehicle station is higher than the largest value in the table the last two points are extended in a straight path Under normal conditions the vehicle is placed with the middle of the front axle at on the path as defined on this screen The yaw angle is oriented so the vehicle is initially traveling parallel to the path The mathematics underlying the closed loop controller are described in Appendix I a Input Target Path for Closed Loop Steer Control Ioj Xx File Edit Text Page Tools Data set Double Lane change I gt Hew Delete GO v Back Changed ID S7 O Hotes 12 26 17 Global Y coordinate m Update Plot Tidy Table 4 Path Profile X 0 0 50 100 150 Global X coordinate m The vehicle can be steered by a Maximum SVV angle Color used in animation driver model that attempts to follow Previews time 4 a target path with a lateral offset Driver time lag Animation The wire frame animator will show the target path as a dashed line The path is valid for the full range of station numbers covered by the vehicle in the simulation even if it is nowhere close to the path The animator draws the path in a color specified on the screen User Settings Note U
5. 45 RUNS 894 ERD 45 RUNS 808 erd 45 plot setup 814 par Z 45 RUNS 894 ERD 45 RUNS 808 erd 45 plot setup 795 par Z HoH Es n Z 45 RUNS 894 ERD 45 RUNS 808 erd 45 plot setup 817 par ry i PAHPPAHP PAH P BoE Es PARS RUN FILE EnC ED 45 RUNS 894 ERD FILENAME C ED 45 RUNS 808 erd PARSFILE C ED 45 plot setup 810 par RUN Screen END ea Zw 264 Appendix D Plotter Files and Keywords The lines in the PLT file are grouped into plot sets separated by lines beginning with the RUN keyword For example Listing D 1 has four sets defining four plots Lines within a plot set can be arranged in any order The PLT file is normally read by WinEP when you click a Plot button from the Runs screen or from the Plot Setup Batch screen Although less common you can also read one interactively in WinEP by selecting the File menu option Load Batch File Table D 1 PLT batch plot file format Instruction to Program FILELIST Line 1 Identify this as a list of plot descriptions FILENAME ERDfile Read the file ERDfile for data to plot ERDfile should follow the ERD format Simple text files with tables of numbers can also be specified PARSFILE filename Open the file filename and read a parsfile with information PROT ev ent tat ete op ona ai ge END In order to support real ti
6. E 700 par set_superimpose off 31 par z 63 par title Front view bi E g 707 par g 31 par E 63 par Parsfile path and filename 712 par D CARSIMED ANIMATESCAMERAS 4212 par g 31 par File can t be found Keyword error Create LpiFile Reload File Load New File Exit a Figure 6 4 Parstree window Toggling Between the Database and the Animator The basic method for editing shapes and testing animator data sets is as follows Create animator settings using the animator libraries described in Chapter 9 Link to the new settings on the Cars screen via the Animator Group link To test new camera settings link to the new settings from the Runs screen via the Camera Setup link Go to the Runs screen and click the Animate button The run should use the Car data set with the link to the new animator settings View the animation When you are ready to modify the settings stop the animation Press the space key or use the Stop command from the Animation menu Without quitting the animator switch back to the CarSimEd Runs screen Use Alt Tab in Windows to switch between running programs Within CarSimEd navigate to the screen with the animator data to be edited e g an animator shape data set Chapter 6 The Animator 7 10 11 Edit the data in the CarSimEd data set As soon as you modify any data and move the cursor to another field you will see a red circle in the upper right corner of the window
7. Data set Step steer car v 4l I gt Hew Delete cor Back Model Parameters amp Inputs Vehicle car zl Input Steer 30 dey step steer Input Braking NoBraking d Input No data set selected gt Run Control Output amp Post Run Simulation 2 Anim Speed kmh Stop sec Mu Camera Setup Computation Parameters ot 0025 20 Hz output jw Wiew Echo Fite Simulation Type 3D Vehicle Dynamics Add Delete gt 3D Vehicle Dynamics Figure 10 3 Link to a solver program Note The utility functions on the Simulation Type menu G are visible only if you have specified Advanced Mode in the CarSimEd preferences To access the preferences use the Tools menu item Preferences or click the button amp in the ribbon bar Replacing an Existing Program With Another Program If the New Program Has the Same Name As the Old Program 1 Replace the old EXE file with a new one Note 233 As installed all stand alone EXE solver programs reside in the folder Programs Chapter 10 Advanced Topics 2 Make a run to confirm that the new program is used If so you re done If not keep going Use the pull down menu G to choose the option Find Solver For Type where Type is the desired simulation type In the case of a stand alone program you will then be prompted to locate the EXE file associated with the currently select vehicle and simulati
8. Input File C CARSIMED 45 RUNS_3D 627 PAR Run was made 12 23 on Jan 20 2000 FORMAT BINARY IPRINT 20 number of time steps between output printing counts STARTT 0 simulation start time s STEP 0 0025 simulation time step s STOPT 10 simulation stop time s PARAMETER VALUES ASW_MAX 360 Maximum allowed steering wheel angle in driver model deg CSFY 1 0 0003 Front suspension compliance d steer d Fy deg N CSFY 2 0 Rear suspension compliance d steer d Fy deg N CSMZ 1 0 004 Front suspension compliance d steer d Mz deg N m CSMZ 2 0 002 Rear suspension compliance d steer d Mz deg N m CSMZF 0 001 Steering system compliance d steer d Mzl Mzr 2 deg N m CTFX 1 0 0004 Front suspension compliance d toe d Fx deg N CTFX 2 0 Rear suspension compliance d toe d Fx deg N DSC 0 75 Front damper rate at shock absorber N s mm DS 0 75 Rear damper rate at shock absorber N s mm HCG 550 Nominal height of entire vehicle C G mm HRC 1 100 Nominal height of front axle roll center mm HRC 2 100 Nominal height of rear axle roll center mm HWC 1 285 Undeflected height of front wheel center mm HWC 2 285 Undeflected height of rear wheel center mm IW 1 1 1 Spin moment of inertia of front wheel kg m2 IW 2 1 1 Spin moment of inertia of rear wheel kg m2 IXX 400 Moment of inertia of entire vehicle kg m2 IXZ 0 Product of inertia of entir
9. _ _ Choose the program you want to use z V Always use this program to open this file k lt Cancel Other 4 Make sure the box Always use this program to open this file is checked 5 Click the OK button to close the dialog box You have now associated the file type TBK with the program Tb4Orun in its new location Update Pathnames in PAR Files The solver programs require absolute pathnames and CarSimEd creates them behind the scenes using PAR text files When CarSimEd is installed it looks at its location and generates many files using that location to create pathnames For example if it is in folder c mycar then all pathnames are automatically set to begin with c mycar If you move the CarSimEd directory you must instruct CarSimEd to regenerate all of the absolute pathnames in the PAR files After you have moved the root CarSimEd folder to a new location to regenerate the absolute pathnames do the following 1 Use the GO button in the ribbon bar to go to the CarSimEd startup screen Startup tbk 2 Goto the data set Install 221 Chapter 10 Advanced Topics Update All PAR Files Data Set for Start button No data set selected x Done 2 Change Settings G Start Figure 10 1 Lower right corner of Startup screen 3 Click the Change Settings button This will hide the CarSimEd logo and reveal more buttons including th
10. 5 After viewing the plot exit the plotter by clicking the x in the upper right corner of the screen Viewing Several Pre Defined Plots Start from a Runs screen see Figure 4 1 on page 30 The simulation run must have already been made in order to view a plot 1 Check the box Multiple Plots 14 This reveals three more links to plotter data sets 7 as shown in Figure 4 5 Figure 4 5 Additional plot and run links 2 Select up to four plot setups using the links and 17 3 Click the Plot button 13 Note Multiple plots can be viewed in WinEP in several modes The WinEP Windows menu can be used to locate any existing plot window All of the plots can be viewed simultaneously by using the vertical or horizontal tiling options from the Windows menu 4 After viewing the plots exit the plotter by clicking the x in the upper right corner of the screen or by using the File menu or by typing Ctrl Q Overlaying Plots for Multiple Runs Start from a Runs screen see Figure 4 1 on page 30 Multiple simulation runs must have already been made in order to view plots involving them 38 Chapter 4 The Basics of Using CarSimEd Check the box Overlay Runs 15 This reveals two links labeled Overlay Run 2 and Overlay Run 3 18 see Figure 4 5 Select another run of interest from the pull down menu next to Overlay Run 2 18 If you want to overlay three runs link to another run of interest using the link
11. Linear interpolation is used between rows and columns For X and Y values outside the range of the table linear extrapolation is used Keyword This keyword is required for a solver program to make use of the data in the table G Unlike most CarSimEd libraries the keyword is not hidden If the keyword in this field is not recognized by the solver program then the data will not be used In order 158 Chapter 9 Alphabetical Library Reference for the data to be used the keyword must be provided and it must be spelled correctly However the keywords are not case sensitive Location in CarSimEd This library does not have a default position in CarSimEd You can link to it from any blue field in the CarSimEd libraries File Location Generic Gen2dtab Gen2dtab tbk Generic Data Group Use this screen to create groups of data Discussion There are at least three applications for this library 1 Create sets of related inputs such as combinations of braking steering and speed 2 Create sets of vehicle parameters that you want to apply as a group For example you could make a group that overrides tire data normally associated with the simulated vehicle without making a new vehicle data set 3 Specify parameter values that do not fit in existing data screens For the standard CarSimEd package there are only a few e g ROLL_STOP V_STOP However if you add new vehicle models then you might want to use this
12. Unlike most of the libraries in CarSimEd each data set in this library can represent a different kind of data This is possible because the keyword used by the simulation solver programs to identify tabular data is a part of the data set User Settings Note User settings that are common for all tabular data screens are described in Chapter 8 in the section Tabular Data 4m Generic Table Iof x Eile im Text Page Tools O Hotes 12 25 43 Keyword for this table PBRAKE TABLE Update Plot Tidy Table Line pressure psi 2 Table Data 90 80 70 60 50 40 30 20 10 pi aay ee 2 GO shows a pull down menu of data libraries Takes you to the library selected Figure 9 5 Example generic table 161 Chapter 9 Alphabetical Library Reference Cc Keyword This keyword is required for a solver program to make use of the data in the table 4 If the keyword in this field is not recognized by the solver program then the data will not be used In order for the data to be used the keyword must be provided and it must be spelled correctly However the keywords are not case sensitive Label for Y axis This label is not used by the solver programs It is a user comment field provided as a means for documenting the information on the screen Label for X axis This label is not used by the solver programs It is a user comment field provided as a means f
13. Pop up menu for selecting the type of filter User Settings O Filter type Press the adjacent button to display the pull down menu shown in the figure with the choices of LoPass HiPass BandPass or no filter If a filter is selected one or both of the fields for defining baselengths are shown C 3 2 Low pass baselength This is a baselength for a moving average when the filter type is either low pass or band pass This field is hidden if the filter type is no filter or high pass As noted above this defines an interval used to smooth the plot by averaging A long baselength performs more averaging and removes more high frequencies by smoothing A shorter baselength results in less averaging leaving more of the original content 3 High pass baselength This is a baselength for a moving average when the filter type is either high pass or band pass This field is hidden if the filter type is no filter or low pass As noted above this defines an interval used to define a smoothed set of numbers that are subtracted from the original A long baselength removes only the static values and very low frequencies A shorter baselength results in less averaging meaning that more of the original data are removed 4 Offset values subtracted from the variables being plotted One column has values subtracted from the variables plotted on the X axis and the other has values subtracted from the variables plotted on the Y axis The units
14. The Data Section The data section of the ERD file contains nothing but numbers organized into columns and rows The form in which the numbers are stored depends on the value of the KEYNUM parameter from line 2 of the header see Table C 1 The total number of values that will appear in the data section is NCHAN x NSAMP All of the numbers in the data portion are stored in the same format and there can be no missing values Text Data The text format can be used for transporting data in ERD files between different computers and sometimes even for reading the same file with different programs on the same computer It is also convenient when numbers are typed in manually or when numbers are to be edited using a text editor However there are penalties for using text representations of numbers First the computer must work hard to translate the text numbers into binary form It takes about 10 times longer to read a text file than a binary equivalent Second text files take up much more disk storage than binary files When data are stored in text form the numbers are kept in the same file as the header with the numbers beginning immediately after the header The ERD file in Listing C 2 shows an example of numerical data in text form Another option is available when the numbers are always separated by delimiters such as spaces or commas This occurs when the numbers are obtained by a commercial analysis program or when they are captured
15. You must associate the file type TBK with the file To40 run exe If you know how to do this go ahead and do it If not the following steps describe a method that will work 1 From the desktop or Windows Explorer find the file Startup tbk in the CarSimEd folder Double click the file to try to open it If CarSimEd launches congratulations No work is needed However more likely Windows will not know how to open the file and will bring up a dialog box that looks something like this 219 Chapter 10 Advanced Topics Open With 21x Click the program you want to use to open the file STARTUP TBK If the program you want is not in the list click Other Description of TBK files _ Choose the program you want to use 2 Click the button Other This brings up the next dialog box Open With 271 xi Lookin Smo AA HEE M Tb40net exe Fase Tb40run exe id Thload exe R File name Tb40run exe Files of type Programs z Cancel 3 Locate the file TB40run exe in the folder Tb40 in CarSimEd After selecting the file click the Open button to complete the selection and close the dialog box The previous dialog box should now show the program 220 Chapter 10 Advanced Topics Open With 20 x Click the program you want to use to open the file STARTUP TBK If the program you want is not in the list click Other Description of TBK files
16. an up Example HNN Tre Tx omw body X CarSimEd data screens m 150 408 me as Wire frame animator C_CAR_3D _ ol x Vehicle dynamics solver programs Engineering plotter Figure 1 1 Four parts of CarSimEd Data screens serve as your primary interface to CarSimEd They contain vehicle model parameters control inputs and run settings The data screens are part of a database that maintains libraries of related data sets CarSimEd includes about 30 libraries each with multiple data sets that are linked together to make up the database Vehicle dynamics solver programs use equations of motion in mathematical models to calculate output variables The process of performing these calculations is called making a simulation run or simply a run CarSimEd includes the models in two forms a as stand alone EXE application files and b as DLL plug in files also called CMEX files for use with SIMULINK A wire frame animator shows the resultant vehicle motions You can view the simulated motions zoom in and out with a simulated camera and interactively move around the simulated vehicle to change your point of view The Windows Engineering Plotter WinEP creates plots of vehicle variables as functions of time or as cross plots of output variables Use this tool to view any of the hundreds of variables computed by the simulation models Pl
17. CarSim Educational User Manual VERSION 4 5 MSS Mechanical Simulation Corporation J anuary 2000 NOTICE This manual describes the CarSim Educational software 1996 2000 Mechanical Simulation Corporation All Rights Reserved Mechanical Simulation Corporation 709 W Huron Ann Arbor MI 48103 Phone 734 668 2930 FAX 734 668 2877 http www trucksim com Table of Contents lelntrod ction poneo neni Maver ahaa ave us E EE alas vend TS 9 About This Manual ceee eee e eE eee E E EE E EE ee EE EREA SEke ERES ee i 9 What GarSimEd DO Si enasini niei a EEE eE EEEE A E EA EE iis 9 CarsimEd Model Feature Sinisira eita eE E E E i E E Ea a ERE A a Ekaa 11 How Ca rSimEd Worksin ee n eae a aae aE E Ea E EEE E a a i les 13 Whiat CarSimEd Does Not DOs hentce sels teed sdadetegsole bees a ta apa aa EEE 15 Notational Conventions in This Manual eeeeeeeeeececccececececceeceeeeceeceeeeeeeeeeeeeeeeeeeeeeess 16 2 CALM Installationen iaaa EEE EAS E S 17 Comp terR qguirements issos ea aw a Sesh AT A i E ETA 17 Installation of CarSimld sneseno ikin sieben inenika eii 18 Linking to SIMULINK and MATLAB seseseseseesererererererererererererererererrrererererererererererees 18 3 Database esa ntZ AUD rsa hiindurets cites coisa aster EEEE SEENTE EEE DASO EE SETE DKE es 21 Introduction to the CarSimEd Database eseseseseererererererererererererererrrerererererrrererereeens 21 D ta SCreems isis cgbcs hs c
18. LF spring OUT 25 Fs_LR N LR spring force gen name Spring force rigibody name LR spring OUT 26 Fs_RF N RF spring force gen name Spring force rigibody name RF spring OUT 27 Fs_RR N RR spring force gen name Spring force rigibody name RR spring OUT 28 Fx_LF N LF tire longitudinal force gen name Tire longitudinal force rigibody name LF tire OUT 29 Fx_LR N LR tire longitudinal force gen name Tire longitudinal force rigibody name LR tire OUT 30 Fx_RF N RF tire longitudinal force gen name Tire longitudinal force rigibody name RF tire OUT 31 Fx_RR N RR tire longitudinal force gen name Tire longitudinal force rigibody name RR tire OUT 32 Fy_LF N LF tire lateral force gen name Tire lateral force rigibody name LF tire OUT 33 Fy_LR N LR tire lateral force gen name Tire lateral force rigibody name LR tire OUT 34 Fy_RF N RF tire lateral force gen name Tire lateral force rigibody name RF tire 330 Appendix J Model Input and Output Variables OUT 35 Fy_RR N RR tire lateral force gen name tire lateral force rigibody name RR tire OUT 36 Fz_LF N LF tire vertical load gen name name LF tire OUT 37 Fz_LR N LR tire vertical load gen name name LR tire OUT 38 Fz_RF N RF tire vertical load gen name name RF tire OUT 39 Fz_RR N RR tire vertical load g
19. Type p Options No filter High pass baselength p 5 High pass Low pass baselength p 6 C Low pass P 2 4 O Band pass Filter using original data Cancel No filter button When this button is selected the data are not modified High pass button When this button is selected the Y variables are processed with a high pass filter A high pass moving average filter works by applying a low pass smoothing filter with baselength G and then subtracting the smoothed points from the original leaving deviations from the smoothed data This removes low frequencies bias and drift It leaves the high frequencies intact Low pass button When this button is selected the Y variables are processed with a low pass filter A low pass moving average filter transforms a series of numbers by replacing each number with the average value where the average is taken over some number that corresponds to the specified baselength 6 The number of points used in the average is the baselength divided by the interval between points The averaging process smoothes the data removing high frequencies and passing low frequencies Band pass button When this button is selected the Y variables are processed with a band pass filter The data are processed by a high pass filter using the high pass baselength G and then by a low pass filter using the low pass baselength 6 High pass baselength This is a reference used to define the scope of a
20. rev s AVY_LR Spin rate of LR wheel U 12 rev s AVY_RF Spin rate of RF wheel U 13 rev s AVY_RR Spin rate of RR wheel U 14 rev s 22 Forces FSLF LF suspension spring force Acts on the entire vehicle from the If wheel through LF upper suspension attachment point Magnitude FM 1 Direction sz FSLR LR suspension spring force Acts on the entire vehicle from the Ir wheel through LR upper suspension attachment point Magnitude FM 2 Direction sz FSRF RF suspension spring force Acts on the entire vehicle from the rf wheel through RF upper suspension attachment point Magnitude FM 3 Direction sz FSRR RR suspension spring force Acts on the entire vehicle from the rr wheel through RR upper suspension attachment point Magnitude FM 4 Direction sz FAUXF Front anti sway bar force Acts on the lf wheel from the rf wheel through mass center of the If wheel Magnitude FM 5 Direction sz FAUXR Rear anti sway bar force Acts on the Ir wheel from the rr wheel through mass center of the Ir wheel Magnitude FM 6 Direction sz FDLF LF suspension damper force Acts on the entire vehicle from the 1f wheel through LF upper suspension attachment point Magnitude FM 7 Direction sz FDLR LR suspension damper force Acts on the entire vehicle from the Ir wheel through LR upper suspension attachment point Magnitude FM 8 Direction sz FDRF RF suspension damper force
21. 14 Gear ratio 16 degideg ratio Steering wheel angle mass center of road wheel angle entire vehicle Complanee 15 001 _ degin 7 550 road wheel angle c Comp ERA aeamnaae Susp La 2 2700 y ae Aligning moment ve is applied to both in millimeters road wheels with the steering wheel locked Csusp is suspension compliance Masses and Inertias Front and Rear Front G3 Rear Braking System Vehicle mass supported by both tires 1000 700 fkg Front gain ico Nema y A E 3 Rear gain S 4 N m MPa Inertia Properties Entire Vehicle Optional Radii of Gyration N Roll Inertia 1xx Pitch Inertia lyy Yaw Inertia Izz Product Ixz kg m2 Estimate Izz Rx m gain gm2 8 Jstimate t Ry 10 13 m privetine kg m2 Estimate Izz RZ m Front gain 500 Nem g M2 Estimate inertia with eq M R Rear gain oOo Nem drive torque one wheel aJa 2704 driver input Front Suspension 12 Rear Suspension 12 driver input l Front Tire Rear Tire Animator Group 18 Example Small Tire T Example Small Tire v Q3 Sa Vehicle mass supported by wheels keyword MF for front two wheels and MR for rear two wheels These are the masses that would be measured when the front and rear of the car are alternatively driven over a scale These two values added together give the total mass of the vehicle Roll Moment of Inertia of entire vehicle keyword IX
22. Any line in brackets lt gt indicates a category heading Double click on a line to remove it from the list This is the same as selecting the line and then clicking the Remove button 4 Double clicking on a line in brackets will remove the entire category Parameter Sets 1 2 and 3 These lists hold overriding data If used each line typically has a keyword followed by a value For example to set the speed to 60 km h enter the line speed 60 See Appendix F for the keywords recognized by CarSimEd models Any parameters specified in these fields will be used instead of the ones referenced in the Runs data set or in data sets linked to the Runs data set This field should be left blank if you do not want to modify the input parameters or model descriptions for the runs to be made Links 1 2 and 3 Use these links to apply data from any other CarSimEd library If the data in the library can be applied to different parts of the vehicle for example a tire description can be applied to either the front or the rear axle of the vehicle a reference to a part of the vehicle must be specified in the preceding Parameter Set 6 with an appropriate keyword e g iaxle 1 The Make Runs button Click to run all of the data sets listed in the Data Sets to Run list G Hold down the control key to interrupt the runs in progress Location in CarSimEd Accessed from the Tools menu and the ribbon bar button al 203 Chapter 9
23. Braking in a turn Vehicle lateral acceleration g s Tire vertical load N 04 000 me 6000 tA Wiccan 02 i IIA 4000 01 AX long accel of CG Braking in a turn Wy wheel speeds Braking in a turn Vehicle long acceleration g s Longitudinal velocity kph 02 ONS Vehicle CG 0 i LF wheel 4 i LR wheel 02 RF wheel RR wheel 044 Time sec Vehicle CG x 0 y 7 175e 017 step interval 0 Figure 7 1 The WinEP workspace In addition to the X Y data each plot window has a set of formatting attributes such as the colors of the lines the size of the labeling text the type of grid etc You can show the data points with connecting lines symbols or both You can use linear or log scaling and you can choose from several axis types The formatting can be set independently for each plot and changed interactively at any time You can print the WinEP plots or copy them to the clipboard There are no built in limits to the number of active plot windows that can be maintained by WinEP The only limits are imposed by computer memory Batch and Interactive Operation WinEP can be started in one of two modes When you click the Plot button from the CarSimEd Runs screen or the Make Plots button from the Plot Setup Batch screen CarSimEd starts WinEP in batch mode It sends WinEP a file with information that you specified on the Runs screen Based on the contents of this f
24. Click the Calculate button 19 Check your work by clicking the Plot button 10 148 Chapter 9 Alphabetical Library Reference a W N p Note The interpretation of symbols X Y etc changes when you go from Create mode to Transform mode In the first case there is one independent variable X defined by the values in the fields 22 23 and 24 In the second X is the name for the first number in each row Y is the name for the second Y2 for the next and so on Create an Animation Shape Data Set for the Circle The animator requires X Y Z values on each line separated by spaces no commas The values generated above for the circle are X and Y coordinates A Z coordinate must be inserted for each line Select the Transform radio button 21 Enter the following definition into field 13 x y Q Click the Calculate button 19 Click the Delete button 5 Available Functions The compute button processes standard arithmetic operations An exponential is indicated with the carrot character e g X 2 In addition the compute button can process the following functions abs lt number gt Absolute value of number acos lt number gt Arccosine number in radians asin lt number gt Arcsine number in radians atan lt number gt Arctangent number in radians atan2 lt numberl gt lt number2 gt Arctangent of lt numberI gt divided by lt number2 gt numbers in radians a
25. EB 374 par E 375 par E 376 par E 377 par E 378 par E 379 par B 380 par B 381 par E 377 par 378 par 379 par E 382 par E 383 par 380 par E 381 par 382 par B 384 par B 385 par H 48 par E 70 par a Design of CarSimEd Data Screens front suspension iaxle 1 HiS SUSP_ED HMM Front object name parsfile C CARSIMED 45 VEHICLES SUSP_ED 47 par gt Parstile path and filename C CARSIMED 45 WEHICLES CARS_ED 44 par Create LpiFile Reload File Load New File Exit a Figure 8 2 The Parstree window displayed by clicking the Parstree button File can t be found Keyword error Preferences button Click this button to bring up a floating window used to set global preferences for CarSimEd This is equivalent to the Tools menu Preferences command 4m Preferences O Auto lock every data set gt Advanced Mode allow changing links Have 256 or more colors on monitor must move to another screen to see effect Auto Lock When checked CarSimEd automatically locks every data screen when you leave it Otherwise data sets are locked only when you click the locked boxes 21 manually Advanced Mode When checked you can change links to connect with different libraries When not checked you must live with the links the way they are Have 256 or more colors on monitor Check this box if your video display supports 256 or more colors
26. Scale factors for coordinate variables for X Y and Z keywords set_scale_var_x set_scale_var_y set_scale_var_z These values are numbers used to replace the symbol SFe in Equation 1 If no number is entered a value of 1 0 is used 4 Names of Euler angle variables for roll pitch and yaw keywords set_roll_name set_pitch_name set_yaw_name These are short names in the ERD files associated with the variable A in Equation 2 If no name is listed then a constant value of 0 0 is used A value of 0 0 is also used if the name is not found in the ERD file Offsets for Euler angle variables for roll pitch and yaw keywords set_offset_var_roll set_offset_var_pitch set_offset_var_yaw 138 Chapter 9 Alphabetical Library Reference These values are numbers used to replace the symbol Ao in Equation 2 If no number is entered a value of 0 0 is used 6 Scale factors for Euler angle variables for roll pitch and yaw keywords set_scale_var_roll set_scale_var_pitch set_scale_var_yaw These values are numbers used to replace the symbol SFg in Equation 2 If no number is entered a value of 1 0 is used Rotation sequence for Euler angles keyword set_euler_angles There are 12 possible sequences of body fixed orientation angles A constraint is that there cannot be two consecutive rotations about the same axis Thus there are three choices for the first rotation two for the second and two for the third Ho
27. The animator group is one of the more difficult to understand screens in CarSimEd It may help to browse through the groups that are installed with CarSimEd to see by example how complex systems are assembled using this screen Note 135 Chapter 9 Alphabetical Library Reference User Settings Miscellaneous links Links are used to include other groups wheels shapes and reference frames A group wheel or shape appearing in one of these links is attached to the reference frame link most immediately above it If none of the links are made to a reference frame then all wheels and shapes are attached to the most recently introduced reference frame That reference frame is defined in a data set above this one 2 Miscellaneous fields Use these fields to assign values to arbitrary keywords The format is that each line has a keyword and value separated with white space at least a single space These keyword values apply to the previously read data which is found from the link immediately preceding the yellow field These fields can be used to add to shape or wheel data For example to mirror an object from the left to the right side enter the keyword set_scale_y followed by a value 1 see Figure 9 2 All Y coordinates will be negated for the current shape using data from the preceding link Note The scale factors are reset to unity and the offsets are reset to zero whenever a new shape is introduced These fie
28. The keyboard command is Ctrl G Note WinEP will ignore the Y axis log option and revert to the linear option if there are one or more zeroes or negative Y values in the data set However if you zoom in to exclude the zero and negative values the log option can be used for the data shown Re Draw Current Scale Use this command to re draw the active plot with the current formatting It is sometimes needed if the window display gets corrupted by another window being in front You can accomplish the same thing by clicking in the plot area with the mouse Re Draw Original Scale ea Use this command to re draw the active plot without any zooming The current scaling option is used as specified with the Customize Plot Format option under this menu The keyboard command is Ctrl R Customize Plot Format Use this command to display a preferences dialog box for setting most plot formatting options The keyboard command is Ctrl F This dialog box is used for four sets of data selected with tabs Customize Plot Format xi Axes xv Data Set Plot Layout Font x Axis Type Y Axis T EO ne O v gt Max and Min Values Y Max and Min Values Auto G e Auto To o Or Manual a C Manual o 96 Click this tab to toggle the axes scaling and to type in the desired range of axes values in the next plot 9 Chapter 7 The Plotter GUU X Y axis type These controls
29. Un check it if your display is limited to 16 or fewer colors Close Click here to exit the Preferences window and apply the current preference settings 114 Chapter 8 Design of CarSimEd Data Screens Check Boxes Locked box Click this box to check or un check it When checked the data set is locked and you cannot change text in any of the edit fields or any links You also cannot delete the data set using the Delete button unless you simultaneously press the shift key Notes box Click this box to check or un check it When checked the Notes field is displayed Otherwise it is hidden The contents of a Notes field are strictly for your use in documenting data They are not sent to the solver programs This button hides the Notes field but does nothing to the contents You do not lose your notes when you hide them When you create a copy of a data set using the New button 6 the contents of the Notes field are also copied even if the box is not checked Data Set Information Changed circle The small circle is normally transparent However a red dot appears when a link is changed or when a field is changed and you leave the field by clicking somewhere else using the Tab key etc The red dot indicates that the PAR file associated with the current data set will be updated when you leave the screen Click on the red circle to force CarSimEd to overwrite the PAR file immediately such as when testing new animat
30. Ynew Yo Sy y Znew Zo Sz Z where Xo Yo and Zo are offsets and sx sy and sz are scale factors specified with the keywords set_offset_x set_offset_y set_offset_z set_scale_x set_scale_y and set_scale_z The keywords for scale factors and offsets are optional For each part the scale factors default to values of 1 and the offsets default to 0 By setting a scale factor to 1 a user can easily mirror a part The offsets allow a user to change the location of a part within the reference frame without calculating new values for the coordinates The scope of a part begins when the keyword add_part is encountered and continues until another part wheel or reference frame is added Values associated with most of the keywords shown in Table E 3 are applied to the current part as defined by the previous add_part command Wheels A wheel is approximated by drawing an object consisting of two polygons whose corresponding vertices are connected by lines An optional radial line is drawn to show the wheel rotation angle There are five properties that can be set for a wheel name radius thickness line thickness color and the presence of a radial line All properties except the name have a default value and therefore the commands shown below add_wheel1 are optional It is likely that the same wheel definition will be used several times and therefore the name is not necessarily unique 279 Appendix E Animator Files a
31. _ Plot Hovery mms Plot 1 Setup Fz vertical forces xl O Show More After Starting All CarSimEd screens include a standard ribbon bar with navigation buttons The GO button displays a pull down menu when clicked 32 Chapter 4 The Basics of Using CarSimEd 1 Click the GO button in the ribbon bar GO to display a pull down menu more gt Open startup tbk tun_cmex run_cmex tbk tuns_2d runs_2d tbk runs_3d runs_3d tbk tuns_sus runs_sus tbk anim meras cameras tbk mes tbk 2 Select the desired Runs screen from the menu From the Plotter or Animator The CarSimEd plotter and animator are independent programs When you launch one of them by clicking a button on the Rums screen the Runs screen is still there However it might be covered by the windows of the other programs especially if you are not using a large computer monitor The recommended way to return to the Runs screen from the plotter or animator is to exit the program 1 To exit the plotter or animator click the box in the upper right corner of the WinEP or Animator screen Making a New Run Stand Alone Use this method to make a new run in CarSimEd using a stand alone solver program without SIMULINK Existing runs are left intact and their output can still be viewed with the plotter and animator Start from the Runs screen see Figure 4 1 on page 30 1 Using the navigation buttons 2
32. and dp relative to the axle Y axis The spin axis for a wheel is wy cos 5 ay sin d ax 1 Point Wo is located in the wheel plane and is nominally coincident with the precise definition of CTC see Figure H 1 The X Y and Z coordinates of We are zero for independent suspensions For the solid axle suspension the coordinates in the axle body are Wx 0 Lrk Wey 2 Wez Heca Here Ly is the axle track to the center plane of the wheel The algebraic signs of the TK L terms in the Y coordinate depend on the side of the axle left right ar 308 Appendix H The Tire Model Ground Geometry The coordinates of the absolute position of We in the global frame N are Xc Nx pos Wo Yo ny pos W 3 Zc Nz pos Wo For a three dimensional ground surface the ground normal r is determined as a function of the location of point W rz Xpz Ny Yaz Ny Ze N7 4 where Zorounp Xrz gt Ypz Zaz func X Yc 5 and func X Yc is a function of Xo and Ye that returns the four variables shown in braces For a flat level surface r nz Vertical Tire Deflection Vertical tire deflection is needed to calculate F A is the vertical distance between point W and the road in the plane of the wheel Ar ZGROUND Zc 6 Fx Fy and F act on the axle or wheel through a point CTC that is nominally coincident with W but which moves vertically by the displacem
33. as shown below Clee Hee AE ID 441 5 00 11 510 97 Changed O Hotes O Locked Click on the red circle in the upper right corner This causes CarSimEd to update the PARSFILE using the new data from the screen Note Normally communication between the database and the animator is transparent All necessary files are properly updated when you click the Animate button in the Runs screen Here you are bypassing the normal operation and must force the SGUI to update the PARSFILE before it would normally do so Switch back to the animator use Alt Tab Select the menu item Reload Current Files under the File menu or type Ctrl R to see the effect of the new data Optionally switch back to the SGUI screen and repeat steps 6 through 9 as needed 77 7 The Plotter You can view plots of the CarSimEd simulation results with a program called Windows Engineering Plotter WinEP WinEP is a versatile tool you can use to plot any two variables against each other You can also overlay data from the same file or different files Updates The plotting program is used in a number of software packages The latest version is generally available from the Internet at http www trucksim com winep index html Updates of the plotter program are backward compatible If you download a newer version replace the file Winep exe in the Plot folder in CarSimEd Overview of Operation WinEP has a workspace defined by a main
34. lt gt indicates a category heading Double click on a line to add to the Selected Data Files list 6 Add button Click to add highlighted lines from the Runs list 2 to the Selected Data Files list 6 Shift click to add all Remove button Click to remove highlighted data sets from the Selected Data Files list 6 Shift click to remove all Add ERD File button Calls up a dialog box for you to select ERD files that are added to the Selected Data Files list 6 The dialog box will continue to request selections until you click the Cancel button Selected Data Files list List of the selected data sets from the Runs list These are the data sets that will be plotted Any line in brackets lt gt indicates a category heading Double click on a line to remove from the list This list cannot be edited directly You use buttons G G to modify the list Plot Setup link This pull down menu has two options 1 to go to the currently selected library or 2 to pick a new library The linked library must contain plot setup information When you pick a new library the field below is updated automatically to show the names of all of its data sets Plot Setups list List of all of the plot setups in the EP setup library Any line in brackets lt gt indicates a category heading Double click on a line to add it to the Selected Plots list 11 Add button Click to add highlighted lines from the Plot Setups list to the Selected
35. negative spring rate etc b Repeat the run using a smaller time step c If the run made some progress before crashing use the animator and plotter to try to figure out what part of the model misbehaves first Plotter and Wire Frame Animator The plotter and animator viewer programs do not create data nor do they open data files with write permission Neither is likely to corrupt any of your data The worst they can do is crash The potential problems fall into two categories the file system and numerical errors File System Problems The animator reads the same PAR files as the solver programs plus it reads the ERD files created by the solver programs The plotter reads a similar file with extension PLT and also the ERD files If any of these files have been deleted or renamed either viewer will show an error message and quit Here is a quick check list 239 Chapter11 Trouble Shooting e Has the run been made If a run has not yet been made then there is no ERD file to read The viewer will show an error message naming the missing ERD file e Are the links from the Runs screen valid and all links down the tree If not either viewer will show an error message naming the missing PAR file Try to locate the problem using the Parstree program as described earlier on page 236 e Was the output simulation file specified to be plain text If so neither viewer will work right Check the Computation Parameter
36. ocked Model Parameters amp Inputs Run Control Output amp Post Processing Vehicle Classic car 4 cea ae Run Simulation Animate ES Steer Speed km h Stop sec Mu Camera Setup 11 Ramp i degisec X Qm EEO o J ozs _ mpata 6 Braking omputation Parameters 12 No Braking NN o dt 0025 10 Hz output x View Echo File All Parameters hi Input o 3 13 Plot Multiple Plots zl aperia da Plot 41 Setul Plot 2 Setup Rolvsay d Plot 3 Setup Payer ecco to Plot 4 Setup deg G understeer plot x CO Show More GO shows a pull down menu of data libraries Takes you to the library selected Figure 4 1 The Runs screen Chapter 4 The Basics of Using CarSimEd The settings in the left hand portion of the screen give you access to the inputs for the mathematical vehicle models used to simulated tests the settings and buttons in the right hand region give you access to views of the simulation outputs and the settings and button in the center are used to run the simulated test The circled numbers will be used in the following sections to describe common actions A different Runs screen is used for making runs with SIMULINK as shown in Figure 4 3 on page 35 Notes Figure 4 1 shows one possible appearance of the Runs screen It is obtained when the Overlay Runs and Show More boxes are not checked CarSimEd includes four Runs screens thr
37. offsets added to coordinates and Euler angles default 0 0 sequence of rotation by Euler angles used to define orientation of the reference frame reference lengths associated with the coordinate of points in parts associated with the reference frame actual lengths to be used by the animator to scale coordinates of points in parts within the reference frame The keyword add_reference_frame has three effects 1 It starts the scope of a new reference frame 2 It ends the scope of the previous one 275 Appendix E Animator Files and Keywords 3 It assigns a name to the new frame that can be used with the set_ camera_reference_frame and set_lookpoint_reference_frame keywords see Table E 1 Each reference frame must have a unique name Position and Orientation of the Reference Frame Overall a reference frame is defined by six variables three coordinates X Y and Z and three Euler angles The animator reads the required six variables from the output files generated by the solver programs The six keywords used to specify ERD file short names determine how the three coordinates and three Euler angles are defined White space between the keyword and the short name is ignored by the animator and then the next eight characters are taken literally including spaces However if the line ends before eight characters are read the animator pads the short name with spaces until it is eight characters long All six
38. page 66 Focal length This is the distance from the camera point to the 2D plane used to project the 3D objects See Figure 6 1 for a description of the geometry X Y and Z coordinates of the camera point in its reference frame X Y and Z coordinates of the look point in its reference frame Cancel button Click to exit the dialog box without changing the camera settings OK button Click to exit the dialog box and apply the new settings This menu is standard in Windows for providing information about a program 75 Chapter 6 The Animator About Engineering Animator Select this option to display the current animator version and creation date Pop Up Menu Click on the right mouse button to display the following menu All items on this menu are copies of items on the main menus and perform the same functions when applied from the right click pop up menu The menu is provided so you don t have to move the mouse as much to perform common actions Open Simulation File Open Parsfile Reload Current Files Save Parsfile As Image Copy Camera Coordinates Look point Coordinates Start From Beginning Continue From Current Position Stop v GrdOn Set Frame Rate Superimpose Vehicle Modify Grid Modify Camera Locations Exit Time Control Slider Under the animator window there is a time control slider that provides random access to the animation Use it to jump to any
39. through the data sets in the library and to go to other libraries and programs in CarSimEd see the buttons near 2 In addition some of the libraries have special buttons for functions such as running a simulation running an animation etc Blue links with pull down menus These buttons are always marked with a triangle e g item 4 This indicates that if you click over the button with the left mouse button then a pull down menu will appear Chapter3 Database Organization File Edit Text Page Tools Dasa Hmmwv O Changed 1 44 o O Hotes 12 05 43 C M Locked 7723 99 Steering System Gear ratio degideg ratio Steering wheel angle road wheel angle mass center of 1320 entire vehicle Compliance on degim road wheel angle _ p ooo S imensi Comp pe Csusp 3300 dimensions are mae GE aio n St 3 in millimeters amog Qe is appl road wheels with the steering wheel locked Csusp is suspension compliance Braking System Frontgain 15 N miMPa Reargain 8 N miMPa Masses and Inertias Front and Rear Front Rear Vehicle mass supported by both tires kg Inertia Properties Entire Vehicle Optional Radii of Gyration Roll Inertia Ixx 14669 ka m2 Estimateizz Rx 65 m gain eee Pitch Inertia lyy kg m2 Estimate l Ry 125 m Driveline Yaw Inertia Izz kg m2 Estimate lzz Rz 1 25 m C so AR Product xz 0 0 ko m2 Estimate inertia with e
40. www trucksim com carsimed index html What CarSimEd Does CarSimEd is a software package for simulating and analyzing the behavior of four wheeled vehicles in response to steering braking and acceleration inputs It produces the same kinds of outputs that might be measured with physical tests involving instrumented vehicles Chapter 1 Introduction CarSimEd Advantages Detailed mathematical models for simulating automotive vehicle dynamics have been in use for decades However simulation with detailed models has too often been considered to be an advanced form of analysis that is only practical for experts in simulation technology and vehicle dynamics Here are some reasons that CarSimEd makes simulation practical for students and engineers 1 It is much easier to use than older vehicle simulation programs All aspects of the software have a point and click graphical user interface 2 It requires no special hardware CarSimEd runs on ordinary Windows desktop and laptop PCs 3 Itruns fast Simulations run faster than real time on any current PC 4 It includes a database that minimizes the time needed to build a vehicle description and set up run conditions Vehicles components inputs existing runs all kinds of data are accessible with pull down menus in the database 5 CarSimEd requires no additional software It includes a graphical database solver programs plotter animator and utility programs However CarS
41. 0 12 2000 15 4000 23 6000 36 8000 52 ENDTABLE IAXLE 2 Table ID number TRAIL TABLE 0 12 2000 15 4000 23 6000 36 8000 52 ENDTABLE FINAL CONDITIONS XO 219 8114951976 Abs X trans of SO m YO 142 1095052499 Abs Y trans of SO m ZO 0 003076073890054 Abs Z trans of SO m YAW 67 51149098427 Abs Z rot of Spp deg 291 Model Files and Keywords Appendix F PITCH ROLL JNC_WLF JNC_WLR JNC_WLR JNC_WRR ROTLF ROTLR ROTRF ROTRR TANLF TANRF TANLR TANRR IVERR VXS VYS VZS AVZ AVY AVX JNCR_WLF JNCR_WLR JNCR_WLR JNCR_WRR AVY_LF AVY_LR AVY_RF AVY_RR END Model Files and Keywords 0 00224071736904 Y rot of Sp rel to Spp deg 1 963382153352 X rot of S rel to Sp deg 0 02247700439532 Trans of WLFO rel to WLFJ m 0 0242091532937 Trans of WLRO rel to WLRJ m 0 01650853050917 Trans of WRFO rel to WRFJ m 0 01828318644881 Trans of WRRO rel to WRRJ m 55688 11428731 Rotation angle of LF wheel deg 55628 85102808 Rotation angle of LR wheel deg 56038 73084637 Rotation angle of RF wheel deg 55983 15443978 Rotation angle of RR wheel deg 0 03409684625009 Slip angle tan of LF tire with time lag 0 03168883381219 Slip angle tan of RF tire with time lag 0 02750321007954 Slip angle tan of LR tire with time lag 0 02625441847659 Slip angle tan of RR tire with time lag 0 181071087701 Integral of velocity err
42. 3 and summarized in the equations below Longitudinal force is mainly determined by the brake torque and rolling radius for sub limit behavior The tire seeks a spin in which the torque balance of equation 11 is maintained The tire model mainly determines how much longitudinal slip occurs to generate the longitudinal force For the purpose of producing a longitudinal slip that is within an order of magnitude of the correct one a simple equation for longitudinal tire force is used Fxo Kfx K 16 Lateral force is determined for a the combined effect of camber and lateral slip Fyo Kfy Fz amp Kfy Y 17 where Kfy is a nonlinear table lookup that defines cornering stiffness as a function of load Aligning moment is defined as the product of lateral force and a moment arm called pneumatic trail Mzo Fyo Ltrail Fz 18 312 Appendix H The Tire Model where Ltraj is a nonlinear table lookup that defines trail as a function of load To account for friction limits the following terms are defined First lateral slip and inclination angle are combined Kin Ty tan a y 19 Fy Next longitudinal and lateral slip are combined 2 2 KT EK p AET 7 uF where u is the tire road friction coefficient A normalized force is defined to provide a shape for the transition from linear to sliding 3 F kK Plot of equation 20 A different shape function is used to define normalized aligning m
43. 44 par 3 H 70 par x hs dy File can t be found Keyword error Create LpiFile Reload File Load New File Exit Figure 9 1 View of input PAR files using Parstree followed by some pathnames This means that when any indexed parameters including values read from other libraries are read that involve the keyword IAXLE they are applied to axle 1 A few lines down from the first occurrence the IAXLE keyword is repeated with a value 2 If an indexed parameter is read again the value is applied to axle 2 Location of Library Each section ends with the location of the library explained from two points of view First is a list of the screens needed to reach the library using the user interface For example to get to the Animator Camera Setup screen start with the CarSimEd Startup screen then press the Start button to go to the Runs screen then follow a blue link to go to the Animator Camera Setup screen This sequence is written at the end of the reference section as Location in CarSimEd CarSimEd Startup Runs Animator Camera Setup 128 Chapter 9 Alphabetical Library Reference Note The names shown under Location in CarSimEd match the window titles and the subheading titles in this chapter They sometimes match captions of the blue links but not always In addition a relative pathname is given for the library TBK file e g Animate Cameras Cameras tbk These pathnames are relative to
44. Acts on the entire vehicle from the rf wheel through RF upper suspension attachment point Magnitude FM 9 Direction sz FDRR RR suspension damper force Acts on the entire vehicle from the rr wheel through RR upper suspension attachment point Magnitude FM 10 Direction sz 304 Appendix G The 3D Car Model FXLF LF longitudinal force Acts on the lf wheel from the inertial reference through CTCLF Magnitude FXLF Direction z 189 nx z 186 ny FXLR LR longitudinal force Acts on the Ir wheel from the inertial reference through CTCLR Magnitude FXLR Direction z 202 nx z 199 ny FXRF RF longitudinal force Acts on the rf wheel from the inertial reference through CTCRF Magnitude FXRF Direction z 215 nx z 212 ny FXRR RR longitudinal force Acts on the rr wheel from the inertial reference through CTCRR Magnitude FXRR Direction z 228 nx z 225 ny FYLF LF tire side force Acts on the If wheel from the inertial reference through CTCLF Magnitude FYLF Direction z 234 nx z 231 ny FYLR LR tire side force Acts on the Ir wheel from the inertial reference through CTCLR Magnitude FYLR Direction z 240 nx z 237 ny FYRF RF tire side force Acts on the rf wheel from the inertial reference through CTCRF Magnitude FYRF Direction z 246 nx z 243 ny FYRR RR tire side force Acts on the rr wheel from the inertial referen
45. Basics of Using CarSimEd J three times to select the third variable that begins with the letter J 4 Add the selected variables to the list of data to plot O by using the Add button G Note You can also add a pair of variables by double clicking on the name in either the X 6 or Y 6 lists You can also type Alt A 4 Make the plot by clicking the Plot button 4 5 To make another plot repeat steps 2 through 4 To clear the list of the data to plot use the Clear button 2 See Chapter 7 for more information on using the plotter interactively Viewing All Model Parameters and Inputs Start from a Runs screen see Figure 4 1 on page 30 The simulation run must have already been made in order to view a list of all parameters 1 Click the button View Echo File All Parameters 12 2 This loads a text file into the default text editor The text file is created when a solver program is run and lists all model parameter values definitions and units Notes CarSimEd is shipped with a free text editor called WinVI If you want to use a different text editor as your default see the section Assigning the Default Text Editor in Chapter 10 3 Return to the Runs screen in CarSimEd with the text editor still active by pressing Alt Tab Or exit the text editor to return to the Runs screen Printing a Data Set You can print any screen in CarSimEd Copies of the data screens are sometimes helpful for showing mo
46. Division at The University of Michigan Transportation Research Institute UMTRI designed the format Data processing programs for ERD files obtain most of the information needed from the file itself For example the high level of automation in the animator and plotter exists because both were designed to work with ERD files The format of an ERD file is described in Appendix C Appendix J contains a list of all of the variables in the ERD and BIN files for one of the CarSimEd models Text Output Files CarSimEd can be made to produce text only ERD files In this case the header information in the ERD file is followed immediately by the numbers written in text and there is no BIN file You can also use CarSimEd to produce simple text output files for export to spreadsheet programs and other analysis software See the section Computation Parameters in Chapter 9 for details of how to generate text output files CarSimEd always uses the DOS file extension ERD for simulation output files When you make a text output file this might be considered be misleading the file has plain text and does not follow the ERD format Log Files The input parameter files extensions PAR can reference other PAR files much like an INCLUDE directive in C or Fortran As the solver processes the parameter files it writes the names into a LOG file Most users will never have occasion to look at the LOG files They exist because they can help to debu
47. Driveline section of the Cars screen The solver programs use linear interpolation and flat line extrapolation with this table For values of time that are less than the range covered in the table the first value of throttle is used For values of time larger than the range covered the last value of throttle is used The table needs at least two lines of data or else an error message is generated Location in CarSimEd CarSimEd Startup Runs 3D Handling Input Throttle File Location Input Throttle Throttle tbk 172 Chapter 9 Alphabetical Library Reference Input Wheel Height Above Ground Use this screen to specify vertical movement of the wheel carrier spindle for a suspension suspension analysis run This screen is only used for suspension analysis runs If it is linked to a 3D handling or 2D ride run the data are ignored 4m Input Wheel Height Above Ground olx Fie Edit Text Page Tools Data set 220 mm range Changed ID 47 z O Hotes 8 43 47 cetegory Locked 7 28 88 Height of wheel center mm 300 200 100 100 200 0 A 2 3 4 5 6 T 8 3 A Time s es Foe This data set is locked Unlock data set to view the context sensitive help in this status bar Discussion The 3D suspension model is called a kinematical model because it has zero dynamical degrees of freedom It has a single input vertical position that is specified as an arbitrary
48. E T UE a E aA E aTa colitis 306 Appendix H The Tire Model csc sytecisacdinissnsvixiesasans cergyiaedunnsenedessuvedentauvardiovbneduandins 307 Tire Wheel Kinematic soe Svcd eet eels aeaa r a elves goed e e aE e a a iie aei 307 Fire Forces and Moments iore ie KENN ERE ARRE IRER ANRE RERE SA 312 Low Speed Exceptions sesiis i e i ie e ae EE i e e a EdE ia VE est 314 Sequence Of CaleulatiohSnri neer eee Aa ae i eee ee 316 Sign CONVENTIONS yes cock heviveccasebecedscssvecchensoensdersvecehus oobdussovedehoneteuduerbuedsnssieeednasb ereheds 316 References si tossiuticesstisecaensdebicestiepdectsustcoteareyeotnaterteoetapeehed aaar aa aa ane ai abata 317 Appendix I The CarSimEd Steer Controller cee cssssssssssssseesssscesessesessssssvsesessoes 318 Optimal Control THEOTY scere ea 4 rand egesie e an epea i aere aee S enea aeeoa Garth 318 Application to Vehicle Controls og sasnoed ira a E ET E E ew L 320 EEA A E AE A E E E E E E E E 325 Appendix J Model Input and Output Variables e sseeseeeeeeseeeeseeseerereresrsseeresess 326 Types of Output Variables serne ieii eiiie tida eede aeieea aeai e tiaa aeiaai 326 Inputs and Output VariableSs enp rera a aaria Wee ea ed Regt eects 328 Creating Lists Of Outputs wists coctsssicothoiicecsld tethstedvntocnta sr os ae oaa bees aaa a iaae aei lee 335 vii viii 1 Introduction This chapter begins an overview of the rest of this manual It then continues with a summary
49. EXE to PIF in order to see the PIFs See the Chapter 4 section Changing A SIMULINK Model for instructions on using this menu Location in CarSimEd The Runs SIMULINK CMEX Version screen can always be accessed from the GO menu and the CarSimEd Startup screen CarSimEd Startup Runs_cmx The Tools menu and the button in the ribbon bar will take you to one of the Runs libraries in CarSimEd As installed these are shortcuts for getting to the stand alone Runs screen If you primarily use the SIMULINK model rather than the stand alone solvers you can change these shortcuts by Control clicking the S button in the ribbon bar This brings up the file browser dialog box which you can use to identify the file Runs_cmx Runs_cmx tbk as the default Runs library File Location Runs_cmx Runs_cmx tbk Runs Suspension Analyses The Runs screen is central to the user interface in CarSimEd It is used to set up simulation runs and to view results with post processing programs 199 Chapter 9 Alphabetical Library Reference 4m Runs Suspension Analysis Iof x File Edit Text Page Tools bata set Suspension New petete cor sack 2 cranes 10 es O Hotes 4 33 18 Categor Z Locked 01 13 00 Model Parameters amp Inputs Run Control Output amp Post Processing Suspension 5 link Example Geometry x Run Simulation ____ Animate Input spindleZ Stop sec Camera Set
50. Explorer to find the files with the ID numbers as a name with extensions LPO and LPF e g 430 LP0 430 LPF Either one contains all keywords recognized by the solver program Indexed Keywords Many of the parameters in the CarSimEd models are applied in several places on the vehicle For example each tire has a similar set of parameters The same data screen is used to describe a tire whether it is on a left front or right rear wheel The location of the wheel is specified with the additional keywords IAXLE and ISIDE Parameter values such as an axle mass are written in the PARSFILE with numerical indices e g MUS 1 indicates the unsprung mass of axle 1 Tabular data are written with keywords in front of the table to indicate which axle side etc are associated with the table 287 Appendix F Model Files and Keywords Keywords and Parameters for the 3D Car Model CarSimEd has two separate programs for solving the equations of motion of the 3D car model one is a stand alone program the file extension is EXE and the other is a dynamic link library the file extension is DLL for use with MATLAB SIMULINK Both have the same equations of motion and use the same keywords to identify parameters and tables PARSFILE CarSimEd 3D vehicle Generated by AutoSim 2 81 PPC Dev on January 20 2000 Copyright 1996 2000 Mechanical Simulation Corporation All rights reserved TITLE Step steer car
51. Formatted floating point text The format must be specified using the FORMAT keyword For KEYNUME 0 1 and 5 the data are stored with all channels for the first sample together then all channels for the second sample etc For KEYNUM 10 11 and 15 the data are stored with all samples for the first channel together then all samples for the second channel etc STEP real sample interval e g time step KEYOPT integer auxiliary number used by some programs Optional records Each record begins with an 8 character keyword followed by information associated with that keyword Table C 2 lists keywords that have been used to date END indicates the end of the header 259 Appendix C ERD File Format Listing C 1 Short Header for an ERD File with Binary Data a RDFILEV2 00 929 Ly A2327 dy 1 00000 iz ITLE 1993 RPUG Study Dipstick Section 1 Measurement 1 HORTNAMLElev RElev NITSNAMft fE ABEL Distance UNITS ft D a Axx GnNHN Z Listing C 2 shows a longer header for a file with its data in text form Note that the data begin immediately after the END line of the header Listing C 2 Typical Header for an ERD File with Text Data ERDFILEV2 00 pe D29 Ly 1423240 Le e LELT k ITLE 1993 RPUG Study Dipstick Section 1 Measurement 1 HORTNAMLElev RElev ONGNAMELeft Elevation Right Elevation ITSNAMfFt ft ENNAME Profile Elevation Prof
52. J shows a list of variables contained in a typical CarSimEd ERD file Other information such as program settings definitions of parts shape information etc is described with keyword based text files typically with the extension PAR These files called PARSFILEs have the same general design as the input files read by the solver programs A single top level PARSFILE contains the names of other PARSFILEs with camera information vehicle information reference frames etc Chapter 6 The Animator PAR files ERD file Animator set up and shape Motion information from information from data base a simulation program Animator Figure 6 2 Animator input files Appendix E describes the keywords used in the animator PARSFILEs The keywords are also mentioned in the documentation for the animator library screens contained in Chapter 9 Units The animator requires all angles to be in degrees and all coordinates to be in the same units of length CarSimEd uses meters for animation length units The animator allows user defined scale factors for all coordinates variables and groups of shapes in a reference frame This means that a mixture of units can be accommodated For example if some coordinates have units of meters and others millimeters the values in millimeters can be associated with a scale factor of 0 001 to convert them to meters See the sections Animator Reference Frames and Animator Shapes in Chapter 9 for details on how to
53. Save Data button described in the next paragraph Show Channel List Select this item to view all variable names from the current ERD file Unlike the short names shown in the Channel Select dialog box see Figure 7 6 these names are longer and include the units Text shown in the window can be copied to the clipboard and the entire contents can be saved to a file by using the Save button The same function can be performed using the File menu command to Save Channel List Show Channel List x Channel List Time Time sec AAy_LF LF wheel angular acceleration rev s2 AAy LR LR wheel angular acceleration rev s2 AAy_ RF RF wheel angular acceleration rev s2 AAy RR RR wheel angular acceleration rev s2 Alpha_LF wheel slip angle without lag deg Alpha_LR LR wheel slip angle without lag deg Alpha_RF RF wheel slip angle without lag deg Alpha_RR RR wheel slip angle without lag deg AYVx Body roll rate deg s AVy Body pitch rate deg s AVy_LF LF wheel angular velocity Wows eo oO rev s rev s rev s AVy_RF RF wheel angular velocity AVy_LR LR wheel angular velocity rev s AVy_RR RR wheel angular velocity AVz Vehicle yaw rate deg s Vehicle longitudinal accel g s Vehicle lateral accel g s Vehicle vertical accel g s Beta Vehicle slip angle deg Betadero Aerodynamic slip angle deg Fd_LF LF damping force N Fd_LR
54. Supplement to Vehicle System Dynamics vol 22 1993 pp 254 262 4m Suspensions 5 Link Independent Iof x File Edit Text Page Tools Dataset Example Geometry Ib Hew Delete Gow Back Ona ID 38 O Hotes 4 29 47 The 5 link suspension can be configured to represent a short long arm SLA design set the coordinates for points X1 and X2 to be equal and also points X4 and X5 Use link 3 as the tie rod Geometry shown is for a wheel on left side of vehicle P1 Bs AnimatorGroup 5 Link Suspension o Wheel Spin Axis Orientatiop Bs is a point on the wheel spin axis Global Coordinates of Points Fixed in Body GO shows 4 pull down menu of data libraries Takes you to the library selected User Settings Link to an animator group data set The animator group should be set to provide a wire frame matched to the suspension parts 2 Y coordinate of point B the wheel center keyword BY The X coordinate is defined as zero and the Z coordinate is a variable that is varied during a run The Y value changes during a run the specified coordinate applies when the points X1 to X5 are at their specified locations 5 G Wheel spin orientation keywords BSY BSZ The orientation of the spin axis is defined by a second point BS lying outboard of point B The Y and Z coordinates of this point determine how the spin axis is oriented when the points X1 t
55. The three keywords shown in Table E 6 can appear anywhere in the input PAR files The Itarg_table input is not used in CarSimEd it is present in the commercial CarSim and TruckSim packages that use the same animator program 282 Appendix F Model Files and Keywords This appendix describes the input and output files associated with the solver programs in CarSimEd It also lists an example echo file with the keywords recognized by the CarSimEd solver programs File Types Every time a new run is made from the Runs screen the seven files listed in Table F 1 are created Table F 1 Standard files created when a simulation is run Creator SGUI Batch control file SGUI List of parameters read as input by program lt id gt LPO Runs Program List of parameters written as output by program Also contains initial conditions Can be used to repeat a run lt id gt LPF Runs Program List of parameters and final conditions written as output by program Can be used to continue a run Program Header for ERD file needed by plotter and animator programs binary form BIN lt id gt LOG Runs Program List of all PARSFILEs that were processed to make a run One file always has the same name Simfile The other six all have the same base name the current ID number displayed in the upper corner of the Runs screen Simfile Simfile is a batch control file When a solver program sta
56. When checked it displays three plot setup links in addition to the first one 14 2 When checked it allows you to create up to four plots with a single click of the Plot button AD 192 Chapter 9 Alphabetical Library Reference If the box is not checked the additional plot links are not cleared They are just hidden and are not used Overlay Runs check box This check box has two effects 1 2 When checked it displays two links for other runs or ERD files When checked it allows data from up to three files to be overlaid One file is the output associated with the current Runs data set The other two are specified with the additional two links If the box is not checked the additional links are not cleared they are just hidden Plot Setup link The linked data controls what information will be extracted from the output file and how that information will be displayed Up to four plot setup links can be set to create four independent plots at a time Only the first link is displayed if the Multiple Plots box 12 is not checked 15 Show More check box This check box has a single effect it shows more control objects as shown in Figure 9 10 4m Runs 3D Handling ofl x File Edit Text Page Tools O Hotes 2 05 12 Cetegory CLocked 1227 88 Model Parameters amp Inputs Run Control Output amp Post Processing Vehicle Classic car Hw G 3 Run Simulation Ani
57. When you quit WinEP the settings from this dialog box are automatically saved to a file named Epprefs txt which stores these settings Preferences Eg m General Program start with toolbar I G Startup window mode Tie Vert Y 2 4 Cancel m Directories Formats fe wehsim 1 plot format 5 Temp Jc vehsim 1 plot tmp 6 Data Jc vehsim 1 plot 7 Batch c vehsim 1 plot tmp 8 Image c vehsim 1Splot The numbered items in the dialog box are described below Toolbar display mode When checked the toolbar is displayed when the program starts Otherwise the toolbar is hidden and you must select the Toolbar item on the View menu to show it Q Startup window mode You use this menu to specify the initial appearance of the plot windows when WinEP is started in batch mode For the Cascade setting the individual plot windows are smaller than the WinEP workspace and overlap each other For the Maximize setting the active plot window is maximized to fill the WinEP workspace Chapter 7 The Plotter ao wW WU hiding any other plot windows For the Tile settings multiple plots are tiled to fill the WinEP workspace OK button Click to close the dialog box and apply the new preferences Cancel button Click to close the dialog box without changing anything keep the previous preferences Folder from where the last format file was read The next time the File menu comma
58. Y data set in a text file It is a handy way to extract data from an ERD file two channels at a time A similar option show numbers is available under the View menu for viewing the data Save Channel List This command creates a text file listing all of the channels in an opened ERD file WinEP brings up a dialog box for saving a text file with the list of channels A similar option Show Numbers is available under the View menu for viewing the data Save Transform Settings Use this command to save the current data transforms and offset settings The default extension is PAR the default file is PLotTran par The settings can be applied in the future using the File menu command to Load Transform Settings When loaded the formatting file will cause WinEP to redraw the current plot with the new settings Save All Images Use this command to save all the plots as image files with BMP format The folder used for saving images can be set using the Edit menu command Preferences The keyboard command is Ctrl I 87 Chapter 7 The Plotter Print 8 Use this command to make a hard copy of the active plot using the current Windows printer The keyboard command is Ctrl P Print Preview Eal This command opens a window showing how the active plot would be printed using the current print settings Print Setup This command brings up the Windows dialog box for changing printer information Exit El Use this comm
59. Yy axis is lateral The directions should coincide with the earth fixed axis system when the vehicle is upright and aligned with the Xy axis parallel to the Xg axis See Figure B 2 SAE ISO Vehicle plane of symmetry the lateral center plane of the vehicle The Yy direction is normal to this plane Vehicle reference frame reference frame associated with the vehicle body It is typically defined to coincide with the undeformed body of the vehicle body structure 249 Appendix B Vehicle Dynamics Terminology Wheel axis system Xw Yw Zw right handed orthogonal axis system whose Yw axis is parallel with the spin axis of the wheel and whose Xw axis is perpendicular to ZG See Figure B 3 Mathematical Definitions All of the coordinate systems and axes are built from four reference directions 1 vertical as defined by the direction of the gravity vector Zp 2 the X axis of the vehicle reference frame Xy 3 the Y spin axis of a wheel of interest Yw and 4 the direction normal to the ground at the center of tire contact ZG Table B 1 defines the intermediate wheel and ground axis systems in terms of Xp YE and Zp Xv Yvy and Zy Yw and Zg Two equivalent definitions are provided for the X and Y directions intermediate axis system Table B 1 Axis system definitions Earth XE YE ZE Vehicle Xv Yy Zy Intermediate X Y Z Z ZE Wheel Xw Yw Zw Ground XG YG ZG XG Xw
60. a dialog box for you to enter a new category name and then modifies the category field for the selected data sets The result is the same as if you went to each data set and changed the category field Note Categories are solely for grouping the data sets in the library and have no effect on the data set name or parameter values This change has no effect on parameter values It only affects how the data sets are grouped in pull down menus Delete button This button will remove all data sets currently selected in 7 This is the same as going to each data set and clicking the Delete button for that screen A warning message appears giving you a chance to back out Be aware that there is no un do option once the data sets are deleted they are gone List of data sets from the linked library The buttons G through 6 affect the data sets that are highlighted Select data sets by clicking on them Use shift click to select a continuous range and use control click to select lines that are not consecutive 175 Chapter 9 Alphabetical Library Reference Location in CarSimEd Accessed from the Tools menu or the ribbon bar with the button isa File Location This editor is not contained in a conventional CarSimEd library file It is stored with SGUI code in Sgui_lib Bootfile tbk Plot Format The format screen determines the style and layout properties of a plot These formats cover line style axis and grid options and fon
61. a different Windows editor if you prefer To assign a new editor start with any data screen in CarSimEd 234 Chapter 10 Advanced Topics 1 Control click on the text icon in the ribbon bar 4m Plot Setup Single OF x File Edit Text Page Tools bata set Yaw rate fal new neiete cov sock Category Vehicle motion Vehicle motion ss motion i j Changed ID 724 Sela e 4lals lot eked 7808 far nanan Control Clickhere T7 7o here This should bring up the following dialog box A a text editor Please locate a text editor File Name Directories is exe Eyes Network parstree exe E carsim 451 a exe winvi32 exe programs List Files of Type Drives exe Ez c pe disk 2 Link to a text editor using the above dialog box 3 Click the OK button after you have selected the desired text editor 235 11 Trouble Shooting This chapter lists some problems that can occur with CarSimEd along with suggested solutions CarSimEd is an integrated collection of programs solver programs the database the animator the plotter and a few utility programs The potential warnings error messages and crashes are organized by the type of program in CarSimEd All parts of the software are susceptible to problems related to filenames and therefore this topic is addressed first File System Errors Information is passed between the various parts of the Car
62. about how you can subtract constant values from each data set to apply offsets Create a new data set with the desired offset values 226 Chapter 10 Advanced Topics 4 Go back to the Plot Setup Single screen and go to the plot setup for the plot in which you want to apply the offsets Set the Data Transforms link 12 to the newly created screen Go to the Runs screen and make plots using this modified Plot Setup data set Re Scaling Tabular Data You may have occasion to import measured tabular data into CarSimEd If the units used for the data do not match the requirements for the CarSimEd data screen you can use a built in calculator tool to convert the units You might also want to take an existing table of number and re scale it For example to make a tire 20 stiffer This process is as follows Copy the tabular data to the clipboard From any CarSimEd data screen click the calculator tool button in the ribbon bar or select the Calculator command from the Tools menu olx ools Md j I gt Hew Deiete Go Back Changed ID 724 O Hotes 12 46 23 Erec jess heraa ama Click here Paste the tabular data into the tabular data field of the calculator data screen Select the Transform button 6 to configure the calculator for transforming an existing series of numbers as opposed to creating a new series of numbers Type definitions for the transformed X and Y valu
63. be unlocked using the same method except that you click the button Unlock Data Sets Selected library runsiruns tbk gt Lock Data Sets Unlock Data Sets Change Category Delete Braking a Base Car Brk split mu Base car DLC lt Ramp steer Base car RS Step steer Base car SS Figure 4 6 Library Editor Automatically Locking All Data Sets As You Create Them 1 From any CarSimEd data screen click the g button in the ribbon bar or select the Tools menu Preferences command This brings up a dialog box with a few check boxes as shown in Figure 4 7 46 Chapter 4 The Basics of Using CarSimEd am Preferences o4 Auto lock every data set Advanced Mode allow changing links EJ Have 256 or more colors on monitor must move to another screen to see effect Figure 4 7 Preferences window 2 Check the box Auto lock every data set 1 3 Close the dialog box by clicking the x 2 in the upper right corner Notes When the Auto Lock feature is enabled every data set that you view will be locked automatically when you leave it This option does not change the status of any existing data sets They will be locked after you visit them This feature can be disabled at any time by returning to the preferences screen and un checking this box Automatically Locking All Data Sets in CarSimEd You can extend the above method to cause CarSimEd to lock all data sets 1 Follo
64. chapter describes how you define them All of the numbers shown on this screen can be modified interactively when the animator is running See Chapter 6 for details a Animator Camera Setup of x File Edit Text Page Tools bata set Top view i new neiete cov sack 2 changes 0 244 T CO Hotes 6 24 42 cts iii E oeea 112308 About the Reference Frames Origin of global reference frame i The coordinates for the camera and look point are relative to the origins of reference frames The camera point must be located in its own reference frame and the look point must be located in an existing frame typically 2D image the camera frame or a vehicle part beal arget Frame Rate Origin of moving A 6 10 pictures sec reference frame a The actual frame rate depends on the time A C A step in the ERD file and the CPU speed Pa A ae 7 JO Check CPU clock Max speed _ Camera point Viewing p Focal engin EC Mal Eae Camera Look Point Grid Settings 10 X coordinate ___ 100 _ X coordinate _ 1 Color light gray 74 Y coordinate o 2 Y coordinate EO x y Z coordinate 500 Z coordinate oOo terval oo Camera Reference Frame Existing Reference Frame Minimum Ooa OnT Camera tracking X Y N w Camera tracking X Y 5 v Maximum EON User Settings Focal length of the simulated camera keyword set_focal_length A large value produces a telephoto lens effect
65. comes with about 30 installed plot templates You can modify any of these plus you can define new ones Once a template is defined it can be selected from the Runs screen and applied routinely to all runs to generate plots User Settings and Controls The Data to Plot list keyword plotchannel1s This is the list of variables that will be plotted when a Plot is made Each line contains the Y axis variable the X axis variable and an optional label for the data set When the optional label is not specified the plotter labels the data set based on standard keywords obtained from the header portion of the ERD file The contents of this field can be edited manually just like any other yellow field However names can also be inserted with mouse clicks C by scanning an ERD file button Click to add the selected channels in the X and Y axis lists 4 and to the Data to Plot list 1 Check box to show long names and units When checked CarSimEd will generate long names for display in the wide field below 4 On slow computers this adds a little time to the process of scanning the file If the ERD file contains several hundred variables memory limits can prevent the long names from being generated Y Axis list of variables This shows all the variables in the selected run or data file 7 Double click on a line to add it and the associated line highlighted in the X Axis list to the Data to Plot list 1 X Axis list of
66. coordinate system to absolute coordinates in the global coordinate system This conversion is defined by the global position of the origin of the moving coordinate system its global X Y and Z coordinates along with the orientations of its three axes Note Appendix B includes a formal discussion of reference frames and coordinate systems in the context of defining output variables related to vehicle dynamics The orientation of a reference frame is defined by three consecutive rotations that are called Euler angles For vehicles the angles are commonly called yaw rotation about the Z axis pitch rotation about the new Y axis and roll rotation about the new new X axis 137 Chapter 9 Alphabetical Library Reference Starting such that the X Y and Z axes of the moving frame are parallel with those of the global frame the moving frame can be oriented by consecutive rotations about its axes For example first rotate the frame about its Z axis by a yaw angle After this is done the new Z direction is the same as the old but the X and Y axes are pointed in new directions called X and Y Next rotate about the new Y axis Y by a pitch angle After the pitch rotation the Y axis is still in the Y direction but the X and Z axes are pointed in new directions called X and Z Finally rotate a third time about the most recent X axis X by the roll angle Although it might not be obvious at first if you are
67. data ee using the first number on each line for an X value and the second number for a Y value The axes are scaled automatically to include the full range of numbers in the table Except when the data set is locked when the mouse pointer is positioned over the plot the corresponding X and Y values are shown in the status bar Clicking the left mouse button causes the currently displayed X and Y values to be appended to the table This feature can be used to rapidly build a new data set The new data points are not plotted until the Update Plot button G is clicked 117 Chapter amp Design of CarSimEd Data Screens 4m Input Road Profile of x File Edit Text Page Tools Data set Big bump v j I gt Hew Delete co Back O Changed ID 60 O Hotes 4 30 46 Road elevation m Update Plot Tidy Table A Road Profile m m 09 08 OF 06 05 04 03 02 01 0 0 5 10 15 Longitudinal distance m Animator Reference Frame Animator Data shapes Fixed Road Big Bump x Figure 8 3 Example screen for tabular data Table field Each line in this field should have an X value followed by a Y value The numbers must be separated by a comma Additional information can be added after a second comma These numbers are passed to the solver programs exactly as they appear in the field Note The table field requires at least two lines of data in order to create a
68. dealing with the details of how these programs work However it can sometimes be useful to understand how they read and write files Overview of Program Operation Stand Alone The solver programs are so called console applications Each behaves as a terminal console with no user interface other than the display of text and the acceptance of keyboard entries They have the same appearance as a plain DOS text program although they are technically 32 bit Windows programs see Figure 5 1 lolx CarSimEd 3D vehicle Generated by AutoSim 2 8 on July 23 1999 Portions Copyright 1996 1998 Mechanical Simulation Corporation Portions Copyright 1993 1996 The Regents of The University of Michigan All rights reserved Simfile found batch operation Input file with parameter values C ACARS IMED 45 RUNS_3D 629 PAR Echo file with initial conditions C CARS IMED 45 RUNS_3D 629 LPO Echo file with final conditions C CARSIMED 45 RUNS_3D 629 LPF Output file with time history data C CARSIMED 45 RUNS_3D 629 ERD Output file with log of nested inputs C CARSIMED 45 RUNS 3D 629 L06 Figure 5 1 Screen display when solver program is running When the program starts it creates a window in which text is displayed The name of the program file is typically shown as the window title The solver programs can be run interactively or in batch mode The mode is determined by the existence of a batch control file with the na
69. easy CarSimEd does have a means to protect your data from inadvertent changes Protecting a Single Data Set 1 Check the Locked box in the upper right corner of a data screen Back Changed ID 450 O Hotes 11 47 06 Locked 213 97 Click here Notes When the locked box is checked try modifying a blue link or a yellow field You will find that all pull down menus next to blue links allow only the navigation option to go to the currently selected data set You will also find that clicking on a yellow field brings up a message telling you that the data set is locked At any time you can unlock the data set by clicking the box again to un check it The locked box protects only the data shown on the screen Data sets in linked libraries are not affected For example you might lock a Runs data set However you could still go to the vehicle data linked to the run and change the vehicle data set if it is not locked 45 Chapter 4 The Basics of Using CarSimEd Locking Multiple Data Sets All At Once 1 From any data screen in the library of interest click the IEF button in the ribbon bar or select the Library Editor command from the Tools menu This brings up the floating palette shown in Figure 4 6 2 Select the data sets to be locked from the list in the dialog box 3 Click the Lock Data Sets button 4 Click the upper left corner of the floating palette window to close it Note Multiple data sets can
70. fields WARNING While you are using this option it is possible to trick the underlying ToolBook runtime system leading to errors that will corrupt your files Use this option with caution Text Menu The Text menu contains commands involving the display of text in edit fields and notes Although text formatting has no effect on how the simulations are run you can control the appearance of the text in notes and data fields if you wish Character Ctrl D Paragraph Ctrl M Regular Ctrl Space v Bold Ctrl B Italic Ctrl l Underline Ctrl U Strikeout Ctrl k Superscript S ubscript la v Normal Script Subscript Ctrl L Superscript Ctrl Shift L Note The items in the Text menu apply only to the currently selected text in a single field Character Select this menu item to bring up a floating window to change the character properties of the selected text Font Font Style Size etc The keyboard command is Ctrl D Paragraph Select this menu item to bring up a floating window to change the spacing e g Alignment Indentation Spacing etc of the selected text The keyboard command is Ctrl M 123 Chapter amp Design of CarSimEd Data Screens Regular Select this menu item to remove any special character properties of the selected text such as bold underline etc The keyboard command is Ctrl Space Bold Select this menu item to toggle the selected text between bold and not bold The keyboard com
71. file with a 1 line header and numbers separated by commas The animator does not work with TEXT files This should be be used for simple export to analysis software spreadsheets math packages etc The file still has the extension ERD but it is not inthe ERD format ERDTEXT ERD text file which is readable by external programs and also contains the header information needed by the animator and plotter Discussion The solver programs operate by numerically integrating a set of nonlinear differential equations over time Taking relatively small time steps they approximate the integration using a numerical integration algorithm This data screen contains parameters that have little to do with the vehicle model or its inputs Rather they are related to the form of the output file used to store the computed results User Settings O Integration time step keyword STEP The CarSimEd solver programs generate output files by solving equations of motion in a mathematical model of the vehicle They repeat the calculations at small intervals of simulated time where the interval is called a time 155 Chapter 9 Alphabetical Library Reference step The time needed to run a simulation is inversely related to the time step If you increase the time step by a factor of two the program runs about twice as fast because it only makes half as many calculations However the calculation method is valid only for tim
72. find an existing data set that is close to what you want The main thing to look for is whether there is a steering input steer vs time or a path input e g follow a circle because the two are mutually exclusive 2 Click the New button G in the ribbon bar 3 Inspect and edit the simulation inputs a Select the vehicle of interest from the linked vehicle library D b Select a steering or path input from the linked library 5 c Select a braking and or throttle input from the linked library d Specify the speed using the yellow field 8 Chapter 4 The Basics of Using CarSimEd e Specify the simulation stop time 4 Click the Run Simulation button 7 A console application window DOS style appears while the simulation runs A bar graph at the bottom of the window indicates the progress When the simulation finishes the DOS window disappears and you are returned to the Runs screen lt 3D_CAR Pala FS an oee sf al CarSimEd 3D vehicle Generated by fAutoSim 2 81 CPPC Dev on January 20 2000 Copyright 1996 2000 Mechanical Simulation Corporation All rights reserved Simfile found batch operation Input file with parameter values C CARSIMED 45 RUNS_3D 627 PAR Echo file with initial conditions C CARS IMED 45 RUNS_3D 627 LP0 Echo file with final conditions C CARSIMED 45 RUNS_3D0 627 LPF Output file with time history data C CARSIMED 45 RUNS_3D 627 ERD Output file with log of nested
73. for calculating the position and velocity of CTC are well defined but complex In nearly all vehicle dynamics models that have been developed by hand without multibody programs approximations to CTC for a flat surface have been used The exact expressions can be obtained easily with the aid of a multibody program However the complexity of the exact equations requires many mathematical operations per time step during numerical integration Most of the complexity arises from terms that are negligible When the ground surface is permitted to take on an arbitrary shape calculating the location of CTC becomes even more complex This is because r is a function of the global location of CTC but at the same time r determines the instantaneous tire deflection which in turn affects the location of CTC The general solution of the location of CTC on an arbitrarily shaped surface requires an iterative solution at each time step To obtain shorter run times and avoid the complexities associated with the precise definition of CTC CarSimEd uses a point W fixed in the wheel or axle body depending on whether the wheel is in an independent or solid axle suspension Point We is used to determine the slip angle but point CTC is used as the point of application for the resulting tire forces Wheel Plane Each tire has an associated wheel plane that is perpendicular to the wheel spin axis wy For the front axle the wheels are steered with angles 5
74. for extrapolation by assuming their gradient for values outside the defined range G Update Plot button Click this button to create a new plot of the data in the field 2 4 Tidy Table button Click this button to clean up the appearance of the numbers in the table field A space is inserted after the comma and additional information after a second comma is removed This operation is useful when tabular data are pasted into the edit field from some other source such as an echo file created by a CarSimEd solver program File Menu The File menu contains commands pertaining to library TBK files In CarSimEd this menu is not used as much as in most Windows programs because the opening and saving of files is handled automatically File Open Ctrl O Save Ctri S Print Setup Print Data Set Print Library Compact Library Backup Library Import Data from Other Library Exit Ctrl Q Open Select this menu item to open an arbitrary TBK library file The keyboard command is Ctrl O Save Select this menu item to immediately save the current TBK file to disk The files are automatically saved whenever you move from one library to another so this command is used mainly when the machine stability is in doubt and you fear a program crash The keyboard command is Ctrl S 119 Chapter 8 Design of CarSimEd Data Screens Print Setup Select this menu item to select a Windows printer and opti
75. further down in the menu The currently affected point is checked in the menu and is written in the animator status bar at the bottom of the animator window The camera and look points are shown in Figure 6 1 on page 64 The camera point defines where the camera is located and the look point defines the direction in which the camera is looking For example consider changing the Z coordinate height of either point Increasing the Z coordinate of the camera has the effect of raising the camera as if you are viewing the vehicle from a helicopter that rises On the other hand increasing the Z coordinate of the look point has the effect looking up When you look up everything in view shifts down X Coordinate Plus Select this command to increase the X coordinate of the camera or look point The keyboard command is the x key Chapter 6 The Animator X Coordinate Minus Select this command to decrease the X coordinate of the camera or look point The keyboard command is Shift X Note The keyboard commands are assigned so plain key commands increase things and using the shift key decreases things For example s steps forward Shift S steps backward x increases an X coordinate Shift X decreases it Y Coordinate Plus Select this command to increase the Y coordinate of the camera or look point The keyboard command is the y key Y Coordinate Minus Select this command to decrease the Y coordinate of the camera o
76. in Table J 1 the coordinate variables begin with the letters X Y and Z The rotation variables begin with the names Yaw Pitch Roll and Rot Pitch and Rot both involve the same conceptual rotation about a Y axis however the Rot variables apply to the rolling wheels and have units of revolution rather than degrees 327 Appendix J Model Input and Output Variables Inputs All vehicle controls that involve the driver are available for plotting the steering wheel angle Steer_SW the throttle Throttle and the brake input Pbrk_con Inputs and Output Variables The output variables written into the ERD file are also defined as outputs of the CarSimEd S Function for use in SIMULINK In order to view the variables from within SIMULINK it is necessary to know the index number This information is summarized in a README text file in each folder in the CarSimEd Matlab folder Along with the block of output variables the SIMULINK versions of the CarSimEd model include a block of input variables These are also listed in the README file The following two subsections list the inputs and outputs for the 3D car model The text is taken straight from the file Mat lab cmx_md1l Readme txt 7 Input Variables INPT 1 INPT_STEER deg External steering wheel input INPT 2 INPT_RSTEER deg External rear wheel steer angle input INPT 3 INPT_TBRK_LF N m External brake torque input LF wheel INPT 4 INPT_TBRK_RF N m E
77. includes references to other PAR files In fact every blue link on the screen is represented in the PAR file with the keyword PARSFILE followed by a full pathname to another PAR text file If any of those pathnames are not valid the animator will generate an error message and quit without showing an animation Bad pathnames can be quickly located by using the PARSTREE program in CarSimEd To run it just click on the button with the tree icon E Alternatively go to the Tools menu and select the item View Parstree The PARSTREE program brings up a window with two panes similar in format to the Windows Explorer For the example shown in Figure 6 4 the file 211 par is marked to indicate an invalid reference The panel on the right displays the contents of the selected PAR file 212 par From reading the PAR file that references the nonexistent file it is seen to be in the animator FRAMES folder Inspection of the FRAMES library should reveal that one of the data sets is nonexistent causing the bad link Chapter 6 The Animator ra ParsTree isl E3 Parstile tree Structure Contents of the selected file PARSFILE set_camera_reference_frame Camera tracking x y Yaw parstile D CARSIMEDSANIMATESFRAMES4211 par set_lookpoint_reference_frame Camera tracking x y Yaw set_lookpoint_z 0 set_focal_lenath 1 add_arid set_interval_x 10 set_interval_y 5 set_color dark gray
78. intended to convey some of the ideas and concepts used in earlier vehicle models for applications using modern multibody programs The model that will be described was implemented using the AutoSim multibody code generator 8 9 AutoSim generates equations symbolically performs coding optimizations and generates a custom simulation program The simulation program obtained by AutoSim has run time performance comparable with and usually better than that of a hand coded program based on the same model Overview of Factors Affecting Vehicle Behavior Figure G 1 shows a free body diagram of a four wheeled vehicle as viewed from the top There are just three governing equations the sum of the tire shear forces must equal the vehicle mass times its acceleration in both the vehicle X and Y directions and the moment of those forces about the vehicle mass center must be equal to the product of the yaw acceleration and the vehicle yaw moment of inertia Thus the main objective of the vehicle model is to accurately predict tire shear forces xe Dfj x e M dV y Lfizy Ma d d dt z Lriyfi ze lO dt center Figure G 1 Primary factors influencing vehicle system motions A vehicle is also subject to aligning moments in the tire contact patches The aligning moment has a negligible direct effect on the vehicle yaw but due to steering compliance 297 Appendix G The 3D Car Model it can have a sig
79. is the distance from the front axle to the mass center b is the 323 Appendix I The CarSimEd Steer Controller distance from the rear axle to the mass center Vx is the forward component of vehicle speed and Izz is the polar moment of inertia of the vehicle in yaw The control u is the steer angle of the front wheels Terms can be added for 4 wheel steer The output variable of interest is the lateral position of the front axle Thus the C matrix is defined as C l a 0 Of 23 The task performed by the driver model is to calculate a new value of steering angle at the front wheels as the simulation proceeds using Equation 14 and the target location from Equation 21 Consider the terms needed to make the calculation The solution involves a summation over m intervals m is presently programmed as 10 For a given speed the relation between interval i and time is fixed t iT m Each time the driver model is called it is provided Xo and the information needed to determine ytarg for each interval The coefficients Fj gj and gi depend only on speed and do not need to be re computed unless the vehicle speed has changed The free response coefficients in the array Fj define the lateral position of the vehicle at the end of interval i due to non zero initial conditions Although the internal 2 DOF vehicle model has four state variables the choice of axis systems simplifies the calculations Figure I 3 shows that the initial valu
80. maximum roll angle that is allowed before the run is ended can be set here e to continue a run perhaps after changing one or more model parameters see Chapter 5 section Continuing a Run e to make a run using a vehicle description whose parameter values have been lost the based on method reads from an LPF echo file rather than the normal PAR files associated with the SGUI screens or e for certain debugging operations such as confirming that the parameters specified in the screen are being processed by the solver program Based On link This link is sometimes used to base a new run on the data from an old run If a new run is made all model parameters and inputs from the old run will be read by the solver program before any of the inputs from this data screen are read The final conditions from the other run are also read which means that the new run will continue where the old one left off Any inputs specified on this page will overwrite the data from the previous run The Chapter 5 section Continuing a Run explains some of the uses of this link Overriding Data link This link is used by the system when batch runs are made using the Runs Batch library If a run is made under batch control this link can be used to go to the batch data set This is described in more detail in the section for the Runs Batch screen As shown by the sequence of items on page 190 data from this link override everything else on the screen except t
81. model axis system Inertial Y Driver model Y axis Inertial X Target path Origin front axle 5 Predicted path constant steer Driver model X axis Mass center Xv Yv inertial coordinates Figure I 3 Axis system of driver model The target lateral translation in this coordinate system is calculated by first getting the inertial X and Y coordinates of the path as functions of the station at the target location Starg and then applying the transformation Ytarg LY Starg Yy cos y X Starg Xy sin y 21 Calculating the Optimal Control Within the world of the driver model the vehicle always is located at the origin of the axes shown in Figure I 3 the time is 0 and the target path is known from time zero to the preview time T The vehicle speed Vx is constant and the vehicle is assumed to be described by four state variables x1 Y coordinate of the vehicle mass center in the driver model axis system x2 Yaw angle of vehicle in the driver model axis system x3 Vy the lateral component of velocity in the vehicle axis system and x4 Yaw rate The A and B matrices are defined as follows o 0 1 V 0 lo 0 0 1 o C C C b Ca C 0 0 oot V t oe MV MV P 1M o o Cerca C a C b Ca L l V l V ES 22 where Cf and Cr are tire cornering stiffness coefficients for the front and rear axles M is the total vehicle mass a
82. name matching the ID of the current data set and the specified extension 20 This is done automatically when a new run is made However you can click this button to force the program to scan the file immediately This is done mainly after changing the contents of the keywords field Q2 Overlay Run links These links are used to generate overlay plots in which variables from the current simulation run are plotted with the same variables from other files To overlay variables from two or three simulation runs link to this library Runs and then pick another run from which to extract variables to plot To overlay variables with ERD files not from this library for example measured test data use the menu command to open an ERD file Location in CarSimEd The Runs screen can be accessed from the Tools menu and the ribbon bar button It can also be accessed from the CarSimEd Startup screen CarSimEd Startup Runs 3D Handling File Location Runs_3D Runs_3D tbk Runs SIMULINK CMEX Version The Runs screen is central to the user interface in CarSimEd It is used to set up simulation runs and to view results with post processing programs Note The Runs Screen has several possible appearances depending on whether various check boxes are checked Figure 9 11 shows the simplest display The most complex is shown in the next section Discussion CarSimEd includes four Runs screens Three are for running the stand alone solver progr
83. of CTC Figure B 3 Tire and wheel axis systems Earth fixed coordinate system coordinate system based on the earth fixed axis system Its origin normally lies somewhere on the Earth s surface Inertial Newtonian reference a reference frame that is assumed to have zero acceleration both linear and angular and zero angular velocity Intermediate axis system X Y Z right handed orthogonal axis system whose Z axis is parallel to Zp and whose Y axis is perpendicular to both Zg and Xy This axis system can be obtained by rotating the Earth fixed axis system about Zg by the vehicle yaw angle yw See Figure B 2 ISO Reference frame a geometric environment in which points remain fixed with respect to each other at all times Ground axis system XG YG ZG right handed orthogonal axis system whose ZG axis is normal to the ground at the center of tire contact and whose XG axis is perpendicular to the wheel spin axis Yw For uneven ground a different ground axis system can exist for each tire See Figure B 3 SAE Iso Ground plane a reference plane tangent to the ground surface at the tire contact center For uneven ground a different ground plane can exist for each tire Vehicle axis system Xv Yvy Zy right handed orthogonal axis system fixed in the vehicle reference frame The Xy axis is primarily horizontal in the vehicle plane of symmetry and points forward The Zy axis is vertical and the
84. of mechanical advantage is used to include components such as springs and dampers in the vehicle dynamics model without requiring details about their points of attachment or the complex suspension linkage geometry The effect of a suspension component at the wheel is calculated in three steps 1 multiply the suspension compression measured at the wheel by the kinematic ratio to determine the compression at the component 2 apply a known functional relationship e g spring force vs compression to determine the force generated by the component and 3 multiply the component force by the kinematic ratio to obtain an effective vertical force at the wheel 301 Appendix G The 3D Car Model For a linear spring the three steps can be combined to define an effective spring rate at the wheel K R 2 For nonlinear relations it is necessary to perform all three steps A similar treatment is made for the shock absorber using the derivative of the suspension displacement the damper mechanical advantage Rg and a functional relation between damper force and stroke rate The effect of the anti sway bar is modeled for the independent suspension with a linear spring between the two wheels linked by the bar The two points are on the two wheels the direction of the force is sz and the magnitude is a spring rate multiplied by the vertical movement difference between the two points The parameter is a torsional spring rate It is conve
85. of the variables depend on what is being plotted 186 Chapter 9 Alphabetical Library Reference Location in CarSimEd CarSimEd Startup Runs Plot Setup Single Plot Transform File Location Plot Transfrm Transfrm tbk Runs 2D Ride The Runs screen is central to the user interface in CarSimEd It is used to set up simulation runs and to view results with post processing programs 4 Runs 2D Ride ojx File Edit Text Page Tools Data set Sine Sweep v 4I I gt New Delete Gow Back Changed ID 640 OWotes 5 31 14 Model Parameters amp Inputs Run Control Output amp Post Processing Vehicle classic car enere Je Run Simulation Animate Input road Speed kmh Stop sec Camera Setup Sinusoidal Swesp zl Seve Input Computation Parameters No library selected x dt 0025 400 Hz output x View Echo File All Parameters Input EJ i No Library Selected x Plot pecan sf Heri Plot 1 Setup Fz vertical forces x Plot 2 Setup Fs spring forces x Plot 3 Setup Fd damping forces x Plot 4 Setup Az vert accel of CG x O Show More Discussion CarSimEd includes four Runs screens Three are for running the stand alone solver programs 3D Car 2D Ride and Suspension Analysis and the other is for running with SIMULINK These screens are nearly identical in appearance and function The 2D Ride screen is identical to the 3D Car screen see Figure 9 9
86. of what CarSim Educational can do and how it works Throughout this manual CarSim Educational is called CarSimEd About This Manual This manual is intended to help you understand and use CarSimEd e The first three chapters provide an overview of CarSimEd its use installation and program structure e Chapter 4 provides instructions for performing common operations in CarSimEd e Chapters 5 through 9 provide reference material Chapter 9 the largest in the manual describes the CarSimEd data screens in alphabetical order e Chapter 10 provides instructions for performing operations that are more advanced than those covered in Chapter 4 e Chapter 11 contains tips to help diagnose problems and identify errors e The appendices provide technical details such as a glossary vehicle dynamics terminology file formats model parameter definitions output variable names and assorted modeling details Although we would not discourage you from reading this manual from beginning to end we recognize that your time is valuable and that you might start by reading only what you think is absolutely necessary Please read Chapters 1 through 4 In particular Chapter 4 has the essential information about how you use CarSimEd The majority of user questions from the past few years are covered in this chapter Other chapters can be read as needed or for reference The most recent version of this manual can be obtained free from the web site
87. on page 189 except for the title and the lack of a yellow field for specifying tire ground friction Please refer to the 187 Chapter 9 Alphabetical Library Reference section for the 3D Car version for descriptions of the controls and settings of this Runs screen Note The only meaningful input for the 2D Ride model is a road input height Z as a function of longitudinal posistion X Therefore discussions of steering braking and throttle do not apply when using the 2D Ride model Location in CarSimEd The Runs 2D Ride screen can always be accessed from the GO menu and the CarSimEd Startup screen CarSimEd Startup Runs 2D Ride The Tools menu and the E button in the ribbon bar will take you to one of the Runs libraries in CarSimEd As installed these are shortcuts for getting to the stand alone Runs screen If you primarily use the 2D ride model you can change these shortcuts by Control clicking the al button in the ribbon bar This brings up the file browser dialog box which you can use to identify the file Runs_2d Runs_2d tbk as the default Runs library File Location Runs_2d Runs_2d tbk Runs 3D Handling The Runs screen is central to the user interface in CarSimEd It is used to set up simulation runs and to view results with post processing programs Discussion CarSimEd includes four Runs screens Three are for running the stand alone solver programs 3D Handling 2D Ride and Suspension Analysis
88. one If a data set already exists with the same name the copy is given a unique name by appending a number Notes This method is 100 reliable for libraries with only yellow data fields For libraries with blue links the names of the linked data sets are copied However if the data sets do not exist in the new CarSimEd installation then the links are not valid and must be reset by hand If you are importing data from several libraries you should import from the low level libraries first to avoid invalid links when importing from high level libraries For example when importing animation data import reference frames and shapes before importing groups or camera settings This is because the groups and camera settings are linked to frames and shapes If you select more than 10 data sets to import a warning message appears warning of possible problems Due to a low level interaction between ToolBook and Windows ToolBook will sometimes crash while trying to import many data sets It is recommended that you import less than 10 data sets at a time and that you back up the library file that is the target of the import process 5 After importing the data go to the startup screen and update the PAR files The instructions page 221 can be summarized as a Use the GO button to go to the startup screen Startup tbk b Go to the data set Install c Click the Change Settings button d Click the Update All PAR Files
89. one or more objects The keywords add_wheel and add_part have the effect of starting the scope of a new object They also have the effect of ending the scope of the previous object However they do not affect the scope of the current moving reference frame In the example listing descriptions of parts and wheels are contained in other PARSFILEs identified with pathnames following the parsfile keyword 276 Appendix E Animator Files and Keywords Resizable Objects The animator has a provision for re scaling all parts within the scope of a reference frame This is used in CarSimEd to stretch or shrink vehicle bodies based on wheelbase and track width Separate scale factors are used for X Y and Z coordinates of all parts associated with the reference frame The relation shown for the X direction is defined by a reference length and an actual length For the X direction the keywords are x_ref_length and x_length The conversion is x_length Mew HA ee x_ref _length Where X pew is the newly scaled coordinate X is the coordinate from the part or wheel description x_length is the wheelbase used in the model and x_ref_length is the reference wheel base The scaling is done only if both the length and reference lengths are specified Otherwise the re sizing is omitted and the original coordinates are used to define the points Parts Shapes A part is a set of points connected by straight lines Each point is defined by a set of
90. plot 1 If you attempt to make a plot or leave the screen with only one pair of X Y points an error message is generated The plot O shown on this type of screen covers only the range of data In the simulation values might extend beyond the range shown For example if the simulation runs longer than 210 seconds the independent variable time would have a value outside the range covered by the table The solver programs in CarSimEd have two methods for extrapolating outside the range of a table e For variables that are inputs to the vehicle controls such as steering wheel input or disturbances such as wind flat line extrapolation is used If the independent variable is less than the first value in the table the first value of the dependent value is used If the independent variable is greater than the last highest value in the table then the last value of the dependent variable 118 Chapter amp Design of CarSimEd Data Screens is used For example the data shown in Figure 8 3 would cause a steering wheel angle of 0 0 to be used for values of time less than zero For values of time greater than 210 seconds the steering wheel angle would be 230 degrees e For variables that describe vehicle properties for example spring force vs deflection constant grade extrapolation is used Depending on whether the independent value is less than or greater than the range of the table the first or last two points are used
91. pull down menu with three options no grid coarse grid or fine grid The current selection is shown in the white field 5 Change Fonts button Press this button to display a pull down menu for selecting font properties for the title legend axes labels and tick labels Figure 9 6 identifies these parts of the plot After making a pick from this screen a standard Windows dialog box for specifying font properties appears and is used to specify the font properties 6 Current font settings This table shows the current font settings for the four types of labels appearing in the plot You cannot change the values shown directly you must go through the Change Fonts button G 177 Chapter 9 Alphabetical Library Reference File identifier The two options available from the pull down menu are file title and file name Because most ERD files generated with CarSimEd have numbers assigned by the database as their names the title option is recommended Data set identifier Variables overlaid in a plot are identified in a legend Variables from the same file can be identified by the items provided in the pull down menu 9 Legend location The button has a pull down menu with five possible locations for the legend that identifies data sets in overlay plots The choices are to the right of the plot or on the four corners within the plot area The current selection is shown in the white field WinEP Yaw velocity Lane chan
92. runs save the MDL file In doing so SIMULINK makes the file fully compatible with your version 20 3 Database Organization You will generally spend most of your time interacting with the CarSimEd database This chapter provides an overview of how the database is organized Introduction to the CarSimEd Database Throughout this manual the database is considered at five levels Starting with what you see on the screen the levels are 1 Data screens Any screen display in CarSimEd that has editable fields or other forms of user settings is called a data screen Data sets A data set is the information you provide and can edit in a data screen minus the screen itself The data screen is a view of a data set as seen through the CarSimEd user interface a Cars Ele Edt Test Page Tools Data set HMMWV Category 4 i New Detete Gov Back izt MEE Changed 10 44 S 1205 43 Jotiaeaaaale Brora as Steering System Gear ratia 20 ratio Steering wheel mass center of otal wheal age entire vehicle Compliance 001 Je dimensions are in milimeters Csusp is suspension compliance Braking System Front ganf 15 Rear gain 8 gain brake torque ne whe Ei Driveline Masses and Inertias Front and Rear Front Rear Vehicle mass supported by both tires 1460 2490 jka Inerti
93. set scale factors Chapter 6 The Animator File Menu The file menu is used to read files write files and exit the program Printing is not functional in the current version To print a graphic 1 copy it to the clipboard using the Edit menu item Image Copy Ctrl C 2 paste it into another application e g WordPad and 3 print from the other application Open Simulation ERD File Ctrl E Open Parsfile Ctrl 0 Reload Current Files Ctrl R Save Parstile As Exit Ctl O Open Simulation ERD File Select this command to open an ERD file with the Open dialog box Recall that the six variables needed to define each reference frame are obtained from the ERD file produced by a solver program If you read a new ERD file the animator will show motions from that simulation without changing the camera point of view shape descriptions etc The keyboard command is Ctrl E Open Parsfile Select this command to open a PARSFILE extension PAR with the Windows file browse dialog box If you read a new PARSFILE the animator will show the same motions as before using the new camera point of view shape descriptions etc as defined in the new PARSFILE The keyboard command is Ctrl O Reload Current Files Use this command to restore the original settings by reloading the current ERD file and PARSFILEs The keyboard command is Ctrl R Besides restoring settings this menu command can speed up the process of cre
94. solver programs For example choose the No Steering data set for the steering wheel angle as a function of time The control inputs are all tabular functions of time so just specify data sets where the input variable is zero for all values of time Specify the associated inputs in SIMULINK using the SIMULINK and MATLAB modeling capabilities See the README file in the Matlab folder to identify the input variables For example specify a mathematical function for the steering wheel input contribution INPT 1 Going Directly to Any CarSimEd Library 1 You can jump directly from any CarSimEd library to any other library Press the GO button in the ribbon bar to display a menu of other libraries in CarSimEd Select a library from this menu to leave the current library and go to the selected one input spindlez spindlez tbk input steering steering tbk Open input throttle throttle tbk 7 startup tbk plot format format tbk ZG RAGE peg eee re plot setup setup tbk z i tuns_2d runs_2d tbk tuns_3d runs_3d tbk tuns_sus runs_sus tbk animate cameras cameras tbk animate frames frames tbk animate groups groups tbk animate shapes shapes tbk animate wheels wheels tbk batch plot_bat plot_bat tbk batch runs_bat runs_bat tbk comp_par comp_par tbk generic gen2dtab gen2dtab tbk generic gendata gendata tbk generic gentable gentable tbk input braking braking tbk input road road tbk plot transfrm
95. standard elements in a data screen such as the ribbon bar at the top and the blue links are described in more detail in Chapter 8 Making New Data Sets Every CarSimEd screen includes a New button in the ribbon bar This is one of the most essential buttons in the SGUI click it to make a copy of the current data set One of the reasons that CarSimEd can be such a productive tool is that data sets do not have to be re entered Rather than modifying an existing data set the normal practice is to make a new copy and modify the copy This way you can switch back to the original whenever necessary On Line Help Every CarSimEd screen includes a status bar at the bottom of the screen Move the cursor over an object to read a one line description of its function in the status bar A Map of the CarSimEd Libraries and Screens Except when using CarSimEd with SIMULINK all information used by the CarSimEd solver programs is obtained from the data sets seen in the CarSimEd data screens The plotter and animator also work from the same data Each screen design is associated with a separate library file CarSimEd includes the following types of libraries e vehicle parameters e control and environmental inputs for simulation runs e run setups including simulation and post processing control e plot setups e animation setups and e batch controls The top level of CarSimEd is shown graphically in Figure 3 3 24 Chapte
96. steer due to tire forces except vertical and moments SAE ISO Damper mechanical advantage Rq Ratio of damper compression per unit of wheel jounce This ratio is usually less than unity Driver steer 54 portion of steer due to steering wheel angle with no forces or moments applied by the ground to the tires and with no suspension movement Jounce vertical movement of wheel or axle relative to the vehicle reference frame Jounce is positive for compressive movement wheel moving up relative to the body There is no standard definition of zero jounce SAE 7 Kinematical camber camber measured with no tire forces or moments other than vertical Also defined as camber minus compliance camber 19 253 Appendix B Vehicle Dynamics Terminology Kinematical steer 5x steer measured with zero steering wheel angle and no tire forces or moments other than vertical Also defined as steer angle minus compliance steer and minus driver steer 10 Pitch center imaginary point in the Xy x Zy plane through the lateral center of the vehicle reference frame at which a longitudinal force applied to the vehicle body is reacted without producing suspension jounce front or rear An alternate definition is that the pitch center is the intersection of the two lines shown in Figure B 4 Note this definition of pitch center does not take into account the wind up effects of drive train torque applied to the wheels fro
97. that a rollover accident was inevitable keyword ROLL_STOP e The absolute vehicle speed dropped below a specified threshold keyword V_STOP The low speed threshold V_STOP is set on the Input Braking screen The other parameter or both can be optionally set using the Misc Data field 17 described below Road tire friction parameter keyword MU This parameter is used to scale the tire forces when the road tire friction parameter generally called u to be used for a run is different than the u of the testing equipment used to generate the tables of the selected tire s cornering stiffness and pneumatic trail Computation Parameters link The linked data set specifies the integration time step the print interval the type of integration and related parameters For details see the section Computation Parameters in this chapter 191 Chapter 9 Alphabetical Library Reference Animate button Click to run the wire frame animator program and view motions of the vehicle as predicted by the simulation An error message will be printed if the output file does not exist which usually indicates that the run has not yet been made Camera Setup link The linked data establish the camera parameters and motion For details see the section in this chapter called Animator Camera Setup View Echo File All Parameters button This button opens a text editor with an echo file produced by the solver program The e
98. the active plot has only a single data set then this command has no effect 104 Chapter 7 The Plotter View Menu Use this menu to toggle the display of the status bar the tool bar and to generate information about the data files Toolbar v Status Bar Show Numbers Show Channel List Display Log Toolbar Toggle this item to display or hide the toolbar Status Bar Toggle this item to display or hide the status bar at the bottom of the WinEP work space Show Numbers Select this item to view the currently plotted data in tabular form Numbers shown in the window can be copied to the clipboard and the entire contents can be saved to file by using the Save Data button Fz vertical forces Braking in a turn olx Show Numbers Fz vertical forces Braking in a turn Fz LF Tire vertical load N 0 4903 33 000 F 4854 75 LF tre 4655 85 LRtire 4363 66 RF fire 4098 9 a iji F 3919 46 ee 3846 47 3828 82 3815 77 3777 6 3710 3634 3570 3535 3527 3537 3554 3571 3 3584 26 23 4 6 6 7 8 9 10 3595 5 Time sec 3607 5 3621 32 3636 13 3649 82 If the plot includes many numbers it can take some time for the window to appear 105 Chapter 7 The Plotter The same function can be performed using the File menu command to Save Data Note Sometimes due to memory limitations only some of the values will appear in the list When this happens use the
99. the beginning of each time step the values of all of the state variables are known including the t variables The various quantities necessary for the tire equations are calculated in the following sequence 1 Compute F which depend only on the state variables 2 Compute Fx Fy and M with the static tire model table look up combined slip theory using T 3 Compute including the effect of steer compliances coupled with tire actions of Fy Fy and M 4 Determine t and ty 5 Calculate terms that depend on t and ty e Apply forces F and F to the axles e Calculate the time derivatives of T Sign Conventions For the above definitions of longitudinal and lateral slip 1 positive K generates positive Fy 2 positive generates negative Fy and 3 positive small generates positive M3 When the longitudinal speed of the wheel center is negative the conventions for tire X and Y axes would be reversed according to standard tire kinematics conventions However in the CarSimEd models the X axis remains pointing towards the front of the vehicle and the Y axis continues pointing to the vehicle left Therefore the signs of Fx and Mz are reversed when the wheel speed is negative The sign of Fy is not reversed due to the use of Ivx in the definition of tan 316 Appendix H The Tire Model References 1 Loeb J S et al Lateral Stiffness Cornering Stiffness and Relaxation Length of the Pneumati
100. the first non blank character following the keyword The PARSFILE is similar to those used by the solver programs It should begin with a line containing the single keyword parsfile It should end with a line containing the single word end However the end keyword is optional If not present the animator reads to the end of the file Blank lines and lines with unknown keywords are skipped when the file is read Multiple lines with the same keyword are permitted The PARSFILE Keyword Links to other PARSFILEs are provided with the parsfile keyword parsfile pathname where pathname is the path to another PARSFILE Through the use of these parsfile links data for each object can be contained in a separate file For example each part data set can be placed in a separate file The data set for a reference frame can be in a file that contains a parsfile link to each part associated with the frame The entire animation data can be just a set of parsfile links to the non moving parts followed by the data sets for the moving reference frames 272 Appendix E Animator Files and Keywords Organization of Animator Inputs At the top level the animation shape data should be organized by reference frame When a shape is introduced it must be associated with a specific reference frame After a new reference frame is introduced all following inputs are said to fall within the scope of that reference frame For example a shape is in the
101. the mouse to create a zoom rectangle Press the left button to anchor one corner at the current cursor location then drag with the button still pressed to define the rectangle When the rectangle covers the desired range release the button WinEP will re draw the plot using the region of the rectangle as the new limits for the axes Figure 7 2 shows the appearance of a plot with a zoom rectangle drawn just before the mouse button is released Figure 7 3 shows the same plot window immediately after the button is released Note WinEP rounds off the maximum and minimum values for the axes The new plot is drawn to include the full range of the rectangle you drew with the mouse plus some additional range to round off the axes For example the maximum Y value from the zoom rectangle shown in Figure 7 2 is about 4500 The maximum value in the zoomed plot of Figure 7 3 is rounded up to 5000 If you click in a plot window without drawing a rectangle WinEP re draws the screen without changing the scale 297 Chapter 7 The Plotter Fz vertical forces all Base Car Brk in Turn Fz vertical forces all Base Car Brk in Turn Tire vertical load N LF tire amp LR tire RF tire RR tire Time sec Figure 7 2 Plot before zooming l Fz vertical forces all Base Car Brk in Turn Fz vertical forces all Base Car Brk in Turn Tire vertical load N 5000 l LF tire Ps LR tire 400
102. the root directory of CarSimEd For example the absolute pathname would be something like C CarSimEd Animate Camera Cameras tbk The relative pathnames are useful to know even if you are not looking for a file because they appear in the pull down menu of the GO button in the ribbon bar Animator Camera Setup The Animator Camera Setup screen defines the location of the virtual camera in the animator the direction in which the virtual camera is looking the amount of zoom and the properties of an optional grid Discussion Imagine you have a video camera and are viewing a vehicle as it moves down the road Your location actually the location of the camera you are holding determines your point of view From that point you can aim the camera anywhere However you will probably pan the camera to keep the vehicle in view If the camera has a zoom lens you might zoom in or out to control the size of the vehicle in the viewfinder In CarSimEd there is no physical vehicle to look at However to go along with the simulated vehicles the animator program described in Chapter 6 simulates the motions that you would view with a video camera Use the Animator Camera Setup screen to establish various camera positions and aiming strategies The parameters in this library are associated with two geometric points illustrated on the screen the camera point 2 and the look point 4 At each output time interval the animator generates a 2
103. the tire to the forward speed at the wheel center This number is larger than the loaded radius by an amount Fz Kt vertical force divided by linear spring rate Linear tire vertical spring rate keyword KT IAXLE ISIDE This coefficient is used in the model to calculate change in vertical load due to tire compression The behavior is linear until the load reaches zero Once the tire lifts off the ground the force remains at zero unless contact is made again Tire relaxation length keyword LRELAX IAXLE This is about one third the distance that the tire must roll before side force due to slip angle builds up to its full value It can be thought of as a spatial version of a time constant Spin moment of inertia of one wheel keyword IW IAXLE This should include all parts that rotate with the wheel as a single rigid body including the tire brake rotors and possibly driveline elements Cutoff speed for tire relaxation equations keyword VLOW_ALPHA IAXLE The concept of relaxation length is valid for a range of speeds but leads to strange behavior as speeds approach zero because the time constant associated with the dynamic lag goes to infinity The time constant associated with relaxation is frozen when the speed drops below this value Cutoff speed for longitudinal tire forces keyword VLOW_KAPPA IAXLE The classic model for predi
104. three coordinates X Y Z The animator starts with the first point and draws connecting lines to each following point in a list Parts are called shapes in the graphical database and are described in the Chapter 9 section Animator Shapes All coordinates are assumed to be in a local coordinate system associated with the active reference frame There are four properties that can be set for a part a name a list of XYZ coordinates line thickness and color Listing E 2 shows an example PARSFILE containing a complete part description The keywords are defined in Table E 3 277 Appendix E Animator Files and Keywords pa Listing E 2 Part data description rsfile add_part hood set_Color blue set_coordinates 6273 0 7344 0 8721 5355 0 4131 0 8874 4896 0 0000 0 9027 5355 0 4131 0 8874 6273 0 7344 0 8721 0000 0 7191 0 7803 5202 0 6579 0 6732 6426 0 2601 0 6885 6579 0 0000 0 6885 6579 0 2601 0 6885 4590 0 6885 0 7038 0000 0 7191 0 7803 0 en se se se en 6273 0 7344 0 8721 d_coordinates t_scale_x 1 t_scale_y l t_scale_z 1 t_offset_x 0 t_offset_y 0 t_offset_z 0 d Table E 3 Keywords for describing parts Value add_part name of part starts scope for new part the name itself is treated like a comment set_color color 9 choices color used for lines drawn to connect the black white red blue points in this part green magenta yellow dark gray ligh
105. throttle input specifed on this screen The speed controller can be turned on and off using the keyword SPEED_ON_OFF This library throttle control automatically sets the controller off This means that the speed specified on the Runs screen is used to set the initial condition but after the run starts the only drive torque that is applied is proportional to the input on this screen If you with to run at constant speed do not link to any data sets in this library from the Runs screen That way the speed controller will remain enabled Note that the simulation only runs when the absolute vehicle speed is greater than a threshold V_STOP This allows the simulation to stop automatically in braking runs In order to make a run starting from a low speed the threshold must not be greater than the starting speed To run at any speed including zero set the threshold to a negative value One way to do this is to type into the Misc Data field on the Runs screen the line V_STOP 1 User Settings Note User settings that are common for all tabular data screens are described in Chapter 8 in the section Tabular Data O Two column table of throttle input as a function of time keyword THROTTLE_TABLE Each line should have a value of time followed by a corresponding value of throttle with a separating comma The throttle input specified with this table is multiplied by front and rear drive torque gains specified in the
106. to its essence with a minimal number of parameters and variables and just three degrees of freedom DOF From the 1960 s to the early 1980 s the proliferation and improvement of analog and then digital computers led to a new phase of vehicle modeling in which many automotive simulation programs were developed and refined by research engineers The new computer models were more complex typically with 10 to 20 DOF 4 5 The additional complexity accounted for nonlinearity and more detailed suspension kinematics Equations were still formulated by hand and coded by hand in computer language for numerical solution in specialized programs The more detailed models involved many years of development not counting the efforts spent in validation and verification Starting with the mid 1980 s engineers started using newly available multibody simulation programs to describe the model geometrically assembling the system model from components 6 7 Modelers no longer had to derive equations and therefore the efforts and potential errors associated with deriving equations and coding them were nearly eliminated Automotive manufacturers and many others now use multibody programs to perform simulations of automotive handling and braking behavior 8 The tendency has been to include nearly all moving parts in the suspensions and steering systems Inputs include coordinates of most joints between parts and mass properties of individual pa
107. to predict time histories of variables of interest These time histories are stored in a binary data file with the extension BIN A companion file with extension ERD describes the layout of the BIN file and also contains labeling information for each variable The format of an ERD file is described in Appendix C Appendix J contains a list of all of the variables contained in the ERD and BIN files for one of the CarSimEd models LOG Files The input parameters for the simulation models are spread over many screens in the CarSimEd database Each data set is written in a PARSFILE When the solver program reads the inputs it writes a record of every PARSFILE into a LOG file This is mainly used for debugging most users will never have occasion to look at LOG files When the solver program executes it reads the PARSFILE specified in the SIMFILE If that PARSFILE includes the keyword PARSFILE the named file is opened and the program continues reading from the newly opened file For example the top level file shown in Listing F 2 contains PARSFILE keywords that identify other files with more specific types of data Vehicle parameters are obtained by reading the file C CARSIMED 45 VEHICLES CARS 58 par steering input data are obtained by reading the file parsfile C CARSIMED 45 INPUT STEERING 27 par a braking input is obtained by reading the file C CARSIMED 45 INPUT BRAKING 75 par
108. to the display shown in Figure 5 2 on page 57 You are now through with the CarSimEd part of the process 3 Click in the SIMULINK window to make it active 4 Type Ctrl T to start the run Or select the Start menu item from the Simulate menu 5 When the run is complete you can view the results with SIMULINK and MATLAB tools or with CarSimEd tools The CarSimEd tools are described in the rest of this chapter Making Additional SIMULINK Runs Use this method to make a run when SIMULINK and MATLAB are already running in the background Start from the Runs SIMULINK screen see Figure 4 3 1 Prepare to make a run as described earlier page 30 2 Click the Update Data button 2 This copies the specifications for the run into a batch control file that will be used by the S function in the SIMULINK model You are now through with the CarSimEd part of the process 3 Click in the SIMULINK window to make it active 4 Type Ctrl T to start the run Or go to the Simulate menu and select the Start item Viewing an Animation Start from a Runs screen see Figure 4 1 on page 30 The simulation run must have already been made in order to view an animation 1 Choose a camera setup using the blue link 11 See Figure 4 4 2 Click the Animate button 10 3 If there is no motion go to the Animation menu and select the item Start from Beginning Ctrl S in the Animator screen Chapter 4 The Basics of Using CarSimEd 4
109. to the point of instability If you are attempting to follow a path closely without trying to simulate driver response dynamics a value of 0 0 is recommended This results in the most accurate steering control 170 Chapter 9 Alphabetical Library Reference Location in CarSim CarSim Startup Runs Input Target Path for Closed Loop Steer Control File Location Input Path Path tbk Input Throttle Control Use this screen to define the throttle position as a function of time for a 3D handling run This screen is only used for the 3D car model If it is linked to a 2D ride or suspension analysis run the data are ignored wm Input Throttle Control ioj x File Edit Text Page Tools Data set 0 2 Throttle Changed ID 84 CO Hotes 11 18 46 Throttle Input Update Plot Tidy Table 2 Time sec Throttle 0 A 2 3 4 5 6 a 8 9 1 Time second Discussion CarSimEd has two basic ways to control vehicle speed 1 Closed loop speed control In this mode you specify the vehicle target speed on the Runs screen and a controller is used to determine a drive torque that is 171 Chapter 9 Alphabetical Library Reference applied directly to the wheels The assumption is that the driver does what s necessary to manipulate the throttle to control the speed 2 Open loop throttle control In this mode drive torque on the wheels is proportional to a
110. transftm tbk vehicles cars_ed cars_ed tbk vehicles link_sus link_sus tbk vehicles susp_ed susp_ed tbk vehicles tires kfp kfy tbk vehicles tires tires_ed tires_ed tbk vehicles tires trail trail tbk CarSimEd menus The menu typically contains more items than will fit on a monitor with VGA resolution 640 x 480 In this case the first item in the menu is More Highlight it to view more menu items 44 Chapter 4 The Basics of Using CarSimEd Notes After using the GO menu you can return to the previous library using the Back button from the ribbon bar When you go to a library using the GO menu CarSimEd shows you the most recently viewed data set This data set is not necessarily one that is used in the most recently made run Different menus are created for the GO button when you start the software depending on the simulation type For example when you start with the 3D suspension simulation most of the vehicle data sets are not shown in the GO menu because they cannot be used with the suspension model To run with a GO menu that includes all data sets in CarSimEd start with the data set Install in the Startup library Locking Your Data CarSimEd is designed to make it easy to answer What if questions Changing vehicle parts inputs run conditions etc is simple and rapid However you might overwrite some data you meant to keep and you will no doubt conclude that changing parameters is too
111. up the Channel Select dialog box again File name This field shows the name of the current data file The name can be copied to the clipboard but there is no reason to edit it directly To change the file you must click the File button 6 Title This field shows the title from the data file if 1 the file is an ERD file and 2 the optional TITLE keyword is used in the ERD header All ERD files created by CarSimEd models show the title of the corresponding Runs data set Offsets m Subtract x Y offsets from data No Offset Y Offset No X Offset Y Offset e Tt We To E wp p es PP wf p pe shi Pp pf Pf a E gt P wf Pp PP sf pf a mE e Cancel oo uN oO A A U N 98 Chapter 7 The Plotter Cre Select this command to bring up the Offsets dialog box Use this dialog box to specify offsets for up to 20 data sets laterally X or vertically Y The values you enter in these fields will be subtracted from the values obtained from the data file For any fields left blank no offset is applied When you are finished specifying the offsets click the OK button These offsets will be applied to data in the active plot Filters Select this command to bring up the Filters dialog box Use this dialog box to filter the Y values in the data sets of the active plot using a moving average The numbered items in the dialog box are described below
112. variables This shows all the variables in the selected run or data file 7 Double click on a line to add it and the associated line highlighted in the Y axis list 4 to the Data to Plot list 1 Optional labels for the X and Y axes Normally the plotter labels the axes based on keywords read from the header of the ERD files However you can override those labels and specify your own If any text appears in these fields it will be used to label the axes instead of the information from the ERD file Link to Runs library or ERD file The blue field shows the title of the currently selected run or ERD file When a run is selected the associated ERD output file is scanned for labels that appear in the X and Y axis fields O and O Format link The linked data set determines the look and scale of a plot See the section describing the Plot Format screen for information about the format options Transform link This is for applying a filter to the data for plotting The available filters are moving average high low and band pass See the section describing the Plot Transform screen for information about the transform options 182 Chapter 9 Alphabetical Library Reference X and Y Log Scaling check boxes When one of these boxes is checked the corresponding axis is drawn with log scaling Otherwise the scaling is linear Note Log scaling is only used if the box is checked and the associated values of the variables are all positi
113. wheel moves laterally as the suspension compresses The longitudinal movement has a similar effect involving pitch due to longitudinal tire force As shown in Figure 9 12 for the lines of motion illustrating the ratio of longitudinal movement per unit of vertical movement of the wheel center Changes in steer due to compliance and suspension kinematics can drastically affect the response of a car with respect to steering inputs The compliance is represented with linear coefficients Kinematical effects are represented with nonlinear tables 204 Chapter 9 Alphabetical Library Reference Suspensions Independent Iof x File Edit Text Page Tools casa Rear 1 new perete cow eek e rrara me es 46 cegos ts ES So SS 4 GIG Brockea 79098 Unsprung Mass Springs and Shock Absorbers Ratios of component compression Wheels tires etc L R C o kg Suspension per unit of vertical wheel movement L compression Spring Shock atthe wheel 7 10 10 8 ymin Kinematics E Roll center Compression of component spring or shock Spring rate Ks Damper rate Ds Auxiliary roll stiffness Kaux suspension roll stiffness minus stiffnes N sec mm g N mideg due to springs and track width 20 Nimm a Dimensions are mm Suspension Steer and Toe Compliance Ratio longitudinal Steer movement per unit of Toe vs Fx O deg wheel plane ver
114. 0 s gt _ RF tire ii RR tire 56 58 6 6 2 64 Time sec Figure 7 3 Plot after zooming Tool Bar WinEP includes a toolbar with buttons for applying some of the most commonly used commands Place the cursor over a button to read its function in a pop up box and also in the status bar FA winEP Ay vs Station A BUS Alt 3 R lane lolx File Edit Format Data View Window Help cece S a SHm Aaeeea a Chapter 7 The Plotter All toolbar buttons provide actions that duplicate menu items The actions are described in the following descriptions of the menu items When a menu item has an associated toolbar button the button is shown in the heading for the menu item If the toolbar does not appear in your plot window click on the View menu command Toolbar Printing Plots Making a Hard Copy 1 If there are more than one plot windows select the plot window of interest 2 Select the menu item Print from the File menu The keyboard command is Ctrl P The plot in the current window will be sent to the current Windows printer 3 To print additional plots repeat steps 1 and 2 for each plot window of interest Controlling the Printed Plot Size Plots in WinEP are scaled on the screen to fit in their windows which you can size within the limits of your monitor resolution To determine how a plot will be printed select the menu item Print Preview under the File menu When printed the size of the p
115. 1 vehicleswehicleswehicles tbk a 2 Import All Car ind Driveline PAD Full Time PAD Full Time GM Engine PAD PAD Differential Lock lt Rear Solid Axle gt Car solid axle Car solid axle 1A4_trailer GMX320 Solid axle WHF T Link to the selected source TBK file The adjacent button can be used to select a different file 2 Import Selected button Click this button to import the data sets selected in the field 4 Each data set in the source library is copied into the currently open target library If a target data set already exists with the same name it is given a unique name by appending and a number The importing process involves taking every record field yellow or blue that exists in both the source and target data sets and copying the values from the source to the target If a field does not exist in the source the value shown in the current data set in the target is unchanged If the field does not exist in the target the value is not copied G Import All button Click this button to import all data sets from the linked file shown in 1 The process is the same as described above for the Import Selected button 2 Note If you select more than 10 data sets to import a warning message appears warning of possible problems Due to a low level interaction between ToolBook and Windows ToolBook will sometimes crash while trying to import many data sets It is recommended that you imp
116. 1 Show Series Calculator check box If this is not checked most of the items on the screen are hidden Only those involved with the simple calculator are not affected by this box 14 AD 2 Show Simple Calculator check box If this is not checked the items associated with the simple calculator 14 17 are hidden All other items are unaffected 144 Chapter 9 Alphabetical Library Reference ey ar aa Tabular Data field This is where the tabular data values are created and edited The data are assumed to fit in a tabular organization with each line in the field representing a row Each row should have the same number of items columns separated by commas and or spaces All values in the table must be numbers The values in this field are shown graphically in the adjacent plot 18 The buttons underneath O 11 are used to change the precision of the numbers determine whether commas separate the numbers and to modify the column row structure of the table The fields and buttons in the bottom area of the screen 83 C are used to perform calculations to create the tabular data from scratch or to transform existing values The only part of the screen that is not related to the tabular data field is the simple calculator with items a7 Insert button Click to ensure that all numbers in a row are separated with commas If commas already exist this has no effect except possibl
117. 20 data sets meaning that there are potentially 40 offsets to specify Listing D 3 shows an example PARSFILE with a few of the 40 offset keywords If not specified the default offset is 0 Listing D 3 Plot transform settings ry BANDPASS 10 1 ET_X1 ET_Y1 FSET_X2 FFSET_Y2 FSET_X3 ITLE Vx D The valid values associated with the keyword FILTER are None Hipass Lowpass and Bandpass For a value other than None the baselength s associated with the filter should follow on the same line Note Because a PARSFILE can reference other PARSFILEs the list of channel offsets can be spread over several files Plot Format Files The initial appearance of a plot is read from a format file Format files are plain ASCII text files which contain keywords with parameters that tell WinEP how to format a plot All format files follow the PARSFILE format and have the extension PAR The keywords used in a format file are described in Table D 2 266 Appendix D Plotter Files and Keywords Table D 2 Format keywords and descriptions Y axis type Valid values are log and linear XMAXMIN type Either a keyword specifying that the X axis is auto scaled or two numbers the minimum and maximum values for the axis YMAXMIN type Either a keyword specifying that the Y axis is auto scaled or two numbers the minimum and maximum values for the axis SYMBOLS sJ s2 s20 Symbols used for e
118. 3 SAE and ISO call this angle vehicle roll and both use the term roll to denote and Euler angle This appendix emphasizes vehicle roll which is measurable whereas the Euler angle is not 4 Neither SAE nor ISO define the point whose velocity and acceleration vector are being described 5 SAE defines longitudinal velocity and acceleration as the Xy component and forward velocity as the X component The X component of acceleration is not covered 6 SAE defines normal velocity and acceleration using the Zy axis The Z components of acceleration and velocity are not covered 7 SAE does not define angular accelerations ISO defines them as second derivatives of Euler angles 8 SAE defines angular velocities about the Xy Yy and Zy axes ISO defines them as derivatives of Euler angles only the roll derivative is measurable 9 SAE and ISO define camber relative to ZR rather than Zy 10 ISO defines camber angle change due to wheel travel kinematics and steer angle change due to wheel travel kinematics 256 Appendix B 11 12 13 14 15 16 17 18 Vehicle Dynamics Terminology ISO and SAE define both a toe angle and a toe displacement SAE does not define a sign convention for toe angle The ISO definition of inclination is relative to absolute vertical ZR rather than the vector normal to the ground Zo SAE defines longitudinal slip with units of per
119. 4 Category ti z alel Jal 3D Carin Simulink Bere 5 Link Suspension spp Install Vehicle Dynamics Simulation Version 4 5 January 2000 Free software from MSC Mechanical Simulation Corporation USA 709 West Huron Suite 50 Ann Arbor MI 48103 USA FAX 734 668 2877 Phone 734 668 2930 http www trucksim com VMC VirtualMechanics Corporation Japan 1 40 Hagiyama cho Mizuho ku Nagoya 467 0011 JAPAN x p FAX 052 853 7261 Phone 052 853 7309 RS http home att ne jp green v mechanics Download from http www trucksim com Copyright 1996 1989 Mechanical Simulation Corporation MSC _More nfo_ Change Settings Portions copyright Asymetrix Inc ToolBook Runtime package All Rights Reserved Styrt Data screens lists of all of the data screens in this library by catagory Control click for full pathname of currert library Click Here to go to a Runs screen Runs Screen Simulation Setup 4m Runs 3D Handling Jol Fie Edit Text Page Tools Data set Understeer roll test hmmwy cena eee s j Beseri O Locked 12 2799 Model Parameters amp Inputs Run Control Output amp Post Processing Vehicle Classic car anon Run Simulation O Animae Input Steer Speed kmh Stop sec Mu Camera Setup eme tegese pe Input Braking Computation Parameters oaro Je 0050r onpa v View Echo File Al Parameters Input Fo sasse
120. 40 X coordinate of chassis point mm PX 5 210 X coordinate of chassis point mm PY 1 410 Y coordinate of chassis point mm PY 2 430 Y coordinate of chassis point mm 294 Appendix F Model Files and Keywords PY 3 370 Y coordinate of chassis point mm PY 4 390 Y coordinate of chassis point mm PY 5 380 Y coordinate of chassis point mm PZ 1 330 Z coordinate of chassis point mm PZ 2 290 Z coordinate of chassis point mm PZ 3 0 Z coordinate of chassis point mm PZ 4 110 Z coordinate of chassis point mm PZ 5 100 Z coordinate of chassis point mm XX 1 60 X coordinate of carrier point mm XX 2 120 X coordinate of carrier point mm XX 3 190 X coordinate of carrier point mm XX 4 0 X coordinate of carrier point mm XX 5 0 X coordinate of carrier point mm XY 1 640 Y coordinate of carrier point mm XY 2 640 Y coordinate of carrier point mm XY 3 650 Y coordinate of carrier point mm XY 4 740 Y coordinate of carrier point mm XY 5 740 Y coordinate of carrier point mm XZ 1 350 Z coordinate of carrier point mm XZ 2 340 Z coordinate of carrier point mm XZ 3 20 Z coordinate of carrier point mm XZ 4 130 Z coordinate of carrier point mm XZ 5 130 Z coordinate of carrier point mm FINAL CONDITIONS Q 1 60 3664 CALC Abs X rot of R1p deg Q 2 11 1251 CALC Z rot of R1 rel to Rip deg Q 3 50 0164 CALC X rot of W
121. 62 Abs Y rot of S deg JNC_WLF 0 01780941709876 Z trans of WLFO rel to SO m 293 Appendix F Model Files and Keywords JNC_WLR 0 04939780384302 Z trans of WLRO rel to WLRJ m VZS 0 07862732559443 Abs Z trans speed of SCMC m s AVY 4 837102413177 Abs Y rot speed of S deg s JNCR_WLF 0 9013347029686 Z trans speed of WLFO rel to S m s JNCR_WLR 1 783175468445 Z trans speed of WLRO rel to S m s END Keywords and Parameters for the 3D Suspension PARSFILE Echo file created by Kinematic simulation of 5 point suspension Version created by AutoSim 2 58 on February 6 1997 Copyright 1989 1996 The Regents of The University of Michigan All rights reserved TITLE Suspension Input File C CARSIMED 45 RUNS_SUS 641 PAR Run was made 12 11 on Jan 21 19100 CFORMAT binary IPRINT 1 number of time steps between output printing counts STARTT 0 simulation start time s STEP 0 01 simulation time step s STOPT 1 simulation stop time s PARAMETER VALUES BSY 690 Y coordinate of point on wheel spin axis mm BSZ 1 Z coordinate of point on wheel spin axis mm BY 770 Y coordinate of wheel center mm BZ_TABLE ht of point B vs time 0 220 point in table s mm 1 220 point in table s mm ENDTABLE PX 1 60 X coordinate of chassis point mm PX 2 300 X coordinate of chassis point mm PX 3 90 X coordinate of chassis point mm PX 4 2
122. AB are available from the MathWorks Inc SIMULINK provides a graphical user interface for building models as block diagrams The graphical interface is popular for Chapter 1 Introduction developing dynamical models for many fields such as electronics hydraulics chemistry etc SIMULINK is not particularly useful for building equation sets for complex mechanical 3D systems such as the CarSimEd models However it includes S functions system functions to augment and extend the building blocks in SIMULINK to include arbitrary complex systems The S function appears in a SIMULINK model as a block in the block diagram The mathematical behavior of S functions can be defined either as a MATLAB M file or as an executable piece of object code in the form of a DLL dynamic link library obtained by compiling C or FORTRAN source code Such executable functions are called MEX files where the EX stands for executable The S functions in CarSimEd are made from C source code and are thus called CMEX functions CarSimEd includes DLL files that can be loaded and run by SIMULINK The DLL files were created by compiling CMEX files with the same equations of motion as used for the stand alone C programs used to create the EXE solver programs in CarSimEd The simulations can be run from within SIMULINK using the SIMULINK integrators and the SIMULINK environment for setting control inputs to the vehicle model You can build controller models steer
123. After viewing the animation exit the animator by clicking the x in the upper right corner of the screen Output amp Post Processing 10 Animate Camera Setup Pick Library View Echo File All Parametei No Data Set Plot Beer Ly Back View Plot 1 Setup Fixed view from sky Front view Plot 2 Setup Side view Suspension Back View Plot 3 Setup Suspension Top View Top view Plot 4 Setup Top view 5 m grid Az vert accel of CG Figure 4 4 Choosing a camera setup for the animator Viewing a Single Pre Defined Plot Start from the Runs screen see Figure 4 1 on page 30 The simulation run must have already been made in order to view a plot 1 To avoid making multiple plots un check the box Multiple Plots 14 2 To avoid overlaying plots from different runs un check the box Overlay Runs 15 3 Use the pull down menu next to the blue field labeled Plot 1 Setup 16 and select the plot of interest e g spring forces on the left side of the vehicle PI ED O Multiple Plots O Overlay Runs Plot 1 Setup Ax long accel of CG Go To Plot Setup Pick Library No Plot Braking Steering Suspensions Tires Vehicle motion gt Fd Damping forces L side Fd Damping forces R side Fs Spring forces L side Fs Spring forces R side Jounce L side Jounce R side 37 Chapter 4 The Basics of Using CarSimEd 4 Click the Plot button 13
124. Alphabetical Library Reference File Location Batch Runs_bat Runs_bat tbk Suspensions Independent Use this screen to specify the main properties of an independent suspension that affect the overall vehicle system response Discussion In CarSimEd an independent suspension is one in which vertical movement of one wheel does not cause noticeable movement of the other wheel if the anti roll bar is disconnected In contrast a solid axle suspension has an actual axle or linkage system that cause both wheels to roll together CarSimEd only includes independent suspensions The commercial CarSim package supports additional suspension types Independent Suspension Properties The kinematics of the suspension linkages are described in terms of how a wheel moves laterally and longitudinally as the suspension deflects vertically The lateral movement affects the transfer of tire lateral force to the body and the resulting body roll These effects are commonly described using the concept of a roll center The mathematical models in CarSimEd do not include an actual roll center point the wheels are assumed to move in a straight line as shown by the lines of motion in the kinematics section in Figure 9 12 However the direction of the line of motion is specified with a roll center height for compatibility with other models and data sets The CarSimEd model divides the roll center height by half the track to determine the amount the
125. B SIMULINK and then make the run As a user you click the button Start SIMULINK on the Runs_cmx screen to launch SIMULINK CarSimEd initiates the sequence shown in Figure 5 3 and described below CarSimEd Runs_cmx Screen Matlab pif SIMULINK e g indmdl mdl Figure 5 3 Transfer from CarSimEd to SIMULINK Chapter5 The Solver Programs 1 For each SIMULINK model ABS controllers etc there must be an independent PIF in its own folder When you click the Start SIMULINK button CarSimEd creates a SIMFILE in the same folder that contains the PIF For example the PIF pathname might be C CarSimEd 45 Matlab is_cmex Matlab pif 2 CarSimEd then sends a run command to the PIF 3 The PIF is linked to your copy of MATLAB see Figure 2 2 on page 19 It launches MATLAB with the current working directory set to the folder containing the PIF e g C CarSimEd 45 Matlab is_cmex 4 When MATLAB starts it tries to run the command Startup To do so it looks for a file in the working directory called Startup m If found it automatically loads the file and runs it CarSimEd has a file with a single line that is the name of a SIMULINK model For example the file C CarSimEd 45 Matlab is_cmex Startup m might have the single line indmdl 5 The file name mentioned in Startup m is opened For example indmd1 will cause MATLAB to open the SIMULINK model file indmdl mdl The SIMULINK model file in turn loads the DLL file is
126. Cpp rel to R1 deg Q 4 4 45457 CALC Y rot of WCp rel to WCpp deg Q 5 9 65248 CALC Z rot of WC rel to WCp deg Q 6 59 4151 CALC Abs X rot of R2p deg Q 7 11 0191 CALC Z rot of R2 rel to R2p deg Q 8 41 6627 CALC Abs X rot of R3p deg Q 9 3 55033 CALC Z rot of R3 rel to R3p deg Q 10 36 9715 CALC Abs X rot of R4p deg Q 11 0 983953 CALC Z rot of R4 rel to R4p deg Q 12 36 3276 CALC Abs X rot of R5p deg Q 13 0 967013 CALC Z rot of R5 rel to R5p deg END 295 Appendix G The 3D Car Model This appendix describes the modeling assumptions that were used to build the 3D car model in CarSimEd The tire model is described in Appendix H Portions of both appendices have been published previously 1 numbers in brackets refer to documents listed at the end of this appendix Introduction It is often said that an automobile is controlled by forces developed in just four small patches each the size of a man s hand where the tires contact the road In the 1940 s and 1950 s researchers such as Lanchester Olley Rieckert and Schunk Rocard and Segel developed an understanding of how tire forces are generated and affect the steering and braking behavior of the vehicle 2 Segel and other early researchers in the 1950 s developed linear equations by hand and solved them using frequency domain analysis 3 Segel s classic model reduced the vehicle behavior
127. D image based on the relationships between the location and orientation of the simulated vehicle and the camera and look points see the illustration on the data screen The locations and orientations of vehicle parts are determined by the solver program The camera and look points are determined by the information provided in this data set Point locations are defined in 3D space with sets of X Y and Z coordinates The animator program allows both the camera and look points to be associated with any user defined reference frame The reference frame can be fixed or it can be a vehicle part e g a sprung mass It is even possible to define a new moving reference frame using variables that are available in the simulation output files Besides drawing shapes and wheels the animator can draw a flat grid for the ground a 3D grid for the ground and a target path on the ground If the simulation was run over a 129 Chapter 9 Alphabetical Library Reference 3D ground surface the 3D input to the simulation is also used by the animator If not the animator draws a flat grid The grid spacing is specified on this screen Similar information about the target path is specified on the target path screen Input Target Path For Closed Loop Steer Control The grid can be turned off manually within the Animator as described in Chapter 6 Notes Chapter 6 explains reference frames In addition the section Animator Reference Frames in this
128. For example the same data screen is used to describe properties of all tires regardless of their location Parameters that are repeated for each axle are called indexed parameters with the indexing being defined with the keyword IAXLE The indexing keywords can be of interest to advanced users who override vehicle properties using the Miscellaneous fields scattered throughout the CarSimEd data screens Therefore they are specified along with the parameter keyword For example the entry for tire spring rate reads Tire spring rate keyword KT IAXLE You can view the keywords in the PAR file directly by clicking the lA button in the ribbon bar For example Figure 9 1 shows some of the keywords for the Cars data screen Notice that the PARFILE shown in the figure has a couple of lines that read iaxle 1 127 Chapter 9 Alphabetical Library Reference ti ParsTree Of x Parsfile tree Structure Contents of the selected file PARSFILE E 4 7 par TE os 303 par H 373 par H 374 par E 375 par EJ 376 par E 377 par Ej 378 par HB 379 par H 380 par Ej 381 par E 377 par HE 378 par E 379 par rmyth 2 500 E 382 par front suspension EJ 383 par iaxle 1 E 380 par ff5 SUSP_ED HMM WY Front object name parstile C CARSIMED 45 VEHICLES SUSP_ED 4 par Ej 381 par H 382 par P E 384 par E 385 par Parsfile path and filename E 48 par C CARSIMED 45 VEHICLES CARS_ED
129. For the batch run option to work a link is needed to an existing Runs library e g Runs Runs tbk When this data set is opened the linked library is automatically scanned by CarSimEd and the names of all data sets are listed in the 202 Chapter 9 Alphabetical Library Reference field below 2 The adjacent triangle button has a pull down menu that can be used to link to a different Runs library The Data Sets From Runs Library list This is a list of all of the data sets in the Runs library whose local pathname is shown above O Any line in brackets lt gt indicates a category heading Double click on a line to add that run to the list named Data Sets to Run G This is the same as selecting the line and then clicking the Add button G Double click on a line in brackets lt gt to add all runs in the category to the list 5 The Add button Click to add the currently highlighted lines from the Data Sets From Runs Library list 2 to the Data Sets to Run list 5 Shift click to add all runs The Remove button Click to remove highlighted data sets from the Data Sets to Run list G Shift click to remove all Note The Remove button only affects the list of Data Sets to Run G This operation does not delete data sets from the database The Data Sets to Run list This is a list of the selected data sets from the Runs library These are the data sets that will be run using the overriding data to the right 6 O
130. IMULINK model Each SIMULINK model folder contains a shortcut to the MATLAB program a CarSimEd CMEX solver module DLL file and some extra support files To make a new model 1 Choose among the existing SIMULINK models for the one most similar to the envisioned new model 2 Duplicate the folder containing the model For example if you want to make a new model with the basic model duplicate the folder Mat lab cmx_mdl 3 Optional Rename the MDL file If you do this you must also open the text file Startup m and change the name of the MDL file to match the new name 4 Edit the MDL file as desired To open it double click the Mat lab PIF in the new folder Linking to the New Model 1 Use the pull down menu G see Figure 10 3 to choose the option Add You will then be prompted to name the new simulation type and to locate an associated Matlab PIF for the current vehicle type See the next subsection about accessing PIFs from the Windows file dialog box Notes This step must be repeated for each vehicle type to allow CarSimEd to make all of the entries into the internal table 218 Chapter 10 Advanced Topics The new program will not be used until you select the new simulation type for a new run Accessing PIF Shortcut Files Early versions of Windows used Program Information Files PIFs to provide shortcuts to programs They appear in file browsers as files with the extension PIF They have largely bee
131. Image Copy Ctrl C Preferences Image Copy Select this command to copy the screen display to the clipboard as a bitmap The keyboard command is Ctrl C Preferences Select this command to set options for the animator that are saved when you quit the program The preferences are stored in a file Prefs par described in Appendix E Preferences x General 100M Display wamings IM Run animation after loading files Default frame rate 30 frames sec 4 Use Computer Clock Open o Speed End of run pause 0 5 secs Log file The numbered items in the dialog box are described below D Check box to display warnings When checked the animator will print messages to help diagnose errors in the input files Check box to run after loading files When checked the animator starts running as soon as the files have been read If the box is not checked the animation must be started by typing Ctrl S or using the Animation menu G Default frame rate This value will be used when the animator is started The frame rate can also be modified interactively see Figure 6 3 on page 73 If the frame rate is larger than the rate defined by the time step in the ERD file generated during a simulation run the animator will ignore this frame rate 4 Radio button for real time animation If the animation needs to be slowed down to real time select this button to slow it down to real time When this bu
132. LR damping force Fd_RF RF damping force Fd_RR RR damping force Display Log This displays an error message window sometimes used for debugging 106 Chapter 7 The Plotter Windows Menu Use this menu to control the appearance of the plot windows in WinEP Window New Window Cascade Tile Horz Tile Vert Arrange Icons Next Window PageDown 1 Ay lat accel of CG s 4WS 30 deg SS 2 Yaw rate 4WS 30 deg SS 3 Roll 4WS 30 deg 55 v 4 Steer Road wheel steer JWS 30 deg SS New Window Use this command to create a new window with the data and all format settings from the currently active window The new window will be displayed in front of the other windows Cascade f Use this command to arrange all plot windows in a cascade as shown below for two windows FA WinEP Yaw rate DLC File Edit Format Data View Window Help a Y vs X trajectory DLC Yaw rate DLC Yaw rate DLC Vehicle yaw rate deg s 10 Time sec 107 Chapter 7 The Plotter Tile Horz Use this command to tile the plot windows with horizontal divisions as shown below for two windows If there are four or more windows they are arranged in columns and rows FA WinEP Yaw rate DLC olx File Edit Format Data View Window Help B Yaw rate DLC ol x Yaw rate DLC Vehicle yaw rate deg s 20 Time sec BY vs X trajectory DLC Y vs X trajectory DLC
133. MATLAB folder to describe the specific input and output variables for the model associated with the folder Portions of a README file are presented in Appendix J The CarSimEd database includes four Runs libraries Three are for stand alone simulations without SIMULINK and one is for SIMULINK The screens are nearly identical in appearance the main differences are 1 the screens have different window titles and 2 the SIMULINK compatible screen has two buttons for accessing SIMULINK whereas the stand alone screens have just one button for running the EXE solver program 29 4 The Basics of Using CarSimEd This chapter explains the basics of how to use CarSimEd It assumes no prior knowledge other than what has been covered in the preceding chapters Each section covers a specific task and includes step by step instructions The sections are fairly compact covering just the essence of how to accomplish each task The detailed reference information is covered in following chapters After the reference material in Chapters 5 through 9 Chapter 10 continues by explaining how to do more advanced tasks in CarSimEd About the Runs Screen Figure 4 1 shows the Runs screen the screen most central to the operation of 4m Runs 3D Handling CarSimEd Computer Simulation gt Output Math Model File Edit Text Page Tools Undenfeeo text mmo x Input O hanged 1D 629 Data set Category 01 04 00
134. Note the axes names Xw Yw and Zw have a different meaning in ISO 8855 Entire vehicle Size Wheelbase Lwp the distance between the centers of tire contact on one side of the vehicle Wheelbase usually varies slightly with suspension deflection ISO 250 Appendix B Vehicle Dynamics Terminology Components of vectors Forces moments and motion vectors for the entire vehicle are commonly decomposed into three rotational and three translational terms The following adjectives should be used Lateral Y component of force or translational motion vector ISO Longitudinal X component of force or translational motion vector ISO Pitch Y component of moment or rotational motion vector ISO Roll X component of moment or rotational motion vector ISO Vertical Z component of force or translational motion vector ISO Yaw Z component of moment or rotational motion vector ISO Points C G Center of gravity a point in the vehicle reference frame that coincides with the center of mass of the entire vehicle when the suspensions are in equilibrium and the vehicle is resting on a flat level surface Aerodynamic reference point a point in the vehicle reference frame that lies in the intersection of the vehicle plane of symmetry and the ground plane mid way between the front and rear axles when the suspensions are in equilibrium and the vehicle is resting on a flat level surface Verti
135. Plots list 1 Shift click to add all Remove button Click to removes highlighted data sets from the Selected Plots list aD Shift click to remove all Selected Plots list List of the selected plot setups in the EP setup library These are the plot setups that will be used for the plots Any line in brackets lt gt indicates a category heading Double click on a line to remove it from the list This list cannot be edited directly You use buttons 9 and 10 to modify the list 180 Chapter 9 Alphabetical Library Reference 12 One Plot Per Data File button Click to cause the next set of plots to be made with a separate plot for each combination of a run and plot setup The total number of plots will be the number of data sets multiplied by the number of selected plots 13 One Plot For All Data Files button Click to cause the next set of plots to be made by overlaying all runs for each plot setup The total number of plots will be the number of selected plots Make Plots button Click to start the program WinEP and instruct it to make a series of plots based upon the selected runs plot setups and overlay options selected Location in CarSimEd Accessed with the Tools menu or the ribbon bar button File Location Batch Plot_bat Plot_bat tbk Plot Setup Single The data sets in this library each define a graphical plot with specifications of the data channels and files to plot formatting preferences and filt
136. RF Car Wheel RR Car heel Car body Fixed 174 Chapter 9 Alphabetical Library Reference Ore Discussion The Library editor is available from any CarSimEd library through the ribbon bar and the Tools menu When you bring it up it automatically links to the current library Use it to delete a group of data sets from the library lock and unlock multiple data sets or to organize data sets into categories User Settings and Controls Link to a library You can edit only one library at a time and this blue field shows the one that is active When the editor is opened the current library is loaded into this link Note Items 1 and 2 are similar to the standard blue link However instead of this being a link to a data set it is a link to the entire library Rather than showing the name of a data set it shows a pathname to a library file The pathname is relative to the root CarSimEd folder For example if the root CarSimEd folder is c CarSimEd then the relative pathname Runs Runs tbk refers to the file c CarSimEd Runs Runs tbk Triangle button Press this button to bring up a command for changing the library link shown in cy Lock Data Sets button Click this to lock all data sets currently selected in D Unlock Data Sets button Click this to unlock all data sets currently selected in 7 Change Category button Click this to change the category for all data sets currently selected in D It calls up
137. Runs Batch OF x File Edit Text Page Tools Data set Ride 2D batch Changed ID 123 EJ Hotes 3 47 24 Categor s O Locked 010300 Runs To Make Overriding Data Hotes Simulation Library Parameter Set 1 runs_2avuns zat C1 Jx Big Jump real fast HMMVVY over bump Link 1 Ride over bump No library selected 7 v Sine Sweep Parameter Set 2 Link 2 naa G 4 Remove to iray seen 7 Data Sets to Run Parameter Set 3 Link3 Mokras 7 Jw S Make Runs If no overriding data values or links are provided in step 2 the effect is exactly the same as going to each of the data sets from the Runs library and making the run again However if any parameters are specified or links are made each data set in the Runs library is modified to use the overriding data A link called Overriding Data from Batch is made to this data set For example in the figure above the name of the data set is Example If any runs were made each affected run would have the following link set automatically LINK No data set selected x Overriding Data from Batch x Excerpts From Output File 710 pf File ext STOPT 5 simulation stop time s This link is made so you can get from the runs data set back to the batch data set and see what parameters and links were used when the run was made User Settings and Controls O Simulation Library link
138. S Figure I 2 shows the relationship between the last station number So with corresponding coordinates Xo and Yo and the current vehicle location as defined by the coordinates Xy and Yy So Xo Yo Figure I 2 Geometry used to calculate new station The new station S is S So AS 18 where Ax Ay Re FN Y A As Yy A 2 2 2 R 2 As As To calculate the optimal steer control uc with Equation 14 the target position is needed at each point being considered in the summation The value of S obtained with Equation 18 is the station number of the vehicle at its current position The station for a target location is AS 19 iV T m S S 20 targ i where i 1 m and Vx is the forward vehicle speed assumed within the world of the driver model to be constant Target Position The controller calculations are made using a special axis system shown in Figure I 3 At time t 0 the origin of the X and Y axes coincide with the center of the vehicle front axle and the axes are aligned with the longitudinal and lateral axes of the vehicle In the world of the driver controller the vehicle movements will be predicted relative to these axes The axes are fixed in the inertial reference and are rotated from the inertial axes by the 322 Appendix I The CarSimEd Steer Controller vehicle yaw angle y The initial lateral displacement of the vehicle and the initial yaw angle are both zero in the driver
139. SE eanan ie ikain Siaa 53 5 HSS Ol Ver PIORTAMIS of fadatenccee rawrirdi ct edn ne eae uated eae 55 Overview of Program Operation Stand Alone eee cece cece eeeecececececececeeececececeeeeeeeeeeeeess 55 How a Simulation Run Is Made in SIMULINK 0 ce eeeeeeenereneneneneneneneneneneeeeaeaees 56 BI PY POS socisichcottisey oee Gocnak duce cnstencesabs wy pashatehcees ta buenchabastes sen ve voshedel coteua le dacandestest boxe yordis 59 6 The ANMA sherri ri iets nun E E N EE E literal uated 63 Updates ea eea e eE E E aE EEKE eE ESE iar acai EE hata arden Loa 63 Overview of OPeratiofissrie vesiensvscgess eTEN EER E E 63 Reference Pramess y cerir eei ee eae ita e aeaee a iaaa e aa ata e aaa aaiae reie E ie 64 EE E E E E ET 65 Onar E A E TN 66 Pile Menus a siete site Ae tied iid ere re ie es ae ee i 67 Edit Men sscsec eecksie teenin ereit aa ee EEVEE CE EEEE EaR EEEE EN e EEEa eE decnawecuasadoe sees 69 Animation Men siscsescodeiccsisctinadttieistovediaduntydiotsrertunadsbieislovernadantedeteudesasiealibitisboyedadiastae 70 Coordinates Menusa irran ree ire aE E i EE A EE EAA REE T eae 71 Options MENU ess ieoa e e ea eae E eia aE a E E a E eas e a a aa e aa EEA 73 Help Menuer snee e yae rear city eena REEERE EREE E oean SEREAS EEE KESE Erea oi Ear tHE 75 Pop Up Meir na es RE A EEEN Arns OSA E nEaN N oaa TNE SSN OERE a NaS 76 Time Control Slider oyes gee e eE eiee EE eae ae a a ed a edad a a 76 Testing Animator Data Sets sccsiiissa i
140. SimEd that is used for editing and viewing text files Yellow field a rectangular box for text or numerical information on a data screen that you can edit directly For example to change the vehicle wheelbase find the yellow field click on the field and change the value using the mouse and keyboard 244 Appendix B Vehicle Dynamics Terminology This appendix defines specialized terms applicable to vehicle dynamics solver programs The definitions draw on two sources 1 SAE Recommended Practice J670e Vehicle Dynamics Terminology first issued 1952 last updated 1976 2 ISO 8855 Road vehicles Vehicle dynamics and road holding ability Vocabulary 1991 This appendix is provided because neither of these two sources fully define the terminology that is now common in the field of vehicle dynamics simulation SAE J670e was last updated before solver programs existed for complex models ISO 8855 is more simulation oriented but is limited in scope Note SAE is in the process of replacing J670e with a version that includes more modern definitions Although the parts of J670 that are related to coordinate systems and basic terminology are complete it is the practice of SAE to discourage distribution of draft material Nonetheless the definitions in this appendix are thought to be compatible with the future version of J670 This appendix is intended to establish useful conventions for vehicle dynamics simulati
141. SimEd through text files If CarSimEd attempts to access non existent files error messages are generated However CarSimEd has a way to automatically update all filenames making this kind of error reasonably easy to prevent Moving CarSimEd to a New Location When you move CarSimEd to a different folder pathnames written in hundreds of text file are no longer valid they reference the old folder name and location It is also possible that the ToolBook program needed to run the database will not be found To avoid errors when you move CarSimEd be sure to follow the instructions in the Chapter 4 section Installing CarSimEd in a New Directory The key steps in this process are 1 Go to the CarSimEd startup screen 2 Click the Change Settings button to reveal more buttons 3 Click the button Update All PAR Files Changing Names of Data Sets The same kind of problem can occur when you import data from another copy of CarSimEd or when you change the name of a data set that is referenced from elsewhere in the database If you click the Run Simulation button and the solver stops with an error message that a file can t be found then there are two possible solutions 1 First go to the startup screen and click the button Update All PAR Files as described above 236 Chapter 11 Trouble Shooting 2 If that doesn t work there is probably a link to a data set that no longer exists because the original was deleted or re
142. SimEd works with SIMULINK SIMULINK is a separate software package from the MathWorks that is obtained and installed independently of CarSimEd Computer Requirements Operating Systems The complete software package runs under Windows 95 98 and NT Note The vehicle dynamics solver programs in CarSimEd are not specific to Windows Similar versions have been compiled and run on other operating systems such as UNIX Windows 3 1 DOS and MacOS However the animator plotter and graphical interface are currently available only for Windows 95 98 and NT Networks In general CarSimEd should not be run from a remote server If CarSimEd is posted on a network server you should copy the entire directory to your disk and run the local copy Installation is simple just copy the root CarSimEd directory and follow the instructions in Chapter 10 in the section Installing CarSimEd in a New Directory Although CarSimEd should not be run completely from a remote server it is possible to access data from a server For example you might have several standard vehicle data sets on the server that can be used as inputs for runs made on local machines However there are a few restrictions 1 The network must be configured such that the drive containing CarSimEd appears with the same volume name for all users e g drive R Portions of CarSimEd use full pathnames so it is essential that each pathname be valid for all users 2 It is recomm
143. T 66 Roll_WRR deg RR wheel inclination angle gen name Inclination angle rigibody name RR wheel OUT 67 Rot_WLF rev Rotation of LF wheel gen name Rotation of wheel rigibody name LF wheel OUT 68 Rot_WLR rev Rotation of LR wheel gen name Rotation of wheel rigibody name LR wheel OUT 69 Rot_WRF rev Rotation of RF wheel gen name Rotation of wheel rigibody name RF wheel OUT 70 Rot_WRR rev Rotation of RR wheel gen name Rotation of wheel rigibody name RR wheel OUT 71 Steer_LF deg LF road wheel steer angle gen name Steer angle at road rigibody name LF wheel OUT 72 Steer_LR deg LR road wheel steer angle gen name Steer angle at road rigibody name LR wheel OUT 73 Steer_RF deg RF road wheel steer angle gen name Steer angle at road rigibody name RF wheel OUT 74 Steer_RR deg RR road wheel steer angle gen name Steer angle at road rigibody name RR wheel OUT 75 Steer_SW deg Steering wheel angle gen name Steering wheel angle rigibody name Control OUT 76 Throttle Throttle input gen name Input rigibody name Control OUT 77 Vx kph Vehicle longitudinal velocity gen name Longitudinal velocity rigibody name Vehicle CG OUT 78 Vx_IErr m Integrated velocity error gen name Translation rigibody name Control OUT 79 Vx_LF kph LF wheel rolling speed gen name Effective rolling
144. T STEERING 27 par 45 INPUT BRAKING 75 par 45 INPUT FRICTION 23 par 45 COMP_PAR 41 par os i ee 2 a es A J iw used by animator program PARSFILE C CARSIMED 45 ANIMATE CAMERAS 244 par used by plotting programs PARSFILE C CARSIMED 45 RUNS 751 pl1 testid 751 title Base test EN 284 Appendix F Model Files and Keywords When you click the Run button a new PAR file is created in the folder containing the Runs library i e the Runs which contains Runs tbk file The PAR file contains information from the Runs screen As shown in the following example the file is relatively short Each link seen in the Runs screen is represented with a full pathname to an existing data file In the above example the data from the selected vehicle is contained in the file 58 PAR in the directory C CARSIMED 45 VEHICLES VEHICLES The keyword PARSFILE is similar to the INCLUDE directive in C or FORTRAN it instructs the program to open the specified file and to continue reading from the new file When the new file has been scanned to its end the program continues reading from the original file PARSFILEs are often nested five or six layers deep In order to view all of the parameters used in a simulation run you could trace the input files the same way as the program start with the Simfile to find the name of the input PAR file Then open the input file and view any
145. The process of checking the computer clock introduces a small delay The delay depends on the computer and how your system is set up 131 Chapter 9 Alphabetical Library Reference If the animation is already running slower than real time checking the computer clock will slow it down even more If the animation is running slower than real time and you want to speed it up you must decrease the target frame rate 6 Also select button to eliminate the delay caused by checking the clock Radio button for maximum speed animation keyword set_use_cpu_clock off When selected the animator does not access the computer clock allowing maximum display speed In general you should select this box if the animation is running slower than real time on your computer Viewing mode check box keyword set_superimpose When this box is checked the animator does not erase each frame before drawing the next It superimposes images The values associated with the keyword written into the text PAR file are on and off Grid color keyword set_color This is text that specifies the color of the grid Valid colors are provided in a pull down menu Grid intervals for X and Y keywords set__interval_x set_interval_y The units for these values are meters Minimum X and Y values covered by the grid keywords set_min_x set_min_y The units for these values are meters If not specified the default values are zero To ha
146. Tools Data set Yaw rate Md j I gt Hew Delete Go Back Changed ID 724 7 am O Hotes 12 46 23 Category Vehicle motion HBC Aaa 4 GIS O Locked 7998 far lnannnA Control Click here 2 Select the desired Runs library As installed the four options are 1 Runs_2d Runs_2d tbk 2 Runs_3d Runs_3d tbk 3 Runs_cmx Runs_cmx tbk 4 Runs_sus Runs_sus tbk Changing a Solver Program You will probably never have occasion to add new programs to CarSimEd However if you use the AutoSim code generator or are working with someone who is making custom versions of the CarSimEd models you might be given a new solver program This section explains how to install it 232 Chapter 10 Advanced Topics CarSimEd supports multiple solver programs When you click the Run Simulation button on the Runs screen CarSimEd searches an internal table for an entry containing the current type of vehicle and the current type of simulation Note box at the bottom of the Runs screen To see the type of simulation you must check the Show More For example in Figure 10 3 the vehicle type displayed above the Vehicle blue link is car and the Simulation Type G is 3D Vehicle Dynamics The table contains a corresponding pathname e g Programs 3d_car exe for a solver program that will be run when the Run Simulation button 2 is clicked Runs 3D Handling Fie Edit Text Page Tools Category
147. X The moment is taken about the mass center of the entire vehicle normal to an X axis longitudinal that is parallel with the ground when the vehicle is at rest on a flat level surface This value can be entered directly or it can be calculated using an estimated radius of gyration 11 and the associated button Estimate Ixx 10 Pitch Moment of Inertia of entire vehicle keyword IYY The moment is taken about the mass center of the entire vehicle normal to a Y axis lateral that is parallel with the ground when the vehicle is at rest on a flat level surface This value can be entered directly or it can be calculated using an estimated radius of gyration 12 and the associated button Estimate Iyy 10 Yaw Moment of Inertia of entire vehicle keyword IZZ The moment is taken about the mass center of the entire vehicle normal to a Z axis vertical that is parallel with the gravity vector when the vehicle is at rest on a flat level surface This value can be entered directly or it can be calculated using an estimated radius of gyration 13 and the associated button Estimate Izz 10 X Z Product of Inertia of entire vehicle keyword 1XZ The product is taken about the mass center of the entire vehicle and is defined as the negative of the volume integral Ixz ol Vasady 216 Chapter 9 Alphabetical Library Reference 0 The product is positive when the principal X axis tilts down l
148. Y coordinate m Car body Centerline 150 200 250 X coordinate m Tile Vert T Use this command to tile the plot windows with vertical divisions as shown below for two windows If there are four or more windows they are arranged in columns and rows FA winEP Yaw rate DLC OF x File Edit Format Data View Window Help Bly ys X trajectory DLC of x Biyaw rate DLC Of x Y vs X trajectory DLC Yaw rate DLC Y coordinate m Vehicle yaw rate deg s 4 10 Car body Centerline X coordinate m Time sec 108 Chapter 7 The Plotter Arrange Icons Use this command to tidy any iconized windows in the WinEP workspace Next Window Use this command to change the active plot window The keyboard command is the PageDown key If there are more than two plot windows keep pressing the PageDown key until the desired window becomes active Help Menu This menu has a command to open the About WinEP dialog box Use it to obtain the version number and the current web site for updates About WinEP 109 8 Design of CarSimEd Data Screens This section describes several standard elements in the CarSimEd design that are shared in many of the data screen All data screens have the same set of controls at the top in a ribbon bar All have the same menu bar Also data screens with tabular data have a common layout The Ribbon Bar Almost every screen in C
149. _cmex d11 which has the compiled CMEX model in the form of an S function When this process is completed in a few seconds MATLAB is running with a SIMULINK model in the foreground Start the run using the SIMULINK Start command from the Simulation menu The CarSimEd S function will read data from the CarSimEd database using information contained in the SIMFILE The integration method the start time and the time step are all obtained from SIMULINK However the stop time is read from the CarSimEd SGUI Making Additional Runs in SIMULINK After the first run is made you might want to make more runs using different vehicle parameters If you change any vehicle properties in the CarSimEd SGUI set up a new run by clicking the button Update on the Runs screen to create a new SIMFILE step 1 above Then make the new run by selecting the Start command from the Simulation menu in SIMULINK Discussion of SIMULINK CarSimEd Integration There are two tricky parts about making a run with CarSimEd and SIMULINK together 1 The directories used by CarSimEd must be properly communicated to MATLAB 2 Because the input files from the CarSimEd SGUI are controlled from the CarSimEd Runs screen and the simulation is controlled from the SIMULINK screen it is up to you the user to assure that inputs are properly updated before a run is made Chapter5 The Solver Programs With respect to the first item directories the PIF is used to set up a workin
150. a Car Hood A ot zl Link 12 shapes Link 17 FETTE Link 4 shapes Car LF Fender I Car LR Door si ou Car LF Door 1 x set_scale_y 1 set_scale_y 1 Link 5 shapes 2 2 Car LF Fender 1 x Link 6 shapes Link 13 TI Link 18 ace ae nn Car LF Light O on Car LR Fender A on Link 7 shapes Car LF Window 1 x set_scale_y 1 set_scale_y 1 Link 8 shapes C Car LR Door 1 x Link 9 shapes Link 14 shapes Link 19 shapes Cer LR Fender 1 Car LR window 1 LR Window 1 x cer RWindow 1 R Window Link 10 shapes Link 15 shapes Link 20 group Car LR Light 1 x Car R Bumper 1 xi Sedan more 1 This data set is locked Unlock data set to view the context sensitive help in this status bar Figure 9 2 Animator group for body assembly When combining reference frames and other data sets be aware that the data are sent to the animator in the same order they are numbered on the screen top to bottom then left to right If one of the links is to a reference frame it should be the first one Link 1 That becomes the active reference frame until another one is defined 134 Chapter 9 Alphabetical Library Reference Resizable Vehicle Shapes A recently added feature of the animator is the support of resizable shapes Coordinates in shapes associated with a reference frame can be re scaled in the X Y and Z directions by these ratios e X coordinat
151. a Properties Entire Vehicle Roll inertia dixx 1669 __Jkgm2 Pitch inertia lyy 6172 kg m2 Yaw Inertia izz 6172 kgm2 Product iez ___0 0 komz Optional Radii of Gyration Estimatelex R 65 m Estimate ias Ry 125 m Estimate tzz Rz _125 m Estimate inertia with eq I M R degideg je Rael EY Coa Aligning moment Me is applied to both road wheels with the steering wheel locked NemMPa NemMPa Front gain 500 Nan Rear gain 500 Nem drive Torque one whee ver np Front Suspension Rear Suspension HMMWV Front Hw Rear z Front Tire Rear Tire Animator Group Example HMW Tire z Example HMA Tre x MMV body 7 7 17 99 A data screen is a view of one data set through the simulation graphical user interface SGUI CarSimEd is composed of individual data sets in a library of the database Figure 3 1 Contents of a CarSimEd Library Chapter3 3 Database Organization Libraries A library is a collection of one or more data sets plus the information needed to provide a view in the user interface Figure 3 1 shows the contents of a library multiple data sets plus a graphical view of one data set at a time The CarSimEd database CarSimEd includes about 30 libraries The Simulation Graphical User Interface SGUD The architecture of CarSimEd is called the SGUI It includes the d
152. a library This manual has many references to the act of going from one screen to another Changing the screen means taking an action that changes the view to show data in a different library SGUI Simulation Graphical User Interface The architecture of CarSimEd data screens plotter solver programs animator has been used for other software packages The generic architecture created at UMTRI and currently developed and maintained by MSC is called the SGUI SIMULINK a software package for modeling simulating and analyzing dynamical systems in general It runs under MATLAB SIMULINK and MATLAB are available from the MathWorks Inc Versions of the CarSimEd models CMEX DLL files are provided for users who wish to run in the SIMULINK environment Solver program a program that numerically solves the equations of motion of a vehicle model to simulate a test The CarSimEd solver programs are customized with the equations of motion for specific vehicle models They handle all required calculations and input output TBK files binary files that contain the CarSimEd libraries In addition some of the code needed to make the CarSimEd buttons work is stored in TBK files All necessary TBK files are provided in the CarSimEd installation and they are managed automatically by CarSimEd TBK files are native to the ToolBook software ToolBook a Visual Authoring System from Asymetrix Inc The SGUI is largely pr
153. abels that are too long are truncated to fit in this space Location in CarSimEd CarSimEd Startup Runs Plot Setup Single Plot Format File Location Plot Format Format tbk Plot Setup Batch The batch plot screen is used to combine a list of runs with a list of plot conditions to automatically generate a set of plots Plot Setup Batch 41 i new pete Go Baek Bor ee oe4lols fruns_2dvuns 2dihk 1 pitisetupisetuptok 7 Brake Pressure Input Mybrk brake torques Mydry drive torques Vx wheel speeds Tire Fz vertical torce 11 lt Vehicle motion Az vert accel of CG 179 Chapter 9 Alphabetical Library Reference Description The standard Runs screen allows multiple plots to be specified and the results from multiple runs to be overlaid However it is limited to four plot setups and three runs If you want to trigger more plots with one button click or overlay data from more than three runs use this library User Settings and Controls Runs Library link This pull down menu has two options 1 to go to the currently selected library or 2 to pick a new library The linked library must be a runs or simulation library that has corresponding ERD files When you pick a new library the field below is automatically updated to show the names of all of its data sets Runs list List of all of the data sets in the currently selected Runs library Any line in brackets
154. ach X Y data set There must be a total of 20 symbols indicated Symbol key 0 No symbol 1 Square 2 Triangle 3 Diamond 4 Cross X 5 Plus 6 Circle LINESTYL sJ s2 53 520 Line style for each X Y data set There must be a total of 20 styles indicated Line style key 0 No Line 1 Solid Line 2 Dotted Line 3 Heavy Solid Line 4 Dash Line 5 Dash Dot Line 6 Dash Dot Dot Line 267 Appendix D Plotter Files and Keywords LEGENDLABEL bJ b2 b3 b4 Names to use in creating the legend Values are 0 do not b5 b6 use or 1 use The sequence is bl shortname b2 longname b3 genname b4 rigidbody name b5 file title b6 file name LEGENDLOCATION name Location in plot window for legend Options are toLocation RightOfPlot OnPlotUpperLeft PlotUpperRight OnPlotLowerLeft and lotLowerRight GRID type Type of grid Options are NoGrid CoarseGrid and FineGrid COLORS c1 c2 c3 c20 Color for each channel There must be a total of 20 colors indicated Color key 0 Black 1 Maroon 2 Red 3 Green 4 Bright Green 5 Dark Blue 6 Light Gray 7 Light Blue 8 Blue 9 Muddy Yellow 10 Yellow 11 Gray 12 Purple 13 Teal 14 Bright Purple To apply the format settings from a file load the format file using the File menu command Load Plot Format To create a format settings file use the File menu command Save Plot Format 268 A
155. all including locked sets or only the unlocked data sets To Delete an Arbitrary Group of Data Sets 1 Click the CF button in the ribbon bar or select the Tools menu item Library Editor This brings up the floating palette shown in Figure 4 6 It has controls for selecting data sets by their titles and a button for deleting the selected data sets all at once Making Five or More Plots for a Single Run The Runs screen has links to set up four plots If you want to quickly generate five or more plots you can use the Plot Setup Batch screen shown in Figure 4 8 Start from any CarSimEd data screen 1 Click the button in the ribbon bar or use the Batch Plotting command from the Tools menu This takes you to the Plot Setup Batch library 2 Go to a data set in the library that is linked to the current Runs library As installed the library contains a single data set linked to the CarSimEd Runs library 48 Chapter 4 The Basics of Using CarSimEd 3 Click the New button 15 to create a new data set for your new combination of plots and runs Using the Add 3 and Remove 4 buttons for the Data Files put the name of the run of interest into the field with Selected Data Files 6 Using the Add 9 and Remove buttons for the Plots put the names of all Plot Setups of interest into the field named Selected Plots 11 Click the Make Plots button 14 This starts the program WinEP and instructs it to make one plo
156. ams 3D Car 2D Ride and Suspensions Analysis and the other is for running with SIMULINK These screens are nearly identical in appearance and function This section 196 Chapter 9 Alphabetical Library Reference describes two buttons that are unique to the SIMULINK version along with the links to the vehicle and simulation type These are the four numbered items in Figure 9 11 All other features are the same as in the stand alone version and are described in the next section Runs 3D Handling S Runs SimuLink CHEX Version OF x File Edit Text Page Tools Data set Acceleration in a turn w 41 I gt New Delete GO v Back Changed ID 844 CO Hotes 11 58 10 Model Parameters amp Inputs Run amp SimuLink Control Output amp Post Processing Vehicle Classic car G Generic SS MStar SimuLink Updatey Animate Input Steer Speed kmh Stop sec MU Camera Setup 30 deg step steer s JL gt Input Braking Computation Parameters NoBraking Braking and Driveline dt 001 x View Echo File All Parameters Input Throttle Simulation Type Multi 2 Multiple Plots gt vero nie Ny Plot__ Fi Overtey ans Plot 1 Setup Ax long accel of CG x Plot 2 Setup Vx wheel speeds x Plot 3 Setup Fx long forces x Plot 4 Setup Mydry drive torques x O Show More Figure 9 11 The Runs screen for SIMULINK User Settings O Link to ve
157. and a small value produces a wide angle lens effect Focal length has units of meters X Y and Z coordinates of the camera point keywords set_camera_x set_camera_y set_camera_z These coordinates have units of meters The coordinates apply to the reference frame specified in G 130 Chapter 9 Alphabetical Library Reference G Link to the reference frame in which the camera is located The reference frame can be fixed or moving The camera must have its own named reference frame in the example above itis Camera tracking X Y Notes The animator program requires each reference frame to have a unique name The reference frame used to define the camera coordinates cannot be used anywhere else If you want to position the camera in a vehicle reference frame e g the sprung mass then create a copy of the reference frame of interest give the copy a new name and link to the copy Although vehicle reference frames can be used for the camera it is more common to define a custom reference frame 4 X Y and Z coordinates of the Look Point keywords set_lookpoint_x set_lookpoint_y set_lookpoint_z These coordinates have units of meters The coordinates apply to the reference frame specified in G Link to the reference frame in which the look point is located The reference frame can be fixed or moving It is typically the same as the camera point reference frame G Unlike the camera reference frame the loo
158. and an aligning moment M3 Fx Fy Fz and M are applied to the axles and reacted by the ground as shown in Figure H 1 Overturning moment My and rolling resistance moment My have an insignificant influence on vehicle braking and handling behavior and are ignored F is determined by assuming the tire behaves as a linear spring when deformed vertically F Fy and M are more complicated to compute Tire Wheel Kinematics Most of the arithmetic operations in the expressions for tire forces and moments arise from deriving expressions for various kinematical quantities associated with the tires wheels It is necessary to 1 define a point where the tire forces act on the multibody model 2 establish the unit vector directions for the tire X and Y directions tx and ty respectively given the ground normal rz and 3 determine expressions for K and a These steps are explained below Center of Tire Contact The tire model in CarSimEd makes use of a point called the center of tire contact CTC for the definition of the location of the tire on the ground the calculation of slip angles and the point of application of tire forces In the nominal configuration in which the 307 Appendix H The Tire Model vehicle is at rest in equilibrium on a flat level surface CTC corresponds to the point We shown in Figure H 1 CTC remains in the ground plane as the wheel moves up and down For a flat surface the kinematical expressions
159. and return to the status as installed If a default library file is already in the field it is not added again 6 Add Libraries button Use this to add new libraries files to CarSimEd For example if you have so many data sets in a library that it is unwieldy you can duplicate the TBK file and its folder then delete all but one data set from the copy Give it a new name and add it to the system Click the button to bring up the Windows Find File browser dialog TBK files selected with the browser are added to the list 4 FE Library Please locate library OK File Name Directories Lox startup tbk cs EJ trucksim si C animate batch comp_par generic List Files of Type Drives f tbk Sc Note You can add more than one file at a time After you click OK the dialog re appears When you are through adding files click the Cancel button 153 Chapter 9 Alphabetical Library Reference Remove Libraries From List button Click to remove any selected lines from the list 4 The actual files are not affected by this only the list is altered Move to Top button Click to move any selected lines in the list to the top For example to make the 3D Runs library the first item on the GO menu select the line RUNS_3D RUNS_3D TBK in the list 4 and then click this button Move to Bottom button Click to move any selected lines in the list to the bottom S
160. and the other is for running with SIMULINK These screens are nearly identical in appearance and function This section describes the 3D version in full detail Three other sections describe the differences between those screens and this one The Runs screen controls all aspects of a CarSimEd simulation Regions of the Runs Screen Notice that the screen image is divided into three regions see Figure 9 9 1 Model Parameters amp Inputs this has links to inputs to the computer model including the vehicle and control inputs 188 Chapter 9 Alphabetical Library Reference 2 Run Control this includes parameters that control the extent of the run and a button to make the run 3 Output amp Post Processing this has controls for viewing outputs generated by the run The Runs screens is special within CarSimEd because it has several buttons that cause other programs to run and do things run a vehicle simulation animate results show graphs of output variables However like all the other screens covered in this chapter it defines a data set within a library In this case the data set defines the conditions covered by a run Data in the left most two regions do not have anything to do with outputs of a run They define the inputs and parameters that will be used in the computer model if and when a run is made In order to have an effect changes must be made before a run is made At any time 1 any of these input
161. and to exit WinEP To use the keyboard type the keyboard command Ctrl Q or Alt F4 or Alt F X Note Alternatively you can click the x in the upper right hand comer of this screen to return to the Runs screen Edit Menu The Edit menu has commands to support the clipboard and to set preferences When a dialog box is in front the Edit menu cannot be used with the mouse However the keyboard commands are functional and can be used to cut copy and paste within text fields Unde nt LA mijt Copy Ctrl C Paste trl Py Preferences Undo Undoes the most recent change in a dialog box The keyboard command is Ctrl Z Chapter 7 The Plotter Cut Cuts currently selected text to the clipboard This item is only in effect when editing text in dialog boxes Modification of the graphic display is not supported The keyboard command is Ctrl X Copy This command copies the plot from the active plot window to the clipboard The graphic is copied as a bitmap If a dialog box is active this command copies currently selected text to the clipboard The keyboard command is Ctrl C Paste Pastes text from the clipboard into the current cursor location If text is selected it is replaced by the contents of the clipboard This item is only in effect when editing text in dialog boxes Modification of the graphic display is not supported The keyboard command is Ctrl V Preferences This command brings up the Preferences dialog box
162. animating simulation results as wire frame representations of vehicles AutoSim a code generator that was used to create the solver programs in CarSimEd AutoSim originated at UMTRI and is now licensed maintained and supported by MSC Blue field Blue fields with adjacent triangle buttons are common in CarSimEd Each represents a link to another data set The name of the data set is shown in the blue field and the triangle button is used to display a pull down menu see Link CarSim the commerical version of CarSimEd CarSim can be licensed in several forms from MSC CarSim comes with more detailed vehicle dynamics models that include a driveline 3D ground input wind and variable ground friction Many of the linear coefficients in the CarSimEd models are replaced with nonlinear tables in order to accurately simulate a wider range of conditions CarSimEd an integrated software package for automotive vehicle dynamics simulations CarSimEd short for CarSim Educational is free and can be downloaded from the MSC web site www trucksim com Unless otherwise noted the name CarSimEd refers to the basic package with stand alone solver programs EXE files and MATLAB SIMULINK DLL plug ins CarSimEd database the collection of all data libraries within CarSimEd CarSim Educational see CarSimEd CMEX an executable module for MATLAB SIMULINK that was created by compiling C code The CMEX versions of the CarSimE
163. apter amp Design of CarSimEd Data Screens Buttons Library triangle button Press this button to display a pull down menu listing of all of the data sets in the library grouped by categories Data set Stepsteer car sd Stepsteer car sd car Constant Radius Test car Category O O00000 O O til EEEE in a tum Constant Speed Test car Braking in a turn Double Lane Change Sine steer Rollover Step steer car Figure 8 1 Pull down menu by the Data Set field Library Left button The data sets in the library are ordered alphabetically first by category and then by title Click this button to go to the preceding data set If the current data set is the first one this button takes you to the last one the ordering is circular Library Right button The data sets in the library are ordered alphabetically first by category and then by title Click this button to go to the next data set If the current data set is the last one this button takes you to the first one the ordering is circular New button Click this button to make a full copy of the data set The copy is identical to the original except that the name will be different usually it will have a number appended to it When the copy is made the Data Set field will be highlighted to encourage you to type a distinctive title for the new data set Delete button Click this button to delete the data set When you click the Delete button two t
164. ar 8 Repeat steps 4 through 6 In this case the change you will make is to select the new data set you created in the library one level down Use the blue link that connects to the library in which you just added a data set 9 Repeat steps 7 and 8 until you are back at the Runs screen At this point you can make a new run or modify the current run Either way you will select the new vehicle data set from the linked library of vehicles Example Suppose you are going to change the spring in the front suspension of the car Starting from the Runs screen you would do the following a b Go down to the vehicle data set Go down to the front suspension data set Make a new suspension data set and then change the spring rate Return to the vehicle data set Make a new one and change the suspension link to use the data set created in step c Return to the Runs data set Make a new one and change the vehicle link to use the data set created in step d Click the Run Simulation button Modifying an Existing Vehicle Description Use the following method to modify an existing vehicle description Start from a Runs screen see Figure 4 1 on page 30 1 Find an existing data set that involves the vehicle whose description you will modify 2 Go down to the linked vehicle data set Change any yellow fields or blue links as needed 42 Chapter 4 The Basics of Using CarSimEd 3 Repeat step 2 to go down more
165. arSimEd database and can be applied easily to any plots 176 Chapter 9 Alphabetical Library Reference initiated from within CarSimEd clicking the Plot button from the Rums screen or the Make Plots button on the Plot Setup Batch screen User Settings O Lines and symbol specifications keywords symbols linestyle colors Clicking on a number or line will bring up the Plot Line palette shown below The palette applies to the highlighted line number For example line 2 is selected in the figure Lines Click on number to access line palette Xx and Y Axes Axes Plot Line Palette Use the navigation keys to select a different line Hold the control key downto change all lines gg V Uata ets VY ams RigidBody Name Y When the above ida 14 Choose the color line style dotted thin thick and the symbol for the selected line To change a different line click on a different line number or use the up and down arrow keys To change all of the lines at once hold down the control key when selecting the style color or symbol 2 Axis selection The button has a pull down menu with two options no axes or axes The current selection is shown in the white field 3 Frame selection The button has a pull down menu with three options no surrounding frame a rectangular frame or a frame with tick marks The current selection is shown in the white field 4 Grid selection The button has a
166. arSimEd has a standard ribbon bar at the top It contains the name of the data sets information about the last time the data set was modified and a number of navigational controls lel Es 2 ID TO a 4 Runs 3D Handling Fie Edit Text Page Tools Data set Braking ina tum in a turn mirren e Category 90090000Q Q ee s er ete cor Back Fields O Data Set field This field shows text entered by you the user to name the current data set There are a few restrictions on titles 1 each data set in the library must have a unique title 2 the title cannot include a comma the software will automatically replace it with a semicolon and 3 the length of the title is limited to 32 characters Note On the Runs screen this is where you give a unique name to the run of a specific vehicle maneuver and simulation model In a vehicle screen it typically serves to identify the vehicle and its properties and so on for other screens 2 Category field This field shows text you use to create a sub menu for listing the contents of the library The Category field is provided as a convenience for you to divide large numbers of data sets into logical groups in pull down menus as shown in Figure 8 1 If the category field is blank then the title is shown in the top level menu Note Data sets in different categories are still subject to the restriction that they cannot have the same names 110 Ch
167. are optional If not specified the animator uses a value of zero for that variable After reading the six variables each coordinate and Euler angle is calculated with a relationship of the form coordinate Co C SFe angle Ag A SFag where C and A are the translation and angle variables obtained from the ERD file Co and Ao are the constant offsets and SF and SF are scale factors gains The offsets and scale factors are specified by the keywords shown in Table E 2 set_offset_var_x set_offset_var_y etc The scale factors are commonly used to convert angles to degrees from radians or revolutions The offsets are used in some other applications to convert relative coordinates to absolute coordinates The keyword set_euler_angles is used to specify the type of transformation used There are two options yaw_pitch_roll used for vehicle sprung mass reference frames and yaw_roll_pitch used for rolling wheel reference frames Scope of the Reference Frame The scope of a reference frame begins when the keyword add_reference_frame is encountered and continues until this keyword is used again to start the scope of a different reference frame All of the keywords shown in Table E 2 can be repeated several times in a file Each time the value associated with the keyword is applied only to the current reference frame as defined by the previous add_reference_frame command Within the scope of each moving frame you should specify
168. as options for deleting a simulation type and for specifying exactly which EXE file will be run when you click the Run Simulation button CarSimEd allows you to associate EXE files and PIFs Program Information Files with the Run Simulation button If you want to link to a software package that requires arguments the way to do it is to make a PIF with the desired properties and then link to that When the Windows file dialog box comes up it is set to show only EXE files If you want to link to a PIF change the extension in the dialog box from EXE to PIF in order to see the PIFs See the Chapter 5 section Changing A Solver Program for instructions on using this menu 194 Chapter 9 Alphabetical Library Reference Q Misc Data field This is a field where any parameter can be set The format for each line of text should consist of a parameter name then a blank space and then the parameter value This field can contain any text that would be recognized by the solver program See Appendix F for a list of all the keywords and parameters that can be specified This link is provided for special applications Most users never need it A few cases where you might consider using it are e to override a parameter to perform a quick what if run without making new data sets in other libraries e to set some of the seldom used parameters that are not contained in any of the CarSimEd libraries for example the
169. ase a simulation program Figure E 1 Animator input files The motions predicted in a simulation are defined by variables that are written in the ERD file that is written by the solver programs whenever a run is made Appendix C provides details of the ERD file format and Appendix J shows a list of variables contained in a typical CarSimEd ERD file Overview of a PARSFILE Most information about objects and how they are viewed is read from an input PARSFILE Listing E 1 shows part of a PARSFILE 271 Appendix E Animator Files and Keywords Listing E 1 PAR file with some animators settings parsfile parsfile generated 10 13 99 12 04 09 _camera_reference_frame camera tracking x y z _camera_x 1 000000 _camera_y 50 000000 _camera_z 0 000000 t_focal_length 0 100000 _lookpoint_reference_frame body _lookpoint_x 1 500000 _lookpoint_y 0 000000 _lookpoint_z 0 000000 set_use_cpu_clock off set_superimpose off end A PARSFILE can contain several kinds of information 1 numerical constants such as coordinates of points 2 names of variables in the ERD file that must be read by the animator 3 names associated with objects e g body and 4 pathnames for linked PARSFILEs with more data In all cases white space immediately following the keyword is skipped and the remainder of the line is interpreted as the value to be assigned to an internal variable Spaces are significant after
170. ata The second line of the file shown in Listing C 1 shows that the file contains data for 2 channels with 529 samples channel stored as 1 binary record consisting of 4232 bytes that the data storage format is type 1 4 byte binary that the interval between samples is 1 00 and that the status of the auxiliary numbers is 1 258 Appendix C ERD File Format Table C 1 Summary of records in an ERD file header 1 ERDFILEV2 00 identifies file as having ERD format 2 NCHAN NSAMP NRECS NBYTES KEYNUM STEP KEYOPT use commas to separate numbers NCHAN integer Number of data channels NSAMP integer Number of samples for each channel The total number of sampled values in the data portion of the file is NCHAN x NSAMP If unknown use 1 NRECS integer Number of records of data record line Ignored for text data KEYNUM 5 If unknown use 1 NBYTES integer binary data Number of bytes per record If KEYNUME 0 1 or 5 this should be chosen such that each record begins with channel 1 that is NBYTES K x NCHAN x B where K is an integer and B is the number of bytes number B 2 for integer B 4 for floating point If KEYNUM 10 1l or 15 this should be NSAMP xB text data Number of samples per record Thus each record contains NBYTES x NCHAN numbers for KEYNUMSS5 KEYNUM integer Indicates how the data are stored 0 10 2 byte integer binary 1 11 4 byte floating point binary 33 15
171. atabase the code for managing the database plus utilities such as the plotter and animator CarSimEd automatically handles the transfer of information between the libraries and solver programs You do not have to know where the libraries are file names or what they contain file formats However it is important to understand the distinction between data screens data sets and libraries Specifically you should understand that Each CarSimEd data screen shows one data set from the library associated with the screen title Changes made on a data screen affect the one data set but all other data sets in the library are unaffected Links between data sets can be made and broken as you see fit In this way vehicles components inputs etc can be rapidly swapped When a data set is changed simulation results will be affected only if a the changed data set is linked to the run and b the simulation is run again after the changes were made Data Screens Common elements in a data screen are introduced for the example screen shown in Figure 3 2 Each data screen has three kinds of elements that you use 1 Yellow fields These contain data that you can edit directly For example to change the vehicle wheelbase find the yellow field G with the current wheelbase value click on the field and change the value using the mouse and keyboard Buttons All of the library screens include buttons at the top to quickly navigate
172. ating new shapes or other animator inputs as described later in this chapter in the section Testing Animator Data Sets on page 77 Save Parsfile As Select this command to save most of the animator settings The animator data from the CarSimEd SGUI are spread over the animator libraries described in Chapter 9 Multiple shapes and reference frames are commonly used which means that the animator program might read 20 or more PARSFILEs when it runs This menu command creates a single PARSFILE with all of the information consolidated 67 Chapter 6 The Animator This PARSFILE can be used later as an input to the animator to exactly recreate the current settings The file can also be viewed in a text editor to debug inputs that cause problems or to obtain camera and look point coordinates that were set interactively using the Coordinates menu When you select this command it displays the following dialog box The numbered items in the dialog box are described below o ee Exit Write Echo Parsfile xi Save to file 2 Si i c wehsim 1 animate echo par l wi 1 Cancel File Options v Include Shape and Frame Definitions Include Grid Definitions Include Path Definitions Include Camera Definitions Include Lookpoint Definitions Pathname for the file to be created The default is echo par in the same folder as the animator program You can type a new pathname in this field or
173. ault Runs Library eeeeeeeeeeeeseeseesessrsrsrsrsrsrererersrsrsrersrererererererersrereee 232 Changing a Solver Program 5 0 0seseeesedesenese detours denonenectoneneddsonenedeenereddeonenetenonees 232 Changing the Default Text Editor cernis eee eecccccccccceceeeceeeeeeereeeeeeeeeeeeeeeeeeeeeeeeeeee es 234 ti Trouble SO OLN coer titan ore aae ESEE EEA EES E td SEEE EKSE E Aans 236 Fil System Brrors s cc aryiceg ee eaeoe ean Eriein a a atena ache es Oh Ae adeeb aa it 236 Database ToolBook Problems ccceseecccesseececeaeeececeeaeseeceaseeseeeaseneeeeaaaeeeeaaaeeeeeaa 237 Solver Prosrams 433 wie Aiea avid Be aye ae a Bas 239 Plotter and Wire Frame Animator cceccccceccceccccceceeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee es 239 Appendix A Glossary niiin sioria iena ei A a Ging while Manaulaaes 241 Appendix B Vehicle Dynamics Terminology s sesesesesesesesesesesesesesesrsrereseeeeees 245 Vectors and Angles cs s2 svete iraga a Ea ae sit ys peed aE Mh aan ete ees 246 Axis Systems and Coordinate Systems ccececccceccccececceceeeeeeeeeceeeeeeeeeeeeeeeeeeeeeeee es 247 Britire vehicle s scs2sss errara da neh ate fe EE atdeanes one dates ate de chiens E AA E ES EEA 250 Suspensions and steering sissen agesi a leas shes epeay a i snes E ai 253 Tires And Wheeled n a a A cote ays atte A A A E ays A E te 255 NOUS ra Sees sas Beach cehc svat Leese aad EAA EE EEA a fostea necks ebpsedesebaateenses tu
174. based on the spring rate the mechanical advantage of the suspension and the track width The total roll stiffness may differ from the rate calculated for the springs alone Additional stiffness is provided by anti sway bars and by over constrained suspension linkages On the other hand compliance in the suspension can sometimes result in less roll stiffness than would be predicted from the spring rates In this case you would specify a negative value for auxiliary stiffness 206 Chapter 9 Alphabetical Library Reference Coefficient for change in toe per change of tire longitudinal force keyword CTFX IAXLE A forward tractive force tends to bend a suspension forward steering the wheel inward positive toe Therefore this parameter is likely to have a small but positive value Coefficient for change of steer angle per change of tire lateral force keyword CSFY IAXLE For wheels which can be steered the steer axis is usually inclined to intersect the ground in front of the center of tire contact Thus a positive lateral force to the left acting behind the steer axis usually causes some steer to the right negative This coefficient is therefore likely to have a small negative value for a steered wheel For rear wheels is should have a value close to zero Coefficient for change of steer angle per change of tire aligning torque keyword CSMZ IAXLE The suspension element
175. button e Click the START button Exporting Data to Other Plotting and Analysis Software CarSimEd is designed for rapid viewing of simulation results using the installed plotting and animation software However the software also has provisions for exporting simulation results to other software packages for analysis and viewing Two methods are described below 223 Chapter 10 Advanced Topics C0 i es ee Creating Text Output Files from the Solver programs By default the output files generated by the solver programs store numerical values in binary format This speeds up reading and writing and also conserves disk space Alternatively the output data can be generated into text files This file contains all output variables and can be imported into other software Start from the Runs screen Go down to the linked Computation Parameters data set Click the New button to create a new data set Change the output file format to Text or ERDText use the adjacent button to access a pull down menu e The Text option will cause the simulation to create a simple text output file with a 1 line header followed by columns of numbers The items on each line will be separated by commas These files can be imported into spreadsheets and analysis programs that allow comma delimited columns However they cannot be plotted or animated using the built in CarSimEd tools e The ERDText option will cause the simulation to create a text output
176. c Tire SAE Paper No 900129 1990 2 Bernard J E Clover C L Tire Modeling for Low speed and High speed Calculations SAE Paper No 950311 1995 3 H Radt Tire Data Treatment Chapter 14 of Race Car Vehicle Dynamics W F Milliken and D L Milliken SAE 1995 pp 473 487 317 Appendix The CarSimEd Steer Controller This appendix describes the theory and application of an algorithm used to control a road vehicle to follow a prescribed path The technique was developed by Charles MacAdam of UMTRI in 1980 1 2 and has been used in various forms in many computer programs since then In recent research for the Federal Highway Administration FHWA the algorithm has been streamlined and re formulated to work with roadway centerline geometry Optimal Control Theory The algorithm is intended to provide optimal control for a linear system xX Ax Bu 1 y Cx Du 2 where x is an array of n state variables u is a control input y is an output variable of interest and A B C and D are matrices with constant coefficients The control objective is to determine the optimal value of u to causes the predicted output y t to match a target trajectory ytarget t over some previewed time T In the above equations A is an n X n matrix In the general case u and y could be arrays involving more than one control and or output variable However in this derivation the only case considered is the one in whic
177. cal position Z ZR coordinate of the C G X position X Xp coordinate of the C G Y position Y Ypg coordinate of the C G Translational Motion Lateral acceleration Ay Y component of acceleration vector of the C G SAE ISO 4 Lateral velocity Vy Y component of velocity vector of the C G SAE ISO 4 Longitudinal acceleration Ax X component of acceleration vector of the C G ISO 45 Longitudinal velocity Vx X component of velocity vector of the C G ISO 4 5 Vertical acceleration Az Z component of acceleration vector of the C G ISO 4 6 Vertical velocity Vz Z component of velocity vector of the C G ISO 46 Angles Aerodynamic sideslip angle Baero angle from X to velocity vector of air relative to the vehicle reference frame SAE 251 Appendix B Vehicle Dynamics Terminology Euler angles y 8 6 sequence of consecutive rotations about Zp Y and Xv axes to convert from the earth fixed axis system to the vehicle axis system Note that is not identical to roll Ov SAE ISO The relationship is 6 sin sin y cos Pitch angle from X to Xy about Y SAE ISO 8 can be calculated using a vector dot product 6 sinl Xy T Roll y angle from Xg x Yg plane to Yy about X SAE ISO 3 Roll can be calculated using a vector dot product dy sin Yy Zp It can also be calculated from the Euler angles O and 0 dy sin cos 6 sin Sideslip a
178. ce through CTCRR Magnitude FYRR Direction z 252 nx z 249 ny FZLF LF vertical tire force Acts on the If wheel from the inertial reference through CTCLF Magnitude FM 11 Direction nz FZLR LR vertical tire force Acts on the Ir wheel from the inertial reference through CTCLR Magnitude FM 12 Direction nz FZRF RF vertical tire force Acts on the rf wheel from the inertial reference through CTCRF Magnitude FM 13 Direction nz FZRR RR vertical tire force Acts on the rr wheel from the inertial reference through CTCRR Magnitude FM 14 Direction nz 4 Moments MZLF LF tire aligning moment Acts on the If wheel from the inertial reference Magnitude MZLF Direction nz MZLR LR tire aligning moment Acts on the Ir wheel from the inertial reference Magnitude MZLR Direction nz 305 Appendix G The 3D Car Model MZRF RF tire aligning moment Acts on the rf wheel from the inertial reference Magnitude MZRF Direction nz MZRR RR tire aligning moment Acts on the rr wheel from the inertial reference Magnitude MZRR Direction nz References 1 M W Sayers and D S Han A Generic Multibody Vehicle Model for Simulating Handling and Braking Vehicle System Dynamics Vol 25 supplement 1996 2 Segel L Keynote Address Some Reflections on Early Efforts to Investigate the Directional Stability and Control of the Motor Car Transportation S
179. centage a factor of 100 higher than the ISO definition ISO uses the symbol Sxw instead of K K is used by Pacejka 99 66 SAE uses the names aligning torque rolling resistance moment and wheel rolling moment and driving moment 39 66 torque for aligning moment respectively ISO uses the names lateral force at wheel longitudinal force at wheel and vertical force at wheel SAE uses the name normal force for negative force relative to the SAE Z direction and vertical load for the negative of normal force SAE calls compressive suspension deflection compression SAE does not define the point about which aerodynamic moments are taken 257 Appendix C ERD File Format The ERD file format was developed by the Engineering Research Division ERD of the University of Michigan Transportation Research Institute UMTRI to facilitate automated plotting of simulation data experimentally measured data and data from various analysis programs A freely available plotter called EP Engineering Plotter has been developed for viewing data in ERD files Versions of EP exist for the Mac and Windows platforms The Windows version is called WinEP The animator program embedded in CarSimEd is also designed to work with ERD files An ERD file contains two independent sections the header and the data The header contains only text and the data sect
180. cho file has the extension LPF and is similar to the file listed in Appendix F If the run has not yet been made or if it aborted without writing the LPF file then the text editor will show a blank window If you click this button and get an error message or a file browser dialog as shown below then CarSimEd could not find the text editor Please locate a text editor File Name Directories mplayer exe AS EJ windows mshearts exe nbtstat exe net exe sym netdde exe I command netstat exe J config notepad exe E cursors packager exe List Files of Type Drives exe Pa Sc The default text editor is a program called WinVI Winvi32 exe located in the Programs directory If you want to change the default text editor you can Control click this button to bring up the file dialog and choose a different text editor Plot button Click to view a plot of output variables calculated during the simulation run The plots are drawn by the WinEP program An error message will be printed if the output file does not exist for example if the run has not yet been made Up to four separate plots can be automatically generated each with many variables taken from up to three runs In order to generate more than one plot the Multiple Plots box 12 must be checked The plot s shown by the plotter are defined by the linked plot data sets 14 12 Multiple Plots check box This check box has two effects 1
181. click the Start Simulink button 2 or the Update button G the CarSimEd database writes the simulation control file SIMFILE into the folder associated with both the current simulation type and the vehicle type Simulation Type ABS Model Matlab Simulink Add Delete gt Find solver for gt ABS Model Matlab Simulink 198 Chapter 9 Alphabetical Library Reference The menu lists all of the installed simulation types followed by three utility commands Note CarSimEd supports multiple solver programs and this link is the interface to them When you click Start Simulink or Update buttons CarSimEd searches a hidden table for an entry containing the current vehicle type displayed above the blue link in Figure 9 11 the vehicle type is independent and also the simulation type Simulation Type in Figure 9 11 where the simulation type is Vehicle Model The table contains a corresponding pathname e g mat lab is_cmex matlab pif for the MATLAB PIF associated with the vehicle type and simulation type When new SIMULINK models are made they can be added to the system without replacing the old ones by using the pull down menu 4 to add a new simulation type The menu also has options for deleting a simulation type and for specifying exactly which file will be run when you click the Start Simulink button When you use the Add menu item to link to a new MATLAB PIF change the extension in the dialog box from
182. common way to start using the software The default is that clicking the button will take you to the most recently used data set in the Runs library However you can modify the function of this button as described below Each data set in the Startup library can point to a different Runs library As installed the four installed data sets point to the three Runs libraries in CarSimEd 4 CarSim Educational Startup OF x File Edit Text Page Tools Data set 3D Handling w 41 I gt Hew Delete Gov Back Eeki me a es 242 caw dL aja GIS Brockea zane List of libraries for the GO menu Add and Remove Files in List STARTUP TBK 5 Add Defautt Libraries RUNS_2D RUNS_2D TBK RUNS_3DIRUNS_3D TBK 6 i RUNS_SUS RUNS_SUS TBK 7 Remove Libraries From List RUNS_TRKIRUNS_TRK TBK ANIMA TEVANIMATE TBK Change Order of Files in List ANIMATE CAMERASICAMERAS TBK 3 Move to Top Select All ANIMATEFRAMES FRAMES TBK ANIMATE GROUPS GROUPS TBK ANIMATE SHAPES SHAPES TBK ANIMATEWVHEELSWYHEELS TBK BATCHIPLOT_BATIPLOT_BAT TBK BATCHIRUNS_BATIRUNS_BAT TBK COMP_PAR COMP_PAR TBK Data Set for Start button 14 INPUTIBRAKING BRAKING TBK a INPUTISTEERINGISTEERING TBK INPUTITHROTTLEITHROTTLE TBK Download from http www trucksim com G Q Copyright 1995 The Regents of The University of Michigan More Info Change Settings Copyright 1996 1998 Mechanical Simulation Corporation MSC Portions copyright Asymetrix Inc T
183. contents of the tabular data field G with calculated numbers As noted in the description of the formulas the operation depends on whether the Create or Transform button 20 D is selected When the Create button is selected the number of rows created will be equal to End Start 1 Step where the values of Start End and Step are obtained from the fields 22 3 and 24 When the Transform button is selected the number of rows is the same in the table field is the same after the calculations are made Create button When selected the fields Q2 63 and are displayed and the function of the Calculate button is defined to create a new series using the definitions in the formula field 13 Transform button When selected the fields CD 63 and are hidden and the function of the Calculate button is defined to transform an existing series using the definitions in the formula field 13 Start value This is the value assigned to X for the first row of numbers created in the tabular data field G when you click the Calculate button 19 147 Chapter 9 Alphabetical Library Reference gt cle a End value This is the value assigned to X for the last row of numbers created in the tabular data field G when you click the Calculate button 19 Step This is the interval used to calculate X for every row between the first and last in the tabular data field G when you click the Calculate button 19 Example
184. converted to units of MPa This screen also has a parameter that controls whether a simulation stops when the vehicle comes to rest User Settings Note User settings that are common for all tabular data screens are described in Chapter 8 in the section Tabular Data 163 Chapter 9 Alphabetical Library Reference Two column table of values of brake input pressure as a function of time keyword BRKIN_TABLE Each line should have a value of time followed by a corresponding value of braking input with a separating comma The solver programs use linear interpolation and flat line extrapolation with this table For values of time that are less than the range covered in the table the first value of pressure is used For values of time larger than the range covered the last value of pressure is used This table needs at least two lines of data or else an error message is generated 2 Stop speed keyword V_STOP A simulation continues until one of several conditions occurs e The simulation time reaches the stop time specified on the Runs screen keyword STOPT e The vehicle roll angle exceeds a specified limit that implies that a rollover was inevitable keyword ROLL_STOP The rollover limit can be specified in the Misc Data field on the Runs screen e The absolute vehicle speed drops below a specified threshold keyword V_STOP It is the last case that is associated with braking simula
185. cssone Min 125 Y Min 5 d x Max j Y Max g cme x Spacing E Y Spacing E Grid Color v Set Frame Rate Select this command to display the following dialog box and control the rate at which the animator plays back a simulation run The keyboard command is Ctrl F The items numbered in Figure 6 3 are described below Set Frame Rate x Frames rate from ERD file 20 00 frames sec Time step 0 050 sec Frames rate for animation 10 frames sec Time 4 0 100 sec Use Computer Clock O C Open Loop Maximum Speed o Figure 6 3 Setting the frame rate O Maximum frame rate possible given the data in the ERD file The frame rate is the reciprocal of the time step 2 This value is for reference only 73 Chapter 6 The Animator Time interval between stored data points from the ERD file header This value is specified in line 2 of the header of the ERD file This is the minimum time possible between animation frames This value is for reference only Target frame rate for animation If the animation is running too slowly you can specify a lower frame rate to speed it up Alternatively you can use a higher frame rate to slow it down Typically frame rates of 10 to 30 frames per second can run in real time on Pentium computers If the target frame rate is very high more than 100 the computer will not be able to refresh the screen in real time and the animation will run in
186. cting longitudinal force eliminates a direct dependency on speed by using a normalized longitudinal slip However the definition of longitudinal slip is singular at zero speed At speeds approaching zero the classic model can predict maximum tractive force oscillating in the forward and rearward directions This behavior is reduced in the CarSimEd model by attenuating the slip when the wheel is locked by the brakes and the speed drops below the level specified in this field see Appendix G for details Cutoff speed for wheel spin acceleration keyword VLOW_SPINA IAXLE Brake torque is the result of friction and always opposes the wheel spin When the wheel spin approaches zero lock up a numerical instability can occur due to the reversal of the direction of the brake torque To avoid numerical problems the wheel spin equation is modified when the effective speed spin multiplied by rolling radius drops below the level specified in this field Thickness of wheel object drawn by wire frame animator keyword set_thickness This dimension is used for creating the wire frame animation but is 211 Chapter 9 Alphabetical Library Reference not used by the solver programs Unlike most yellow fields this must be given a value because the library automatically converts the units from mm to meters Number of points in polygons used to represent the wheel in wire frame animations keyword set_num_points This val
187. cting the desired starting point click the Start button to go to a Runs screen Discussion This screen provides a starting point for the software It also includes settings that help configure CarSimEd for your particular installation As installed CarSimEd has four data sets One called Install is required for the automatic installation to work The other three provide entry points to the three kinds of simulation available in CarSimEd 2D ride 3D handling and suspension analysis 150 Chapter 9 Alphabetical Library Reference 4m CarSim Educational Startup iof x File Edit Text Page Tools Data set 5 Link Suspension Back Oo Changed ee cates Ba Biokea ras n CarSim Educational i Vehicle Dynamics Simulation Version 4 5 January 2000 Free software from MSC Mechanical Simulation Corporation USA 709 West Huron Suite 50 Ann Arbor MI 46103 USA FAX 734 668 2877 Phone 734 668 2930 http www trucksim com VMC VirtualMechanics Corporation Japan 1 40 Hagiyama cho Mizuho ku Nagoya 467 0011 JAPAN FAX 052 853 7261 Phone 052 853 7309 http home att ne jp green v mechanics Download from http Awww trucksim com 1 Go z Copyright 1996 1999 Mechanical Simulation Corporation MSC More info into nae Settings Portions copyright Asymetrix Inc ToolBook Runtime package All Rights Reserved Start Note The CarSimEd Startup Screen has two possibl
188. cupy no more than 50 of window G o o o 15 Plot Layout tab Click this tab to show the settings that control the display of the axes frame and grid Chapter 7 The Plotter Axes Press the button to display a menu with the choices Axes or No Axes The No Axes option doesn t work unless you also select No Grid with the Grid pull down menu and No Frame with the Frame pull down menu 20 Max digits for Y axis This is the number of digits set aside for the tick labels of the Y axis For example if set to 3 WinEP draws the Y axis of every plot with enough space for 3 digit labels for the Y axis If set to 0 WinEP determines the spacing automatically A value of 0 is recommended unless you want all plots to be drawn in exactly the same place relative to the left edge of the window Grid Press the button to display a menu with the choices No Grid Coarse Grid grid lines at major tick marks or Fine Grid grid lines at minor tick marks Legend location Press the button to display a menu to choose among five possible locations for the legend used to identify the X Y data sets in overlay plots The sixth option is to let WinEp select the location automatically Legend location Auto Location x The legend and other labels in the plot are shown in Figure 7 4 Tire vertical load Braking in a turn Tire vertical load Braking in a turn Title Tire vertical load N Y axis
189. d deleting simulation types and for locating a solver program extension EXE Unless you add new solver programs you should never use this menu In fact the menu is disabled unless the check box for Advanced Users is checked in the Preferences screen To access the preferences use the Tools menu item Preferences or click the button in the ribbon bar When you click the Run Simulation button G the CarSimEd database launches the EXE file associated with the type of vehicle indicated above O and the simulation type Simulation Type 3D Vehicle Dynamics 3D Vehicle Dynamics Add Delete gt Find solver for 3D Vehicle Dynamics The menu lists all of the installed simulation types followed by three utility commands Note CarSimEd supports multiple solver programs and this link is the interface to them When you click the Run Simulation button CarSimEd searches a hidden table for an entry containing the current type of vehicle displayed above the blue link O in Figure 9 10 the vehicle type is independent and also the Simulation Type in Figure 9 10 the simulation type is 3D Vehicle Dynamics The table contains a corresponding pathname e g Programs 3d_car exe for the solver program associated with the vehicle type and simulation type When new versions of solver programs are made they can be added to the system without replacing the old ones by using this pull down menu to add a new simulation type The menu also h
190. d from that measurement Brake gains keywords RMYBK 1 RMYBK 2 These are the ratios between brake torque N m and brake input MPa Driveline gains keywords RMYTH 1 RMYTH 2 These are the ratios between drive torque N m and dimensionless throttle input Link to an animator group data set The animator group should be set to provide a wire frame matched to the vehicle Location in CarSimEd CarSimEd Startup Runs Vehicles Car File Location Vehicles Cars_Ed Cars_Ed tbk 217 10 Advanced Topics This chapter explains how to perform tasks in CarSimEd that might be helpful after you have some experience The descriptions in this chapter are similar to those in Chapter 4 each section is fairly compact covering just the essence of how to accomplish a task Adding a New SIMULINK Model CarSimEd is installed with a SIMULINK CMEX plug in DLL file that has the same equations of motion as in the stand alone solver EXE program It also comes with several example SIMULINK models files MDL that make use of the DLL As you work with CarSimEd in SIMULINK you will no doubt create new SIMULINK models with new controller designs or output options The CarSimEd database accommodates an almost unlimited number of models Creating a New SIMULINK Model The integration between CarSimEd and SIMULINK is done with software contained in the folder Mat lab which in turn contains one folder for each S
191. d models are contained in DLL dynamic link library files Data screen a view of a data set contained in the CarSimEd data base A data screen is where you enter the parameters that define your target simulation It is a data set as viewed through a graphical user interface Data set a collection of parameter values and related information organized for display on a CarSimEd screen Data sets are contained in library files and edited in data screens DLL dynamic link library Files with this extension contain library code that is loaded into memory as needed Echo file a text file produced by a solver program that lists every input parameter The echo file documents the conditions that were simulated in a run All echo files made 241 Appendix A Glossary by CarSimEd solver programs are written in the PARSFILE format see Appendix F Echo files can also be used as inputs to the solver programs for future runs to restart continue a run ERD file a file stored in a standard format that supports automated plotting animation and other forms of post processing Output files produced by CarSimEd solver programs are written in ERD format see Appendix C The plotter and animator programs in CarSimEd read ERD files ERD stands for Engineering Research Division the group at UMTRI that originated this format Go in the context of CarSimEd going to a different data set screen or library means having Ca
192. d on your computer the Mat lab PIF in each model folder points to the default location shown in Figure 2 2 You will have to change the Command Line field if your MATLAB installation is not standard To do so Matlab Properties 21x General Program Font Memory Screen Misc A E atlab Cmdline c MATLAB bin matlab exe minimize Working PO Batch file PO Shortcut key Nons Bun Minmized s s siS IM Close on exit Advanced Change Icon Cancel Figure 2 2 Properties of the Matlab PIF 1 In the Windows explorer locate the MATLAB PIF file 2 Right click on the Matlab pif depending on your settings the file might appear simply as Matlab From the pop up menu select the item Properties A properties window will appear see Figure 2 2 3 Inthe Properties window select the Program tab see Figure 2 2 4 Change the pathname in the Command Line field to the location of MATLAB on your hard drive 5 Click the OK button to close the window 6 Repeat steps 1 through 5 for all other MATLAB PIFs 19 Chapter 2 CarSimEd Installation MATLAB Versions CarSimEd 4 5 has been tested with SIMULINK MATLAB versions 5 2 and 5 3 The first time you make a run in SIMULINK you might get a stream of warnings in the MATLAB window This is because the SIMULINK MDL file was created with a different version of SIMULINK than the one you are using version 5 2 vs 5 3 To prevent this in future
193. ded to go down to more detailed levels To start go down to the linked data set for a vehicle If you are interested in making a new component or subsystem data set tire suspension etc use the appropriate link to go down to it As indicated in the map shown in Figure 3 4 on page 26 it is possible to go down through several levels of detail For the purpose of making changes you are at the bottom when e the current screen has no blue links or e the current screen has blue links but the data sets available from the menus associated with the links are suitable for your purposes In other words you do not have to modify or create any data sets that are further down in the database 4 Click the New button in the ribbon bar to copy the current data set 5 Give the new data set an appropriate title in the yellow Data Set field O A Chapter 4 The Basics of Using CarSimEd 6 Modify the data set Modify the values in the yellow fields as needed Change the data sets in any blue links using the adjacent pull down menu Note When you clicked the New button you created a new data set that is now available for use in CarSimEd It is in the same library as the original and appears in pull down menus that show the library contents However it will not be used in any simulations until you have linked to it from a higher level data set 7 Go back up one level using the Back button in the ribbon b
194. define whether the axis will be drawn with a linear or log scale They duplicate the Format menu commands Log X Axis and Log Y Axis Autoscaling X and Y axes Check these buttons to cause WinEP to scan the data and size the axis to include the full range of data This setting is recommended for routine use Manual scaling X and Y axes Check these buttons to scale an axis according to the range specified in the adjacent fields 5 This setting is provided for situations in which you wish to make plots with the same axes regardless of the range covered by the data Range of data values covered by an axis Specify minimum and maximum values for scaling the axes These are used only when the manual scaling button is selected OK button Click to close this dialog box and apply the settings as displayed Cancel button Click to close this dialog box and revert to the previous settings The Apply button is not functional in the current release The Help button is not functional in the current release Customize Plot Forggat Ea Axes XY Data Set Plot Layout Font x Y Data Set Fz_L1 ba Line Attributes Symbol Type Vert Rectangle Solid Line Color paos X Y Data Set tab Click this tab to show the settings that control the display of a data set Note An X Y Data set is a set of X and Y values from a specific file Each data set is represented graphically in a plot When multiple data sets are shown in the
195. del parameters as they appear when using the software However a more efficient method is to view all of the parameters in a text editor as described in the previous section and then print them from the text editor Start from a Runs screen see Figure 4 1 on page 30 The simulation run must have already been made in order to view a list of all parameters 1 Click the button View Echo File All Parameters 12 2 Select Print from the File menu of the text editor 40 Chapter 4 The Basics of Using CarSimEd 3 Exit the text editor Making a New Vehicle Data Set Use the following method to create a new vehicle data set that can be used for future runs Using this process leaves existing vehicle descriptions intact The parameter values for a vehicle model are spread over several data sets Typically you will want to change a few and leave most of the rest the way they are Note In the following instructions the concept of going up and down is based on the map shown in Figure 3 4 on page 26 Method Start from a Runs screen see Figure 4 1 on page 30 1 Find an existing data set that involves the type of vehicle you are interested in To navigate through the Runs library use the buttons 2 next to the Data Set title box O 2 Go down to the linked vehicle data set Vehicle Classic car Go To Data Set Pick Library No Data Set bad brakes Generic HMMA 3 Repeat step 2 as nee
196. ditional information is shown in plain typeface e g independent e The triangle button is used to display a pull down menu There are two keyboard modifiers for the triangle button 1 Press the Ctrl key when clicking the button to get the full pathname of the linked library e g C CarSimEd Vehicles Vehicles Vehicles tbk 2 Press the Shift key when clicking the button as a shortcut for selecting the menu item Go To Data Set This will take you to the linked data set it is the same as selecting the first menu item This is usually quicker than using the menu The Data Link Menu Front Suspension Example Front Suspension Go To Data Set Pick Library No Data Set Example Front Suspension Example rear suspension The items of the data link menu perform the following functions e Go To Data Set Goes to the currently linked data set e Pick Library Brings up the file browser dialog box to select a new TBK library file for the link The browser may request a library of a certain type e g Vehicle If the TBK file that is selected does not contain the right kind of data a warning is displayed However you can override the warning and make the link anyway This is not recommended for beginning users This menu item is dimmed when the preferences for CarSimEd are set with the Advanced mode disabled If you want to pick a new library and the menu command is dimmed you must go to the preferences window by clicking t
197. e the same wheel shape is usually linked to every moving wheel reference frame In contrast there is only a single camera point and a single look point 133 Chapter 9 Alphabetical Library Reference 3 In CarSimEd 4 2 and older versions this screen would include links to wheel data from an Animator Wheels screen In newer versions of CarSimEd the information needed to draw the tire wheel objects is taken from the tire data sets The Animator Wheels library is no longer needed and has been eliminated 4 This data screen is unusual in CarSimEd because it is common for one data set to have links to other data sets in the same library This is done when more links are needed that can be specified in one data set An animator group can be set up several ways but the most common one is to group several shapes or wheels together without associating them with a reference frame For example Figure 9 2 shows how the body of a car is assembled from many individual shapes 4m Animator Groups OL x File Edit Text Page Tools Data set Sedan body w 41 I gt Hew Delete GO Back Changed ID 193 O Hotes 5 18 51 Link 1 shapes iee a 11 shapes aea een 16 shapes Car F Bumper 1 x Car LF Door lt LF Door Car LF Door 1 J Car LF Window LF Window Car LF Window 1 Link 2 _ shapes set_scale_y 1 set_scale_y 1 Car F Window 1 x 2 2 Link 3 shapes net h
198. e SIMULINK inputs are all elements in an array and are typically referenced in SIMULINK by the array index Each folder for a SIMULINK model includes a copy of the README text file that defines the inputs for the 3D vehicle model and tells how they are combined with inputs from the SGUI For example Appendix __ lists part of the README file Given that each model input is the sum of two parts one from the SGUI and one from SIMULINK one or both of the components are typically set to zero If both are zero the input to the model is zero If the SGUI input is zero then all control comes from SIMULINK And if the SIMULINK input is zero then all control comes from the SGUI To Specify Inputs from the CarSimEd Libraries SGUI 1 Specify inputs as described earlier for making runs with the stand alone solver programs For example choose an open loop steering input that defines steering wheel angle as a function of time 2 Attach the associated inputs to ground in SIMULINK in this context ground is the electrical concept that sets a variable to zero See the README file in the Matlab 43 Chapter 4 The Basics of Using CarSimEd folder to identify the input variables For example connect the steering wheel input contribution INPT 1 to ground Or just don t specify it at all because the default value is Zero To Specify Inputs from SIMULINK Select inputs as described earlier for making runs with the stand alone
199. e appearances The above figure shows the simple display There are at least three reasons why you might someday want to modify the CarSimEd settings or make a new Startup data set with different settings 1 If you move the CarSimEd software to a new hard disk volume or folder all of the text files used to communicate between CarSimEd data screens and the CarSimEd solver programs must be updated Otherwise the solver programs will give error messages about files not being found The settings are made automatically by clicking the Update button 13 shown in Figure 9 4 2 If you make many data sets in a library e g a Runs library you may want to create a new folder and create a second library If you add any folders to CarSimEd you should install them in the Startup library 3 You may want to change the GO menu to show fewer libraries or re order them On the other hand you may never need to change the settings contained in this library User Settings Simple Display More Info button Click this button to go to screens with information about CarSimEd that involve the version copyright information etc 151 Chapter 9 Alphabetical Library Reference Change Settings button Click this button to show additional settings that can be modified When clicked the CarSimEd pictures are replaced with the settings shown in Figure 9 4 Start button Click this button to go to a Runs library This is the most
200. e browser to make a different library the default The default link is Plot Setup Setup tbk Batch Runs button Click this button to go to the Runs Batch library This is equivalent to the Tools menu Batch Runs command Control click to get a file browser to make a different library the default The default link is Bat ch Runs_bat Runs_bat tbk Runs button Click this button to go to a Runs library with settings to make a single simulation run This is equivalent to the Tools menu Runs command Control click to get a file browser to make a different library the default The default link is Runs Runs tbk Parstree button Click this button to run the Parstree program for viewing the contents of the PAR file associated with the current data set plus the PAR files for all of its linked data sets For example Figure 8 2 shows the display for a data set from the Runs library The file 94 par is selected in the left pane and the contents of that file are shown in the right pane If it is not currently linked control click to get a file browser to locate an executable program file and establish a link to it The default link is Programs Parstree exe Print button Click this button to print a copy of the current screen display 113 Chapter amp ti ParsTree x Contents of the selected file Parsfile tree Structure fe 47 par B 325 par HB 303 par E 373 par
201. e change per unit jounce at rear axle RCAM 1 0 Wheel camber change per unit jounce at front axle deg mm RCAM 2 0 Wheel camber change per unit jounce at rear axle deg mm RDAMP 1 1 Front ratio of jounce at wheel to damper stroke RDAMP 2 1 Rear ratio of jounce at wheel to damper stroke RMF 0 588235 CALC Ratio proportion of load on front axle RMR 0 411765 CALC Ratio proportion of load on rear axle RMYBK 1 10 Front wheel ratio of brake torque to pedal input N m MPa RMYBK 2 4 Rear wheel ratio of brake torque to pedal input N m MPa RMYTH 1 500 Front wheel ratio of drive torque to throttle input N m RMYTH 2 0 Rear wheel ratio of drive torque to throttle input N m ROLL_STOP 45 Roll angle for stopping the simulation deg RSPRNG 1 1 Front ratio of suspension jounce to spring compression RSPRNG 2 1 Rear ratio of suspension jounce to spring compression RSW 16 Steering gear ratio RTIME 0 1 CALC Computational efficiency sec sim sec RTOE 1 0 006 Wheel toe change per unit jounce at front axle deg mm RTOE 2 0 006 Wheel toe change per unit jounce at rear axle deg mm SPEED 100 Vehicle forward speed kph SPEED_ON_OFF 1 Speed control switch 0 0 gt off 1 0 gt on STARTS 219 798 Starting station number beginning of simulation m 289 Appendix F Model Files and Keywords STOPS 10000 Stopping station number stop simulation w
202. e contact about ZG See Figure B 3 SAE ISO Spin axis Yw axis of rotation of wheel about spindle See Figure B 3 SAE Wheel center intersection of spin axis and wheel plane See Figure B 3 SAE ISO Wheel plane central plane of wheel normal to the spin axis See Figure B 3 SAE ISO 255 Appendix B Vehicle Dynamics Terminology Forces and Moments Forces and moments acting from the ground on the tire are summed into a single resultant force vector and a single resultant moment vector taken about the center of tire contact Aligning moment Mz ZG component of ground resultant moment SAE ISO Overturning moment Mx XG component of ground resultant moment SAE ISO Rolling moment My YG component of ground resultant moment SAE 4 ISO Driving moment Yw component of moment applied by the vehicle to the wheel about the spin axis SAE 4 Lateral tire force Fy YG component of ground resultant force SAE ISO 5 Longitudinal tire force Fx XG component of ground resultant force SAE ISO 15 Vertical tire force F ZG component of ground resultant force SAE ISO gt Notes 1 The ISO wheel axis system is similar to the ground system defined in this document except ISO does not account for inclined ground surfaces 2 Neither SAE nor ISO is explicit about the reference frame for the vehicle coordinate system although both clearly involve the body
203. e edit field c Click the Set button 6 to apply the change Edit field used to change a name in the selected legend Set button Click to set the name selected in the Names list 4 to match the text in the edit field 5 OK button Click to close the dialog box and apply the new settings to the active plot 2a Cancel button Click to close the dialog box without modifying the active plot Show Data Points E This command toggles the mode of showing a cursor on the plot and the associated coordinates in the status bar The keyboard command is Ctrl D FA WinEP Yaw rate DLC iof x File Edit Format Data View Window Help lej x Yaw rate DLC Vehicle yaw rate deg s 10 0 5 10 15 Time sec AVZ x 2 4 y 13 295 step interval 0 Pal NUM Us 102 Chapter 7 The Plotter When you select this option a cursor will appear at the first data point contained in the data file For time history plots the first point is at the far left side of the plot However for cross plots the first point may be located somewhere else The X and Y values associated with the cursor are displayed in the status bar For example in the figure below the cursor is at the point time 2 4 sec Yaw velocity 13 295 deg s Note When there are multiple plot windows the cursor and X Y values are always associated with the active window Cursor Position Info This menu item displays a sub menu whose ma
204. e format keyword FORMAT Use the pull down menu to choose among the three options BINARY the solver program creates a binary output file extension BIN and an ERD header file This option is the most efficient for using the integrated plotter and animator Less time is needed to run the simulation and view output and less disk space is needed to store information However binary files are not imported as easily into other software and the contents cannot be viewed or printed with text editors TEXT the solver program creates a simple text output file that can be imported into other software packages such as spreadsheets Excel Lotus etc and mathematical analysis programs MATLAB etc The first line contains short names for the output variables separated by commas The following lines contain numbers separated by commas Each row has all the values for a single point in time These files cannot be viewed with the animator 156 Chapter 9 Alphabetical Library Reference WinEP can read text files although the plots contain less information because the file has no title no units etc Note When the TEXT option is enabled the output file generated by the solver program will have the same extension ERD However the file does not follow the ERD format described in Appendix C ERDTEXT the solver program creates a text ERD file It has all the labeling information required by the animator and plo
205. e spins out and V assumes a negative value At very low speed the above equation does not work well because the time lag goes to infinity Therefore the gain on the derivative is increased according to the equation 311 Appendix H The Tire Model Eei 14500 1 M dt dt Von nis where vqo is a cut off speed a parameter that can be set by the user Tire Forces and Moments Once expressions are obtained for the needed kinematical quantities the tire force and moment magnitudes can be calculated F must be calculated first because Fy F y and M depend upon it Vertical Tire Force Vertical tire force is proportional to the tire deflection F max 0 Fystar K Ay 15 where Fzsrar is the static tire load and Kpy is the vertical tire stiffness The above definition of F establishes the force to be in equilibrium when the vehicle is in the nominal configuration The use of the max function prevents the magnitude of the force from going negative when the tire leaves the ground Pure Longitudinal and Lateral Slip A relatively simple tire model is used in CarSimEd to predict the linear cornering behavior and the nonlinear limit behavior Fxo F yo and Mzo are values of longitudinal force lateral force and aligning moment that would be obtained in the absense of friction limits They are obtained first and then the values are reduced to account for frictional limits using a normalization method described by Radt
206. e steps that are sufficiently small For typical CarSimEd simulations sufficiently small means about 0 002 seconds for handling runs For braking and acceleration runs to and from zero speed step sizes of 0 001 or smaller might be required Note If you are making many runs with a few vehicle descriptions you may want to determine how small the time step needs to be Make several runs changing only the time step For example try using values of 0 004 0 002 0 001 and 0 0005 second If the runs are valid plots of the same variables should overlay perfectly If the results at a large time step differ from those made with a small time step the typical assumption is that the results made with the large time step are in error 2 Number of time steps between output printing keyword IPRINT The time step determines how often calculations are made The time interval for the output files is the product of the step and this interval IPRINT A print interval between 10 and 30 typically works well Notes This parameter determines the resolution for plots and also the default speed for the animator To run in slow motion say to accurately see wheel rotations use a small value This parameter has only a minor effect on the speed of a simulation run However it has a direct effect on the size of the output files and the time needed to load them into the plotter or animator Big files take longer Output fil
207. e the low frequencies the same averaging is used However as an additional step in the processing the smoothed values are subtracted from the originals Figure 9 8 compares plots of data subjected to a high pass filter and a low pass filter to the original Notice that the high pass focuses on the oscillations while the low pass emphasizes the underlying shape of the curve 184 Chapter 9 Alphabetical Library Reference te Kappa long slip L side GM ABS Brk low mu Kappa long slip L side GM ABS Brk low mu Longitudinal slip 0 5 i fie LR tire 6 High Pass 0 5 sec Time sec Kappa long slip L side GM ABS Brk low mu Longitudinal slip 0 l amp LR tire Low Pass 0 5 sec Time sec Kappa long slip L side GM ABS Brk low mu Longitudinal slip 0 16 LF tire amp LR tire No Filter Time sec Figure 9 8 Results of filters in WinEP Filtering is commonly applied to experimentally measured data High pass filtering is used for variables that drift such as some accelerometers Low pass filtering is used for examining low frequency behavior when the measurement was subject to high frequency vibration and possibly noise from other sources such as accelerometers Sometime both high pass and low pass filters are applied to the same variable This type of filtering is called band pass Because simulation results usually don t have any measurement error
208. e vehicle kg m2 288 Appendix F Model Files and Keywords IYY 2704 Moment of inertia of entire vehicle kg m2 IZZ 3136 Moment of inertia of entire vehicle kg m2 KAUX 1 500 Front auxiliary stiffness including anti sway bar N m deg KAUX 2 350 Rear auxiliary stiffness including anti sway bar N m deg KFX 1 100000 Front tire longitudinal stiffness N KFX 2 100000 Rear tire longitudinal stiffness N KFYCAM 1 60 Front tire camber stiffness N deg KFYCAM 2 60 Rear tire camber stiffness N deg KS 1 30 Front suspension spring stiffness at spring N mm KS 2 20 Rear suspension spring stiffness at spring N mm KT 1 200 Front tire vertical stiffness N mm KT 2 200 Rear tire vertical stiffness N mm LCGT 1111 76 CALC Distance from F axle to total vehicle CG mm LRELAX 1 600 Front tire relaxation length mm LRELAX 2 600 Rear tire relaxation length mm LTK 1 1500 Front axle track width mm LTK 2 1500 Rear axle track width mm LWB 2700 Wheelbase mm MF 1000 Vehicle mass supported by front axle 2 wheels kg MR 700 Vehicle mass supported by rear axle 2 wheels kg MT 1700 CALC Total vehicle mass kg MU 0 75 Tire ground friction coefficient MUS 1 100 Front axle unsprung mass 2 wheels kg MUS 2 80 Rear axle unsprung mass 2 wheels kg RAP 1 0 1 Wheelbase change per unit jounce at front axle RAP 2 0 1 Wheelbas
209. ection in Figure 9 12 The direction of the line of motion is specified with a roll center height solely to maintain compatibility with other models and existing data 4 Wheelbase change per unit jounce keyword RAP IAXLE This should be a positive number for both front and rear suspensions with a value between 0 05 and 0 25 mm mm 205 Chapter 9 Alphabetical Library Reference Note The sign convention shown in Figure 9 12 is designed such that a positive value means the wheel moves away from the center of the vehicle as it moves up In the front this is called anti dive In the rear anti squat Ratio of toe change per unit of suspension compression keyword RTOE IAXLE As shown in the figure positive toe is steer to the inside left steer for the right wheels right steer for the left wheels Suspension kinematics normally cause toe to vary in a complex way with suspension deflection This coefficient should be selected to represent the linear behavior near the nominal suspension compression Ratio of camber change per unit of suspension compression keyword RCAM I AXLE As shown in the figure positive camber is when the wheel leans out at the top Suspension kinematics normally cause camber to decrease with suspension compression Thus this value is often negative Ratio of spring jounce compression to jounce at wheel keyword RSPRING IAXLE This determines the mechanical advantage of t
210. ection of wheel spin but is not dependent on the magnitude of the spin rate As long as the wheel is spinning the brake torque causes angular acceleration that slows the wheel Each time step the numerical integration calculations predict a negative change in speed But when the wheel spin reaches zero the calculated increment in speed is likely to overshoot zero causing the predicted wheel spin to be negative for the next time step Then the brake torque acts in opposition to the negative speed and causes a positive acceleration leading to a positive change in speed and a positive speed for the next time step Each time step the wheel spin and braking moment change sign Because the amount of brake torque does not diminish with the spin magnitude the oscillation does not diminish either The above problem occurs when friction is modeled It is sometimes called a bang bang instability because the large friction force is applied fully in opposite directions with each time step In the real mechanical system brake torque for a locked up wheel is a reaction torque exactly equal to the amount necessary to prevent motion There is no oscillation There are two friction like instabilities associated with zero speed First the instability described above exists when the wheel spin approaches zero due to brake torque An alternate to Equation 8 is used when the brake torque is greater than the moment of the tire braking force plus the driv
211. ector and a single resultant moment vector about a point at which the resultant force vector is assumed to apply The resultant moment vector depends on the location of the point where the resultant force is assumed to apply Resultant force and moment vectors are used to describe actions on the vehicle due to the ground the air and impacts with other objects Axis Systems and Coordinate Systems Discussion Multibody vehicle dynamics models are typically generated using right handed axis systems and coordinate systems The axis orientation for ISO 8855 has X pointing forward Z pointing up and Y pointing to the left hand side of the vehicle SAE J670e has Z pointing down X pointing forward and Y pointing to the right The Z up convention is used in CarSimEd TruckSim and other MSC vehicle models for several reasons e Plots of Y vs X show a top view of vehicle trajectories e plots of Z vs X show a side view of vehicle trajectories e vertical tire forces are always positive and e wheel spin rates are positive for forward vehicle speeds With the Z down convention all of these signs are reversed Appendix B Vehicle Dynamics Terminology Alternative right handed systems are theoretically compatible with the following definition so long as X is longitudinal Y is lateral and Z is vertical However the sign conventions of many variables are dependent on the directions in which the axes are pointing For example yaw angle
212. ed Seve ded ee ase gee 115 iy Wabu lan Data cicccso dk enaa Gehigedc deck hie a a aoa be Rack a TE oea he es 117 Piles Mem Li RESE A OA ter uc ohne A Rew oie shalt aaa AE MN Made eawdk SEs 119 Edit Meni ssiy ctec Sez en rere ena eaa 2a ettvanetactenga A A ca e a ea eaaa eae ets 122 Text Menu aruana nsan a e E dee EE E AE E EE SEa ea E A a A A Ea E 123 Page Menu manse aa ee A e E a ee E a Aa a T ES 124 Tools Men s fick sear yt tacdl isha sevea Sis A R Aa e oveguha Mieltaatadees vatbawta Wide dhvea soenseys 125 9 Alphabetical Library Werere nee cio cots ciastas eaceschcde ears vtadea baad oatere react eas isasi 127 Conventions in This Chapter cccceececcccccccccccccceeceeeeeeeeeeeeeeeeeeeseeeeeeeeeeeeeeeeeeeeeeee se 127 Animator Camera S Ctupirsisis cocsseee cosheueh fece0h bees shadensoceta ey cochaves aea a e aaaeeeaa ur thate osata vs 129 Animator Groups tees aredi ree a E E E R ETER E EREE wv EE EE A eae ieee At 133 Animator Reference Frames icin cede cred ee e e eas eeit e iie eaaa aa aE E a E Eta teien ti 136 Animat r Shapes e e doer coed ciple nigh eee ESEE aed G prev EEEO RE eens A arate haigh 139 Animator Wheels asasini e i aranaise sedesidaepesevldeudechssngbeddsesbvedbvbespeuetess 142 Calculator e iikot e n Wa Ae el eee ee Bin 143 CarsSimEd StartUp ee ecivi tea aise eens ee tees ee eae tices 150 Computation Parameters os cpctcecsissesesdsnsacedstioveesuadercnss livecesdautacoas clevedsundsecasshipevasdage
213. ed by selecting Print Setup from the File menu Chapter 7 The Plotter File Menu The file menu is used to read files write files print windows and exit the program F Load ERD File Ctri E Load Batch File Ctrl B Load Plot Format Ctri 0 Load Transform Settings Ctrl T Close Top Window Ctrle w Save Plot Format Ctri S Save Plot Data Save Channel List Save Transform Settings Save All lmages Ctrl 1 Print Ctrl P Print Preview Print Setup Exit Ctrl Q Load ERD File E Select this command to open an ERD file with the Windows file browser dialog box After the file is opened a dialog box appears that you use for selecting variables from the file to plot The keyboard command is Ctrl E Load Batch File Select this command to process a batch plot file with the Windows file browse dialog box When created automatically by CarSimEd batch plot files have the extension PLT and are located in the directory containing the library where the Plot button was clicked either Runs or Batch Plot_bat When loaded the batch file will cause WinEP to generate one or more plots The keyboard command is Ctrl B Load Plot Format Formatting information for plots can be stored in files These files can be created from within WinEP using the Save Plot Format command from the File menu and also from within the CarSimEd database see the section Plot Format in Chapter 9 Select the Load Pl
214. ee for stand alone solver programs and one for working with SIMULINK The screens are nearly identical compare Figure 4 1 and Figure 4 3 There are many references throughout this manual to a generic Runs screen Unless otherwise specified these references apply to all versions Getting to a Runs Screen Most operations begin with one of the four Runs screens in CarSim Ed When Starting 1 Start CarSimEd to get to the Startup screen a Use the Windows Start menu or b open the file Startup tbk from within the CarSimEd folder or a shortcut to that file 2 Use the triangle button next to the data set title in the ribbon bar to go to the start point for the type of simulation with which you are interested see the figure below x CarSim Educational Startup Oo x File Edit Text Page Tools Data set 3D Car Self Contained 2D Car Ride aie meh es 134 3D Car in Simulink 5 Link Suspension Install ae NU Vehicle Dynamics Simulation 31 Chapter 4 The Basics of Using CarSimEd Choose either e 2D Car Ride OR e 3D Car Self Contained OR e 3D Car in Simulink OR e 5 Link Suspension 3 Click the Start button in the lower right corner of the screen Choose the type of runs Start Screen Four or more options m CarSim Educational Startup File Edit Text Page Tools Data set 3D Car Self Contained 2D Car Ride a genes e es 13
215. eee hush events iin nae wines iade iis 77 Te The ado cca siainen a rear epr rat E E E RA R ASES EsT re Terr ay 80 Updates e ai be le E Ee o erai EEE E EEEa EER ETEO E i ea ENESE o er tiia EiS 80 Overview OF Oper ti i leisiantis teata asa eA 80 Batch and Interactive Operation ecsiic coc cveorsciet a E E EEEE E E erodes 81 LOOMING e e hee Ges dl aes ke EN A E E Mes kn etbdaecevatel Men ade cand dein E E E 82 TOO Bares scc tecssscoesn snes te amp ceepdea EA 83 Printing PlOts is cc03 iccetestgocctan sid ccdedsaeccescsbeeceesngedeaceods caduacdecccdeobdecduersecces sdvesesdeaeecesssbescavers 84 File Mentoe sets he tae eee dere een di eee ee cay 86 Edit Ment erar e aa a aiea EA ivevsivi eens vee ee E ean ins Mee sree eee eal 88 Pormat M nuetitscssicideiolivecaisadsbepcegsee coedaletdeccdscyedacadeheptedsdeehedalebdecchiayededadeteecegstyesedabendeccnse 90 Data M D mann aveehins ets reed tec pent availa pepens E A EE E LE A E E Sev oeeh ees 96 View Men e nieret nea a apentiameivecis a Wb eaa lg dovelthivaces abet ea S 105 Windows Meni siec five sobsc coz eeen LE E cetace sate data Sates cee ca E E EE E eia 107 Help Ment ertoe n eee eh ed eens Wes ed ee el i 109 8 Design of CarSimEd Data Screens iiss sc sasun Wess ciety tetas aean ten Wiaciea ee Wee 110 The Ribbon Batters s ccc cetie th secant eee bien e ede peek dae eee a Seeds eee eh SedbeeseeePiaess ete 110 Data Tet KS cas sete vet 0h saw nels t ohed Sesto Dd eas hie nv ed pte dent
216. eeeeeeeeeeeeeseeeeeeeeeeeeeeeeeeeeeneeeee 38 Defining Plots Interactively ecciesie eiieeii enrestar i a eieiei i ei 39 Viewing All Model Parameters and Inputs eee ee eeececececceceeeceeeeeereeeeeeeseeeeeteeeeeese 40 Printinea Data Setarea e E ee a E ERE EEEE a EE EE ead 40 Making a New Vehicle Data Set otenipiitesnneocati ks eteen oea teiaa a esh iaai 41 Modifying an Existing Vehicle Description eeceececcecceeeececeeeceeeeeeeeeeeeeeeeeereeenes 42 Switching Between CarSimEd and SIMULINK Inputs eseseseseseserererrrerererererrrrrrrrrererees 43 Going Directly to Any CarSimEd Library eere ee ee ereeeerereerereeeseersrereesesreesss 44 Locking Your Data aiiin iaaiaee EE EEE RE EEE ER A NETE ERE EEA 45 Deleting Data Setsri sx itede deeds ealan r eaoaai E te aaea eaii eeaeee e itar eeen tive 48 Making Five or More Plots for a Single Run eeeeeeeeeeeeeeeeeeeseresesssesesesesssssesesssssessssse 48 iii Overlaying Plots for Multiple RUNS eee eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee 49 Making Many Plots in Batch Mode eee ee eeeeeeeeeeeeeeeeeeeeeeeeeseeeeeeeseeeeeeeeeeeeeeeeeneeeee 50 Setting Up Multiple RUNS e eeens cenena eoe renier pe Oe ei ernea sq elven dacstenesavevedeeats 50 Making New Plot Descriptions sesesesesererererererertrtttrerettrtttretttetereteretererererererererererees 52 Linking to Different Libraries 03 ain ted eek BAe ees kaet eree oe TRE
217. eel center gen name Z coordinate of wheel center rigibody name LR wheel OUT 106 Z_WRF m Z coordinate of RF wheel center gen name Z coordinate of wheel center rigibody name RF wheel OUT 107 Z_WRR m Z coordinate of RR wheel center gen name Z coordinate of wheel center rigibody name RR wheel Creating Lists of Outputs A list of output variables can be created from within the software This list is a subset of the information contained in the README files If you happen to use a version of CarSimEd that has been customized you might want to make the list for reference purposes To make a list 1 Go to the Runs library and find a run involving the vehicle of interest 2 Ifthe run has not already been made click the Run button 3 Click the Plot button to bring up WinEP 335 Appendix J Model Input and Output Variables 4 Select the menu item Show Channel List from the View menu 5 A list of all channels will appear In addition to the list of channels the window has two buttons Cancel and Save To save a listing to a file click the Save button The Windows file browser will then appear 6 In the Windows file browseer enter a name for the text file and save it in a directory where you can find it later The default name is Chans txt 7 Click the Save button to create the file 8 You will be returned to the WinEP graphics window 9 Exit WinEP 336
218. eering braking and throttle inputs 2 A 2D pitch plane model for simplified ride analyses 3 A 3D kinematics model no dynamics or compliance of a 5 link suspension 3D Handling Model The main simulation program in CarSimEd is a handling model with full 3D rigid body equations for the vehicle sprung and unsprung masses The major kinematical and compliance effects of the suspensions and steering systems that affect wheel motions are included and are represented with parameters that correspond to standard vehicle properties that can be measured directly Details of the linkages and gears in the Chapter 1 Introduction suspensions and steering systems are not included reducing the amount of information needed to obtain accurate simulations The model has three forms of input steering braking and throttle Steering can be specified explicitly as a function of time Alternatively a path input can be specified e g a circle and a built in driver model will generate the steering wheel angle as needed to try to follow the path Braking and throttle inputs are both specified as tabular functions of time Two solver programs are provided for this model One is a stand alone application program with the file extension EXE and the other is a plug in for use with MATLAB SIMULINK with the extension DLL 2D Ride Model The ride model uses a subset of the input parameters required for the more detailed 3D model Information related to r
219. ehicle Dynamics Terminology Aerodynamic pitch moment Myaero Y component of aerodynamic resultant moment SAE 8 Aerodynamic roll moment Mxagero X component of aerodynamic resultant moment SAE 8 Aerodynamic yaw moment Mzagero Z component of aerodynamic resultant moment SAE 8 Suspensions and steering For solid axles the term suspension normally refers to the suspension for both sides of the axle For independent suspensions the term suspension refers to one side The term axle suspension always refers to both sides Size and Weight Track LTK distance between the centers of tire contact for one axle In case of dual wheels the midpoints of the centers of tire contact for each side are used Track typically varies slightly with suspension jounce ISO Unsprung weight portion of weight supported by a tire that is considered to move with the wheel This usually includes a portion of the weight of the suspension elements SAE Kinematics Camber outward angular lean of wheel relative to vehicle reference frame angle from Zy to the Xw x Zw plane Regardless of the choice of coordinate systems outward lean is positive The symmetric sign convention is convenient for describing certain kinematical and compliance relationships for both sides of the vehicle SAE ISO Compliance camber portion of camber due to tire forces except vertical and moments SAE ISO Compliance steer 5 portion of
220. el angular velocity gen name Wheel angular velocity rigibody name LF wheel OUT 12 AVy_LR rev s LR wheel angular velocity gen name Wheel angular velocity rigibody name LR wheel OUT 13 AVy_RF rev s RF wheel angular velocity gen name Wheel angular velocity rigibody name RF wheel OUT 14 AVy_RR rev s RR wheel angular velocity gen name Wheel angular velocity rigibody name RR wheel OUT 15 AVz deg s Vehicle yaw rate gen name Yaw rate rigibody name Vehicle OUT 16 Ax g s Vehicle long acceleration gen name Longitudinal acceleration rigibody name Vehicle CG OUT 17 Ay g s Vehicle lateral acceleration gen name Lateral acceleration rigibody name Vehicle CG OUT 18 Az g s Vehicle vertical acceleration gen name Vertical acceleration rigibody name Vehicle CG OUT 19 Beta deg Vehicle slip angle gen name Slip angle rigibody name Vehicle CG 329 Appendix J Model Input and Output Variables OUT 20 Fd_LF N LF damping force gen name Damping force rigibody name LF damper OUT 21 Fd_LR N LR damping force gen name Damping force rigibody name LR damper OUT 22 Fd_RF N RF damping force gen name Damping force rigibody name RF damper OUT 23 Fd_RR N RR damping force gen name Damping force rigibody name RR damper OUT 24 Fs_LF N LF spring force gen name Spring force rigibody name
221. elect All button Click to select all lines in the field D The contents of the field usually extend beyond the visible area and can only be viewed by using the scroll bar Clicking this button causes all lines to be selected even if they are not visible Deselect All button Click to deselect all lines in the field 4 Ascending Order button Click to alphabetically sort all lines in the field 4 Update All PAR Files button Click to process all of the CarSimEd library files in the field O updating all text files You should do this if you move CarSimEd or rename any of the TBK files or folders Each data set in the CarSimEd library has an associated text file with extension PAR that is used to communicate with the vehicle dynamics solver programs These files have absolute pathnames in them If any changes have been made to the file system say you moved CarSimEd from drive C to drive D the old pathnames won t work The operation initiated when you click this button will probably take a couple of minutes to complete The amount of time depends on the number of data sets in your CarSimEd installation and the speed of your computer Data Set for Start Button link This link defines what happens when you click the Start button G You can link to a library with no particular data set or you can link to a particular data set within a library If you do not choose a data set then clicking the Start button takes you to the last data set vi
222. em Aligning Moment ee A Fy Low Speed Parameters The models use alternative equations to simulate tire behavior at very low speeds Specify the speeds at which Nimm the low speed equations are used Rolling radius Spring rate Lateral tire dynamics ph K longitudinal slip Dynamic Lag Long tire force 2 49 ph 1 lockup lt 0 braking Tire force or moment Wheel spin accel 11 2 kph 0 free rolling 0 driving j p y tire inclination about X axis Animator Settings Tire thickness 210 12m xia Kt 100000 Q a yray 60 7 JNideg a a Cornering Stiffness 14 color v Example Ky Gizl Warning Unlike most yellow fields Pneumatic Trail the rolling radius and tire thickness Example trail axl must be given values User Settings O Longitudinal stiffness keyword KFX IAXLE This coefficient defines the relationship between longitudinal slip and force for small amounts of slip Although the coefficient is in reality sensitive to load a constant value is used in the model because no matter what the stiffness is the longitudinal force will balance the brake torque The stiffness determines the amount of slip that occurs during that balance and the longitudinal slip does affect the cornering behavior for combined slip see Appendix G However given that the tire model is not adjustable in its combined slip behavior a single value for Kfx is conside
223. en name name RR tire Tire vertical load rigibody Tire vertical load rigibody Tire vertical load rigibody Tire vertical load rigibody OUT 40 JounceLF mm LF susp comp deflection gen name Jounce rigibody name LF suspension OUT 41 JounceLR mm LR susp comp deflection gen name Jounce rigibody name LR suspension OUT 42 JounceRF mm RF susp comp deflection gen name Jounce rigibody name RF suspension OUT 43 JounceRR mm RR susp comp deflection gen name Jounce rigibody name RR suspension OUT 44 Kappa_LF LF tire longitudinal slip gen name rigibody name LF tire OUT 45 Kappa_LR LR tire longitudinal slip gen name rigibody name LR tire OUT 46 Kappa_RF RF tire longitudinal slip gen name rigibody name RF tire OUT 47 Kappa_RR RR tire longitudinal slip gen name rigibody name RR tire Longitudinal slip Longitudinal slip Longitudinal slip Longitudinal slip OUT 48 Mybrk_LF N m LF brake torque gen name Brake torque rigibody name LF Wheel OUT 49 Mybrk_LR N m LR brake torque gen name Brake torque rigibody name LR Wheel 331 Appendix J Model Input and Output Variables OUT S0 Mybrk_RF N m RF brake torque gen name Brake torque rigibody name RF Wheel OUT 51 Mybrk_RR N m RR brake torque gen name Brake torque rigibody name RR W
224. ended that all library files on the server be locked and that all users make runs from a local copy of CarSimEd including their own Runs library 3 Whenever a screen appears showing data from the CarSimEd database the corresponding file is inaccessible to all other potential users Therefore only one person at a time can access data from the server Chapter 2 Installation of CarSimEd CarSimEd Installation The CarSimEd software is provided as a self extracting EXE file that is typically downloaded from the MSC web site Run the EXE file to unpack a folder INSTALL that contains a file SETUP EXE Run SETUP to install the software When asked select the full installation When asked about installing program manager groups click the YES button The program then runs through an initialization process that takes a minute or two If you move the main folder e g C CarSimEd 45 it is necessary to re initialize the software as described in chapter 10 Linking to SIMULINK and MATLAB SIMULINK and MATLAB must be installed on your computer if you wish to combine the CarSimEd and SIMULINK packages Updating the MATLAB PIF The integration between CarSimEd and SIMULINK is done with software contained in the folder Mat Lab which in turn contains one folder for each SIMULINK model Each SIMULINK model folder contains a shortcut to the MATLAB program a CarSimEd DLL solver module and some extra support files Bx Exploring Il
225. ent A in the a direction This movement of the force application point provides a slight correction to the moment arm of the forces Tire Axes The tire X and Y axes tx and ty lie in the plane of the road t rz tx is defined as being perpendicular to the wheel spin axis Thus _ Wy Xr _r Xt r xt 7 3 wy xr Wheel Spin The wheel spin equation is a simple balance of moments about the spin axis Three moments are considered drive torque Mypy brake torque Myp x and the moment of longitudinal tire force acting with a moment arm equal to the deflected tire radius The wheel spin is described with a differential equation 309 Appendix H The Tire Model ae Mypv F Hcca Ar sign Mypx Iw 8 where Heca A is the instantaneous tire radius moment arm of Fy about the wheel center and Iw is the polar moment of inertia of the spinning wheel The wheel spin is integrated to calculate the wheel rotation angle needed for making animations of the rotating wheels Longitudinal Slip Longitudinal slip kK is normally defined as K 9 Wo where o is the zero slip angular speed of the wheel V 0 10 HeGa The slip angle a for each tire is defined in terms of the X and Y velocity of Wc Vx and Vy expressed in the ground plane Vx tx vel WC Vy ty vel WC 11 The slip angle is the arc tangent of the ratio vy vy Tire Relaxation Ti
226. er model Preview time keyword TPREV This is the look ahead time used by the driver controller algorithm to steer the vehicle A shorter time causes the controller to steer more rapidly in response to deviations of the vehicle from the target path A longer time causes the vehicle to look ahead more steering more slowly in response to changes in the target path A realistic value is about 1 second For constant lateral offsets a shorter preview time such as 0 2 seconds can be used to generate more aggressive steering to keep the vehicle on the target path For variable paths the short response time might lead to steering that is too aggressive and cause a loss of vehicle control If the table of S L values has discontinuous changes a preview time of 1 sec is recommended to avoid over steering by the controller For constant radius turns longer preview times can sometimes be used The longer times produce more stable results but lead to lateral offsets due to the curvature of the path To get accurate tracking with maximum stability a lateral offset can be specified to compensate for the curvature Driver lag keyword TDLAG Steering wheel angles generated by the driver controller are delayed by this amount of time to simulate the neuromuscular delay in people A realistic value is about 0 15 sec Larger values can be used to simulated impaired drivers As the lag increases the driver vehicle systems tends to over correct
227. er right corner Size of CarSimEd Data Screens The CarSimEd data screens are designed to fit on a VGA display 640 x 480 1 The upper right corner of the window has three Windows standard buttons PSs ES The middle button maximizes the window to fill the monitor screen see Figure 10 2 If your monitor has a larger display area than VGA the result is that the menu bar is put at the top of the total screen the main part is centered and the space around the main part is filled with gray Note In the maximized display mode pull down menus associated with triangle buttons do not appear in the correct locations when the buttons are pressed 2 To return to the normal CarSimEd display press the F11 key or use the Size to Page command from the Page menu Note If you have modified the window size by dragging the window borders the F11 key or Page menu is the only way to restore the size 229 Chapter 10 Advanced Topics 4m Runs 3D Handling x File Edit Text Page Tools Data set EIA category es ET x IS 4 SIG Grockea 12500 Model Parameters amp Inputs Run Control Output amp Post Processing Vehicle Classi xl Run Simulation Animate Input Steer Speed k op sec Mu Camera Setup Sodey sep sie a Input Braking Computation eman Je a ios zoHradna View Echo Fie a Parameters o cata st soeces o TE Plot Z Muttiple piots amp Overlay Runs Plot 1 Setu
228. ering transform options Plot Setup Single OF x File Edit Text Page Tools Data set Y vs X trajectory Changed ID 817 O Hotes 11 32 17 Category O Locked 7 20 98 Data to Plot Y X Hame for legend ia A wheel angular acceleration rev s Y Design X _Design o LR wheel angular acceler RF wheel angular accelera RR wheel angular acceleration revis gt LF wheel slip angle with lag deg gt LR wheel slip angle with lag deg RF wheel slip angle with lag deg RR wheel slip angle with lag deg Body roll rate deg s Body pitch rate deg s Avy_LF LF wheel angular velocity rev s Avy_LR LR wheel angular velocity rev s Avy_RF RF wheel angular velocity revis View Variables Names from File Avy RR RR wheel angular velocity revis Circle Oto 200 GF AVz Yehicle yaw rate deg s O Plot Format Axis Scaling OY Log Scaling X Log Scaling Note The Max and hin Y __ C Y Manual Range X Manual Range Default Settings MN o values might be used for Cipe as real time plotting even Data Transtorm when the Y tvanual Range Min ae box is unchecked Figure 9 7 The Plot Setup screen 181 Chapter 9 Alphabetical Library Reference Discussion This data set is a template used to specify what a plot should contain and how it should look The template is applied from the Runs screen and the Plot Setup Batch screens CarSimEd
229. ers for the solver program along with links to other PAR files When you click the Run Simulation button the SGUI creates a new PAR file in the folder containing the Runs library e g Runs The PAR file contains information from the Runs screen such as the title of the run pathnames for the data sets linked to the run vehicle steer input etc and input parameters e g stopt The PAR file also includes references to other PAR files Every data screen in CarSimEd has an associated PAR file including the Runs screen When the solver program runs it reads the PAR file generated from the Runs screen and all other PAR files referenced within it The files can be thought of as forming a tree such as the one shown in Figure 3 4 on page 26 Viewing the Tree of PAR Files The actual tree associated with any screen in CarSimEd can be viewed by clicking the Parstree icon in the ribbon bar Kl Clicking the button launches a program called Parstree that displays the PAR file associated with the current data screen Figure 5 4 shows an example display window from the Parstree program Note that many of the input lines start with the word parsfile and are followed by pathnames to other files with more data Chapter5 The Solver Programs El ParsTree O 1x ParsTree lolx Parsfile tree Structure Contents of the selected file PARSFILE UPDATE 2 04 46 12 27 99 E 53 par
230. es are multiplied by the ratio x_length x_ref_length e Y coordinates are multiplied by the ratio y_length y_ref_length e Z coordinates are multiplied by the ratio z_length z_ref_length The scaling is only performed in a direction if both the length and the reference length are specified In CarSimEd the PAR files for the vehicle data sets specify x_length using the wheelbase of the vehicle The PAR files for the suspensions specify y_length using the suspension track width Therefore you can enable the animation data to be resizable by specifying the reference wheelbase using the keyword x_ref_length use mm and the reference track width using the keyword y_ref_length A portion of an Animator Groups screen is shown below with reference X and Y lengths 4m Animator Groups File Edit Text Page Tools Data set ResizableCar sid Car ResizableCar sd 4l te GO Link 4 reference frames Link 11 v No data set selected x Link 2 group Sedan body x Link 3 No data set selected NEE Link 4 No data set selected L No data set selected x Ry _REF_LENGTH 2690 x Link 6 Y_REF_LENGTH 1440 No data set selected x x Link 13 Na amt If the simulated vehicle has a longer wheelbase than the value specified with x_ref_length the animator will stretch out the shape to fit the actual wheelbase If the simulated wheelbase is shorter than the reference the animator will compress the shapes
231. es into the definitions field 4 The definitions should have the form A X B Y where A and B are numerical scale factors For example suppose the X values are in inches and Y values are in pounds To convert to a table where the X values are in millimeters and the Y values are in Newtons use the definition 25 4 X 4 4482216152605 Y Click the Calculate button G to perform the transformations Click the Plot button G to confirm that the conversion was performed as you expect Optional Click the button Remove 2 if the numbers should not be separated with commas e g for animator shape data Select the entire contents of the tabular data field 1 The menu command Select All under the Edit menu Ctrl A is helpful for doing this 227 Chapter 10 Advanced Topics 10 Select the Copy command from the Edit menu Ctrl C 4m Calculator Oy x File Edit Text Page Tools Dataset UnitsChangel sss a 1 New Delete Gor Back O LI ADE Sle Show Series Calculator Show Simple Calculator Changed O Hotes O Locked IDA 5 01 49 841298 Tabular Series Data o i D NPRPRFPRFRFRFOOOSO Baal Insert a O Flip Rows Flip Cols Herp Transpose E gt Sa 5 10 15 Formulas for Items Create or Transform Calculation Options x round y 10 Create Cafeulete Transform O 11 Go to the data screen where the tabular data will be stored 12 Ifa data s
232. es of x1 lateral coordinate Y and x2 yaw angle y are identically zero in the axis system of the driver model Therefore only two coefficients are needed in array Fj fj accounts for initial lateral velocity x3 and f9 accounts for initial yaw rate x4 The coefficient f1 represents the value of y at the end of interval i for an initial value of x3 1 The values are calculated for i 1 m using numerical integration The initial values of all state variables except x3 are set to zero and x3 is set to unity The 2 DOF model is then simulated using an Euler integrator from t 0 to t T and values of the lateral position are saved at the m locations used in the summation The process is repeated to determine the values of f2 except that the initial conditions for the 2 DOF model are that x4 1 and all other variables are 0 The free response coefficients in Fj are also used to compute the control response coefficients g using Equation 7 The coefficient g defines the deviation of the vehicle at the end of interval i due to a sustained steer angle of unity An extra state variable is added whose derivative is y Its integral at the end of each interval i is multiplied by B3 for the initial condition of x3 1 and its integral for the initial x4 1 is multiplied by B 4 The weighted sum is gj Equation 14 is used to determine the optimal control steer The steer due to factors other than the driver is provided as Ug and subtracted from
233. et does not exist for the transformed data create one using the New button and give it a name 13 Paste the clipboard contents into the field used to store the numbers See Chapter 9 for details on using the calculator data screen Improving the Appearance of the CarSimEd Screens Windows has many settings for screen size number of colors and default font size Font Size The CarSimEd data screens look best when the system display properties are set for Small Fonts However the screens should be readable for any valid setting Colors The CarSimEd screens look best when 256 or more colors are supported If your machine is set to support 16 or fewer colors CarSimEd has a setting to produce yellow and blue 228 Chapter 10 Advanced Topics fields using dot patterns rather than solid colors A global setting is used to control whether CarSimEd uses solid colors or patterns 1 From any CarSimEd data screen click the amp l button in the ribbon bar or select the Preferences command from the Tools menu This brings up a dialog box with a few check boxes 4m Preferences O Auto lock every data set Advanced Mode allow changing links Have 256 or more colors on monitor must move to another screen to see effect 2 If your machine is set up to support 256 or more colors check the box Have 256 or more colors on monitor O Otherwise un check this box 3 Close the dialog box by clicking the X in the upp
234. euelansys 155 Generic 2D Tables n ei vec E E E E ects tegen idea Tied eden elegans es 157 Generic Data Groups sccscc ecctadeveetdevebeccuseae dud bs stucensuepeueleviebeccuneee dense tovesonbaeutedeonoveceh ens 159 Generic Table errer erecting a dei hha Adige Dea 161 Input Braking e esseeri irean iaiia cbs E e aei aea Se Taaa a a Ta Aata ai ieira i Eae 162 Inp t Road Profle yetin eiee ten eei eia a ata a a aaie a a chalets bone eet 164 Input Steering Wheel Angle einion ine ae E Ea a Ea EREE apy 166 Input Target Path For Closed Loop Steer Control ceeeeececeecececceeeeeeeeeeeeeereeeeeees 167 Input Phrottle Control cc 0 cenit ea a Ba dd Bk ee ae 171 Input Wheel Height Above Ground eee eeeeeeeecececececececececeeeeecececeeeeeeeeeeeeeeeereeee ss 173 Labrary Editorii tt ik ean uh neh hk senha ee bia iin atanting EAN 174 Plot Format resnem iegareni nenie a EEE N EERE E E a i Ei E 176 Plot Setup Bate iese eeta secede rel weitin ether eucteabebivetwed ence Gea aiaa eaaa e itae att 179 Plot Set p Sinale ra aier EAEE REET E aE AEE ERTO EAEE SA 181 Plot Transforms secre E ie e E Eae Seis eG Sauces EE S EEVEE ii 183 R s 2D Rides i oii i eh Aa ein ee ieee Ain 187 Runs 3D Handling soseen terenn aeii des ives ccsudtostlevereseuhhsedesdteshedsebipiovedssnsvedene s 188 Runs SIMULINK CMEX Version ccceeeececccccecccceeeeceeeeeceeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee ss 196 Runs Suspension Analyse Ssnan an e vets deisvepe
235. f time followed by a corresponding value of steering wheel angle with a separating comma The sign convention in CarSimEd is that positive steer involves turning to the left See Appendix B for details of all CarSimEd sign conventions The solver programs use linear interpolation and flat line extrapolation with this table For values of time that are less than the range covered in the table the first value of steering wheel angle is used For values of time larger than the range covered the last value of steering wheel angle is used The table needs at least two lines of data or else an error message is generated Location in CarSim CarSim Startup Runs Input Steering Wheel Angle File Location Input Steering Steering tbk Input Target Path For Closed Loop Steer Control Use this screen to define the path the vehicle is to follow in a closed loop steering maneuver using the CarSimEd driver model This screen is only used for the 3D car model If it is linked to a 2D ride or suspension analysis run the data are ignored 167 Chapter 9 Alphabetical Library Reference Discussion Modes of Steer Control You can choose between two different ways to control steering in CarSimEd You make the choice on the Runs screen by linking to a data set from one of these libraries 1 Input Steering Wheel Angle Choose this library to apply a steering wheel angle described explicitly as a function of ti
236. ferent variable and each row corresponds to a value of time The values from this file are read by the plotter and animator programs in CarSimEd Types of Output Variables The ERD file contains variables that fall into three groups 1 Vehicle variables that characterize its behavior during the run 2 Additional variables needed to create animations for viewing vehicle motions 3 Controls and disturbances that are the inputs to the mathematical vehicle model Although the ERD file is organized by discrete time steps all variables can be plotted against any other variable Output variables have short and long names plus other information that is used by the plotter However they are identified by their short names which are defined in the ERD file standard as having exactly 8 characters Shorter names are padded with blanks The variables are named using a convention that is summarized in Table J 1 Names can have up to three parts 1 A prefix of first one or more letters to identify the type of variable Force Acceleration etc 2 A following letter further clarifies the type of variable For example the letters x y and z are used to identify directions The letters s and d are used to identify Spring and Damper forces Notes Many quantities of interest are vectors These include acceleration angular velocity and tire force The ERD file contains components of these vectors with the component being identified with a
237. file with a detailed header followed by columns of numbers The header has the same information as in the default configuration with binary files With this option the installed plotter and animator work the same as with the binary option The text portion of the file can be imported into other programs although it might be necessary to delete the header lines at the start of the file Return to the Runs screen by clicking the Back button Select the new Computation Parameters data set before making a run to generate text output files The name of the output file is the ID number shown in the upper right corner of the Runs screen with the extension ERD e g 231 ERD The default location of the output files is CarSimEd Runs Creating Text Output Files from within the Plotter The WinEP plotter has the capability of displaying data in text form This capability can be used to export a subset of variables to other software Start from the Runs screen Go to a run data set that involves output variables to be exported Choose a plot setup involving variables of interest Click the Plot button to launch the WinEP program Select a plot window in WinEP involving variables of interest Select the menu item Show Numbers under the View menu This displays a dialog box called Show Numbers with a scrollable list with numbers separated by spaces 224 Chapter 10 Advanced Topics 6 Note Sometimes due to memory limitations o
238. from another computer The file of numbers can be made into an ERD file by inserting a 3 line header at the beginning of the file If the header of the ERD file does not contain a line with the FORMAT keyword it is the same as if the FORMAT is a blank When this occurs for a text file the file is assumed to contain numbers in free form The only restriction on free format numbers is that adjacent numbers must be separated For example the following line is valid for representing 5 numbers 1 2000 3 4 2 01E 01 14 3 The following line is not because the third and fourth numbers touch 1 2000 3 0000 4 0000 2 01E 01 14 3000 Numbers may be separated by one or more spaces the tab character or a comma Binary Data Reading and writing binary data is efficient because the computer does not need to perform any conversions or transformations as the data values are moved between the file 262 Appendix C ERD File Format and the computer memory When a binary format is used the data portion of an ERD file is a direct copy of a portion of the computer memory corresponding to a two dimensional array having dimensions sized to the number of channels and the number of samples As indicated in Table C 1 two forms of binary data are currently supported 2 byte integer and 4 byte floating point 2 byte integer data are typically obtained by data acquisition systems Each integer value is a sampled reading obtained from a digitizer d
239. function of time In this case the amount of time covered is not important because the typical outputs of interest are cross plots of motion variables as functions of vertical position User Settings Note User settings that are common for all tabular data screens are described in Chapter 7 in the section Tabular Data 173 Chapter 9 Alphabetical Library Reference O Table field for vertical wheel height keyword BZ_TABLE Each line should have a value of time seconds followed by a corresponding height of the wheel center Because the simulation is not dynamic the only purpose it has in the plot is to define a continuous change in height Two point tables such as the one shown above are recommended They simply specify the minimum and maximum ranges to be covered in the kinematical simulation Location in CarSimEd CarSimEd Startup Runs Suspension Analysis Input Wheel Height Above Ground File Location Input spindlez spindlez tbk Library Editor The Library editor is a tool built into CarSimEd to help you organize libraries by performing batch delete locking and renaming operations Library Tool Selected library C1 gt animateframes frames thk v 3 bck Data Sets Unlock Data seta 4 Change Category zCameras moving gt Camera tracking X Y Camera tracking X Y Yaw Suspension Parts Link 1 Link 2 7 Link 3 Link 4 Link 5 Vvheel spindle lt VWheels LF Car Wheel LR Car heel
240. g directory without adding more paths to the MATLAB workspace Adding pathnames can cause conflicts and uncertainty about which version of a file is loaded All files associated with CarSimEd are located in that directory where the potential for conflict with other MATLAB files is minimal With respect to the second item the main point is that you the user must be aware of the role played by CarSimEd and SIMULINK when they are combined The CarSimEd graphical user interface is used to define parameters and properties of the simulated vehicle Control inputs can also be specified in the SGUI However control inputs are also provided from SIMULINK Controls from SIMULINK are added to the inputs from the SGUI To choose the source you should zero out the contribution from the unwanted source To eliminate the input from the CarSimEd SGUI select zero valued inputs from the Runs_cmx screen Any time you change a vehicle property you must remember to click the button Update on the Runs_cmx screen to create a new SIMFILE before making a new run in SIMULINK File Types When run from the graphic interface in CarSimEd i e by clicking the Run Simulation button from a Runs screen all files associated with a run have the same base name and differ only in their extensions The base name is the current ID number displayed in the upper right corner of the Runs screen Table 5 1 shows the files and their extensions Details of the file
241. g problems involving parameters not getting through such as when changes are made to the directory structure of the CarSimEd libraries a The Animator CarSimEd includes a program for animating wire frame figures to visualize vehicle motions The animation is accomplished by drawing images similar to what would be seen with a video camera and updating the images many times per second to show motion Updates The animator program is used in a number of MSC software packages The latest version is generally available from the Internet at http www trucksim com animator index html Updates of the animator program are backward compatible If you download a newer version simply replace the file Animator exe in the Animate folder in CarSimEd Overview of Operation To help understand the animator imagine that you are aiming a video camera at a vehicle as it moves down the road Thirty times per second the camera records an image of the vehicle and ground as seen from your point of view By playing back those images at the same rate thirty times per second you see the vehicle move relative to its surroundings If the camera has a zoom lens you can zoom in to fill the screen with the vehicle Or you can zoom out to shrink its apparent size What you see depends in part on where you are located You could be standing on the ground in which case your position would not change Or you might be in another vehicle that moves wit
242. ge 3a 2a combo File Edit Format Data View Window Help lej x Yaw velocity Lane change 3a2a combo Yaw velocity deg s Y axis label 4 dO 4 2 3 4 5 6 7 8 9 0 11 2 Time sec X axis label AV2_2 5 325 y 3 453 NUM Figure 9 6 Labels in a plot The recommended setting is Auto Location which instructs the plotter to choose one of the four locations within the plot space Legend size limit keyword legendpercent When two or more data sets are overlaid and the legend is located to the right of the plot area WinEP sizes the plot area to leave just enough room to print the legend In the event that at least one of the labels in the legend is long or that the window is not very wide then little space is available for the plot This field is used to set a maximum percentage of the total window width that will be used for the legend This setting has no effect unless three conditions are met 1 At least two data sets are overlaid in the plot 2 The legend is placed to the right of the plot as specified in 9 3 The length of the longest label in the legend exceeds the specified percentage of the window width 178 Chapter 9 Alphabetical Library Reference If the above three conditions are met then the plot is sized giving the legend the specified amount For example if the limit is set to 30 then the plot area is size to leave exactly 30 of the width for the legend L
243. ging font properties using any of the buttons Bl 23 CO will change all of the text in the plot Note To use this function you must check this box before making the selection in the font dialog box shown in Figure 6 5 Data Menu The Data menu has commands that involve the numbers to be plotted and the associated labels from the data files The commands involve the selection of X Y data sets possible transformation of the numbers labels for the plot and viewing the numerical values using a cursor Chapter 7 The Plotter Define New Plot Ctrl N Offsets Filter Statistics Labels Ctrl L v Show Data Points Ctrl D Cursor Position Info gt Define New Plot pg Select this command to bring up the Channel Select dialog box The keyboard command is Ctrl N Use this dialog box to create a list of X Y data sets to plot Each data set consists of three parts 1 a Y channel 2 an X channel and 3 a file name The numbered items in the dialog box are shown in Figure 7 6 and are described below Channel Select x Data to Plot y x file Y Channels Title Figure 7 6 Channel Select dialog box List of X Y data sets to plot This list shows the data sets that will be plotted You cannot edit it directly but can modify it using the buttons es Q List of variables in the current ERD available for defining the Y coordinate in a plot To select a variable for plotti
244. gles yaw_roll_pitch set_x_name _WRF set_y_name Y_WRF set_z_name Z_ WRF set_roll_name Roll WRF set_pitch_name Rot_ wRF set_yaw_name Yaw WAF set_scale_var_pitch 360 ff TIRES_ED Example Small Tire object name parsfile C ACARSIMED 45 WWEHICLESSTIRESSTIRES_ED569 par ht Parstile path and filename C CARSIMED 45 VEHICLES CARS_ED 39 par File can t be found C Keyworderor Create LpiFile Reload File Load New File Exit a Database ToolBook Problems The database in CarSimEd is run under a program called ToolBook from Asymetrix The version being used in CarSimEd includes 16 bit library routines which can crash Most users have never experienced a crash of ToolBook The problem is not reproducible but it does exist 237 Chapter11 Trouble Shooting Whenever you switch from one ToolBook library to another one the file is automatically saved Therefore if a crash occurs you will not lose any data from libraries other than the one that is open Risky Operations Here are the operations that appear to carry some risk e Importing data sets into a library from another CarSimEd library can crash ToolBook The problem has something to do with memory management within ToolBook To reduce the risk do not import more than 10 data sets at a time and save the ToolBook file after each one e Having two copies of ToolBook running is risky and should be avoided If you launch CarSimEd and it is already
245. gular velocity rev s x Eye al LR wheel angular velocity revis RF wheel angular velocity revis View Variables Names from File RR wheel angular velocity revis Acceleration in a turn v FAVZ V 5 rate deq s Axis Scaling OY Lo j ot Format g Scaling O X Log Scaling Piot For Note The htax and Min Y Default settings 11 e AiE BAGELS Yor O Y Manual Range 0 X Manual Range DataTransform 12 real time plotting even Max 100 No Fiter Ne 100 box is unchecked Figure 4 10 The Plot Setup screen Use the navigation buttons 2 in the ribbon bar to find a plot setup similar to what you want Click the New button 3 to make a new data set Type a name for the new data set in the title field O This name will later appear when you view the list of plots with the plot setup menus on the Runs screen Select a run from the library linked to the field named View Variable Names from File 10 When you select a run the output ERD file associated with the run is scanned and all of the variables are listed in fields 8 and 9 The run must have been made in order for the ERD file to exist Notes It doesn t matter which run you use to build the file description so long as the ERD file contains the variables that you want 52 Chapter 4 The Basics of Using CarSimEd 10 11 plotted The only reason an existing run is used to build the description is because it is more convenient to c
246. h the vehicle In the animator your location is defined as the camera point Your view is also determined by how you aim the camera You might have the camera aimed at a fixed point in space The vehicle would only be visible while it is in field of the camera view More likely you would move and aim the camera as needed to keep the vehicle in view In the animator the camera is aimed directly at a look point Figure 6 1 shows the basic geometry and the relationships between the camera point the look point the 3D system being animated and the 2D image that is recorded Chapter 6 The Animator Origin of global reference frame Origin of moving reference frame Camera point Figure 6 1 Geometry of the camera point and the look point The animator allows you the user to build and modify descriptions of the system to be animated In order to use the program effectively it is helpful to understand the concept of a moving reference frame Reference Frames The animator creates images based on a set of visible objects that includes a grid and arbitrary wire frame shapes defined by a sequence of connected lines Some of the wire frame objects are organized into groups that move together For example the body of the vehicle is made up of the bumper rear bumper left front door etc A group of points and objects that maintains a fixed relationship i e that constitute a rigid body is called a reference fra
247. h to make a new run using a different SIMULINK model it is best to exit MATLAB before initiating the next run G Update button This button does half the work of the Start Simulink button 2 It causes CarSimEd to update the information that will be read by SIMULINK but it does not launch SIMULINK If SIMULINK is already open with the model you are using you can use this button to update the information that will be read by the program when it runs In a typical CarSimEd SIMULINK session you will use the Start Simulink button 2 to make the first run and then use the Update button for all subsequent runs 4 Simulaton Type link This shows the current type of SIMULINK model As installed CarSimEd has two example SIMULINK models Once you start using CarSimEd with SIMULINK it is likely you will add more SIMULINK models The triangle button displays a pull down menu with options for adding and deleting simulation types and for locating a folder with the necessary SIMULINK files Unless you add new SIMULINK models you should never use this menu In fact the menu is disabled unless the check box for Advanced Users is checked in the Preferences screen To access the preferences use the Tools menu item Preferences or click the button amp in the ribbon bar As described in Chapter 2 each SIMULINK model resides in its own folder The folder has a program information file PIF that is associated with the MATLAB program When you
248. h u and y are scalars Thus B is a n X 1 matrix and Cisa 1 X n matrix There is a further simplification namely that the output y does not depend explicitly on u Thus the D matrix is not used If the system has initial conditions Xo at time t 0 and a constant control input u its time response has the known solution x t eAlxy f e B udn 3 The term e t is an n X n matrix called the state transition matrix Each coefficient in the matrix is the portion of state variable i at time t that is linearly related to state variable j at time 0 It can be calculated with a power series with eigenvectors or by numerical integration As will be described later numerical integration is the method used in the driver model The product of the state transition matrix eAt and the array of initial conditions Xo is an array of length n with the part of each state variable at time t due to the initial conditions of the system at t 0 This is called the free response The integral defines a contribution to each state variable due to the constant control u over the time interval It is called the forced response 318 Appendix I The CarSimEd Steer Controller Combining Equations 2 and 3 gives the response of the output variable t yit Cx CeAtxo C If eAN dr Bu 4 A free response array F a 1Xn matrix is defined to simplify some of the following notation F relates the state variables at time 0 to the resulting output variable y at
249. hat opposes the steering It is called self aligning torque or aligning moment The pneumatic trail is a function of the shape of the contact patch between the tire and road Therefore pneumatic trail is sensitive to inflation pressure and vertical load This screen is used to describe this sensitivity to load 4m Tires Pneumatic Trail BEI x File Edit Text Page Tools Data set Example trail O Changed ID 35 CO Hotes 12 46 29 Pneumatic trail Mz Fy for small cf mm Update Plot Tidy Table 60 Load H Trail mm 50 40 30 20 10 0 1000 2000 3000 4000 5000 6000 7000 8000 Vertical load N 01 21 00 GO shows a pull down menu of data libraries Takes you to the library selected 214 Chapter 9 Alphabetical Library Reference O User Settings Note User settings that are common for all tabular data screens are described in Chapter 7 in the section Tabular Data Table field for pneumatic trail keyword TRAIL_TABLE Each line should have a value of load N followed by a corresponding value of trail mm The solver program uses linear interpolation and flat line extrapolation with this table For values of load that are less than the range covered in the table the first value of trail is used For values of load larger than the range covered the last value of trail is used The table needs at least two lines of data or else an error message i
250. he 116 Chapter amp Design of CarSimEd Data Screens preferences button in the ribbon bar or selecting the Preferences command from the Tools menu This brings up a dialog box 4m Preferences Ed O Auto lock every data set EJ Advanced Mode allow changing links Have 256 or more colors on monitor must move to another screen to see effect Make sure the Advanced Mode box is checked and then close the preferences window e No data set selected This breaks the current link to a data set The link to the library remains but without a data set data from the library are not used in simulations e Data Set Names All of the menu items after the dividing line are the names of the data sets in the linked library Change the link to a different data set by selecting its name If the current screen has the Locked box checked only the Go To Data Set item is active The other items involve changes in the data set and are not allowed Tabular Data Some CarSimEd data sets involve tables of numbers The values are plotted to show the functional relation graphically and to help identify errors Figure 8 3 shows an example data set Note For these data sets the Notes field is often located on top of the table of numbers 2 Therefore to view the numbers in the table the Notes button must not be checked There are four standard items on each screen with tabular data Plot The plot is based on the tabular
251. he Misc Data field 17 This blue field is normally not linked to anything unless a batch run has been made File extension This determines which echo file is scanned when a run is made or the Rescan File button is clicked The normal values are LPF scan the file made with final conditions or LPO scan the file made with initial conditions Excerpts from Output File This field shows selected lines scanned from one of the output files It is updated whenever a run is made or when the Rescan button 3 is clicked This field is provided along with the supporting items 20 Q2 and 63 to rapidly access information from the echo files produced when you make a run For example you can show the final value of a state variable such as distance traveled roll angle etc 195 Chapter 9 Alphabetical Library Reference To do this look through an echo file click the button View Echo File All Parameters 10 Any keyword from the file can be placed into the keywords list OD and lines beginning with those keywords will be placed into this field Keywords field Each line in this field is a keyword that will be used to scan an output echo file whenever a run is made or when the Rescan button is clicked Rescan button Click this button to cause CarSimEd to scan a file for lines beginning with the keywords listed in the Keywords field C Those lines are copied into the adjacent white field 21 The file that is scanned has a root
252. he figure it is 6 The simulation runs from startt to stopt Change any inputs that you want to be different for the new run Make the new run Optional You can set up overlay plots to show both runs a Check the Overlay Runs box 5 b Select the first turn for the Overlay Run 2 link 6 231 Chapter 10 Advanced Topics If you made the start time for the new run coincide with the stop time for the first all plots will show the entire time histories covered in both runs Note Some of the subsystems perform initializations that prevent perfect continuity However the continuity is close enough for most purposes Changing the Default Runs Library CarSimEd is shipped with four Runs libraries three for using stand alone EXE solver programs and one for working with SIMULINK There are two built in shortcuts to jump directly to a default Runs library One is the Tools menu item Runs and the other is the button E in the top region of every data screen As shipped the menu item and the button are linked to the Runs library used for running the stand alone 3D car solver program If you primarily run CarSimEd with SIMULINK you might wish to change the default link to go to the other Runs library To assign a new Runs library start with any data screen in CarSimEd 1 Control click on the computer icon in the ribbon bar This brings up a find file dialog box 4m Plot Setup Single of Xx File Edit Text Page
253. he suspension with respect to the spring The value is typically between 0 5 for some SLA suspensions and 1 0 for some MacPherson strut suspensions Ratio of damper jounce to jounce at wheel keyword RDAMP IAXLE This determines the mechanical advantage of the suspension with respect to the shock absorber The value is typically between 0 5 for some SLA suspensions and 1 0 for some MacPherson strut suspensions Spring rate keyword KS IAXLE This is the linear rate of a single suspension spring You can take the rate at the spring rather than at the wheel because an additional parameter accounts for the mechanical advantage of the suspension 7 Damper rate keyword DS IAXLE This is the linear rate of a single shock absorber You can take the rate of the isolated damper rather than at the wheel because an additional parameter accounts for the mechanical advantage of the suspension 8 Auxiliary roll stiffness including stabilizer bar keyword KAUX IAXLE This coefficient is provided to account for the difference between the overall roll stiffness and the stiffness provided by the springs along It is usually positive The overall roll stiffness of a suspension is the roll moment N m needed to roll the vehicle body one degree with the other suspension disconnected and the tires replaced with rigid elements The springs provide a certain amount of roll stiffness
254. he time step 4 Also select button 6 to eliminate the delay caused by checking the clock Radio button for maximum speed animation When selected the animator does not access the computer clock allowing maximum display speed OK button Click to exit the dialog box and apply the new settings Cancel button Click to exit the dialog box without changing the settings eTA Chapter 6 Superimpose Vehicle The Animator Select this command to toggle an option to draw new images without erasing old ones This mode is useful with some configurations to show trajectories of vehicle motion or to show amplitudes of oscillations Modify Camera Locations Select this command to display the following dialog box The numbered items are described below Camera Settings x Camera Locations Focal Length x Camera Y Camera Z Camera x Look Y Camera Z Look amo 4 Cancel Z Origin of global n reference frame 3 zy C7 Pa Ba Ae bt oF FF Look point 7 sy 2D image dh O77 at camera Origin of moving E a a E e focal length reference frame _ i Paj a ay p T pai a Camera point Notes Eee Help Menu These settings are similar to those contained in the Animator Camera Setup library described in Chapter 9 Units of length should be compatible with the coordinates used for shapes and reference as described in the section Units on
255. heel OUT 52 Mydrv_LF N m LF drive torque gen name Drive torque rigibody name LF Wheel OUT S53 Mydrv_LR N m LR drive torque gen name Drive torque rigibody name LR Wheel OUT S4 Mydrv_RF N m RF drive torque gen name Drive torque rigibody name RF Wheel OUT S5 Mydrv_RR N m RR drive torque gen name Drive torque rigibody name RR Wheel OUT S6 Mz_LF N m LF tire aligning moment gen name Tire aligning moment rigibody name LF tire OUT 57 Mz_LR N m LR ire aligning moment gen name Tire aligning moment rigibody name LR tire OUT 58 Mz_RF N m RF tire aligning moment gen name Tire aligning moment rigibody name RF tire OUT 59 Mz_RR N m RR tire aligning moment gen name Tire aligning moment rigibody name RR tire OUT 60 Pbrk_con MPa Brake control input gen name Line pressure rigibody name Control OUT 61 Pitch deg Body pitch gen name Pitch rigibody name Body OUT 62 Roll deg Body roll gen name Roll rigibody name Body OUT 63 Roll_WLF deg LF wheel inclination angle gen name Inclination angle rigibody name LF wheel OUT 64 Roll_WLR deg LR wheel inclination angle gen name Inclination angle rigibody name LR wheel OUT 65 Roll_WRF deg RF wheel inclination angle gen name Inclination angle rigibody name RF wheel 332 Appendix J Model Input and Output Variables OU
256. hen this is reached m TDLAG 0 Lag time used by driver model s TPREV 1 Preview time used by driver model s VLOW_ALPHA 1 5 Front low speed threshold for modified tire relaxation equations kph VLOW_ALPHA 2 5 Rear low speed threshold for modified tire relaxation equations kph VLOW_KAPPA 1 2 Front low speed threshold for modified longitudinal slip equations kph VLOW_KAPPA 2 2 Rear low speed threshold for modified longitudinal slip equations kph VLOW_SPINA 1 2 Front low speed threshold for modified wheel spin equations kph VLOW_SPINA 2 2 Rear low speed threshold for modified wheel spin equations kph V_STOP 1 Low speed limit for stopping the simulation kph XDESIGN 219 798 NIL YDESIGN 142 078 NIL Brake input vs time BRKIN_TABLE 0 0 10 0 ENDTABLE Cornering stiffness vs load 30 pts max IAXLE 1 Table ID number KFYA_TABLE 0 0 500 181 1000 356 2000 673 3000 922 4000 1097 6000 1253 8000 1250 ENDTABLE IAXLE 2 Table ID number KFYA_TABLE 0 0 500 181 1000 356 2000 673 3000 922 4000 1097 6000 1253 290 Appendix F 8000 1250 ENDTABLE Steering wheel input vs time Column 1 time sec Column 2 steering wheel angle deg STEERSW_TABLE 0 0 0 1 30 3 30 ENDTABLE Throttle input vs time THROTTLE_TABLE 0 0 25 0 ENDTABLE Pneumatic trail vs load 30 pts max IAXLE 1 Table ID number TRAIL_TABLE
257. hicle data set from the library Vehicles Car The type of vehicle is shown as a sub title above the blue field In the figure the type is independent Start SimuLink button This is the main button for the screen Click to launch SIMULINK with the model associated with the selected Vehicle 1 and Simulation Type 4 Use this if SIMULINK and MATLAB are not already running Note As described in Chapter 2 this button cannot be used unless MATLAB and SIMULINK are installed on your machine They are not part of CarSimEd and must be licensed separately from The MathWorks Inc After clicking this button you should see the model in SIMULINK Type Ctrl T to start the run Or select the Start menu item from the Simulate menu When the simulation 197 Chapter 9 Alphabetical Library Reference runs the CarSimEd module a DLL file containing a CMEX S function with the car model reads all inputs from the CarSimEd libraries and proceeds When the run is completed you can view plots and animations from the Runs screen Also you can use any of the MATLAB analysis tools After completing a run you can quit MATLAB to return to this screen or you can leave MATLAB and SIMULINK open and return to this screen by typing Alt Tab or by using the Windows Task bar If you will be making many runs using the same SIMULINK model it is not necessary to exit MATLAB The new runs can be set up using the Update button G However if you wis
258. hicles cars_ed cars_ed tbk vehicles link_sus link_sus tbk vehicles susp_ed susp_ed tbk vehicles tires kfy kfy tbk vehicles tires tires_ed tires_ed tbk vehicles tires trail trail tbk Open startup tbk Tun_cmex run_cmex tbk tuns_2d runs_2d tbk tuns_3d runs_3d tbk tuns_sus runs_sus tbk animate cameras cameras tbk animate frames frames tbk animate groups groups tbk animate shapes shapes tbk animate wheels wheels tbk batch plot_bat plot_bat tbk batch runs_bat runs_bat tbk comp_parcomp_par tbk generic gen2dtab gen2dtab tbk generic gendatagendata tbk generic gentable gentable tbk input braking braking tbk input road road tbk The menu contains more items than will fit on a monitor with VGA resolution 640 x 480 Note that the first item in the menu is More Highlight it to view more menu items as shown in the figure Back button Click this button to go back to the previous library This is the library that you came from by using a link the GO menu or the History dialog box Number Tools button Click this button to go to the calculator screen This is equivalent to the Tools menu Calculator command The calculator screen is used to create and edit tabular data If it is not currently linked control click to get a file browser to locate the library and establish a link to it The default is Sgui_lib Calc tbk Text Editor button Click this button to go to a utility library used to create and edi
259. hings happen 1 the current data set as displayed on the screen is deleted and 2 auxiliary files associated with the data set are also deleted Thus CarSimEd automatically performs housecleaning If the library has only one data set the Delete button cannot be used there must always be a minimum of one data set in a library Also the Delete button will not work on the current data set if the Locked box C is checked There are two keyboard modifiers for the Delete button e Press the Ctrl key when clicking the button to avoid the confirmation message e Press the Shift key when clicking the button to delete all data sets except the current one There will be a confirmation message giving you a chance to change your mind after clicking the button Be aware that if you go ahead other data sets can be deleted even if their Locked boxes are checked Use this feature with care Note When you position the cursor over the Delete button the Status Bar at the bottom of the window describes the above two keyboard modifications 111 Chapter amp Design of CarSimEd Data Screens GO button Press this button to display a menu of all libraries in CarSimEd Select a library from this menu to leave the current library and go to the selected one input spindlez spindlez tbk input steering steering tbk input throttlethrottle tbk plot format format tbk plot setup setup tbk plot transfrm stransfrm tbk ve
260. ile WinEP initially creates one or more plots Once the initial batch of plots is made WinEP reverts to interactive mode In the interactive mode you can view the plots print them and change their formatting You can also create new plots You can also run WinEP as a normal Windows application You start in this mode by double clicking on the file Winep exe When started in this way the WinEP 8 Chapter 7 The Plotter workspace is empty and you must use a menu command to define the data for the first plot A better way to start is by double clicking on a file with the extension ERD This starts the WinEP program and automatically loads the selected ERD file You must then pick X and Y variables from the file to create the first plot Note The file Winep exe must be associated with the file type ERD if you want to launch it by double clicking on an ERD file The association is made automatically as part of the normal CarSimEd installation You would need to re establish the association only if you move the CarSimEd directory or if you copy the WinEP program to another computer that does not have CarSimEd on it Appendix D describes the batch control file for WinEP which is created automatically by CarSimEd and the keywords that are recognized by WinEP The rest of this chapter covers the interactive use of WinEP Zooming WinEP usually creates each plot window with the axes scaled to show all data points To zoom in use
261. ile Elevation BEL Distance ITS ft AT 2G14 6 FINSTDipstick TORY Converted to ERD format at 23 46 Oct 23 1994 WH MM OGH AHN 00000 0 000000 0 416667E 03 0 141667E 02 416667E 03 0 583333E 03 666667E 03 0 916667E 03 133333E 02 0 133333E 02 750000E 03 0 166667E 02 300000E 02 458333E 02 558333E 02 500000E 02 625000E 02 658333E 02 775000E 02 825000E 02 Optional Lines with Keywords Optional lines in the header begin with an eight character keyword that defines a particular type of data contained in the remainder of the line Keywords are associated with one of five general data types integers floating point real numbers 8 character names 32 character names and 80 character names The number of data items is either 260 Appendix C ERD File Format one per file e g TITLE of data set in the file one per channel e g a short name for each channel an arbitrary number N e g static axle loads for N axles or repeatable Table C 2 lists common keywords recognized by most post processing tools The use of some of these keywords is demonstrated in Listing C 1 and Listing C 2 Table C 2 Keywords in ERD file keyword Description No of Variable DT crc amp n Continuation keyword indicates that the previous line ended in column n and is continued in this line in column 9 Used to break long lines into multip
262. imEd CMEX module If SIMULINK is already running see the next section Start from the Runs SIMULINK screen see Figure 4 3 4m Runs SimuLink CHEX Yersion File Edit Text Page Tools Data set Acceleration in a turn Changed ID 844 CO Hotes 11 58 10 Model Parameters amp Inputs Run amp SimuLink Control Output amp Post Processing Vehicle Classic car enerne de Start SimuLink Update Animate Input Steer Speed kmh Stop sec MU Camera Setup Fenvew d Input Braking Computation Parameters x Braking and Driveline dt 001 x View Echo File All Parameters Input Throttle Simulation Type i xX Multiple Plots gt gt Plot__ Goverlay Runs Plot 1 Setup Ax long accel of CG x Plot 2 Setup Vx wheel speeds x Plot 3 Setup Fx long forces x Plot 4 Setup Mydry drive torques x O Show More Figure 4 3 The CMEX Runs screen Notes The figure shows one possible appearance of the Runs screen It is obtained when the Overlay Runs and Show More boxes are not checked Chapter 4 The Basics of Using CarSimEd If you compare Figure 4 1 and Figure 4 3 you will see that the only differences are in the numbered items O and 2 in Figure 4 3 1 Prepare to make a run as described earlier for the stand alone version page 30 2 Click the Start SIMULINK button O You should see the splash screen for MATLAB and then a window with a SIMULINK model similar
263. imEd is designed to also work with MATLAB SIMULINK as explained on page 12 Due to its ease of use and speed you can run simulated tests far more quickly and easily in CarSimEd than with physical testing It s easy to simulate vehicles and test conditions that are difficult or impossible to conduct experimentally After you run a simulation you can inspect and analyze hundreds of variables Why Use Simulation The reason for using a vehicle simulation program is nearly always to learn something about vehicle behavior Traditionally simulations have been used by experts to learn about specific issues such as 1 How does a specific design change affect vehicle response in certain test conditions 2 Why does an existing vehicle behave in an unexpected fashion under certain specified conditions And what can be done to change that behavior 3 What were the conditions leading to a specific accident or crash Can the event be reconstructed CarSimEd is designed to provide accurate simulation with rapid speed and ease of use This means it can be used by students and engineers who are not yet experts in vehicle dynamics to rapidly gain experience in the subject The same factors speed and ease of use provide the potential to provide an impact on design decisions much earlier in the design process than has traditionally been possible 10 Chapter 1 Introduction CarSimEd Operation Summary The basic operation of Ca
264. in purpose is to remind you of keyboard commands that move the cursor Although the menu items are functional you will usually find it quicker to press the indicated keys Define New Plot Ctrl N Offsets Filter Statistics Labels Ctrl L v Show Data Points Ctrl D Cursor Position Info Forward by 1 gt Forward by 10 gt Shift Forward by 30 gt Ctl Shift Backward By 1 lt Backward by 10 lt Shift Backward by 30 lt Ctl Shift Min Y Point Down Arrow Max Y Point Up Arrow Start of Data Home End of Data End Next DataSet Tab All of the functions on the sub menu are also available as buttons on the tool bar The buttons are dimmed unless the option to Show Data Points is enabled This is indicated visually in the toolbar by the button being pushed in as shown below FE El S Ml 103 Chapter 7 The Plotter gt a A me amp E z ao g Forward by 1 use the right arrow key to move one point forward based on the order the X values are stored in the file When the cursor is on the last point in the file this command has no effect Forward by 10 use the right arrow key plus the Shift key to move 10 points forward based on the order the X values are stored in the file When the cursor is on the last point in the file this command has no effect Forward by 30 use the right arrow key plus the Shift key plus the Cont
265. inate Scale Factors x scale Ysa G Zscale Color xi Miscellaneous An animator shape is a set of points connected by straight lines Normally a number of shapes move together in a single reference frame This screen can be used two ways to store shape data If itis used for a single shape the XZ coordinates should be put into the field labeled Coordinates The animator multiplies all of the coordinates by the scale factors specified in the yellow fields If no scale factor is specified a default of 1 0 is used The offsets shown are added to all of the coordinate If not specified the default offsets are 0 0 If this screen is used for many shapes the defining text can be put into the field Miscellaneous In this case the offsets and scale factors must also be put into the Miscellaneous field Discussion A shape is a set of points connected by straight lines Each point is defined by a set of three coordinates X Y Z The animator starts with the first point and draws connecting lines to each following point in a list All coordinates are assumed to be in a local coordinate system associated with the active reference frame See the discussion on how shapes and reference frames are associated in the section Animator Groups on page 133 The animator also supports offsets and scale factors All of the coordinates are calculated using the equation coordinate Co C SF 1 where C
266. inates The animator transforms the local X Y Z values to global X Y Z values in order to draw the shape To perform the transformation the animator must know the location and orientation of the reference frame relative to the global reference frame This is defined by six variables three coordinates global X Y Z and three rotation angles that are called Euler angles The six variables needed to locate and orient the reference frame for the vehicle bodies and wheels are all computed as part of the simulation It is also possible for you the user to define new reference frames using combinations of the variables computed in the simulations Details for specifying reference frames are provided in Chapter 9 in the section Animator Reference Frames That section also provides more information about Euler angles Files When the animator is started from a CarSimEd Runs screen the necessary files are automatically opened Therefore it is not necessary to know the names of the input files However an understanding of how the animator reads the necessary information from files might be helpful in understanding its operation The animator program reads two kinds of input files see Figure 6 2 As noted above all motion is due to movements of reference frames as defined by up to six variables Those six variables are read from an ERD file that was created by a CarSimEd solver program Appendix C provides details of the ERD file format and Appendix
267. inates of a single point The units are meters The syntax is that each of the values is separated by at least one space Blank lines are not allowed 2 Coordinate Offsets keywords set_offset_x set_offset_y set_offset_z All coordinates in the shape are adjusted by these offsets according to Equation 1 The units are meters If not specified the animator uses default values of 0 0 G Coordinate Scale Factors keywords set_scale_x set_scale_y set_scale_z All coordinates in the shape are adjusted by these scale factors according to Equation 1 The scale factors are dimensionless If not specified the animator uses default values of 1 0 4 Color keyword set_color This sets the color of the lines drawn to connect the points Valid colors are provided in a pull down menu G Miscellaneous field This field is for advanced users It can be used to enter multiple shapes The format is that each line has a keyword and value separated with white space at least a single space The field should look like a portion of a PARSFILE that can be processed by the animator See Appendix E for the animator keywords and some example files Location in CarSimEd CarSimEd Startup Runs Vehicles Car Animator Groups Animator Shapes File Location Animate Shapes Shapes tbk 141 Chapter 9 Alphabetical Library Reference Animator Wheels The current version of the animator supports a single 3D graphic primitive a c
268. inematical and compliance relationships for both sides of the vehicle SAE ISO Forces and Moments Auxiliary roll moment Maux the suspension roll moment minus the moments due to the suspension forces from the two sides A positive moment causes positive vehicle roll Damping force Fg compressive force applied to the vehicle body by a damper Spring force Fs compressive force applied to the vehicle body by a suspension spring Suspension roll moment Mro total static roll moment applied to sprung mass due to suspension roll angle A positive moment causes positive vehicle roll Tires and wheels Kinematics Center of tire contact point at intersection of a line passing through the wheel center and the ground where the line is parallel with Zw The center of tire contact is not necessarily at the center of the tire contact patch See Figure B 3 SAE ISO Inclination y lean angle of wheel relative to ground plane angle from ZG to Zw about Xg SAE ISO 2 Longitudinal slip the ratio 0 where is the angular velocity of the wheel about its spin axis and o is the free rolling angular velocity of the wheel that would be measured at zero slip angle and zero inclination o is the longitudinal velocity of the wheel center divided by the effective circumference of the tire at that speed and load condition SAE ISo 3 Slip angle angle from XG to the velocity vector of the center of tir
269. ing braking etc in SIMULINK and test them with the full nonlinear CarSimEd vehicle models Note SIMULINK and MATLAB are not included with CarSimEd they must be obtained from the MathWorks If you are not already using SIMULINK don t worry CarSimEd is fully functional as a stand alone package SIMULINK is not needed to make runs or view results The extra capability added by SIMULINK is mainly the ability to combine new controller designs with the CarSimEd models How CarSimEd Works CarSimEd combines information from the data screens with vehicle dynamics programs to simulate the vehicle behavior CarSimEd also links the simulation results with animation and plotting programs The CarSimEd package is primarily made up of four tightly integrated software modules as shown schematically in Figure 1 1 and described below Chapter 1 Introduction 4 CarSim Educational Startup Ele Edt Test Page Tools Data set 3D Car in Simulink ir neve perte so as Category BES Sle a e ais pata CarSim Educational 4 5 Vehicle Dynamics Simulation zok Changed Notes E Locked a 1206 43 73189 41 ir new petete o gt Hack E riAS e a e 4 Engrmesra Aras aise Be Ed nd Caminos Dyre Hdp j TEE
270. ing moment because it is inevitable that the wheel is about to lock up Specifically If Mygk gt Fx Heo Ay And Mygg gt Mypy And oI lt ao Then 7 00 eae 28 Wao where ao is a low speed threshold for spin acceleration Note The low speed threshold is provided by the user with the parameter VLOW_SPINA with units of kph The undeflected rolling radius is used to convert VLOW_SP INA to Wao Another instability occurs when a wheel is locked and the vehicle speed approaches zero The longitudinal slip see Equation 9 predicts full longitudinal force in opposition to the vehicle longitudinal motion To prevent violent longitudinal oscillations when the vehicle should be at rest the longitudinal slip is reduced to generate reduced longitudinal force and to use up less of the combined lateral and longitudinal slip In order for the alternate equation to be applied the wheel must be moving slowly and locked up or approaching lockup If 1 lt 1 Wo And o lt xo Then ut nPE 29 if K amp Ke l cos 21 315 Appendix H The Tire Model where xo is a low speed threshold Note The low speed threshold is provided by the user with the parameter VLOW_KAPPA with units of kph The nominal rolling radius is used to convert VLOW_KAPPA to Mxo Sequence Of Calculations The vehicle simulation is run by numerically integrating a set of ordinary differential equations At
271. inputs C CARSIMED 45 RUNS 3D 627 L06 Figure 4 2 Console display when solver program is running Notes If the vehicle comes to a complete stop or rolls over the normal settings cause the program to quit after updating all output files There are a few other occasions when the CarSimEd solver program will not run or will quit prematurely Among them are 1 The output file cannot be written if it is in use by the plotter or the animator this can happen if you are replacing a run as described in the next section 2 In rare circumstances a bad input parameter will cause the program to quit before it can create any output files However in most cases the program will generate the output files even if it quits suddenly Replacing a Run Stand Alone Use this method to replace an existing run Start from the Runs screen see Figure 4 1 on page 30 34 Chapter 4 The Basics of Using CarSimEd 1 Find the existing data set in the Runs library that you want to replace Use the navigation buttons 2 next to the Data Set title box 2 Inspect and edit the simulation inputs vehicle steering or path input braking or throtthle input speed etc 3 Click the Run Simulation button T This makes a run as described in the previous section except that in this case the previous run selected in step 1 is over written Making the First SIMULINK Run Use this method to start up a SIMULINK model that uses a CarS
272. ion contains only numbers The numbers can be written in either text or binary form The text form is convenient for viewing and editing data with a word processor whereas the binary form provides more efficient access for automatic processing If the data section is in text format then both the header and the data are kept in a single file However if the data are in binary format two files are used The header is in an ordinary text file with the extension ERD and the data are in a file with the name of the header file and the extension BIN For example if the header file is named Out erd the name Out bin must be used for the data file For use in the plotter and animator programs in CarSimEd both files must lie in the same folder The Header The ERD file header consists of a series of conventional text lines that are human readable These lines contain the information used by post processing tools to read the numerical data Required Lines As a minimum the header contains three lines of text The first line identifies the file as following the ERD format The second line describes the way that the numerical data are stored in the data section of the file The third required line is an END statement that indicates the end of the header portion Any number of optional lines can be included between line 2 and the END line Table C 1 summarizes the lines in an ERD file and describes the parameters used in line 2 to describe the numerical d
273. ion in CarSimEd You can link to it from any blue field in the CarSimEd libraries File Location Generic Gentable Gentable tbk Input Braking Use this screen to specify the input to the brake system in terms of control pressure as a function of time 162 Chapter 9 Alphabetical Library Reference This screen is only used for the 3D car model If it is linked to a 2D ride or suspension analysis run the data are ignored 4m Input Braking OF x File Edit Text Page Tools Data set Step 0 2 second Changed ID 77 O Hotes 10 53 51 Brake input pressure Update Plot Tidy Table 20 Time sec Input pressure MPa 0 A 0 1 2 3 4 5 6 7 8 9 10 Stop simulation when 2 Time sec abs speed drops below 0 02 kmih This data set is locked Unlock data set to view the context sensitive help in this status bar Discussion You control braking by applying effort at the brake pedal The brake pedal output is a control or application pressure that is applied to the brake system This input is described via a table look up function of brake input pressure as a function of time Note Any units can be used so long as they are compatible with the data in the Brakes Mechanical Properties screen The units on the vertical axis of this screen must match the units on the horizontal axis in the Brakes Mechanical Properties screen However it s recommended that the input always be
274. is always a rotation about the Z axis With Z up ISO MSC positive yaw implies a left hand turn with Z down SABE positive yaw implies a right hand turn Figure B 2 shows the three axis systems associated with the entire vehicle The intermediate axis system is used the most for vehicle level definitions It has a Z axis that is parallel to the gravity vector and an X axis that is in the same vertical plane as the vehicle longitudinal axis Figure B 3 shows the tire and wheel axis systems Notes 1 Z is parallel to Zg 2 X is in the vertical plane containing Xy 3 The angle between Xpand X is w yaw Figure B 2 Earth vehicle and intermediate axis systems Definitions of Terms Axis system a set of three orthogonal X Y and Z axes In a right handed system Z X x Y Here X Y and Z refer to an arbitrary orthogonal axis system Coordinate system a numbering convention used to assign a unique ordered trio of numbers to each point in a reference frame A typical rectangular coordinate system consists of an axis system plus an origin point Earth fixed axis system XE YE ZE right handed orthogonal axis system that serves as the global inertial reference frame The Zg direction is parallel to the gravity vector ZE points up in the MSC and ISO systems See Figure B 2 SO SAE 248 Appendix B Vehicle Dynamics Terminology Wheel plane Center of tire Velocity vector contact CTC
275. is the original coordinate Co is the offset and SF is a scale factor gain The offsets and scale factors allow the shapes to be relocated and resized without requiring all of the coordinates to be changed by hand Applying an offset has the effect of relocating the shape within the reference frame Scale factors can be used to change the size of a shape For example to make a hood twice as long enter an X scale factor of 2 0 Scale factors can also be used to mirror a shape If the scale factor is negative then all of the corresponding coordinates are given the opposite sign For example a left fender can be converted to a right fender by setting the Y scale factor to 1 The shape library can handle two kinds of shape data 1490 Chapter 9 Alphabetical Library Reference 1 A single shape is described using the appropriately labeled fields 2 Multiple shapes can be described using the Miscellaneous field The second approach is useful if there are many shapes used to describe a complex body and they are unlikely to be used for any other purpose By putting the many shapes into one data set fewer files are processed by the animator and there is less likelihood of accidentally modifying a group User Settings Coordinates of points that are connected by lines in the animation keywords set_coordinates to indicate the start and end_coordinates to indicate the end of the list Each line should have the three coord
276. is to the vehicle left All coordinates have units of length and must be the same In CarSimEd all coordinates in the output file have the units of meters Both variable and static coordinates can be converted using scale factors if necessary The camera focal length must also have the same units meters All Euler angles must be expressed in degrees Scale factors are used to convert to degrees if the variables in the ERD file have different units such as radians or revolutions Camera Settings Listing E 1 on page 272 shows part of a PARSFILE that has the animator settings that are related most directly to the camera setup Most of these are sent from the Animator Camera Setup screen described in Chapter 9 Table E 1 lists the keywords that are used to specify camera settings Table E 1 Keywords for the animator camera settings set_camera_reference_frame name of reference reference frame in which the frame camera is situated set_camera_x numbers coordinates of the camera set_camera_y location in its reference frame set_camera_z set_lookpoint_reference_frame name of reference reference frame in which the frame look point is situated set_lookpoint _x numbers coordinates of the lookpoint in set_lookpoint _y its reference frame set_lookpoint _z set_focal_length number focal length of camera distance from point of viewer to 2D image on screen to real time by using the clock set_superimpose on oroff option to superimpose a
277. k point reference frame must be used somewhere else because only the name is provided to the animator from this link The reference frame description is not sent to the animator in order to avoid an error that occurs if the same reference frame name is used twice Target frame rate for animation pictures per second keyword set_frame_rate If the animation is running too slowly you can specify a lower frame rate to speed it up Alternatively you can use a higher frame rate to slow it down Typically frame rates of 10 to 30 frames per second can run in real time on Pentium computers If the target frame rate is very high more than 100 the computer will not be able to refresh the screen in real time and the animation will run in slow motion A high frame rate e g 100 is useful for viewing wheel lock up during brake simulations For handling simulations a lower frame rate ensures that the animation runs approximately in real time If this field is left blank the animation runs at the default frame rate specified under the Preferences option in the Edit menu of the animator see Section 5 Radio button for using the computer CPU clock keyword set_use_cpu_clock on If the animation is running faster than real time you can select this button to slow it down to real time When this button is selected the animator accesses the computer clock and waits if necessary to avoid running the animation faster than real time Notes
278. label LF tire aye ALT LRtire 6000 ATs i gi RF tire EN rete RR ire 4000 He z T TA in IIR LF KOT Legend loo MALL La 2000 OE SOO 0 Oo 1 2 3 4 6 f 6 91 Tick labels Time see X axis label Figure 7 4 Names of plot labels 0 94 Chapter 7 The Plotter 3 Frame Press the button to display a menu to specify how the plot area is enclosed with a frame The options are No Frame Frame and Frame with ticks The No Frame option doesn t work unless you also select No Grid 18 Size limit for legend When WinEP draws the legend for overlay plots to the right of the plot area it uses whatever space is needed If the labels are lengthy or if the window is small this can limit the horizontal space available for the plot Use this field to set a maximum amount of window space that can be taken for the legend This setting does not affect the plots unless 1 there are at least two X Y data sets being overlaid 2 the specified position is Right of Plot and 3 the length of the longest label exceeds the specified percentage Customize Plot Format x Axes x Y Data Set Plot Layout Font 22 Plot Title EX EVR Ws EE E Axes Labels Arial 10 pt Regar 24 E Axes Numbers Arial 1Opt Rer 25 l Legend Labels j 27 I Apply to all Font tab Click this tab to show the settings that control the text used to label the axes and data in the plot The fou
279. labeled Overlay Run 3 On the other hand if you only want to compare two runs choose No data set selected for Overlay Run 3 Select up to four pre defined plots using links and aD Click the Plot button 13 After viewing the plots exit the plotter by clicking the in the upper right corner of the screen or by using the Exit option in the File menu or by typing Ctrl Q Defining Plots Interactively 3 Start from a Runs screen see Figure 4 1 on page 30 The simulation run must have already been made in order to view a plot Start the plotter program by clicking the Plot button See 13 in Figure 4 1 From within the plotter go to the Data menu and select the item Define New Plot or type the keyboard command Ctrl N This brings up a window which lists all of the variables in the simulation output file Channel Select x Data to Plot y x file Y Channels Gamma_LF Time 504 ERD Gamma_LF Time 504 ERD Gamma_FF Time 504 ERD ce Time 504 ERD Delete File G Plot File name C CARSIM RUNS 504 ERD Title F steer car Select X and Y variable names from the X and Y lists G and 6 Note You can select the names by clicking on them with the mouse You can also click in a list to make it active and then type the first letter of a name As with other lists in Windows keep hitting the keyboard letter to go down the list For example hit 39 Chapter 4 The
280. lation calculations then quits and closes the window leaving you back at the Runs screen How a Simulation Run Is Made in SIMULINK Simulation runs can be made by opening a SIMULINK model that includes the CMEX S function and then initiating the run from within SIMULINK For example Figure 5 2 shows a simple model involving a CarSimEd S function called is_cmx The SIMULINK model resembles the flow chart shown in Figure 3 7 on page 29 except that the SGUI input and ERD file outputs are not visible they are part of the CMEX code and cannot be modified in SIMULINK The example model in Figure 5 2 routes a few of the outputs to scopes to generate the time history plots shown When a simulation run is made the text that is shown in the program window for a stand alone EXE CarSimEd program instead appears in the MATLAB window visible in the background in Figure 5 2 Chapter5 The Solver Programs File Edit View Simulation Format pe Al E al OD r S ire Not Used CarSimEd Vehicle model 4w Independent Ready Simfile found batch operation Input file with parameter values C N Echo file with initial conditions C N Echo file with final conditions Czy Output file with time history data C Figure 5 2 A SIMULINK model with a CarSimEd CMEX S function Starting SIMULINK from within CarSimEd When the first run is made in a CarSimEd session it is necessary to launch MATLA
281. lds are also used to define scale factors that are applied to an entire group of shapes In CarSimEd this is done to stretch vehicle shapes according to wheelbase and track width Location in CarSimEd Note This library can be applied in different ways which means there may be links to it from libraries other than those shown below CarSimEd Startup Runs Vehicles Car Animator Groups File Location Animate Groups Groups tbk Animator Reference Frames This screen is used to define animator reference frames and coordinate systems moving or stationary In order to effectively use the animator you need to understand the concept of a reference frame Chapter 6 introduces the notion This section explains how you define animator reference frames within CarSimEd 136 Chapter 9 Alphabetical Library Reference Discussion The animator in CarSimEd shows moving and stationary wire frame figures The lines used to draw each wire frame object may move relative to other objects but the spatial relationships between the lines in a single object are fixed When the relationships between a set of points does not ever change i e they form a rigid structure they are said to exist in the same reference frame Therefore the coordinates that are provided for shapes are constants when based on a coordinate system fixed in the appropriate reference frame 4 Animator Reference Frames iof x File Edit Text Page Tools Data se
282. le short lines recommended for inclusion in all ERD files GENNAME Generic names for variables used for labeling Y NCHAN char 32 axis when several variables are plotted on the same axis e g Force LONGNAME char 32 SHORTNAM char 8 TITLE char 80 UNITSNAM char 8 XUNITS Units of independent variable e g sec char 8 The following line is required for EP to create Channel 0 e g time XLABEL Name of ind variable in ERD file e g time char 32 FORMAT char 32 GAIN Gains for channels Default 1 Usually required real 1 for integer 2 data OFFSET Offsets for channels default 0 Usually required NCHAN real Fi E a PROFINST Instrument or model associated with data _ char 32 RIGIBODY char 32 SPEEDMPH real TESTID real XSTART Starting value of ind variable At each sample i the 1 real X value is X i 1 STEP XSTART Often names associated with a keyword are shorter than the space allowed When more than one name is on the same line the names are padded with blanks as needed so that 261 Appendix C ERD File Format following names begin at the correct column positions For example the header shown in Listing C 1 includes names of the units for each channel as identified with the keyword UNITSNAM The name of units for the first channel ft has only two characters Thus it is followed by six spaces so that the name for the second channel ft begins in the correct column position
283. le of wheel rigibody name LF wheel OUT 93 Yaw_WLR deg Yaw angle of LR wheel gen name Yaw angle of wheel rigibody name LR wheel OUT 94 Yaw_WRF deg Yaw angle of RF wheel gen name Yaw angle of wheel rigibody name RF wheel OUT 95 Yaw_WRR deg Yaw angle of RR wheel gen name Yaw angle of wheel rigibody name RR wheel OUT 96 Yo m Y position of car origin gen name Y position rigibody name Car body 334 Appendix J Model Input and Output Variables OUT 97 Y_CG m Y position of vehicle CG gen name Y position rigibody name Vehicle CG OUT 98 Y_WLE m Y coordinate of LF wheel center gen name Y coordinate of wheel center rigibody name LF wheel OUT 99 Y_WLR m Y coordinate of LR wheel center gen name Y coordinate of wheel center rigibody name LR wheel OUT 100 Y_WRF m Y coordinate of RF wheel center gen name Y coordinate of wheel center rigibody name RF wheel OUT 101 Y_WRR m Y coordinate of RR wheel center gen name Y coordinate of wheel center rigibody name RR wheel OUT 102 Zo m Z position of car origin gen name Z position rigibody name Car body OUT 103 Z_CG m Z position of vehicle CG gen name Z position rigibody name Vehicle CG OUT 104 Z_WLFE m Z coordinate of LF wheel center gen name Z coordinate of wheel center rigibody name LF wheel OUT 105 Z_WLR m Z coordinate of LR wh
284. library to set values for additional parameters that do not exist in the standard models When combining parameters and other data sets be aware that the data are sent to the solver programs in the same order they are numbered on the screen top to bottom then left to right Many of the components are used more than once tires dampers springs etc and a keyword is used to determine where the description of the component should be applied For example the keyword ITAXLE is used to associate axle related data sets to axles Put the line IAXLE 2 in a yellow field and then any links that follow will be associated with axle 2 The screen layout includes six pairs of yellow fields and blue links Therefore it is possible to specify data for six different places The best way to determine how keywords are used to locate data sets is by viewing an echo file produced by the solver program you have used see Appendix F for an example echo file 159 Chapter 9 Alphabetical Library Reference 4 Generic Data Group of x File Edit Text Page Tools a ee es Category ie E Locked 11 30 99 Parameter Set 1 Parameter Set 4 Parameter Set 7 A A a bof hf Ba Link 1 Link 4 Link 7 No data set selected o No data set selected No data set selected Parameter Set 2 Parameter Set 5 Parameter Set 3 A A A a al ad Link 2 Link 5 Link 8 No data set selected o No data set selected N
285. lick on names in a list rather than typing in the names However if you prefer to type you can type the names directly into the yellow field 6 If the ERD file has more than about 150 variables only the short names are shown in fields and 9 If it has fewer variables more information is shown Clear the field called Data to Plot 6 Select the contents of the field and then press the delete key Select X and Y channels of interest from fields and 9 Add them to the list of data to plot 6 using the KJ button or by double clicking in either field or Continue to build the list of data to plot 6 To make another plot setup repeat steps 2 through 8 When you are through making new plot descriptions leave the library by clicking the Back button 4 or using the GO button You can now plot the new plot using the same method as for the standard plots Linking to Different Libraries As installed all blue links are preset to the appropriate libraries In general when you want to make a new data set you should find an existing data set that has links in place to the intended libraries However the CarSimEd database has a provision for changing the linked libraries as needed On any screen select the button next to the link of interest to display the pull down menu If the second item Pick Library is active select it However if it is dimmed you must first change a global setting in CarSimEd a Go to the
286. links and change other components as needed 4 When all changes have been made return to the Runs screen If you are working with the 3D handling model return to the Runs screen by clicking the Runs button in the ribbon bar SB or using the Runs command in the Tools menu However to return to the Runs screen for the ride model or suspension kinematics you must use the GO button or click the Back button repeatedly to retrace your steps back to the Startup screen Warning Almost every data set in the CarSimEd database is referenced by other data sets via the blue links When you change values in a data set you have in effect also changed all data sets that reference it For example if you change a spring rate every vehicle data set that is linked to the affected suspension data set with will use the new spring rate in future simulation runs Hopefully this is exactly what you intend If not then consider using the New button to create a copy of the data set then change the copy and link to it in those places where you want to use the new data Switching Between CarSimEd and SIMULINK Inputs When you run the CarSimEd models from SIMULINK all of the inputs in the database can be used Additionally inputs can be provided from the SIMULINK environment The control inputs for the model are the sums of the inputs from the CarSimEd database the simulation graphical user interface the SGUI and those from the SIMULINK work space Th
287. ll images don t erase between animation frames 274 Appendix E Reference Frames Animator Files and Keywords Understanding the concept of a reference frame is important if you wish to effectively use the animator Chapter 6 introduces the concept and the Chapter 9 section Animator Reference Frames explains how you define a reference frame within CarSimEd Appendix B also defines reference frame to the extent needed to define vehicle dynamics terminology Table E 2 lists keywords associated with reference frames Table E 2 Keywords for the animator camera settings add_reference_frame name of new gives name to new reference frame and starts reference frame its scope set_x_name names of variables set_y_name in ERD file set_z_name set_pitch_name names of variables set_roll_name in ERD file set_yaw_name set_scale_var_x numbers set_scale_var_y set_scale_var_z set_scale_var_roll set_scale_var_pitch set_scale_var_yaw set_offset_var_x numbers set_offset_var_y set_offset_var_z set_offset_var_roll set_offset_var_pitch set_offset_var_yaw set_euler_angles yaw_pitch_roll or aw_roll_ pitch x_ref_length numbers y_ref_length z_ref_length specifies the variables to be read from the ERD file and associated with X Y Z coordinates of the reference frame specifies the variables to be read from the ERD file and associated with Euler angles scale factors for data read from the ERD file default 1 0
288. lot on paper depends on a number of factors e The window dimensions on the screen height and width You adjust the window size as with any other window using the Maximize box in the upper right corner of the window and by dragging borders with the mouse e The Windows display settings To bring up this dialog box 1 Click in the Windows Start button to display the Start menu 2 Click on the Settings menu item to display a submenu 3 Select the submenu item Control Panel to display a folder of control panels 4 Select the control panel Display When the Display settings window appears click on the Settings tab 84 Chapter 7 The Plotter Display Properties Large Fonts x Large Fonts Small Fonts el Apply Note In general the Small Fonts setting is recommended for the CarSimEd software Problems sometimes occur with the display of CarSimEd screens with some combinations of hardware and monitor settings when Large Fonts are selected Also it is more complicated to estimate the size of printed plots e The paper size and orientation portrait or landscape To specify the paper size and orientation select the Print Setup menu item from the File menu in WinEP This brings up a dialog box with settings specific to the printer e The percent reduction which can be specified on some printers particularly PostScript printers Print reduction if available is found from the dialog box obtain
289. m the vehicle body Side view of tires for vehicle Centers of tire contact Lines perpendicular to trajectories Pitch center Trajectories of center of tire contact for vertical suspension movement Figure B 4 Pitch center Roll center imaginary point in the Yy x Zy plane containing the two wheel centers of an axle at which a lateral force applied to the vehicle body is reacted without producing a suspension roll angle ISO SAE An alternate definition is that the roll center is the intersection of the two lines shown in Figure B 5 Note the figure shows a non equilibrium position of the vehicle Front view of tires for an axle Centers of tire contact Lines perpendicular to trajectories Roll center Trajectories of center of tire contact for vertical suspension movement Figure B 5 Roll center Spring mechanical advantage R 5 ratio of spring compression per unit of wheel jounce This ratio is usually less than unity 254 Appendix B Vehicle Dynamics Terminology Steer 5 angle from X to Xw about Z SAE ISO Suspension roll angle angle from line joining the wheel centers of an axle to the Xy x Yvy plane in the vehicle reference frame SAE ISO Toe inward steer of wheel relative to the vehicle reference frame angle from X to Xw Regardless of the choice of coordinate systems inward steer is positive The symmetric sign convention is convenient for describing certain k
290. mand is Ctrl B Italic Select this menu item to toggle the selected text between italic and not italic The keyboard command is Ctrl I Underline Select this menu item to toggle the selected text between underline and not underline The keyboard command is Ctrl U Strikeout Select this menu item to toggle the selected text between strikeout and not strikeout Normal Script Select this menu item to remove subscript superscript formatting The keyboard command is Ctrl K Subscript Select this menu item to toggle the selected text between subscript and not subscript The keyboard command is Ctrl L Superscript Select this menu item to toggle the selected text between superscript and not superscript The keyboard command is Ctrl Shift L Page Menu This menu offers access to previously viewed screens pages and also control of how the current data screen is viewed History Ctrl F2 Size to Page F11 124 Chapter 8 Design of CarSimEd Data Screens History Select this menu item to bring up the following floating window to see a list of the libraries that you have visited during this session From the window you can select a library and go to it by double clicking on it or clicking the OK button Install 4WS 30 deg SS this book Size to Page Select this menu item to set the CarSimEd window to its default size If you happen to click on the Windows zoom icon Windows will fill your screen with
291. mate Input Steer Speed kmh Stop sec _ Mu Camera Setup Rane 1 aegsee gt Jx s0 ojos Sdevew 9 Input Braking omputation Parameters oean e t nas forcound 7 Mew Echo Fie Al Param Input Simulation Typ No data set selected 2 3D Vehicle Dynamics 16 0 Multiple Plots J Overlay Runs Plot 1 Setup Misc Data with K Based On x iNo ibrary selected 18 Piot Setup Overriding Data from Batch x iNo data set selected 19 x Plot 3 Setup ay let acoel of CG 14 Excerpts From Output File 629 pf File ext Gpr 20 Keywords Plot 4 Setup STOPT 42 2266 simulation stop time s 22 RTIME 21 efficiency sec sim sec deg G understeer plot 14 x Overlay Run 2 No data set selected 24 Overlay Run 3 to deta set seeded 24 x 0 0710452 CALC Computational Rescan File 23 Show More Figure 9 10 Runs screen with all controls showing Note Figure 9 10 shows the Runs screen with all three display boxes checked 12 13 and 15 All possible data fields and links are displayed 193 Chapter 9 Alphabetical Library Reference Additional User Settings and Controls Simulation Type link This shows the current type of simulation model As installed CarSimEd has a single type Custom versions may have modified or extended models The triangle button displays a pull down menu with options for adding an
292. mator Reference Frame Animator Data shapes User Settings Note User settings that are common for all tabular data screens are described in Chapter 7 in the section Tabular Data Table field for the road profile keyword ROAD_PROFILE_TABLE Each line should have a X and Z coordinate for the road surface The units are meters for both coordinates Link to an animation reference frame This is typically the installed reference frame Fixed Link to an animator shape file that shows the bump or road profile Location in CarSimEd CarSimEd Startup Runs 2D Ride Input Road Profile 165 Chapter 9 Alphabetical Library Reference File Location Input Road Road tbk Input Steering Wheel Angle Use this screen to define the steering wheel input as a function of time for open loop steering maneuvers via a table look up This screen is only used for the 3D car model If it is linked to a 2D ride or suspension analysis run the data are ignored m Input Steering Wheel Angle iof x File Edit Text Page Tools Data set Ramp 1 5 deg sec v 41 I gt Hew Delete GOY Back Changed ID 48 CO Hotes 12 16 57 Steering wheel angle deg Update Plot Tidy Table 300 Time sec Steer Angle deg 250 200 150 100 50 0 0 50 100 150 200 Time sec GO shows a pull down menu of data libraries Takes you to the library selected Discussion You can ch
293. me Although the reference frame might move and rotate the spatial relationships between objects in the reference frame do not change relative to each other In the animator all motions are associated with reference frames Each reference frame has a rectangular coordinate system that is used to describe 3D locations of points within that reference frame For example Figure 6 1 shows the origins and axes for two reference frames a global non moving frame and a frame that moves with a vehicle body In general it is not possible to tell how many reference frames exist by looking at a single image However by observing an animation it is sometimes possible to see the effects of all reference frames For example the system shown in Figure 6 1 includes six reference frames 64 Chapter 6 The Animator e A fixed global reference frame is used to locate a grid that shows the ground plane The three axes of a coordinate system fixed in this reference frame are shown in the figure e A moving frame is associated with the vehicle body The body is simply a series of lines drawn in this reference frame The three axes of a coordinate system fixed in this reference frame are shown in the figure Given that the coordinate system is fixed in a moving reference frame it follows that the coordinate system moves e Each of the four wheels is associated with a separate reference frame Wire frame shapes are all defined using local X Y Z coord
294. me and the vehicle will be steered in an open loop mode In this case the target path information is not used 2 Input Target Path For Closed Loop Steer Control this screen Choose this library to apply the steering controller from the CarSimEd model Steering control is an input that appears as a link on the left of the Runs screen To use the path follower model the closed loop library must be linked as one of the inputs The easiest way to make a new run using the path follower is to find an existing run made with a path input involving the vehicle type of interest and copy that run However if there are no existing runs close to what you need then you should 1 Link to this library using one of the input links on the Runs screen and 2 Make sure you are not linked to an open loop steering wheel angle data set See the section Data Links in Chapter 8 for details on changing links Station and Path Mathematics The table on this screen is unusual in CarSim because it does not require the rows to have an ascending order in X Instead The X and Y coordinates from the input path are used to compute another variable called station S defined as the distance along the path At the start of the path S is defined as zero For each pair of X Y coordinates a corresponding increment of S is computed by using the Pythagorean theorem This new increment is added to the previous value of S S1 0Si Si 1 Xi Xi1 Yi Yi1 fori gt 1
295. me Simfile a file created Chapter5 The Solver Programs automatically by CarSimEd if this file exists the program runs in batch mode Otherwise it runs interactively Note All normal runs in CarSimEd are performed in batch mode CarSimEd creates Simfile and then launches the solver program that matches the type of vehicle selected on the Runs screen If Simfile does not exist in the folder in which the program is located then the program runs in interactive mode It prompts you for an input file an output ERD file name and two output echo file names After the last file is written the program quits If Simfile does exist then all file names are read from it The program quits when Simfile is fully processed and the solver program writes the last output file Properties of the window created by the solver program can be adjusted by right clicking while the cursor is positioned over the solver program extension EXE found in the folder CarSimEd Programs to display a pop up menu and selecting Properties from the menu As installed the solver programs close their windows when they finish When the window is closed the most recently accessed program comes to the top When run normally from within CarSimEd the most recent program is ToolBook which was showing the Runs screen from which the run was initiated Therefore the normal behavior is that the Solver program brings up a window runs for the time needed to perform the simu
296. me plotting in other software packages similar to CarSimEd this keyword is no longer tested by WinEP Anything on line 1 will be accepted Plot Setting Files A plot setting file contains a list of variables to extract from the data files along with formatting information Setting files are normally created automatically by the CarSimEd library Plot Setup Single and are stored in the same PARSFILE format used throughout CarSimEd Listing D 2 shows an example PARSFILE with information to define a plot Listing D 2 Example plot template file PARSFILE PLOTCHANNELS Vx Time PLOTCHANNELS Vx_LF Time PLOTCHANNELS Vx_LR Time PLOTCHANNELS Vx_RF Time PLOTCHANNELS Vx_RR Time PARSFILE C CARSIMED 45 PLOT FORMAT 31 par PTITLE Vx wheel speeds END Note Because a PARSFILE can reference other PARSFILEs the list of channels and the plot formatting can be spread over several 265 Appendix D Plotter Files and Keywords files For example formatting information can be placed in the template file or in the format file described below Plot Transform Files WinEP supports modest transformations of the data being plotted Offsets can be added to each variable X and Y The variables plotted on the Y axis can also be filtered with a moving average to smooth the data low pass filtering remove low frequency content high pass filtering both band pass filtering or neither WinEP can plot up to
297. method is nearly identical to the one just described for making five or more plots Two additional steps are e In step 4 put more than one run into the field with Selected Data Files 6 e Be sure the One Plot per Data File button 12 is selected Setting Up Multiple Runs It is possible to set up more than one run ahead of time It is also possible to re do a set of runs whose inputs have been modified To do this start from the Runs library Note The batch option is designed for stand alone EXE solver programs Batch operation for SIMULINK cannot be controlled from the CarSimEd database 1 Set up the runs of interest by creating a distinct Runs data set for each combination of vehicle input speed stop time etc that is of interest Do not click the Run Simulation button 2 Go to the Runs Batch library whose screen is shown in Figure 4 9 Get there by clicking the button 9 in the ribbon bar or use the Tools menu item Batch Runs 3 Click the New button to create a new data set for your combination of runs 4 Using the Add G and Remove 4 buttons put the name of the runs of interest into the field named Data Sets to Run 5 5 Optionally enter parameters with keywords in the yellow fields 6 to override the parameters that are specified in the selected Data Sets to Run For example to make all runs with a simulation speed of 100 km h enter the line speed 100 Note See Appendix F for a complete list of key
298. moving average It has the same units as the variable plotted on the X axis For example if the X variable is Chapter 7 The Plotter D time with units of seconds the baselength is the number of seconds covered by the moving average This baselength is also used for band pass filtering Low pass baselength This is a reference used to define the scope of a moving average It has the same units as the variable plotted on the X axis For example if the X variable is time with units of seconds the baselength is the number of seconds covered by the moving average This baselength is also used for band pass filtering Filter using original data check box check to apply the specified filters to the original data the values read from the file When not checked the filters are applied to the data as modified by previous filtering If this box is not checked the data are processed every time the filter dialog box is displayed and exited with the OK button Help button Click to display the following information Filter Help x Low Pass Filter low pass moving average filter transforms a series of numbers by replacing each number with the average value where the average is Original Data taken over some number that corresponds to a base length The number of points used in the average is the baselength divided by the interval between points The averaging process smooths the data removing high frequencies and passing low f
299. mple mathematical expressions 145 Chapter 9 Alphabetical Library Reference 45 atan 1 atan 1 45 57 2957795130823 1 74532925199433e 2 HHHH 57 2958 0 0175 0 0000 57 2958 0 0175 1 2500 H HHHHHHe HH 5 729578e 1 1 745329e 2 1 25 e 0 0 000000E 000 5 729578E 001 1 745329E 002 1 250000E 000 The format field is applied when you click the Format button 9 or the Calculate button 1 Transpose button Click to transpose the columns and rows in the tabular data field O For example 1 2 3 Becomes 1 5 5 6 7 2 6 3 7 12 Plot button Click this to update the graphic based on the current contents of the tabular data field G The graphic is created by plotting values of columns 2 and higher on the Y axis against the values of column 1 on the X axis Thus the number of plots is N 1 where N is the number of columns 13 Formulas for items Create or Transform This field is used to create or transform numbers in the tabular data field G The field is used for two distinctly different purposes 1 It provides mathematical definitions of the numbers that will be calculated and stored in the tabular data field when you click the Calculate button and the Create button 20 is selected In this case all definitions must involve only numbers and a single variable X X is calculated automatically and given a value for each new row based on the three fields 22 3 and 24 2 It provides transforms of existing numbers tha
300. n EXE file compiled from C source code In SIMULINK the numerical integration is controlled by the MATLAB SIMULINK routines The CarSimEd DLL will generate an error message if you try to use a variable step integrator A fixed step integrator is required and the ODE2 Heun is recommended because it runs the fastest for a given level of accuracy In addition to the normal inputs from the SGUI and the output files for the plotter and animator the CMEX program exchanges information with SIMULINK Figure 3 7 shows the the flow of information The CMEX program receives some inputs from SIMULINK and provides output variables to the MATLAB SIMULINK workspace The outputs are identical to the variables that are written into the output ERD file for plotting and animation 28 Chapter3 Database Organization Output ERD file for Vehicle Properties and plotting animation etc Inputs from SGUI CarSim aie file Outputs into MATLAB Control Inputs from Workspace SIMULINK Outputs into SIMULINK Sinks scopes X Y plots etc Figure 3 7 CMEX inputs and outputs The communication between the CMEX S function and SIMULINK follows the S function convention and is made at each time step through predetermined inputs and outputs Communication between the CMEX program and the CarSimEd database is made in the same fashion as for the stand alone EXE program see Chapter 5 A README text file is included in each
301. n optionally be used with CarSimEd MSC Mechanical Simulation Corporation The company that licenses maintains and supports CarSim and CarSimEd Numerical integration a computation method used to solve the differential equations that define a mathematical model of vehicle dynamics Output variables produced by the models in CarSimEd are based on internal variables that are calculated over time using numerical integration of state equations 242 Appendix A Glossary Parameter parameters are quantities that remain constant during a run Any numbers that you see on a data screen are either scalar or tabular parameters Variables on the other hand are continuously computed by the solver programs and are usually viewed with the plotter and animator PARSFILE parameter file a keyword based text file used to communicate between various CarSimEd programs See Appendix F for details about the format Most have the DOS extension PAR but some files have different extensions yet follow the PARSFILE format For example the LPO and LPF files list all parameter values used in arun Ribbon bar the collection of buttons and user controls displayed at the top of nearly every CarSimEd data screen Run Shorthand for run a simulated test e g make a run Also used to refer to the outcome of a simulated test run e g look at a run Screen short for screen layout associated with
302. n replaced by shortcuts seen in DOS as files with LNK extensions ToolBook the program that runs the SGUI part of CarSimEd does not recognize LNK files but does recognize PIFs Therefore PIFs are used to access MATLAB When you use the pull down menu G to choose the option Add or Find Solver For Type the Windows file dialog box comes up for selecting EXE file Change the extension in the dialog box from EXE to PIF in order to see the PIFs and then you can link to one of them Installing CarSimEd in a New Directory You can move CarSimEd to a new place in your file system so long as you do not modify the structure within the CarSimEd directory For example you can move the root CarSimEd folder from drive C to drive D Or you might copy CarSimEd from a network server to a personal computer If you move the CarSimEd files after the initial installation you must make two additional changes 1 Inform Windows of the new location in order to start CarSimEd using the runtime ToolBook software 2 Cause CarSimEd to regenerate text files used to communicate with the plotter animator and solver programs Runtime ToolBook The CarSimEd database is managed by a program called To40run exe located in the Tb40 folder in CarSimEd As part of the CarSimEd installation the To40run program is registered with the file extension TBK If you move the folder containing To40run then you must inform Windows of the new locations
303. n x y or z after the prefix 326 Appendix J Model Input and Output Variables The letters c and t are used for centripital and tangental when used to identify acceleration components 3 The remaining characters identify the part of the vehicle with which the quantity is associated The most common are LF LR RF and RR to identify the four wheels Left Front Left Rear Right Front and Right Rear respectively Table J 1 Naming convention for output variables Alpha Alpha_ur Tire lateral slip angle Beta Beta Vehicle lateral slip angle Jounce __ JounceLF Suspension compression Kappa Kappa_ur Tire longitudinal slip M es w T un O Tire road friction coefficient Pitch angle of rigid body rk Pitch Roll Roll angle of rigid body Et i Rot Rot_WLF Rotation angle of wheel about Y axis similar to pitch except it involve Steer Steer_ur Steerangle V X y Z Vx_LF Velocity component of a point or for E a a XYZ xwr Coordinate ofapoint Yaw Yaw WLP Yaw angle of rigid body Animator Variables In order to locate and orient a rigid body in 3D space six independent variables are needed X Y Z coordinates and three rotation angles For example the car model has five independent moving parts the body and four wheels Each requires six variables to animate Therefore 30 variables in the ERD file are needed to produce full animations As shown
304. named In the second case you should be able to identify the library containing the non existent data set from the error message You need to figure out which library has the bad link For example if the non existent file is in the folder Vehicles Tires Tires_ed then the problem is probably with a tire data set Tires are selected from the car and data screen so that would be the place to look for the bad link Bad links can be quickly located by using the ParsTree program in CarSimEd To run it click on the button with the tree icon 4 Alternatively go to the Tools menu and select the item View Parstree The ParsTree program brings up a window with two panes similar in format to the Windows Explorer Bad links are indicated with the symbol amp For example the figure below shows the ParsTree display for a vehicle PAR file with a bad link for the tire repeated twice EL x ParsTree lolx Parsfile tree Structure Contents of the selected file parstile C CARSIMED 45 VEHICLES SUSP_ED 46 par E 46 par imator body stuff and i i animator bo iY Stull and rear suspension E 326 par Hif2 GROUPS Sedan object name E 49par parsfile C CARSIMED 45 ANIMATE GROUPS 326 par 69 par X LENGTH 2700 69 par iaxle 2 69 par ff6 SUSP_ED Rear object name pa parsfile C CARSIMED 45 VEHICLES SUSP_ED 49 par front tires and animator ref frames iaxle 1 add_reference_frame RF Car Wheel set_euler_an
305. nd Load Plot Format is used WinEP will open the file browser starting with this folder Folder where WinEP creates temporary files Folder from where the last ERD file with numerical data to plot was read The next time the File menu command Load ERD File is used WinEP will open the file browser starting with this folder Folder from where the last batch file was read The next time the File menu command Load Batch File is used WinEP will open the file browser starting with this folder Folder from where image files will be written by the File menu command Save All Images CTRL D Format Menu This menu has commands for controlling the plot appearance Log x Axis Ctr H Log Y Axis Ctrl G Redraw Current Scale Redraw Original Scale Ctrl R Customize Plot Format Ctrl F Log X Axis Use this command to toggle between linear and log scaling for the X axis of the active plot If the log axis is selected the menu item has a check mark The keyboard command is Ctrl H Note WinEP will ignore the X axis log option and revert to the linear option if there are one or more zeroes or negative X values in the data set However if you zoom in to exclude the zero and negative values the log option can be used for the data shown Chapter 7 The Plotter Log Y Axis Use this command to toggle between linear and log scaling for the Y axis of the active plot If the log axis is selected the menu item has a check mark
306. nd Keywords Table E 4 Keywords for describing a wheel Description add_wheel name of wheel starts scope for new wheel the name itself is treated like a comment set_color color 9 choices color used for lines drawn to connect the black white red blue points in this part green magenta yellow dark gray light gray sets number of points in polygon used to approximate a circle set_radius number radius of wheel set_thickness thickness of wheel set_line_width sets thickness of lines drawn for this part if on draw radial line to help show how fast wheel is spinning set_scale_x numbers scale factors applied to all coordinates in set_scale_y the part set_scale_z set_offset_x numbers offsets added to all points in the part set_offset_y set_offset_z The scope of a wheel begins when the keyword add_wheel is encountered and continues until another part wheel or reference frame is added Values associated with most of the keywords shown in Table E 4 are applied to the current wheel as defined by the previous add_wheel command Grid and 3D Ground Surface The animator will draw a grid fixed in the global reference frame If not specified then there is no grid The grid can be flat or it can be based on 3D shape data used for the ground in CarSimEd Table E 5 lists the keywords and Listing E 3 shows an example PARSFILE 280 Appendix E Animator Files and Keywords Table E 5 Keywords for describing part
307. nd to display the Labels dialog box The keyboard command is Ctrl L Use this dialog box to edit the plot title X axis Y axis and legend labels for the active plot Figure 7 7 shows the dialog box along with an example active plot The circled numbers appear both in the plot and the dialog box to indicate the correspondence between the field in the dialog box and the plot HA WinEP Fz vertical forces Braking in a turn File Edit Format Data View Window Help Labels x r Plot Labels Title Fz vertical forces Braking in a tum LF tire X Label Time sec LRiire RF tire Y Label Tire vertical load N 3 RRtire r Legend fe Fz vertical forces Braking in a turn Fz vertical forces Braking in a turn Tire vertical load N 8000 BR tire RR tire new 5 Set 2 5 6 7 9 10 ime sec Cancel 8 Figure 7 7 Labels dialog box 101 Chapter 7 The Plotter Title The title is shown in the top of the plot and also in the title bar of the plot window It can be edited in the dialog box 2 X Label This is the label written underneath the X axis It can be edited in the dialog box G Y Label This is the label written above the Y axis It can be edited in the dialog box 4 Names list used to identify the X Y data sets in the legend To change any of these labels a Select it from the Names list 4 b Edit the name as it appears in th
308. nd ytarget refers to the value at time t iT m where m is an integer number of intervals within the preview time T A further simplification will be made in the application below the arbitrary weighting function will be set to unity The simplified equation is shown below for future reference Y Yure FX fe ce al 14 Application to Vehicle Control The general control method is programmed in the UMTRI driver model to generate a steering wheel angle in a vehicle solver program The algorithm flow is shown in Figure I 1 Given a target path described in terms of X and Y coordinates the driver model computes a steering wheel angle given the current state of the vehicle Full response Full vehicle dynamics simulation target path driver model Xv Yv Vx Vy W W uo Figure I 1 Algorithm flow The vehicle dynamics simulation is usually a complex nonlinear model involving thousands of calculations and tens of degrees of freedom DOF It moves on a 3D surface following a prescribed path that may be simple or complex The start time of the simulation is usually set to zero and the stop time may be set to anything from a few milliseconds to several minutes The complexity of the vehicle simulation is largely hidden from the driver model In the world of the driver model the current time is defined as zero the vehicle is described with a simple model having two degrees of freedom and the driver control i
309. ng a detailed driveline model The braking and handling model has nonlinear steering geometry nonlinear brake torque vs pressure nonlinear suspension geometry toe and camber nonlinear springs nonlinear dampers and nonlinear differentials A more detailed tire model is built in that can match experimental data over a wide range of conditions Friction and ground elevation are specified as functions of ground position Aerodynamic effects are included Closed loop controllers are available for variable speed and steering to follow a prescribed path and speed To obtain information about the commercial version of CarSim please contact MSC or view the web site Mechanical Simulation Corporation 709 West Huron Street Suite 50 Ann Arbor MI 48103 tel 734 668 2930 fax 734 668 2877 email info trucksim com web http www trucksim com 15 Chapter 1 Introduction Notational Conventions in This Manual Some standard conventions are used throughout this manual to make it more concise while still being reasonably easy to read Fonts and Type Face The bulk of this manual is presented using a Times font Other fonts and styles are used to convey special meanings The Courier font is used for keywords keywords are special names used in CarSimEd files and names of computer files and folders It is also used to designate the contents of text files if they re not too long Long text files are shown in the regula
310. ng on the Y axis click on its name Double clicking in this list has the same effect as clicking the Add button 7 G List of variables in the current ERD available for defining the X coordinate in a plot To select a variable for plotting on the X axis click on its name Double clicking in this list has the same effect as clicking the Add button 7 4 Delete button Click to delete a selected data set from the list of data to plot 1 This button has no effect unless a line is selected in the list 1 97 Chapter 7 The Plotter Clear button Click to delete all data sets from the list of data to plot File button Click to bring up the Windows file browser dialog box to choose an ERD file or text file with plot data This button has the same effect as going to the File menu to select the command Load ERD File Note While the dialog box is displayed the WinEP menus cannot be used Therefore the File button is the only way to open a new file from within this dialog box Add button Click to add the selected X Y data sets to the list of data to plot The new data set has the currently selected Y channel 2 the currently selected X channel G and comes from the currently open file shown in Plot button Click to close the dialog box and make a new plot using the current list of X Y data sets O The current settings are not cleared when you make a plot they remain in place if you bring
311. ngle B angle from the X to the projection of the C G velocity vector onto the X x Y plane about Z Sideslip can be calculated from the lateral velocity Vy and longitudinal velocity Vx v B tan SAE ISO X Yaw yw angle from Xx to X about Z SAE ISO Angular Velocity and Acceleration Pitch acceleration Oy Y component of angular acceleration vector of vehicle reference frame Pitch velocity y Y component of angular velocity vector of vehicle reference frame 8 Roll acceleration Ox X component of angular acceleration vector of the vehicle reference frame Roll velocity x X component of angular velocity vector of vehicle reference frame Yaw acceleration amp z Z component of angular acceleration vector of the vehicle reference frame ISO Yaw velocity z Z component of vehicle angular velocity vector of the vehicle reference frame SAE ISO Aerodynamic Forces and Moments Forces and moments acting from the air on the vehicle are summed into a single resultant aerodynamic force vector and a single resultant aerodynamic moment vector taken about the aerodynamic reference point Aerodynamic lateral force Fyaero Y component of aerodynamic resultant force SAE Aerodynamic longitudinal force Fxaero X component of aerodynamic resultant force SAE Aerodynamic vertical force Fzaero Z component of aerodynamic resultant force SAE 252 Appendix B V
312. ngs dampers bump stops and anti sway bars In each case 300 Appendix G The 3D Car Model some of the force generated by a component e g a spring acts to move the wheel affecting the transfer of mechanical energy to and from the sprung mass In addition some of the force is reacted at other points or in other directions that do not move and therefore cannot affect the transfer of mechanical energy For example consider the spring shown in the suspension of Figure G 3 If the wheel moves vertically an amount of A relative to the body the spring is compressed by a lesser amount say for example Rs A where R is a coefficient that defines the mechanical advantage of the spring relative to the wheel The spring exerts a force Fs on the lower control arm Some of the force is reacted at the connection to the body and some is reacted at the wheel by the vertical tire force as shown in the figure Conservation of work requires that the change in force at the wheel center multiplied by its movement must be equal to the change in spring force multiplied by its change in compression Thus the effect of the spring at the wheel is Rg Fs A similar analysis can be made for the damper using a different ratio Rq spring force F displacement at spring R A non working reacton force J displacement at wheel A working force at E wheel R F Figure G 3 Mechanical advantage of suspension component This principle
313. nificant influence in determining the all important shear forces Another behavior that influences the vehicle response involves the rotary motion of the car body in roll and pitch Mechanical energy is transfered to the sprung mass as the vehicle pitches and rolls and these motions contribute to the vehicle transient response Besides the tire road interactions the only forces and moments acting on the vehicle are due to aerodynamic effects They have a secondary influence but are relatively easy to add to multibody models Rigid Body Kinematics The model is based on a rigid body that represents the main body of the vehicle and has six DOF For the vehicle with front and rear independent suspension an additional four bodies are added each with a single translational DOF to account for the vertical movements allowed by the suspensions The wheel bodies are positioned such that the origins of their local coordinate systems are nominally at the locations of the centers of tire contact see Figure G 2 Longitudinally the origins of the front and rear wheels are separated by the vehicle wheelbase Lyp Laterally they are separated by the vehicle front and rear track widths Li and Lk r If the influence of compliances in the suspension and steering system linkages are removed each wheel center of a real vehicle follows a trajectory through 3D space relative to the car body as the suspension moves up and down Due to the kinematics of the
314. nly some of the values will appear in the list When this happens use the Save Data button described in the next paragraph Transfer the numbers a Copy the contents of the field in the dialog box to the clipboard Then go to the other software and paste the numbers into a field or spreadsheet b Or click the button Save Data WinEP will prompt for a file name for a text file with the contents of the field in the dialog box The text file can later be read into other software Changing Plot Formatting Plot appearance is controlled by a format data set You use the formatting to assign the colors of lines the size of text whether a grid is shown etc Each plot description is linked to a format data set see 7 in Figure 9 7 on page 181 As shipped every plot description is linked to a format data set with the title Default Settings If you change the default settings all future plots will have a new appearance Go to the Plot Setup Single library by clicking the plot setup icon in the ribbon bar p or use the Plot Setup command from the Tools menu Go to the Plot Format library by following the link T see Figure 9 7 on page 181 Note Another way to get to the library is through the GO menu Look for the menu item Plot Format Format tbk Refer to the description of the Plot Format screen in Chapter 8 for information about how you can control the plot appearance from the these settings Modify the data set whose ti
315. not experienced with 3D kinematics any conceivable orientation of a reference frame can be described with three Euler angles Note that the values of the angles depend on the order of the rotations different angles are required for sequential rotations about the X Y Z axes than about the Z Y X axes In general a reference frame is defined by six variables three coordinates X Y and Z and three Euler angles The animator reads the required six variables from the output files generated by the solver programs After reading the six variables each coordinate and Euler angle is calculated with a relationship of the form coordinate Co C SFe 1 angle Ag A SFag 2 where C and A are the translation and angle variables obtained from the ERD file Co and Ao are the constant offsets and SFg and SFe are scale factors gains User Settings O Names of coordinate variables for X Y and Z keywords set_x_name set_y_name set_z_name These are short names in the ERD files associated with the variable C in Equation 1 If no name is listed the field is left blank then a constant value of 0 0 is used to compute the coordinate A value of 0 0 is also used if the name is not found in the ERD file 2 Offsets for coordinate variables for X Y and Z keywords set_offset_var_x set_offset_var_y set_offset_var_z These values are numbers used to replace the symbol Co in Equation 1 If no number is entered a value of 0 0 is used G
316. ns tv E EE Steck EEA ePiedal oes 199 RnS Bathe ieties te tos edt nab bea one eea iiaia Codie na E iia e E ea ches E aaa ee ieas 201 Suspensions Independent sentner n aee e Ee eE EAE aa ete SEa cartes 204 Suspensions 5 Link Independent e eere ee ereere reee eereeeesesesesreeseeeeesests 207 Tires CarSimEd M del ie irn iee e a E Ba ei aa Aa 209 Tires Cornermme S til ines s i iee naei a a a a a a ees aaa a aaisa ete 212 Tires Pneumatic Trail ss Sis csieccitastoists veronentes ipia ioaea p onet i aip io aioi ur oat 214 Vehicles Caries rrian E REE E ER REER EER EE ER RRE E E a 215 PO Advanced VOpICS scsceiccegts te tere charset chat clersendk acetates maaan ear ace R ANA Ska 218 Adding a New SIMULINK Model cc eececccccccceccececeeceeeeeeeeeseeeeeeeseeeeeeeeeeeeeeeeee es 218 Installing CarSimEd in a New Directory eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeneneees 219 Importing Data from Another Copy of CarSimEd eeeceecceccceceeeeeeceeeeeeereeeeenes 222 Exporting Data to Other Plotting and Analysis Software eerren 223 Changing Plot Formatting 0 0 8 eerie aa A ee eee 225 Creating Offset Plots 0 ccc esti cake iaa ETa ET ara eaS EAEn uve EEC iata raSi ise 226 Re Scaling Tabular Data i aies tointa Ae a e eo a a e ee es 227 Improving the Appearance of the CarSimEd Screens eeeeeeeeeeeececeeeeeceeeeeeeeeeeeeenes 228 Continuing A RUN eresie a eae a e eaae aa a aaa are a a aE eaa 230 Changing the Def
317. nu item to go to the Runs Batch library same as 16 Batch Plotting Select this menu item to go to the Plot Setup Batch library same as 14 Spectrum This item is reserved for the Spectrum Setup library same as 13 Preferences Select this menu item to bring up a floating window used to set global preferences for CarSimEd same as 20 126 9 Alphabetical Library Reference This chapter describes all of the libraries in CarSimEd They are listed in alphabetical order based on the screen window title Conventions in This Chapter Each section shows an example data screen and describes its data fields links buttons and other user interface objects Standard Objects Standard objects that were described in Chapter 8 are not covered again in this chapter For example the buttons at the top of the screen New Delete etc are the same in every library Keywords Parameter values that are displayed in yellow fields will usually appear in the echo files produced by the solver programs These echo files identify the parameters with keywords and list them in alphabetical order see Appendix F for an example The keywords are defined in this chapter along with the definitions for the parameters so you will know where to look for them in the echo files They are shown in parentheses in the Courier font Many of the parameters in the CarSimEd models are applied both on the front and the rear of the vehicle
318. o X5 are at their specified locations 5 4 Coordinates of points fixed in the body keywords PX 1 PX 5 PY 1 PY 5 P2 1 PZ 5 G Coordinates of points fixed in the spindle body keywords XX 1 XX 5 XY 1 XY 5 XZ 1 XZ 5 These locations define a nominal configuration for the system 208 Chapter 9 Alphabetical Library Reference Location in CarSimEd CarSimEd Startup Runs Suspension Analysis Link Type Independent Suspension File Location Vehicles Susp_5L Susp_5L tbk Tires CarSimEd Model Use this screen to change the constants and links to the table look ups which define the tire properties Discussion This screen provides a location for you to enter a number of tire properties needed in the simulation Tire vertical stiffness determines how the load varies as the tire bounces on the road You can specify a vertical stiffness value here If you are simulating the 2D vehicle ride response this is the only tire parameter that will be used For small amounts of slip lateral or longitudinal the tire produces forces and aligning moment proportional to the slip The coefficients are highly sensitive to load and therefore the screen has links to other data screens that define the load sensitivity in tabular form For braking the dynamics of the spinning wheels are not of great interest Without ABS simulation the wheels generally reach a spin value in which the longitudinal tire f
319. o data set selected Parameter Set 3 Parameter Set 6 Parameter Set 9 A kad v a Link 3 Link 6 Link 9 No data set selected o No data set selected No data set selected User Settings O Miscellaneous parameter set fields Enter keywords and the value you want assigned to them The format is that each line has a keyword and value separated with white space at least a single space The keyword values for the axle identified by the keyword IAXLE are used until the AXLE keyword appears again in the inputs Links are used to include other CarSimEd data sets Note You can link to other generic data groups if the number of fields and links on the screen is not sufficient Location in CarSimEd This library does not have a default position in CarSimEd You can link to it from any blue field in the CarSimEd libraries File Location Generic Gendata Gendata tbk 160 Chapter 9 Alphabetical Library Reference Generic Table Use this screen to store and display tabular data involving a single independent variable for custom CarSimEd models This library is not used with the standard CarSimEd models Discussion All tables in the standard CarSimEd models are associated with libraries in the CarSimEd data base However CarSimEd can be extended to include modified or new models If the new models involve tabular data with one independent variable then this library can be used to store the data
320. oeds sunsets EEEO ETa EEEE ole ESES Fai a ao n 22 Making New Data Sets n 20 sc eroon e heed eae o aS tae e sede aTa eiea E aen ea 24 On Line Helpies REEE aR E EER algae web tents E RATE 24 A Map of the CarSimEd Libraries and Screens eee eeeececececcceccceeeeeeeeeeeeeeeenereeees 24 How CarSimEd Communicates with SIMULINK ee cceceeecccceceeeeeeeeeeeeeeeeeereeeees 28 4 DHE Basics OF Using Cars itd yous eniai iesirea ares 30 About the RUNS SCreeN sss co25s ire a r aa tas dose Vives tiseseuees aE a N 30 Getting toa RUNS Screenisscccclechsccede sees eene E esere katate swed coed the ue aaiae e eieaa beitenys ieaiai bea 31 Making a New Run Stand Alone ccc eeceeececececeeeeeeeeeeececeaeaaeaeeeeeeceeeaeaaeaeeeeeeeeeeaeaaea 33 Replacing a Run Stand Alone eee cececccccccccccceeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee ss 34 Making the First SIMULINK Rum eee cece cc cccccccceecceceeeeceeeeeeeeceeeeeeeeeeeeeeeeeeeeeeeeee ss 35 Making Additional SIMULINK Runs eecececccecccecceceeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee es 36 VIEWING an ANMNALON sessen tree iar o ae aa aaa cote stveedodadeeeeeliveedasticels Lived 36 Viewing a Single Pre Defined Plot 2 20 sscces ne5 sueegssesseansce se egaesebeeenecesnegecebseenece ste eqesubeeenccs 37 Viewing Several Pre Defined Plots cc eecececccccccceccececeeeeceeeeeeeeeeeeeeeeeeeeeeeeeseeeeeeee es 38 Overlaying Plots for Multiple RUNS eee eeeeeeeeeeeeee
321. of SO Q 1 m YO Abs Y trans of SO Q 2 m ZO Abs Z trans of SO Q 3 m YAW Abs Z rot of Spp Q 4 deg PITCH Y rot of Sp rel to Spp Q 5 deg ROLL X rot of S rel to Sp Q 6 deg JNC_WLEF Trans of WLFO rel to WLFJ Q 7 m JNC_WLR Trans of WLRO rel to WLRJ Q 8 m JNC_WLR Trans of WRFO rel to WRFJ Q 9 m JNC_WRR Trans of WRRO rel to WRRJ Q 10 m ROTLEF Rotation angle of LF wheel Q 11 deg ROTLR Rotation angle of LR wheel Q 12 deg ROTRF Rotation angle of RF wheel Q 13 deg ROTRR Rotation angle of RR wheel Q 14 deg TANLHF Slip angle tan of LF tire with time lag Q 15 TANREF Slip angle tan of RF tire with time lag Q 16 TANLR Slip angle tan of LR tire with time lag Q 17 TANRR Slip angle tan of RR tire with time lag Q 18 IVERR Integral of velocity error for speed controller Q 19 m Independent Speeds VXS Vehicle forward speed U 1 m s VYS Abs Y trans speed of SCMC U 2 m s VZS Abs Z trans speed of SCMC U 3 m s AVZ Abs Z rot speed of S U 4 deg s AVY Abs Y rot speed of S U 5 deg s AVX Abs X rot speed of S U 6 deg s 303 Appendix G The 3D Car Model JNCR_WLF Trans speed of WLFO rel to S U 7 m s JNCR_WLR Trans speed of WLRO rel to S U 8 m s JNCR_WLR Trans speed of WRFO rel to S U 9 m s JNCR_WRR Trans speed of WRRO rel to S U 10 m s AVY_LF Spin rate of LF wheel U 11
322. of the file should be NBYTES x NRECS The last record is not read resulting in a loss of data If the records are large this loss could be significant These problems are reduced if a value of NBYTES is specified such that it divides the data into NRECS records of smaller chunks of data 263 Appendix D Plotter Files and Keywords When WinEP is run from CarSimEd it receives the information that describes a plot or set of plots from a text file The passing of information between a CarSimEd data screen and WinEP is automatic and the details of the files used to transfer information do not have to be understood by the user for normal use of CarSimEd The information in this appendix is provided to aid in debugging and for those wishing to use WinEP outside of CarSimEd PLT Batch Control Files Most plots made in CarSimEd are generated when you click the Plot button on the Runs screen or the Plot Setup Batch screen When this occurs the CarSimEd library creates a text file with the extension PLT and sends that file to WinEP The PLT file is similar to the PAR files used in CarSimEd to transfer information from the database to the simulation solver programs It is a plain ASCII text file that contains keywords with file names variables names and other pieces of information that tell WinEP how to make a plot Listing D 1 shows an example PLT file and Table D 1 summarizes the format Listing D 1 Example PLT batch plot file
323. ogrammed within ToolBook The running of ToolBook code and management of ToolBook libraries is done by the ToolBook runtime package which is included with CarSimEd Triangle button a button with a triangle icon f usually located adjacent to a field you click on the button using the left mouse button to display a pull down menu 243 Appendix A Glossary TruckSim an integrated software package similar to CarSimEd available from MSC for simulating and analyzing the braking and handling behavior of trucks and tractor trailer combinations UMTRI The University of Michigan Transportation Research Institute Most of the modeling and simulation technology in CarSimEd are based on knowledge and methods developed at UMTRI Variable an output quantity computed by the CarSimEd vehicle models In contrast to a parameter a variable can change with time in a way that must be simulated using a detailed vehicle dynamics model Output variables can be plotted with WinEP the plotter embedded in CarSimEd Some of the output variables are read by the animator embedded in CarSimEd to create an animation of the simulated vehicle motion WinEP the Windows Engineering Plotter is the plotting program in CarSimEd It makes X Y plots from data read from ERD files and is used to view simulation results It can also be used to view data from other sources such as test data WinVI a public domain text editor included with Car
324. oll or yaw motion is ignored This model can be used to determine how basic ride parameters wheelbase mass center spring and damper rates etc affect the behavior of a car going over an arbitrary road profile 3D Suspension Model The suspension model is of a 5 link design as described in the IAVSD benchmark M Hiller and S Frik Five Link Suspension from Multibody Computer Codes in Vehicle System Dynamics Supplement to Vehicle System Dynamics vol 22 1993 pp 254 262 The model can simulate short long arm SLA wishbone suspensions and also the 5 link rear suspensions used in some Daimler Benz automobiles Outputs You can view simulation results as wire frame animations or as plots of output variables All it takes is a single button click Computer Requirements The software runs on Intel PC s equipped with Windows 95 98 or NT It is self contained requiring no additional programs or tools to run The simulations run much faster than you might expect for such detailed models On any current PC the programs run faster than real time On higher end desktop computers the vehicle models run several times faster than real time In other words a run simulating a 10 second test will finish in just a few seconds Working with SIMULINK and MATLAB SIMULINK is a software package for modeling simulating and analyzing dynamical systems in general It runs under MATLAB a mathematical workshop SIMULINK and MATL
325. oment K KIK M K KIK 22 3 27 oe Plot of equation 21 313 Appendix H The Tire Model A coefficient v is defined to transition between linear and full sliding 1 If K gt 27 then v 1 1 else 1 K K K V 5 1 REY REY cos 23 A force scaling factor is defined F P 24 KHN The scaled forces and moment are F x F F F Ty FR Mz V Loau Tag M Fo 25 Camber Effect The small effect of inclination is handled by modifying the slip angle by an amount 1 Ey Qeff tan tT Y Ry Ry ra 26 a where Ky is a linear camber thrust coefficient and Kq is the cornering stiffness Both coeffients are evaluated at the instant vertical load Fz Low Speed Exceptions Models of the rolling tire can become unrealistic when the rolling stops One problem is numerical equations might have the speed in the denominator of an expression For example the longitudinal slip definition see Equation 9 is singular at zero speed This problem is solved by using limiting the speed used in the equation to a small value V If X lt e Then Wo sign Vx 27 CGA Low Speed Instabilities A general challenge in mechanical simulation occurs whenever a large force or moment is largely insensitive to the magnitude of motion speed but acts in the direction opposite 314 Appendix H The Tire Model the motion For example braking torque resists the dir
326. on maintaining compatibility with SAE and ISO when practical Exceptions are noted when they occur The terminology applies to all simulation software developed and maintained by Mechanical Simulation Corporation CarSimEd TruckSim etc Terms are not defined unless they are necessary for describing vehicle solver programs such as those that are supplied by Mechanical Simulation Corporation The level of detail is matched to models that are system based rather than component based To obtain generality terms are defined without reference to specific models Terms that are defined in this document are written in italics followed by symbols when they exist Definitions that are taken from SAE J670e and or ISO 8855 are designated SAE and ISO respectively in parentheses Conflicts with SAE or ISO are described in numbered notes at the end of this appendix 245 Appendix B Vehicle Dynamics Terminology Vectors and Angles Vectors Acceleration vector linear time derivative of the velocity vector of a point Angular acceleration vector time derivative of the angular velocity vector of a reference frame Angular velocity vector vector describing the absolute 3D angular velocity of a reference frame with respect to the inertial reference Formally it is a quantity that satisfies the equation r xr where r is a vector fixed in a reference frame and is the angular velocity vector of this reference frame Position
327. on types Locate the new EXE file and select it Repeat step 2 If the New Program Has a Different Name Than the Old Program Use the pull down menu 3 to choose the option Find Solver For Type where Type is the desired simulation type In the case of a new stand alone program you will then be prompted to locate the EXE file associated with the currently selected vehicle type Locate the new EXE file and select it Make a run to confirm that the new program is used Adding An Alternative Program Use the pull down menu G to choose the option Add You will then be prompted to name the new simulation type and to locate an associated EXE file for the current vehicle type Notes This step must be repeated for each vehicle type to allow CarSimEd to make all of the entries into the internal table The new program will not be used until you select the new simulation type for a new run Removing a Simulation Type If you want to delete a simulation type from the menu Simulation Type G then Use the pull down menu G to choose the option Delete along with the simulation type that you want removed Note CarSimEd will not delete any EXE files The Delete menu item only removes an item from the menu Changing the Default Text Editor The View Echo File All Parameters button on the Runs screen automatically loads a text file into an editor As installed the default text editor is a program called WinVI You can replace WinVI with
328. onally configure it Print Data Set Select this menu item to print the current screen Print Library Select this menu item to print all data sets in the current library using the data screen layout Compact Library This command causes ToolBook to compact the file eliminating space that was used by data sets that have been deleted Over time the TBK library files can grow more than expected because when you delete data sets the file space is not recovered Use this menu item if you notice that some of the TBK files have gotten very large Depending on the amount of graphic content the normal size of a TBK file can be as small as 70K or as large as 700K Backup Library Select this menu item to make a backup copy of the current TBK library file The copy is given the extension BAK Import Data from Other Library Select this menu item to import one or more data sets from another TBK file into the current one This command is useful for transferring information between separate CarSimEd installations It is also useful for importing data from an old version of CarSimEd into an updated version When the command is selected the Windows File browser appears with a request to locate a TBK file with data to import If a file is selected the contents are displayed in the following dialog box The numbered items are described below 120 Chapter amp Design of CarSimEd Data Screens Import Library Selected library
329. ooking forward Calculator buttons Click one of these buttons to calculate Ixx Iyy or I from the radii of gyration Rx AD Ry 12 or Rz 13 Sometimes measured values for Ixx Iyy and Izz are not available but Rx Ry and Rz can be estimated In this case each inertia parameter can be estimated by combining the radius of gyration with the total mass I M R2 Roll Radius of Gyration not a parameter Use if Ixx is not available and Rx can be estimated If used a guess for Rx might be a third of the vehicle width Pitch Radius of Gyration not a parameter Use if Iyy is not available and Ry can be estimated If used a guess for Ry might be half the wheelbase Yaw Radius of Gyration not a parameter Use if Izz is not available and Rz can be estimated If used a guess for Rz might be half the wheelbase Link to the library Suspension Systems Independent to use an independent suspension model with CarSim data format Link to the screen for the tire properties Steering gear ratio keyword RSW This is the ratio defines as the steering wheel angle divided by the road wheel angle Steering system compliance keyword CSMZF This is the compliance in the steering column and other places not accounted for by the suspension compliance It is calculated by measuring the steer at a road wheel due to applied steering torque with the steering wheel fixed The effect due to suspension compliance is subtracte
330. oolBook Runtime package 3 Start All Rights Reserved Figure 9 4 All controls of the Startup screen Note Figure 9 4 shows the CarSimEd Startup screen after the Change Settings button 2 has been clicked Additional User Settings and Controls 4 List of libraries for the GO menu This list is also used for other functions within CarSimEd it tells CarSimEd what library files exist and where they are located The files are represented as pathnames relative to the CarSimEd root directory For example if CarSimEd is in c Carsimed then the partial pathname 152 Chapter 9 Alphabetical Library Reference RUNS_3D RUNS_3D TBK means the full pathname for the file is c Carsimed Runs_3d Runs_3d tbk This list is used by CarSimEd for two purposes 1 It defines which files are affected when text data files are updated if you click the Update All PAR Files button 13 2 It determines which files are listed in the pull down menu that appears when you press the GO button in the ribbon bar 16 In both cases files are included only if they are listed in the field and if they actually exist This list cannot be edited directly Lines in it can be selected by clicking on them and the contents are manipulated by using the adjacent buttons 12 Add Default Libraries button Click to add all of the library files included in the CarSimEd installation This button is provided as a way to undo damage
331. oose between two different ways to control steering in CarSimEd You make the choice on the Runs screen by linking to a data set from one of these libraries 1 Input Steering Wheel Angle this angle Choose this library to apply a steering wheel angle described explicitly as a function of time and the vehicle will be steered in an open loop mode 2 Input Target Path For Closed Loop Steer Control Choose this library to apply the steering controller from the CarSimEd model 166 Chapter 9 Alphabetical Library Reference Steering control is an input that appears as a link on the left of the Runs screen To use the steering wheel input the open loop library must be linked as one of the inputs The easiest way to make a new run using steering wheel input is to find an existing run made with a steering input involving the vehicle type of interest and copy that run However if there are no existing runs close to what you need then you should 1 Link to this library using one of the input links on the Runs screen and 2 Make sure you are not linked to an closed loop path following data set See the section Data Links in Chapter 8 for details on changing links User Settings Note User settings that are common for all tabular data screens are described in Chapter 8 in the section Tabular Data E Two column table of values of steering wheel angle as a function of time keyword STEERSW_TABLE Each line should have a value o
332. or documenting the information on the screen Tabular data Each row in the table should have two numbers separated by a comma The first number is the independent variable normally plotted on the X axis The second is the dependent variable normally plotted on the Y axis The solver programs in CarSimEd have two methods for extrapolating outside the range of a table 1 For variables that are inputs to the vehicle controls such as brake pressure or disturbances such as wind flat line extrapolation is used If the independent variable is less than the first value in the table the first value of the dependent value is used If the independent variable is greater than the last highest value in the table then the last value of the dependent variable is used 2 For variables that describe vehicle properties for example spring force vs deflection constant grade extrapolation is used Depending on whether the independent value is less than or greater than the range of the table the first or last two points are used to extrapolate by assuming the same gradient between the dependent and independent variables The method of extrapolation is built into the solver program and cannot be changed If you are in doubt about which method will be used make sure the range of the independent variable in the table goes well beyond the range that can be covered in any simulation Location in CarSimEd This library does not have a default posit
333. or for speed controller m 27 77553913376 Vehicle forward speed m s 0 514535513897 Abs Y trans speed of SCMC m s 0 01654330461462 Abs Z trans speed of SCMC m s 6 771926099055 Abs Z rot speed of S deg s 0 2306196465965 Abs Y rot speed of S deg s 0 000486247 1536275 Abs X rot speed of S deg s 9 358694147682e 006 Trans speed of WLFO rel to S m s 5 518184953048e 005 Trans speed of WLRO rel to S m s 2 486989249608e 005 Trans speed of WRFO rel to S m s 3 936770925572e 005 Trans speed of WRRO rel to S m s 15 47666753711 Spin rate of LF wheel rev s 15 4610040621 Spin rate of LR wheel rev s 15 57431795697 Spin rate of RF wheel rev s 15 56005195726 Spin rate of RR wheel rev s Keywords and Parameters for the 2D Car Model PARSFILE 2D Simple ride model dynamic simulation Version created by AutoSim 2 8 on February 26 1999 Copyright 1999 Mechanical Simulation Corporation All rights reserved TITLE Sine Sweep Input File C CARSIMED RUNS_2D 640 PAR Run was made 17 31 on Jul 23 1999 FORMAT BINARY 292 Appendix F Model Files and Keywords IPRINT 1 number of time steps between output printing counts STARTT 0 simulation start time s STEP 0 0025 simulation time step s STOPT 13 simulation stop time s PARAMETER VALUES DSC 0 75 Front damper rate at shock absorber N s mm DS 0 75 Rear damper rate at shock absorbe
334. or settings as described in section Testing Animator Data Sets in Chapter 5 on page 77 ID Number Each data set in the library has a unique ID number The number is used to automatically name the PAR files associated with the data set For example if the ID is 131 a file 131 par is created automatically by CarSimEd and located in the same folder as the TBK library file Time of last change This is set whenever the PAR file is updated Date of last change This is set whenever the PAR file is updated Data Links Each CarSimEd screen contains a data set that is part of a relational database Data sets are linked together approximately in a top down hierarchical fashion as shown earlier in Figure 3 4 on page 26 Parts of a Data Link The object used to link data sets together is called a data link As shown below a data link has several components 115 Chapter amp Design of CarSimEd Data Screens Link label Type Triangle button Vehicle independent cr dd Data set name e The name of the linked data set is shown in the blue field e g Car ind Notes No library selected appears in the blue field if the link is not pointing to anything No data set selected appears if the link is pointing to a library but has not yet been linked to a specific data set in that file e Most data links have labels in bold typeface that describe the type of data to which the link points e g Vehicle In some cases ad
335. or the 3D model are not required for the 2D simulations The extra data are ignored when the simulation runs CarSimEd Startup Runs 3D Runs 2D Runs Susp Road Inputs Cars Plot Setup Cameras Groups Suspensions Tires Formats Filters Ref Frames Shapes Ref Frames Wheels Figure 3 5 Partial map of the CarSimEd libraries Map for the 3D Suspension Model Figure 3 6 shows a map of the libraries for the 3D suspension model This model does not use any of the vehicle data but shares the libraries for the animator and plotter Chapter3 Database Organization CarSimEd Startup Runs 3D Runs 2D Runs Susp Plot Setup Cameras Suspension data Groups Spindle input Formats Filters Ref Frames pindle inpu Wheels Figure 3 6 Partial map of the CarSimEd libraries How CarSimEd Communicates with SIMULINK The SIMULINK version of a CarSimEd solver program works almost the same as the stand alone version It has the same equations of motion the same model parameters and the same control inputs and disturbances All of the files that are read and written by a standard CarSimEd solver program are also read and written by the SIMULINK version Therefore the CarSimEd post processing plotter and animator work nearly the same as with the stand alone version Note There is just one mathematical difference in the way the SIMULINK program a DLL file compiled from CMEX source code runs relative to the stand alone program a
336. orce just balances the applied brake torque The model uses a single coefficient to relate longitudinal slip to force For cornering a quick equilibrium is not reached and the relation between lateral slip and lateral force has a strong influence on the handling behavior of the vehicle The CarSimEd tire model is described in Appendix G It is based on an analysis of tire mechanics from Chapter 14 of the book Race Car Vehicle Dynamics Milkier amp Milkier SAE 1995 When a tire experiences a slip angle it does not immediately generate a lateral force but must roll some distance to generate the lateral deflection necessary to sustain a force Under a step steer the force builds up like a first order lag in distance You can input this distance known as the relaxation length on this screen At low speeds the determination of tire forces can become erratic because of numerical problems in calculating the slip conditions In order to avoid these problems you can specify a cut off speed below which such mechanisms as relaxation length are modified All properties are specified for a single tire 209 Chapter 9 Alphabetical Library Reference mq Tires CarSimEd Model ojx File Edit Text Page Tools Data set Example Small Tire I gt Hew Delete GO E Changed ID 69 CO Hotes 4 06 42 Shear Lan Vertical Spin Inertia Forces Force Vheel Tire spin moment of inertia and 14 s Ji
337. ort less than 10 data sets at a time and that you back up the library file that is the target of the import process 4 List of data sets in the linked library indicated in O 121 Chapter amp Design of CarSimEd Data Screens Exit Select this menu item or use the keyboard command Ctrl Q to exit from CarSimEd Edit Menu The Edit menu supports the clipboard and the Find command Edit Undo Ctrl Z Cut Ctrl Copy Ctrl C Paste Ctrl V Clear Del Select All Ctrl A4 Find Undo Select this menu item to undo the most recent entry or change in a text field The keyboard command is Ctrl Z Cut Select this menu item to cut the currently selected text to the clipboard The keyboard command is Ctrl X Copy Select this menu item to copy the currently selected text to the clipboard The keyboard command is Ctrl C Paste Select this menu item to paste the clipboard to the current cursor location If text is currently selected it is replaced by the contents of the clipboard The keyboard command is Ctrl V Clear Select this menu item to clear the currently selected text The keyboard command is the delete key 122 Chapter 8 Design of CarSimEd Data Screens Select All Select this menu item to select all text in the field where the cursor is currently located The keyboard command is Ctrl A Find This command can be used by advanced users to locate information in CarSimEd data
338. ose shown in Figure 10 1 4 Click the Update All PAR Files button O Note The process of updating all PAR files to generate new absolute pathnames can take several minutes on some computers The time required depends on the speed of your computer and the number of data sets you have in the CarSimEd database 5 Click the Start button to resume your work Importing Data from Another Copy of CarSimEd There are several occasions where you may want to import data from another copy of CarSimEd If you obtain an update for CarSimEd this is how you transfer data entered in the older version Another reason might be that CarSimEd is installed on several computers and you want to import data from one installation into the other To import data both installations of CarSimEd must be accessible from the same computer 1 Go to the library in CarSimEd from which you want to receive the imported data Any data screen in that library will do 2 Go to the File menu and select the item Import Data from Other Library CarSimEd will bring up a file browser dialog box 3 Select a library TBK file of the same type as the current one For example if the current library contains tire data you should open only another tire library file Often the two files have the same name but are in different folders 222 Chapter 10 Advanced Topics 4 Click OK CarSimEd will copy each data set of the old library and paste the contents into the new
339. ot Format command to load one of these format files This command brings up the Windows file browser dialog box to open a file with the extension PAR When loaded WinEP will redraw the current plot with whatever new formatting information was loaded The keyboard command is Ctrl O Note Format files created within the CarSimEd graphical user interface are in the CarSimEd folder Plot Format Chapter 7 The Plotter Load Transform Settings Transform and offset information for plots can be stored in files These files can be created from within WinEP using the Save Transform Settings command from the File menu Select the Load Transform Settings command to load one of these settings files This command brings up the Windows file browser dialog box to open a file with the extension PAR default file is PlotTran par When loaded WinEP will redraw the current plot with whatever new settings information was loaded The keyboard command is Ctrl T Close Top Window This closes the top active plot window The keyboard command is Ctrl W Save Plot Format Use this command to save the current plot formatting information The default extension is PAR The formatting can be applied in the future using the Load Plot Format command from the File menu When loaded the formatting file will cause WinEP to redraw the current plot with the new format The keyboard command is Ctrl S Save Plot Data TA Use this command to save the current X
340. ot any combination of variables and overlay plots from different runs If test measurements are available you can overlay simulation and test results 14 Chapter 1 Introduction What CarSimEd Does Not Do CarSimEd is not a general purpose simulation tool It is customized for the kinds of simulations described above Simulations with other models are not possible without adding programs Some limitations of the models in CarSimEd are e The 3D vehicle model does not support closed loop speed control for variable speed e The suspension springs dampers compliance and kinematics are modeled with linear coefficients There are no bump stops e The handling model assumes constant steer ratios no Ackerman effect e The brakes are modeled with linear gains between brake torque and brake input e The tire model does not allow specification of forces and moments for large slip angles Large slip is handled using built in functions that are reasonable but which cannot be adjusted by the user e The road surface is smooth and level with a constant friction coefficient e CarSimEd has no driveline dynamics Throttle inputs are related to drive torque by constant coefficients The ride model assumes a constant vehicle speed e The vehicle models do not have aerodynamic effects e The five link suspension model does not include compliance A commercial version of the software is available with more extensive modeling includi
341. ot be seen in the grid To view detailed ground features it is best to create a part description associated with a non moving reference frame The scope of the grid information is unlimited for all of the keywords except set_color The scope for set_color begins when the add_grid keyword is encountered and continues until a part wheel or reference frame is added Target Path The animator can show target paths specified as inputs to the driver model in CarSimEd There are three kinds of input recognized by the animator the color of the path a design path and an offset to the design path The target path for the controller is the combination of the design path plus the offset as described in the Chapter 9 section Input Target Path For Closed Loop Steer Control The target path including the lateral offset is drawn by the animator with dashed lines and the design path without the lateral offset is drawn with solid lines Table E 6 Keywords for describing parts set_path_color color 9 choices color used for design and target black white red blue green paths magenta yellow dark gray light gray yin_table list of X Y coordinates 2 coordinates of design path endtable numbers per line Itarg_table list of S L coordinates 2 lateral offset of the target path from endtable numbers per line the design path S distance along design path L lateral offset to the left The scope of the target path inputs is unlimited
342. otes 11 13 12 Name of Yaxis 1 This screen is used for data represented with a 2D table a variable 5000 that depends on two other variables 6000 00 The first row has values of Y the first 4000 column has values of X The value in row 1 column 1 is ignored 3000 Table Layout y values 2000 x values tixy 2000 1000 Keyword for Table TEMP_KEYWORD_CARPET _ i TEMP_KEYWORD_CARPET 4 0 1 015 0 2 0 25 0 3 E 2 No of columns 3 _ Update Plot 000000 2000 6000 00 100000 500 3600 00 G 200000 1500 4500 00 300000 1500 4500 00 Unlike most of the libraries in CarSimEd each data set in this library can represent a different kind of data This is possible because the keyword used by the simulation solver programs to identify tabular data is a part of the data set User Settings Note User settings that are common for all 2D tabular data screens are described in Chapter 8 in the section 2D Tabular Data Label for Y axis This label is not used by the solver programs It is a user comment field provided as a means for documenting the information on the screen Label for X axis This label is not used by the solver programs It is a user comment field provided as a means for documenting the information on the screen Tabular data The first row has values of the first independent variable the first column has values of the other independent variable and all other numbers are the values of the dependent variable
343. oups of shapes and wheels are grouped and associated with reference frames to build a detailed visual representation of a road or vehicle As explained in Chapter 6 reference frames are used to define motions of vehicle parts As the inputs to the animator are processed each shape or wheel is moved with a reference frame When the animator is reading input data there is always a single active reference frame By definition each shape and wheel that is processed moves with this frame It is important to understand that all objects in a reference frame must be processed together For example suppose there is a reference frame with the title sedan body The animator will not allow some shapes to be processed for sedan body then process shapes for another reference frame and then switch back to sedan body Once the animator starts processing data for a particular reference frame it is no longer possible to add shapes or wheels to reference frames that were previously processed Notes 1 Although shapes and wheels are always associated with the active reference frame the camera and look point coordinates are not However because the camera and look point data are contained in the library Animator Camera Setup you should not have occasion to deal with them in an Animation Groups data set 2 The reason that shapes and wheels are handled differently than camera and look point data is that shapes and wheels can be duplicated For exampl
344. p 41 I gt Hew Delete GOY Back Changed ID 665 O Hotes 11 51 25 Model Parameters amp Inputs Run Control Output amp Post Processing Vehicle car Genere Je Run Simulation _ Animae Input path Em kmh Stop sec Mu Camera Setup zi Co JE e Cos rotvew 1 mpfi Braking Computation Parameters x dt 0025 20 Hz output x View Echo File All Parameters Simulation Type No data set selecte __30 Verice Dynamics o pemen i Plot 1 TIET Misc Data with o Based On Runs Basedon ws lt a Y vs XK Y vs X trajectory x startt 1 8 Step steer ca J Dio disatansesd Data from Batch No data set No data set selected Mo data set selected Excerpts From Output File 665 pf File ext Ipt Keywords Overlay Run 2 Step steer car Rescan File Overlay Run 3 No data set selected x 4 K Show More 07 2499 Go to the Runs data set for the run you want to continue Click the button New to copy the data set Make sure that the Show More 4 box is checked Use the Based On link 2 to select the run that will be continued Optional To make the time scale for the new run start where the previous run left off type startt time where time is the stop time from the first run shown in the Stop field O e g it was 1 8 in the original run Step Steer car If you do this change the stop time parameter name stopt to a larger value e g in t
345. p y eacee j Plot 2 Setup Fe vetica wes Plot 3 Setup e Plot 4 Setup awe el Overlay Run 2 iNo asta set selected Overlay Run 3 No data set selected xl Asur ES AD O Eroina 3 E amp Runs a0 HPasTee MPasTes Page 1 25AM Figure 10 2 Appearance of a data screen that has been maximized Continuing a Run The solver programs in CarSimEd are capable of starting a new run right where a previous one left off However in the new run you are free to change anything you want Some applications of this are e You can simulate a drastic change in the vehicle properties such as a brake failure tire blow out etc e You can change controller strategies For example specify a hard step steer input for a second and then resume the run with the driver model trying to bring the vehicle under control e You can reproduce an existing run changing just a few parameters of interest to rapidly investigate vehicle sensitivity to any of the modeled properties Note It is helpful to know which settings on the Runs screen have priorities over others See Chapter 9 section Runs for a description of how priorities are determined 230 Chapter 10 Advanced Topics oP eS ee The way to continue a run is to use the Based On link of the Runs screen to select an existing run 4m Runs 3D Handling OE x File Edit Text Page Tools Data set Recovery from ste
346. parameter values in it Open any files identified with the keyword PARSFILE and continue the inspection A program called Parstree is included in CarSimEd to rapidly inspect the tree of PARSFILEs To use it just click the Tree button in the ribbon bar a See Chapter 5 for more information ra ParsTree Ox Parstile tree Structure Contents of the selected file PARSFILE ff2 CARS_ED Generic object name E E 39 par E 46 par parsfile C CARSIMED 45 VEHICLES CARS_ED 39 par P parsfile C CARSIMED 45 INPUTSSTEERINGS 42 par a E 326 par parsfile C CARSIMED 45 INPUT BRAKING 84 par 303 par ff COMP_PAR dt 0025 20 Hz output object name fe 390 par parsfile C CARSIMED 45 COMP_PAR 49 par S 391 par Son f spee E 392par mu 0 75 393 par parsfile C CARSIMED 45 BATCH RUNS_BAT 122 par 394 par 395 par used by animator program 396 HanimateLink CAMERAS Front view object name Pa PARSFILE C CARSIMED 45 ANIMATE C amp MERAS S261 par 397 par used by plotting programs E 398 par PARSFILE C CARSIMED 45 RUNS_3D 627 plt 392 g ee testid 627 S 39 4 a title Step steer car E 399 par END E 400 par E 395 par B 396 par off E 397 par B 401 par Parsfile path and filename S E 327 par C CARSIMED 45 RUNS_3D 627 par H 402 par i Q File can t be found Keyword error Create LpiFile Reload File Load New File Exit a Figure F 1 Dis
347. play of nested PARSFILEs with Parstree 285 Appendix F Model Files and Keywords However there are faster ways to get the information The list of all files is contained in the LOG file and the list of all parameter values is contained in both the LPO and LPF files LPO and LPF Echo Files In CarSimEd the input parameter values are typically spread over many files When a solver program runs it creates summary files that list each and every parameter value that is being used in the current simulation These even include parameters that were not given values in these cases the default values are listed One of these files is created before the run LPO and the other is created at the end of the run LPF Both contain all parameter values used in the simulation In addition the LPO file contains the initial conditions of the state variables in the simulation model The information in the LPO file is sufficient to exactly repeat a run using only the LPO file as an input An example LPO file is listed later to show all of the keywords recognized by a CarSimEd model The LPF file is nearly identical except that instead of the initial values it contains the final values of the state variables By modifying the start and stop time parameters an existing run can be continued if the LPF file is used as the input file for the simulation solver program ERD and BIN Files Generally the main purpose of each solver program is
348. point in arun This can be convenient when working with long simulation runs because you can go right to an event of interest without viewing the early parts a 100 0 44 50 sec O Start time from the input file 76 Chapter 6 The Animator 2 Finish time from the input file G Current animation time This is the simulation time associated with the currently displayed animation view 4 Slider control The slider moves as the animation proceeds Its relative position indicates graphically the time associated with the currently displayed view You can use the left button of the mouse to move the slider and change the current animation time Testing Animator Data Sets The animation setup information is contained in the CarSimEd database but is displayed by the animator program It is helpful to know how to use both the database and the animator to test and debug new animator settings Viewing the PARSFILE Tree As shown in Figure 6 2 on page 66 all information about shapes camera position reference frames etc comes into the animator through PARSFILEs CarSimEd generated files with extension PAR At the top level the animator receives the name of an ERD file and the name of a PAR file Both have the same base name the number appearing in the upper right corner of the Runs screen as shown below a Changed es d uin F Locked 7998 The top level PAR file is associated with the Runs screen and
349. ppendix D Plotter Files and Keywords Preference File Format The preference file Epprefs txt is used to set and save information that is retained between WinFP sessions This information includes the window positions and paths to directories The information can be viewed and edited using the Edit menu command Preferences Listing D 4 shows an example preferences file Listing D 4 Example Preferences file ep prefs temp folder path C CARSIMED 45 PLOT tmp last datafile path C CARSIMED 45 PLOT last batchfile path C CARSIMED 45 PLOT tmp last formatfile path C CARSIMED 45 PLOT format last imagefile path C CARSIMED 45 PLOT image startup window mode tile ver startup toolbar mode false plot window position 10 10 727 550 end The preferences file is created automatically by WinEP whenever the program quits so it is not necessary to be concerned with its format Text Files Although WinEP is mainly intended to plot data contained in ERD files it is also capable of reading numerical data from tables stored in plain text files Plain text files can be made by the solver programs in CarSimEd to simplify the importing of data into spreadsheets or other programs If this form of output is chosen WinEP can still be used to view the results althought the labeling is not as nice Also WinEP can be used to view data exported from spreadsheets or other mathematical packages Listing D 5 shows part of a text file
350. preferences window by clicking the 9 button in the ribbon bar or selecting the Preferences command from the Tools menu b Make sure the Advanced Mode allow changing links box is checked and then close the preferences window c Try step 1 again When you select the menu item Pick Library a Windows File Select dialog box appears Browse your file system to locate the intended TBK file and select it Chapter 4 The Basics of Using CarSimEd Note If you are not sure where the library of interest is located you can refer to the description in Chapter 9 which will include the pathname to the TBK file Alternatively you can display the GO menu see page 44 and view the relative path name of the TBK file of interest from the menu 3 After linking to a library the blue field will read No data set selected Although you have linked to the library you still have to link to a data set within that library You do this with the same pull down menu which will now display the names of the data sets in the newly linked library Simply pull down the menu and pick a data set to link to 255A 5 The Solver Programs CarSimEd contains programs that solve the equations of motion for vehicle models predicting motions forces and other output variables A solver program is run automatically whenever you click the Run Simulation button from the Runs screen CarSimEd allows you to set up inputs to the programs and view their outputs without ever
351. q M R Rear oe Nom gain drive toi ue one wheel Front Suspension Rear Suspension driver input HMA Front w o HMw Rear x Front Tire Rear Tire Animator Group 4 Example HMA Tire gt Example HMVWWV Tire HMMA body x Figure 3 2 Example data screen The yellow field in the upper left corner of the screen is the title of the data set e g HMMWV 1 The title is just text that you choose to identify this data set in the library It has no significance to the solver program However it can have great use for organizing your data sets Each blue field represents a link to another data set The name of the data set is shown in the blue field and the triangle button is used to display a pull down menu For example click the triangle button 4 to view the following menu Front Suspension Go To Data Set Pick Library No Data Set Example Front Example rear suspension The menu can be used to select a different data set in the linked library choose the data set of interest from the list displayed at the bottom of the menu It can also be used to go to the linked data set choose the menu option to Go To Data Set After using Go To Data Set to go to a different library you can return to the previous screen using the Back button shown below located in the upper right corner of each data screen 93 Chapter3 Database Organization Changed O Notes a O Locked The
352. r the screen display shows how a series of X Y coordinates are created for a circular input path Note This screen does not directly feed numbers to a solver program To use the data you must copy the numbers to the clipboard and then paste them into the appropriate data screen 143 Chapter 9 Alphabetical Library Reference Calculator Iof x File Edit Text Page Tools CO Hotes 11 03 38 Category C Locked 8713198 Simple Calculator 12 0254 500 400 4 8 Phd 3 aa z5 s9 ae Formulas for Items Create or Transform Calculation Options 20 152 4 cos x 57 29578 e CO cate ea sin x 57 29578 o End X 630 23 o O Transform Step DX Figure 9 3 The calculator screen The screen design is fairly complex offering the following capabilities e It plots tabular data for one or more pairs of X Y data points e It performs simple calculations by evaluating a mathematical expression and printing the numerical result e It evaluates mathematical expressions involving values in a 2D table updating the entire table with a single button click For example you can convert the units for different columns in a table using different scale factors for each column e It creates tabular data from scratch based on start and end conditions for a series After the settings are described a few examples are provided to show you how they are used User Settings and Controls
353. r N s mm HWC 1 285 Height of front wheel center used only for animation mm HWC 2 285 Height of front wheel center used only for animation mm IYY 2704 Moment of inertia of entire vehicle kg m2 KS 1 30 Front suspension spring stiffness at spring N mm KS 2 20 Rear suspension spring stiffness at spring N mm KT 1 200 Front tire vertical stiffness N mm KT 2 200 Rear tire vertical stiffness N mm LTK 1 1500 Front axle track width used only for animation mm LTK 2 1500 Rear axle track width used only for animation mm LWB 2700 Wheelbase mm MF 1000 Vehicle mass supported by front axle 2 wheels kg MR 700 Vehicle mass supported by rear axle 2 wheels kg MUS 1 100 Front axle unsprung mass 2 wheels kg MUS 2 80 Rear axle unsprung mass 2 wheels kg RDAMP 1 1 Front ratio of damper stroke to suspension movement RDAMP 2 1 Rear ratio of damper stroke to suspension movement RSPRNG 1 1 Front ratio of spring compression to suspension movement RSPRNG 2 1 Rear ratio of spring compression to suspension movement RTIME 0 CALC Computational efficiency sec sim sec SPEED 72 Vehicle forward speed km h Road profile Z coord vs X coord ROAD_PROFILE_TABLE 0 0 1 5 0 2 99 0 002 259 4 0 043 ENDTABLE FINAL CONDITIONS XO 260 0313110352 Abs X trans of SO m ZO 0 003454771125689 Abs Z trans of SO m PITCH 0 024403592571
354. r Times font because it is more compact and easy to read Bold is usually used for things that you the user might click on buttons menus menu items etc It is used for text that is shown in bold on the screen such as titles of data sets It is also used for section names e g Section Animator Shapes Underline is used to indicate text that you the user might type For example In the speed field type 100 Italics are used to indicate variable names and place holders E g id LPO represents a file name where id is some value If id were 171 then the file name would be 171 LPO Pathnames Pathnames are specified folder is C CarSim Runs Runs tbk Terminology relative to the CarSiml Ed The folder C R Ed folder For example suppose the root uns Runs tbk would be named as Specialized terms are defined in the first two appendices Appendix A is a glossary of words used throughout this manual in a manner that is specific to CarSimEd e g keyword run library The glossary also defines file types and names of software packages that might otherwise be unfamiliar e g CMEX ToolBook SIMULINK Appendix B defines specialized terms applicable to vehicle dynamics It also defines the coordinate systems axes and sign conventions used in the CarSimEd models 16 2 CarSimEd Installation This chapter describes how CarSimEd is installed on your computer It also describes how Car
355. r look point The keyboard command is Shift Y Z Coordinate Plus Select this command to increase the Z coordinate of the camera or look point The keyboard command is the z key Z Coordinate Minus Select this command to decrease the Z coordinate of the camera or look point The keyboard command is Shift Z Camera Coordinates Select this command to cause the camera position to be controlled by the first six menu items The keyboard command is the Shift C key Look Point Coordinates Select this command to cause the look point position to be controlled by the first six menu items The keyboard command is the Shift L key Increase Focal Length Select this command to increase the camera focal length This is the same as zooming in The keyboard command is the f key Decrease Focal Length Select this command to decrease the camera focal length This is the same as zooming out The keyboard command is Shift F Chapter 6 The Animator Options Menu This menu has commands for setting several options in the animator operation Options v GridOn Modify Grid Set Frame Rate Ctrl F Superimpose Vehicle Modify Camera Locations Grid On The grid can be set to be displayed on or not displayed off Select this command to toggle the grid display Modify Grid Select this command to display a dialog box for setting properties of the grid Move X Close Alt F4 Grid Settings Re
356. r types of labels controlled with items 23 26 are shown in Figure 7 4 Plot title font attributes Click the selector button Bal to bring up a Windows font selection dialog box as shown in Figure 7 5 The properties selected in the box will be applied to the plot title After choosing the font properties click the OK button to make the change or click the Cancel button to keep the original properties Chapter 7 The Plotter Font 21x Font Font style Size Regular fn Italic Cancel Arial Rounded MT Bol T Augsburger Initials Bold F Baskerville Old Face Bold Italic Bauhaus 93 H Beesknees ITC T Bemard MT Condense Effects Sample I Strikeout T Underline aabo Color MM Black Script Figure 7 5 Font dialog box Axes labels This is similar to the plot title button 3 except that the settings made using the Windows font dialog box see Figure 7 5 are applied to the text used to label the X and Y axes 25 Tick labels This is similar to the plot title button 63 except that the settings made using the Windows font dialog box see Figure 7 5 are applied to the text associated with the tick marks Legend labels This is similar to the plot title button 3 except that the settings made using the Windows font dialog box see Figure 7 5 are applied to the text used to label the individual data sets in the legend 7 Apply to all check box When this is checked chan
357. r3 Database Organization You normally start CarSimEd at the Startup screen Clicking the Start button on that screen takes you to the Runs screen The Runs screen is the window to a library of many run descriptions each with links to vehicles inputs and various settings The Runs screen also has three buttons for e running new simulations e using the plotter to view simulation results and e using the animator to view simulated motions Figure 3 4 shows a partial map of the various libraries screens For example from the Startup screen you can go down to a Runs screen From there you select the various inputs braking steering etc the vehicle and the parameters that control the numerical solution methods used to make a simulation After the simulation is run you specify the plot and animation setup to view results 7 Post processing programs Start screen __Animator Runs screen a Plotter Simulation setup pepee Solver programs Figure 3 3 Role of Runs screen in CarSimEd In the map data sets from different libraries are connected with links For example here is a link between the Runs library and a vehicle library 25 Chapter3 Database Organization Type of vehicle to be simulated Vehicle independent 4ND Full Time x Name of specific vehicle data set In general libraries shown near the top of the map are more systems oriented and librarie
358. rSimEd change the screen display to view a different data set The new data set could be from the same library or a different one A Go button is in the ribbon bar of every data screen and is used to transfer to different libraries The triangle button next to the data set title is used to transfer to different data sets within the same library Keyword a word comprised of letters and other characters that is recognized by a computer program In CarSimEd all vehicle parameters are identified in input files with keywords Keywords in CarSimEd are not case dependent speed SPEED and SpeED all appear the same to the solver programs Keywords cannot include spaces Library a file containing one or more data sets of the same type plus a standard graphic interface for viewing these data sets All CarSimEd library files have the extension TBK Link a connection from one data set to another indicated with a blue field and an adjacent triangle button For example here is a link to a vehicle data set Link label Type Triangle button Vehicle independent carina Sd Data set name The adjacent button has a pull down menu that can be used to rapidly change the link to a different data set or library The menu can also be used to follow the link and go to the data set MATLAB a mathematical computation and visualization package available from The MathWorks Inc An add on module called SIMULINK ca
359. rSimEd involves this sequence 1 Select a vehicle to run As needed modify its properties dimensions mass etc components brake system steering system shock absorbers springs etc and possibly the properties of its components If you use only existing data sets you can assemble the vehicle with pull down menus alone 2 Specify the control inputs for steering braking and throttle Again this can be done with pull down menus if you are using existing data sets 3 Run the simulation with a single button click As the run proceeds CarSimEd writes force and motion variables into an output file for later analysis 4 Click a button to view an animation of the simulated test to get an overall view of the vehicle behavior 5 Click another button to view plots and analyze the resultant behavior in more detail With practice you will be able to quickly see how component and vehicle design changes affect critical aspects of behavior such as braking performance understeer and transient response CarSimEd Model Features This section provides a short summary of the features of CarSimEd that pertain to vehicle dynamics and its mathematical models Models CarSimEd has several separate simulation programs Each solves equations of motion numerically for a mathematical model designed to predict an aspect of vehicle behavior The models are 1 A comprehensive 3D handling model that computes response time histories for st
360. red to be adequate for most conditions 2 Camber thrust coefficient keyword KFYCAM IAXLE This coefficient defines the relationship between wheel inclination and side force The sensitivity to inclination is an order of magnitude less than the sensitivity to slip steer Even though the coefficient is known to be sensitive to load a constant value is used in the CarSimEd model due to its relatively small overall contribution to the tire force With the ISO coordinate system used in CarSimEd shown in the screen figure positive inclination leaning to the right causes negative lateral force the force also goes to the right Therefore this coefficient should be negative Note With the SAE coordinate system this coefficient would be positive Therefore check the sign if you are obtaining data from a source where the SAE convention was used 210 Chapter 9 Alphabetical Library Reference Link to cornering stiffness data The linked data set specifies cornering stiffness as a function of load Link to cornering pneumatic trail data The linked data set specifies pneumatic trail as a function of load Undeformed rolling radius keyword HWC IAXLE ISIDE This is the distance the tire rolls at zero load divided by 27 It is approximately the height of the wheel center when the tire is unloaded lightly resting against the ground fully inflated It is used in the simulation model to relate rim speed of
361. rence Notes To see the details of how the inputs from the screen are passed to the solver program view ParsTree use the Tools menu item View ParsTree or click the button This link is visible only when the Show More box 15 is checked User Settings and Controls Simple Display Link to vehicle data set from the library Vehicles Car The type of vehicle is shown as a sub title above the blue field In the figure the type is car Note In CarSimEd there is just one kind of 3D car model However in the commercial version there are several kinds of vehicles and the type is shown here Links to screens for inputs and disturbances The main inputs used in CarSimEd are braking steering and throttle Run Simulation button This is the main button in CarSimEd Click to run the appropriate vehicle solver program using the current model parameters and inputs Speed keyword SPEED The vehicle model applies a closed loop speed controller to maintain this speed until the brakes are applied Alternatively one of the input fields 2 can be linked to a data set defining a throttle input in which cas the speed is used only to set the initial condition for the simulated test Simulation stop time keyword STOPT The simulation normally runs until this time is reached However the 3D handling model will stop earlier under some other conditions e The vehicle roll angle exceeds a specified limit that implies
362. requencies High Pass Filter 4 high pass moving average filter works by applying a low pass smoothing filter and then subtracting the smoothed points from After High pass Filter the original leaving deviations from the smoothed data This removes low frequecies zj After Low pass Filter Cancel button Click to exit the dialog box without changing the data in the active plot OK button Click to exit the dialog box and apply the specified filter to all Y variables in the active plot Statistics Select this command to display a dialog box with simple statistics for the plotted variables The numbered items in the dialog box are described below X Y data set name Use the pull down menu to pick the data set in the active plot whose statistics will be displayed Statistics for specified data set The field is sized to display the statistics for the two variables making up a single X Y data set If you choose to show the statistics for all data sets in the plot then the scroll bar can be used to view the statistics for the data sets after the first 100 Chapter 7 The Plotter Statistics Y Data Set LF tire ave deviation 6 122450e 001 std deviation 7 144345e 001 ave deviation 2 518160e 003 std deviation 2 8051 40e 003 3 OK button Click to exit the dialog box Show All button Click to display the statistics of all data sets in the active plot Labels Use this comma
363. res develop shear forces in response to deformation of the tire structure The forces do not develop instantaneously but build as the tire rolls 1 For example Figure H 2 shows how Fy builds in response to a step change in slip angle 310 Appendix H The Tire Model Q p x F Y y5 p x 3L Figure H 2 Tire relaxation Two methods are commonly used for including the tire lag in a vehicle model 1 use a tire model with the dynamics built in or 2 use a static steady state tire model with a separate filter to account for the lag The second approach is used in CarSimEd because it offers two practical advantages First it allows the use of any static tire model from the literature independently of the method used to introduce lag Second it simplifies the calculation of the kinematical variables used as inputs to the tire model Lag is introduced into the slip angle such that the instantaneous response calculated for the lagged slip angle yields the lagged side force and aligning moment A method described by Bernard 2 is used to account for the lag in tire response In this method a lagged slip angle is defined as the arc tangent of an auxiliary state variable T aL tan t 12 A state variable is added for each wheel and defined with a first order differential equation dt __ Vxl Vy c dt LpreLax Vxl _ W lyx LRELAX 13 The absolute value of Vx is used to maintain continuity in case the vehicl
364. rol key to move 30 points forward based on the order the X values are stored in the file When the cursor is on the last point in the file this command has no effect Backward by 1 use the left arrow key to move one point backward based on the order the X values are stored in the file When the cursor is on the first point in the file this command has no effect Backward by 10 use the left arrow key plus the Shift key to move 10 points backward based on the order the X values are stored in the file When the cursor is on the first point in the file this command has no effect Backward by 30 use the left arrow key lt plus the Shift key plus the Control key to move 30 points backward based on the order the X values are stored in the file When the cursor is on the first point in the file this command has no effect Min Y Point use the down arrow key J to locate the point with the minimum Y value for the points currently displayed Max Y Point use the up arrow key 7 to locate the point with the maximum Y value for the points currently displayed Start of Data use the Home key to find the first point This is the same as pressing the left arrow repeatedly End of Data use the End key to find the last point This is the same as pressing the right arrow repeatedly Next Data Set use the Tab key to move the cursor between currently displayed data sets in overlay plots If
365. rted to a translational spring rate by the simulation solver program Summary of Major Model Variables The CarSimEd models are documented in README text files in the folder with the CarSimEd DLL MATLAB PIF and SIMULINK model The folders are contained in the CarSimEd Mat lab folder Input and output variables from the README file are listed in Appendix J Other information is listed below The details are presented for the CMEX version of the all independent vehicle model The only differences between the CMEX and stand alone models are that the CMEX versions include additional inputs that can be defined in the SIMULINK work space Multibody Model Descriptions CarSimEd 3D vehicle is represented mathematically by 33 ordinary differential equations that describe its kinematical and dynamical behavior It is composed of 9 bodies has 10 multibody degrees of freedom 10 multibody coordinates 9 auxiliary coordinates 10 multibody speeds 4 auxiliary speeds and has 22 active forces and 4 active moments 9 Bodies Entire vehicle S parent N trans coords Q 1 Q 2 Q 3 rot coords Q 4 Q 5 Q 6 LF wheel WLF parent S trans coord Q 7 LR wheel WLR parent S trans coord Q 8 RF wheel WRF parent S trans coord Q 9 RR wheel WRR parent S trans coord Q 10 WLEN parent S WREN parent S 302 Appendix G The 3D Car Model WLRN parent S WRRN parent S Multibody Coordinates XO Abs X trans
366. rts In contrast the earlier custom programs were more systems oriented involving generalized movements of wheels relative to the body or even more simply movements of the body relative to the ground The advantage of the detailed multibody programs for development engineers is that they can fine tune designs by modifying component level details However the detailed models also have some disadvantages Engineers who do 296 Appendix G The 3D Car Model not work for car manufacturers may not have access to the geometric design data Even when the full set of input parameters is assembled the programs run slower than custom programs that are less complex With some multibody programs the run time performance is much slower even for comparable models For models with a complexity similar to the one presented in this appendix a numerical multibody programs might be a couple orders of magnitude slower than a hand written program specialized for a specific vehicle dynamics model The creation of CarSimEd was motivated in part by the thought that something has been lost during the evolution from the older models to the newer The insight and expertise that underlay the old hand written models are often lacking in modern multibody models Although the modern models are often highly detailed their accuracy in predicting vehicle response to steering and braking inputs is sometimes not as good as that obtained 40 years ago This appendix is
367. rts it looks for Simfile If the file is not found the program will prompt you for an input file name If Simfile is found the program obtains all necessary input and output file names from it An example Simfile is shown below 283 Appendix F Model Files and Keywords Listing F 1 Example Simfile SIMF IL INPUT C CARSIMED 45 RUNS 575 PA ECHO C CARSIMED 45 RUNS 575 LPO FINAL C CARSIMED 45 RUNS 575 LPF ERDFILE C CARSIMED 45 RUNS 575 ERD LOGFILE C CARSIMED 45 RUNS 575 LOG END Although it is a convention in CarSimEd to use the same root name for all files the individual solver programs are capable of creating any names allowable under the file operating system Notice that the names in Simfile are full pathnames The individual files can be located anywhere on the computer or a network where volumes are accessed using the DOS convention Whenever you click the Run button a new Simfile is created in the same folder as the solver program by convention this is the folder Programs If a file with the name simfile already exists it is overwritten PAR Files The PAR file is read by the solver program and provides values of model parameters for the forthcoming run Listing F 2 Example PAR file PARSFILE parsfile C CARSIM parsfile C CARSIM parsfile C CARSIM parsfile C CARSIM parsfile C CARSIM stopt 2 speed 80 iw 45 VEHICLES VEHICLES 58 par 45 INPU
368. running you will be given a warning and the option to Quit the second instance We recommend you use this option e CarSimEd includes a Find option in ToolBook It can lead to internal ToolBook conflicts and should not be used casually Recovery From a Crash If ToolBook crashes it usually disables the part of Windows that supports 16 bit code requiring that Windows be restarted Usually this is all that is needed Sometimes however when you restart CarSimEd you will get a message that the file Startup tbk has been corrupted CarSimEd includes a backup copy of the Startup tbk file named Startup_ tbk If the main one gets corrupted the simplest fix is to do the following 1 delete the old corrupt file 2 duplicate Startup_ tbk and 3 rename the copy as Startup tbk If you made new data sets in your Startup library you can import the data sets The fix is 1 duplicate Startup_ tbk 2 open the duplicate file in ToolBook double click its icon 3 import the new data sets from the old corrupt Startup tbk file 4 exit ToolBook 5 delete the old corrupt file and 6 rename the copy as Startup tbk If you lose the backup in the CarSimEd folder you can copy the Startup tbk file from the CarSimEd CD Windows will give the Read Only file permission because it comes from a CD You should change this to Read Write permission before trying to use CarSimEd 238 Chapter11 Trouble Shooting Sol
369. s grid set_interval_y lines set_color color 9 choices color used for the grid lines black white red blue green magenta yellow dark gray light gray set_min_x numbers size of the grid in the X and Y set_max_x directions if the min and max are set_min_y set equal the grid is sized set_max_y automatically in that direction z_ground_carpet first line number of columns 3D ground information as used by endtable next lines ground data vehicle models Listing E 3 PARSFILE with grid information parsfile parsfile generated 10 13 99 12 04 09 add_grid set_interval_x 5 000000 set_interval_y 5 000000 set_color light gray set_min_x 5 000000 set_max_x 135 000000 set_min_y 5 000000 set_max_y 5 000000 z_ground_carpet 3 0 0 0 Sy 10 15 20 25 endtable The 3D ground information is read from the same file used by the vehicle simulation programs It is described in the Chapter 9 section Input 3D Ground Surface Elevation The 3D ground is defined over the range of all possible X and Y values it is not limited to the range covered in the table The table lookup function used in the vehicle programs 281 Appendix E Animator Files and Keywords is also used in the animator to generate coordinates at the intersection of the X and Y grid lines The grid spacing is not always compatible with the 3D ground data If the z_ground_carpet table has closely spaced features they will n
370. s Generate a Circle A circle can be approximated by a series of X Y coordinate pairs where X R cos A Y R sin A R is the radius of the circle and A is an angle To generate a set of values that define a circle with a radius of 152 4 m 500 ft and goes through the point X 0 Y 0 and makes two passes do the following see Figure 9 3 Select the Create radio button 20 Set Start X C to 90 the starting angle will be 90 Set End X 23 to 630 the ending angle will be 630 and therefore the difference will be 720 two times around the circle Set Step DX to 2 this will create a table with 361 points with X Y coordinates for every 2 of arc Define the two variables in the formulas field 13 152 4 cos x 57 29578 152 4 1 sin x 57 29578 Note the x in the above formulas is the independent variable used to create the series It is not the X coordinate of the points on the circle Set the format string 10 to 0 Click the Calculate button 19 Check your work by clicking the Plot button 18 Note When making a series for the first time it is quicker to use fewer points For example instead of specifying an increment of 2 for DX 3 you might try a value of 20 to cut the computation time by 90 Rescale the Circle Suppose you want to increase the radius of the circle by 20 Select the Transform radio button 21 Define the transformation in the formulas field 13 Xl a2e VAT 2
371. s calculated 320 Appendix I The CarSimEd Steer Controller to optimize the vehicle response over the preview time T As shown in the figure the driver model requires only seven variables as feedback They are the X and Y coordinates of the front axle of the vehicle Xy and Yy the vehicle based longitudinal and lateral components of the velocity vector Vx and Vy the yaw angle and yaw rate y and y and the steer control due to factors outside the driver s direct control Ug The term uo usually represents steering due to suspension kinematics and compliance The driver control algorithm can be divided into three types of calculations 1 it synthesizes the target path over the preview time 2 it calculates the optimal steer u to minimize deviations of the path of a point the center of the front axle from a target path and subtracts ug to obtain the steering needed by the driver uc and 3 it delays the driver steering control u by a constant time Tg to simulate a well known dynamic characteristic of human drivers Station The target path is normally provided as a sequence of Npts X and Y coordinates Station also called station number is the distance along a reference line typically a road centerline In a road design station is a spatial independent variable For any given value of station there is a unique set of X Y and Z coordinates There may also be other values associated with that position such a
372. s can be changed and 2 a new run can be made The solver program will always get its inputs using the current data from this screen Computer Simulation put Math Model Output 4 Runs 3D Handling File Edit Text Pf ID 629 Data set Chnged O Hotes 2 05 12 O Lofked 12 27 99 Model Parameters amp Inputs Run Control Output amp Post Processing Vehicle Classic car fan Ce C Run Simulation CD Animae Input Steer oF Speed km h Poet sec Mu Camera Setup o g 075 _ 75 Seevew rameters Input Braking 2 computation CECT o Ca Input 2 7 mee x View Echo File All Parameters Fz vertical forces uX ox Show More SS Saas Figure 9 9 The Runs screen simple view 189 Chapter 9 Alphabetical Library Reference Note The Runs Screen has several possible appearances depending on whether various check boxes are checked Figure 9 9 shows the simplest display The most complex is shown later after the basic controls have been described On the other hand settings in the right most region have no use until after a run is made The linked data sets control the appearances of plots and animations Changes in data in this region do not affect a simulation They only affect how the simulation results are viewed Priorities of Data Links The main purpose of this screen is to set up conditions for a run It is pos
373. s data set used for the run If the output file format is set to Text then the viewers will not work Make the run using one of the other output file formats Binary or ERD Text Numerical Problems The animator performs 3D coordinate transformations using data from the shape files and from the simulation output file Occasionally it will try to divide by a zero or otherwise perform an illegal numerical operation Here are two possibilities e Was the simulated test stable It is possible for a solver program to write invalid numbers into the output file When either viewer reads those numbers it crashes To check for this see if the results from the run in question cause problems with both the animator and plotter If so the problem is really with the solver program and is probably due to bad model parameters or a time step that is too big e For the animator have you moved the camera point inside the vehicle Usually this is safe but it will occasionally create a singularity in the 3D transformations Divide By Zero and cause the animator to crash If this happens while changing the camera location interactively you can simply re start the animator If it crashes right away try choosing a different camera setup from the Runs screen 240 Appendix A Glossary This appendix contains a glossary of words that have specific interpretations in the context of CarSimEd Animator a program in CarSimEd that is used for
374. s generated Location in CarSimEd CarSimEd Startup Runs Vehicles Car Tires CarSimEd Tires Pneumatic Trail File Location Vehicles Tires Trail Trail tbk Vehicles Car This screen is used to define the dimensions mass properties and component properties links for the vehicle used in both the 2D Ride and 3D Braking and Steering simulations Discussion One of the useful features of CarSimEd is that you can develop a whole fleet of vehicles but have to define the characteristics of each particular component only once You can then use this particular component in any of your vehicles simply by linking to it with this screen Furthermore these same vehicles can be used in both the 2D Ride and 3D Braking and Steering simulations The 2D Ride solver program ignores the parameters associated with roll and yaw motion User Settings Height of the mass center of the entire vehicle above the ground keyword HCG Wheelbase keyword LWB Longitudinal distance from the center of the front axle to the center of the rear axle This value is also passed to the animator keyword x_length to re size the wire frame shape longitudinally if the wheelbase is changed 215 Chapter 9 Alphabetical Library Reference 4m Yehicles Car of x File Edit Text Page Tools Data set Generic v 4 Hew Delete cov Back eka Ka es 418 aw Oi aaae R 41822 Steering System
375. s shown near the bottom are more component oriented Map for the 3D Handling Model Figure 3 4 shows a more detailed map of the various libraries screens that pertain to the 3D handling model For example from the Startup screen you can go down to the Runs screen for the 3D handling model From there you select the various inputs brake steer etc the vehicle and the parameters that control the numerical solution methods used to make a simulation After the simulation is run you specify the plot and animation setup to view results Notes In order to create the detailed map at a reasonable size the names were shortened from the full screen titles Libraries used for more than one of the simulations are shown in italics CarSimEd Startup Runs 3D Runs 2D Runs Susp Brake Inputs Throttle Inputs Steer Inputs Cars Path Inputs Plot Setup Cameras Groups Suspensions di Formats Filters Ref Frames Shapes Ky Trail Ref Frames Wheels Figure 3 4 Partial map of the CarSimEd libraries 26 Chapter3 Database Organization Map for the 2D Ride Model Figure 3 5 shows a map of the libraries for the 2D ride model Notice that nearly all of the library names are in italics indicating that they are also used for 3D handling braking simulations The main difference is with the inputs the steer braking and throttle inputs for the 3D model are replaced with a road profile input Also some of the tire data required f
376. s superelevation road width etc A simplification is made in the driver model that the path is composed of straight lines connecting points defined as a sequence of X Y values The X Y values are specified at run time The starting value of S is set to match the initial X value 1 X 15 Subsequent values from i 2 to Npts are calculated with the recursive equation Si Si 1 Xi Xi 1 Yi Yiz 16 This calculation is done when the X and Y values are read as inputs After the calculation each point in the path is represented with three numbers S X Y instead of two X Y Because the path connecting two points is assumed to be a straight line the partial derivatives dX 0S and 0Y OS can be calculated with finite difference equations ox AX Xin 7 Xi l AS S S a AY Y Y Ht 17 dS AS S S The forward difference form of Equation 17 means that the it derivative applies for the line segment after the i point between points i and i 1 Table lookup routines are used to provide X Y dX 0S and dY 0S as functions of S at various places in the driver model For station numbers outside the range of the table the last values of 0X dS and dY OS should be held constant to extrapolate X and Y as needed 321 Appendix I The CarSimEd Steer Controller Because S is treated as the independent variable for determining the current path geometry it is essential to know the current value of
377. s usually deflect when a steering torque is applied to the wheel Because the steer and moment have the same sign convention the compliance coefficient is nearly always positive Steering as a result of aligning torque is due both to compliance in the suspension and to compliance in the steering column If equal and opposite steering torques are applied to both the left and right road wheels the resulting deflection is mainly due to the suspension alone The suspension compliance is subtracted from the total steering compliance that would be measured for one wheel to determine the compliance for the steering column specified in the Cars data screen Location in CarSimEd CarSimEd Startup Runs Vehicles Car Suspension Systems Car Suspension File Location Vehicles Susp_ed Susp_ed tbk Suspensions 5 Link Independent Use this screen to specify the geometry for a five link suspension Discussion CarSimEd includes a simulation program to compute changes in steer toe and camber as functions of vertical spindle position In addition the angles for all five links are computed as are the X and Y coordinates of the wheel center Example results for this model have been published with the intention of providing a benchmark for validating new simulation codes 207 Chapter 9 Alphabetical Library Reference M Hiller and S Frik Five Link Suspension from Multibody Computer Codes in Vehicle System Dynamics
378. s_cmex File Edit View Go Favorites Tools Help Address C Carsim 451 MATLABSIS_CMEX gt All Folders x Size Type Modified F a Carsim 451 aj a Indmdl mdl 6KB MDL File 12 9 99 12 23 PM H A Animate s is_cmx dll 320K6 Application 12 7 99 3 36 PM Batch at Matlab 1KB Shorteutto 12 9 99 12 23 PM E Comp_par Readem 38KB Text Docum 11 24 99 2 29 PM Genetic a Simfile 1KB File 12 9 99 12 23 PM Input a Startup m 1KB M File 6 11 99 10 21 AM 3 Matlab s Sx32w dll 36KB Application 7 25 97 4 00 PM B 4ws 5 Abs 3 Is_omex E Sa_cmex H Plot E Programs E Runs E Runs_cmx Squi_lib cia Ga Caiana Each of these folders contains one file that you might have to modify Matlab pif The Program Information File PIF acts as a pointer shortcut to the MATLAB program When MATLAB is started by opening the PIF the default directory is the directory containing the PIF rather than the normal MATLAB default Depending on 18 Chapter 2 CarSimEd Installation your Windows settings the PIF might be displayed without the PIF extension see the next figure Note The PIF was introduced in Windows 3 1 to support DOS programs running in the Windows environment It is supported in Windows 3 1 9x and NT and is also supported by the ToolBook software used to manage the CarSimEd database When the MATLAB folder in CarSimEd is installe
379. same plot they can be distinguished by assigning them different display attributes X Y Data set Press the button to display a pull down menu with the list of Y variables for each data set Select the data set to display and optionally edit its attributes Symbol This field shows the symbol currently associated with the data set aD Press the button to display a pull down menu of available symbols Choose one to change the current symbol 92 Chapter 7 The Plotter 13 Line type This field shows the type of line currently associated with the data set aD Press the button to display a pull down menu of supported types and choose one to change the way connecting lines are drawn between the data points Color This field shows the color currently associated with the data set aD in terms of RGB values 24 bit color composed of components of Red Green and Blue Press the button H to display a palette of colors Then pick a color to change the display color of the line and or symbols Color 21x Basic colors Define Custom Colors gt gt Cancel After selecting a color click the OK button to return to the format dialog box The RGB values for the selected color will be shown Customize Plot Format x Axes XY DataSet Plot Layout Font Layouts Axes 16 Grid is Frame 20 Axes Course Grid Frame Max digit for Y axis Legend location 19 fe G a Right OF Plot 05 Legend will oc
380. scope of a reference frame if its coordinates are defined by the animator as being fixed in that reference frame Overall the animation input data should be organized as follows parsfile lt information about grid camera and target path gt lt information associated with fixed frame gt add_reference_frame name lt information about first moving reference frame gt add_reference_frame name2 lt information about second moving reference frame gt lt more reference frame and associated information as needed gt end Making an Example PARSFILE The animator has the capability of writing a single PARSFILE with all of the current settings reference frames and shapes This is helpful for debugging and documenting an animator setup To make a file go to the File menu and select the item Save Parsfile As This brings up a dialog box with check boxes associated with different kinds of information Check all of the boxes and save the file Write Echo Parsfile x Save to file c vehsim 1 animateecho par ea Gane File Options V Include Shape and Frame Definitions I Include Grid Definitions I Include Path Definitions I Include Camera Definitions I Include Lookpoint Definitions 273 Appendix E Animator Files and Keywords Units Coordinates and Sign Conventions The animator uses the sign conventions and Euler angle definitions described in Appendix B X is forward Z is up Y
381. seeabaaees 256 Appendix C ERD File POmmMal seid ssnstinesssiaccsosatevatusdsese nosiveanundoctmoigesniavelsupeivettse 258 The Header vs iii tev carts Mare ee en ee ae REE aS 258 Phe Data Section s tieccecfsithcotskiepededahetedeshibe reed a apea eare t atea ai Ghote 262 Appendix D Plotter Files and Keywords ssssesssessessseeesscseesseeeesseeeseees 264 PET B teh Control Piles is svsisisissdeistosetesdacts wtoasesiningdst arre a oaee e ia ne ot 264 Plot Setting EUe S ses eveccs ect sotes ra a A EE E EEEE E LERE E EE a 265 Plot Transform Priles scc c ccccesvecoct nes abereei neeite eSEE EEA eria ena RS 266 Plot Pormat Files herre eean eeaeee A aed hans Ob en EEEE arene eee 266 Preference File F rmate eeii nren seeepunesy iaeiei iiien roi inn ieii iae a ii 269 Text Filesi ees eeh aeai a eae a a eaa aeaaea ae e taea Dank ten Gatien ee iaa banta 269 vi Appendix E Animator Files and Keywords s cccscssssccessescsseseesceceseeeceeeaeeeceeeseeeeeeeees 271 Overview of a PARSFILE isendi sn eoii dard a oina E aTi r oina Sina 271 Units Coordinates and Sign ConventionSs ssssseeesssssssserresesssssstrrressssssereresssssseseeee 274 Camera Settings sisin anie e ESEE AA EA EE R e R Mae detweate 274 Reference Prames ties sletvenuteohisivetectonedeuht ln e iaaea eeit e taata reede aaia e eaaa e ie taii 275 Parts Sh pes nre n a r A E E Ee EA O EAR a ea an 277 WHEE EA A E E E E E 279 Grid ajd 3D Ground Surfact
382. ser settings that are common for all tabular data screens are described in Chapter 8 in the section Tabular Data 169 Chapter 9 Alphabetical Library Reference C Two column table of values for X and Y coordinates of the target path keyword YIN_TABLE Each line should have a value of X followed by a corresponding value of Y with a separating comma The coordinates are based on an inertial reference As noted above this table is unusual in CarSim because it does not require rows to have an ascending order in X This is possible because the table is used internally to generate two other tables X vs S and Y vs S where S is computed to ascend Instead the X and Y values are used to derive a third variable called station number S The effect is fairly simple The path is defined by connecting the X and Y coordinates listed in this table with straight lines linear interpolation For negative values of S the first point is used to extrapolate the first gradient backward The gradient is determined from the first two values of X and Y For values of S larger than the range covered the last point is used to extrapolate forward using the gradient between the last two X and Y Animator path color keyword set_path_color Use this field to specify the color of the path as drawn by the animator Maximum SW angle keyword ASW_MAX This specifies the maximum steering wheel angle that is allowed for the driv
383. sible to have conflicting information For example you might specify a speed in the yellow field 4 and also specify a throttle with one of the input links Oy Which takes priority The solver programs in CarSimEd handle inputs very simply each line of input updates the simulation description When there are conflicting inputs the last input read is the one used Therefore the priorities for the inputs specified in the Runs screen are determined completely by the order in which they are sent to the solver programs The first ones have the lowest priority the last ones have the highest priority Here is the order in which the data from fields and links in the screen are sent to the solver programs See Figure 9 10 for the detailed view with all the links 1 The Based On link is first and therefore has the lowest priority Note This link is visible only when the Show More box 15 is checked see Figure 9 10 1 The Vehicle link 1 2 The Input links on the left side of the screen 2 in a top down sequence Thus those at the top are first and have lower priority than those at the bottom 3 The Computation Parameters link 7 4 The Speed 4 and Stop fields 5 The Mise Data field 17 Note This link is visible only when the Show More box 15 is checked see Figure 9 10 1 The Overriding Data from Batch link is last and therefore has the highest priority 190 Chapter 9 Alphabetical Library Refe
384. sited in the library This is the way CarSimEd is set when initially installed If you would like the Start button to always take you to a specific data set link to it here You might change this link if you move the Runs library or if you create a new Runs library in a different folder What if you have several Runs libraries In that case you can make several data sets in the CarSimEd Startup library Click the New button to make a new data set Then in the new data set link to a different Runs library Done button Click to hide all the user settings and return to the simpler view with the CarSimEd logo Location in CarSimEd CarSimEd Startup 154 Chapter 9 Alphabetical Library Reference File Location Startup tbk Computation Parameters Use this screen to set parameters for the numerical integrator and to control the frequency and format of the simulation output file S Computation Parameters lolx File Edit Text Page Tools Data set Suspension model dt 0 01 Changed ID 51 Hotes 3 48 35 Main Integration Parameters Integration time step Too 1 ec Use for suspension simulations Output File Print intervat 1 2 Output 3 binary The sample interval in the output plot BINARY ERD file with BINARY data file This is the most efficient and files is the product of the integration should be used for most runs time step and the print interval TEXT spreadsheet text
385. slow motion If you change this value the animation time step 4 is automatically changed the frame rate is the reciprocal of the time step The default frame rate is specified under the Preferences option in the Edit menu see page 69 Animation time step If the animation is running too slowly you can specify a larger time step to speed it up Use a smaller time step to slow it down If you change this value the animation frame rate G is automatically changed the frame rate is the reciprocal of the time step Note If you specify a time step that is smaller than the value in the file O the value in the file is used To run with the minimum time step show every frame possible you can enter a value of O in 4 and the animator will replace it with the value from the ERD file Radio button for real time animation If the animation is running too quickly select this button to slow it down to real time When this button is selected the animator accesses the computer clock and waits if necessary to avoid running the animation faster than real time Notes The process of checking the computer clock introduces a small delay The delay depends on the computer and how your system is set up If the animation is already running slower than real time checking the computer clock will slow it down even more If the animation is running slower than real time and you want to speed it up you must decrease the frame rate G or increase t
386. speed rigibody name LF wheel OUT 80 Vx_LR kph LR wheel rolling speed gen name Effective rolling speed rigibody name LR wheel OUT 81 Vx_RF kph RF wheel rolling speed gen name Effective rolling speed rigibody name RF wheel 333 Appendix J Model Input and Output Variables OUT 82 Vx_RR kph RR wheel rolling speed gen name Effective rolling speed rigibody name RR wheel OUT 83 Vy kph Vehicle lateral velocity gen name Lateral velocity rigibody name Vehicle CG OUT 84 Vz kph Vehicle vertical velocity gen name Vertical velocity rigibody name Vehicle CG OUT 85 Xo m X position of car origin gen name X position rigibody name Car body OUT 86 X_CG m X position of vehicle CG gen name X position rigibody name Vehicle CG OUT 87 X_WLFE m X coordinate of LF wheel center gen name X coordinate of wheel center rigibody name LF wheel OUT 88 X_WLR m X coordinate of LR wheel center gen name X coordinate of wheel center rigibody name LR wheel OUT 89 X_WRF m X coordinate of RF wheel center gen name X coordinate of wheel center rigibody name RF wheel OUT 90 X_WRR m X coordinate of RR wheel center gen name X coordinate of wheel center rigibody name RR wheel OUT 91 Yaw deg Vehicle yaw gen name Yaw rigibody name Vehicle OUT 92 Yaw_WLF deg Yaw angle of LF wheel gen name Yaw ang
387. ssion erin dite i eas iare dod ee need ovine 280 Target Path pisent eier iire ieee aeee AEE eE NASEER EEE EE E eee aap RE EE 282 Appendix F Model Files and Keywotds cccsssssssssssssecesseecsesseasseeesseseeasseeesseeeeaeees 283 Pale PY Pes renra eve dashes cove de ve deecheb ede ive ieseuss steele ys tessa EEEE E ble releases bas 283 VIE WINS KEY WOLdS ssh ter cccastericcobsvacn Neue cesnas bueosnadenincehipecaMeyehcelsdlivecteadrecolelapetendautivensaste 287 Keywords and Parameters for the 3D Car Model 0 0 0 0 eeeeeeeeeeeecececececeeeceeeeeeeereeenenes 288 Keywords and Parameters for the 2D Car Model eeeeeeeeececeeecececececececeeeeeeeereneees 292 Keywords and Parameters for the 3D Suspension cccecececececeeneeeeeececeeeaeaaeeeeenceeees 294 Appendix G The 3D Car Model vasisscinves seusiatssetessntsronautastonapsicersuetivorsd snuisetanbases ans 296 INtHOdUCHION eeina a aan Sees d aea Ea aE a a RE e E EES dete te eaii 296 Overview of Factors Affecting Vehicle Behavior eeeseeeeeeeeeserersrsrsrsrsrsrsrsrsrererersrerere 297 Rigid Body Kinematics desiere ech od ces ees e ead Bd ete wea 298 Masses and inertas aono eniai ii ia en aa e iieis 300 Suspension Force EffECtS s c coisisieiopdastetersliievs anoi ae eide eaaa adan idat decals be 300 Summary of Major Model Variables eee eececececececececececececececeeeeeceeeeeeeeeeeeeeess 302 RETETENCES eneur Custis o ai ea Ee whl Saatana a
388. ssociated with the keyword written into the text PAR file are on and off Coordinates of center keywords set_offset_x set_offset_y set_offset_z These are the X Y and Z coordinates of the wheel center in the reference frame with which the wheel is associated Default values of 0 0 are used if no values are provided Scale factors in three directions keywords set_scale_x set_scale_y set_scale_z These are dimensionless scale factors in the X Y and Z directions They are multiplied by the coordinates of the wheel centered at 0 0 0 before the offsets 6 are added The Y scale factor adjusts the thickness and the other two can be used to resize the wheel If the X and Z scale factors are not equal the wheel will be elliptical rather than circular Default values of 1 0 are used if no values are provided Location in CarSimEd CarSimEd Startup Runs Suspension Analysis Suspensions 5 Link Independent Animator Groups Animator Wheels File Location Animate Wheels Wheels tbk Calculator Use this screen to create and edit tabular numerical data It is available from a button on the ribbon bar i and from the Tools menu Discussion This data screen is a tool supplied in CarSimEd because there are many times that simple calculations are needed when preparing numbers for CarSimEd data sets This screen can be used to convert units for existing data or to create tables from scratch For example explained in detail late
389. suspension the trajectory is usually not purely vertical For most vehicles the wheels move out laterally as the suspensions are compressed such that track width increases with suspension compression The wheels also move out longitudinally such that the wheelbase increases with suspension compression The direction of the wheel trajectory relative to the main body determines how tire shear forces in the ground plane are transmitted to the vehicle body through reaction forces in the suspension linkages In hand written equations roll and pitch moments due to suspension reaction forces have been written with coefficients with names such as anti roll anti pitch anti dive anti squat and jacking 10 298 Appendix G The 3D Car Model Wore Z Direction of suspension travel A 1 4 Lwb Lik sa nO i p Hyer Lp x Here T Y 4 A Side view Front view Figure G 2 Locations and movements of wheels The multibody model accounts for the interaction between tire shear forces and roll and pitch moments so long as the movement is constrained to follow the proper path A simple approximation is to assume the movement is in a straight line as shown in Figure G 2 Using an axis system based in the vehicle sprung mass x Sy Sz the directions of the movements of the four wheels are 2H left front dir sz sae sy Rp f Sx 2H right front dir sz a Sy Rp f Sx left rear d sy R eft rear dir
390. sz TE Sy Rp r Sx 2H right rear dir sz Po Sy Rp r Sx 1 where dir is a function that returns the direction of a vector and the secondary subscripts f and r indicate parameters for the front and rear In the traditional suspension analyses the roll kinematics are often analyzed to define a point called a roll center 10 The independent suspension model in CarSimEd does not use the roll center concept However for compatibility with this convention the 299 Appendix G The 3D Car Model inclination of the wheel movement in the roll direction is defined by the ratio of a roll center height to the half track distance Note The existence of a roll center parameter should not be interpreted to mean the CarSimEd model has a roll center As with real vehicles the actual roll center moves in the CarSimEd model once it is out of the equilibrium condition Given that the roll center is not used in the model and that it does not correspond to a physical part of a real vehicle a dynamic analysis to calculate a roll center was not included in the CarSimEd models A single coefficient Rp is used to define the longitudinal inclination of the wheel movement Masses and inertias The user of a vehicle model must provide mass and inertia parameters for the bodies in the model In CarSimEd the moments of inertia of the wheel bodies are defined as zero The mass centers are located at the wheel centers nominally a heigh
391. t Fixed camera category dt Changed ID 209 O Hotes 12 25 29 Locked 7 20 98 A reference frame is a moving set of points that maintain z their spatial relationship relative to each other at all times Z Origin of global Points in the frame are specified by coordinates that are reference frame local to the moving frame Origin of moving reference frame x Yy In the animator the reference frame is defined by the position and orientation of a right handed rectangular coordinate system The position is defined by up to 3 global coordinates X Y Z and 3 Euler rotation angles Yaw Pitch Roll Global Coordinates of Origin Yalues for the coordinates and angles are read from an Hame Offset Scale Factor ERD file The names are taken from the yellow fields on the ape aoe St eee ee E left Each coordinate and angle can be given a scale factor 5 fi G 2 G and offset The value used by the animator is Y coordinate V S V 5 Vo value SF where value is read from the ERD file and Z coordinate d d A anis are specified inthe yellow fields to the left Euler Angles for Frame Hame Offset Scale Factor If a name is not specified a value of 0 is used for value A value of 0 is also used if the specified name is not found in the ERD file X rotaton Y rotation Z rotation Rotation sequence 7 x In order to draw the wire frame shapes the animator must convert relative coordinates in a moving
392. t tabular data This is equivalent to the Tools menu Text Editor command This can also be set to go to a text editor such as the Windows Notepad program If it is not currently linked control click to get a file browser to locate an executable program file and establish a link to it The default link is Programs WinVI exe Library Editor button Click this button to bring up a floating window that can be used to edit libraries This is equivalent to the Tools menu Library Editor command The current library is automatically loaded into the editor window Spectrum Analyzer button Click this button to go to the Spectrum Setup library with settings for a spectrum analyzer This is equivalent to the Tools menu Spectrum command Control click to get a file browser to make a different library the default Note The spectrum analyzer and the settings screen are not present in the standard CarSimEd package 112 Chapter 8 Design of CarSimEd Data Screens Batch Plot button Click this button to go to the Plot Setup Batch library This is equivalent to the Tools menu Batch Plotting command Control click to get a file browser to make a different library the default The default link is Batch Plot_bat Plot_bat tbk Plot Setup button Click this button to go to the Plot Setup Single library with plot settings that define plot variables formats etc This is equivalent to the Tools menu Plot Setup command Control click to get a fil
393. t Hwe above the ground The mass of each wheel body should be set to that portion of vehicle mass supported by the tire that is considered to move with the wheel This value is commonly called the unsprung mass and usually includes some of the mass of the suspension elements The mass of the main body the sprung mass is set to the mass of the entire vehicle minus the unsprung masses The inertia properties are also required including the XZ product of inertia Due to lateral symmetry the XY and YZ products are defined as zero It is much easier to measure inertia properties for the entire vehicle than for the body alone The multibody program can be made to calculate the mass and inertia properties of the sprung mass from measurements made for the entire vehicle This is done by adding four more bodies and giving them negative masses These four bodies should be placed at the same locations as the wheel body mass centers However their masses are set to the negative values of the unsprung masses and they are fully constrained with respect to the main vehicle body i e zero DOF The multibody program in accounting for the full constraint of these four bodies will in effect subtract the masses and inertia properties bringing the mass and inertias of the main body down to those of the sprung mass alone Suspension Force Effects Movement of a wheel along the line of motion allowed by the suspension kinematics is affected by suspension spri
394. t for each item listed in the field Selected Plots 11 After viewing the plots exit the plotter 4m Plot Setup Batch Ioj x File Edit Text Page Tools O Hotes 12 25 35 Data Files Runs Library Setup Library runsiruns tbk v No library selected CE Runs lt 3D Surface Tests gt 2 z AAND FT 3D HAD FT Reverse mode 3D Brk in Turn 3D Circle V 0 to 200 3D Plot Setups DLC 3D Indy tr Circle 3D lt Braking Brk low mu gt O O Add Remove Add ERD File Selected Data Files OR Add 10 Selected Plots A a1 12 one Plot Per Data File 13 One Plot For All Data Files 14 Make Plots Figure 4 8 Setup for batch plotting Overlaying Plots for Multiple Runs The Runs screen has links to overlay data from three runs If you want to overlay data from more runs you can use the Plot Setup Batch screen shown in Figure 4 8 The method is nearly identical to the one just described for making five or more plots for a single run Two additional steps are e In step 4 put more than one run into the field Selected Data Files 6 49 Chapter 4 The Basics of Using CarSimEd e Be sure the One Plot for All Data Files button 13 is selected Making Many Plots in Batch Mode You can generate a standard set of plots for many runs Again you will use the Plot Setup Batch screen shown in Figure 4 8 The
395. t gray set_line_width integer sets thickness of lines drawn for this part set_coordinates list of coordinates 3 coordinates of the points making up the end_coordinates numbers per line shape set_scale_x numbers scale factors applied to all coordinates in set_scale_y the part set_scale_z set_offset_x numbers offsets added to all points in the part set_offset_y set_offset_z 278 Appendix E Animator Files and Keywords It is sometimes convenient to use the same part in more than one reference frame Therefore the name is not necessarily unique The part name is used only to make the PARSFILE more readable and possibly to provide more detailed error messages in future versions The color and line thickness default to values of black and 1 respectively Therefore the commands set line width and set_color are optional There is no default set of coordinates so the list must be provided The list of coordinates begins with a line containing the keyword set_coordinates Each following line should contain an X Y and Z coordinate separated by white space until the list ends with a line containing the keyword end_coordinates Within the block defined by the keywords set_coordinates and end_coordinates there must not be blank lines comments or other keywords The coordinates are assumed to apply to the current reference frame The listed coordinates for the part are transformed by the equations Xnew Xo Sx X
396. t lines 183 Chapter 9 Alphabetical Library Reference However if the plot will be printed in black and white distinctions between similar traces are hard to see This screen has fields for specifying constants that are subtracted from the X and Y variables for each data set in the plot For example the figure below shows how an offset of 5 is subtracted from four plots to separate them Alphas with Offsets DLC Slip angle deg a LF wheel LR wheel RF wheel 4 RR wheel 20 Time sec Filtering Filtering is normally used to view measured data It is not routinely applied to simulation results generated by CarSimEd models However it is useful if you have occasion to view experimental data with WinEP WinEP includes a simple algorithm called a moving average for filtering the data It s most basic form is for smoothing As input it takes the original values of the variable plotted on the Y axis Each output point is an average taken of all the adjacent points that are within a specified interval called a baselength For example if the baselength is 0 5 the output value at T 1 0 is the average of all values from T 0 75 to T 1 25 The output at T 1 01 is the average of all values from T 0 76 to T 1 26 This type of filter is called a Low Pass because is filters out high frequencies while allowing low frequencies to pass through unaffected If the intent is to look at the high frequencies and remov
397. t properties Discussion The WinEP program supports a number of options for controlling the format of the generated plots As was described in Chapter 7 dialog boxes are used for setting all options interactively and those options can be stored in text files for future use 4m Plot Format iof x File Edit Text Page Tools Data set Default settings w 41 I gt Hew Delete GO Back Changed D 31 O Hotes 7 51 17 Lines Axis and Grid Options Fonts Click on number to X and Y Axes 2 Change Fonts 7 access ine palette zl Hame Style Size Frame Title 1 Frame G vl Legend Arial Narrow 6 J Reguer 10 Grid Axes Labels i FineGra 4 J Tick Labels Arii Narrow Reguar 10 5 p Legend 8 A legend identifies individual data sets in a plot The labels in 9 the legend are based on names associated with 1 the ERD files and 2 the data sets pair of X and Y variables from each ERD file Identify Files With Location of Legend File Title Right of piot M Identify Data Sets With 9 RigidBody Name When the above identifier is hot unique for all data sets in a file the short name will be pee used instead Limit to legend length Maximum of window This data screen is also used to specify plotting formats Every user setting on this screen can also be set interactively from within WinEP However when set here the formatting information is stored in the C
398. t will be calculated when you click the Calculate button and the Transform button Qt is selected In this case the definitions must involve numbers and the variables X Y Y2 Y3 where X is the first number in each line of the tabular data field Y is the second number Y2 is the third and so on In the first case the field is cleared and all new numbers are put into it based on the series information CD 3 and 24 and the mathematical definitions In the second case the tabular data field is not cleared the existing numbers are processed and then replaced by the values calculated from the formulas In both cases the tabular data field will have the same number of items as the mathematical definitions field Initially items numerical results of the calculations are separated by commas Use the Delete button G to remove the commas if that is required In both cases the variable X can be included in the expressions The meaning is not always the same In the first case X is an arbitrary independent variable whose values are 146 Chapter 9 Alphabetical Library Reference defined by the range and interval specified in the fields C 63 and 24 In the second case X is the first number in the tabular data field G The variables Y Y2 etc are recognized only in the second case They should not be used when generating new numbers with the Create button is selected The variables and function names
399. ta from Batch is set to the batch data set That way you can go back to this data set batch run to see what parameters or links were applied when the run was made The echo files generated for each run show the model parameters that were used in the run regardless of whether they came from the normal Runs data set or from the batch override 5 Chapter 4 The Basics of Using CarSimEd Making New Plot Descriptions CarSimEd comes with about 30 plot descriptions It s easy to make more Start with any data screen in CarSimEd Go to the Plot Setup Single library whose screen is shown in Figure 4 10 Get there by clicking the E button 5 in the ribbon bar or select the Tools menu item Plot Setup 4m Plot Setup Single ioj x File Edit Text Page Tools CO Hotes 5 12 35 Category Vehicle motion O Locked 01 04 00 5 Data to Plot Y X Name for legend Y Axis Z Show Long Hames and Units X Axis Time sec AAy_LF LF wheel angular acceleration rev s AAy_LR LR wheel angular acceleration rev s AAy_R e F wheel angular acceleration rev s AAYy_RRX RR wheel angular acceleration revis Alpha_LF LF wheel slip angle without lag deg Alpha_LR LR wheel slip angle without lag deg Alpha_RF RF wheel slip angle without lag deg Alpha_RR RR wheel slip angle without lag deg s AVX Body roll rate deg s Axis Labels Body pitch rate deg s Y See LF LF wheel an
400. tains pathnames of other files that contain the data see Figure 5 4 Also the PAR file may not reference every parameter used by the solver program For example the initial conditions listed in the LPO file are normally not specified on input they are assigned default values by the solver program The LPF file is nearly identical to the LPO file except that instead of initial values it contains final values of the state variables By modifying the start and stop times an existing run can be continued restarted ERD and BIN Files The main purpose of each solver program is to calculate time histories of variables of interest Those time histories are stored in a binary data file with the extension BIN The BIN files contain numerical data organized by channel number and sample number 61 Chapter5 The Solver Programs similar to test data recorded on a multi track recorder A companion file with extension ERD describes the layout of the BIN file and also contains labeling information for each variable It also contains the information that would normally be put into a log sheet summarizing the data including text needed for preparing graphical plots of the data By itself a BIN file is useless It has no structure and cannot be understood without the layout information contained in the ERD header file By convention ERD and BIN file pairs are simply called ERD files The name ERD is used because the Engineering Research
401. that can be read by WinEP The first line should contain labels and following lines should have numbers The numbers should be separated by at list one white space and or commas 269 Appendix D Plotter Files and Keywords Listing D 5 Portion of a text file with data to plot Time AAy LF AAy LR AAy RF AAy RR 0 000000 000000 000000 0 000000 050000 041291 040227 041170 100000 096683 096122 096175 150000 098988 104285 098771 200000 073881 071838 073669 250000 050576 050680 049884 300000 032560 032437 031484 350000 019510 019438 018365 400000 010514 010540 009256 450000 004606 004626 003102 500000 000949 000990 000582 550000 001096 001043 002610 600000 002020 001971 003566 650000 002229 002178 003693 OOO OO OO 0 0 0 0 0 0 0 0 0 0 0 0 0 270 Appendix E Animator Files and Keywords The animator program reads two kinds of input files as indicated in Figure E 1 All of the settings specific to the animator are read from keyword based text files typically with the extension PAR These files follow the PARSFILE format used throughout CarSimEd A single top level PARSFILE contains the names of other PARSFILEs with camera information vehicle information reference frames etc PAR files ERD file Animator set up and shape Motion information from information from data b
402. the current window However the window doesn t show any more information Use this menu item to restore its appearance Tools Menu Use the Tools menu as an alternative to the buttons in the ribbon bar Calculator Text Editor Library Editor Plot Setup Runs View Parstree Batch Runs Batch Plotting Spectrum Preferences The ribbon bar shown below was described in more detail starting on page 110 125 Chapter amp Design of CarSimEd Data Screens 4m Runs 3D Handling of x File Edit Text Page Tools Data set Brakinginatun sd ina Brakinginatun sd es sl ee nee sorle Back Changed ID 625 CO Hotes 3 00 55 O Locked 7 998 Calculator Select this menu item to go to the calculator screen same as 10 Text Editor Select this menu item to go to a utility library used to create and edit text files same as 1 Library Editor Select this menu item to bring up a floating window used to edit existing libraries same as 12 Plot Setup Select this menu item to go to the Plot Setup Single library with plot settings that define plot variables formats etc same as 15 Runs Select this menu item to go to a Runs library with settings to make a single simulation run same as 7 View Parstree Select this menu item to run the Parstree program and view the tree of PAR files that starts from the current data set same as 18 Batch Runs Select this me
403. the exception would be if some of the inputs were taken from test results filtering is not commonly applied to CarSimEd simulation results 185 Chapter 9 Alphabetical Library Reference 4 Plot Transforms iol x File Edit Text Page Tools Data set Offsets and Filter a I gt Hew Delete Gor Back Changed ID 87 O Hotes 4 29 23 category des SS A GIG Lockea s893 The plotter has two options for transforming data filtering and offsets Data Offset Values Original Data Filtering i Three kinds of filters can be applied f a A A low pass filter smooths out plots Low Pass Fier smocthing removing the effects of high frequency noise and hash This is commonly applied to measured data High Pass Filter Drift Removal 4 high pass filter removes Filter Type smoothed data such as drifting LoPass ass fitter applies both a Low pass baselength 1 HiPass da high pass fiter High pass baselength 02 BandPass None The baselength of the fitter has the same units as the X variable of the data set being plotted e g sec m To create overaly plots similar to classic strip charts you can specify offsets for the Y axis that are different The fitters work by averaging the Y es ee ees ee a tee ea values over the specified baselength as described in the reference manual Although it is less common you can also specify offsets for the Y axis
404. the optimal control to obtain the steer needed by the driver uc The driver steer angle applied to the front wheels is divided by a steering gear ratio to obtain the corresponding angle at the steering wheel Transport Delay The steer angle from the driver Uc is given a pure transport delay to simulate the neuromuscular delay of a human driver Previous research has shown the transport delay 324 Appendix I The CarSimEd Steer Controller to be an important parameter in determining the dynamics of the closed loop man machine system 1 References 1 MacAdam C C Application of an Optimal Preview Control for Simulation of Closed Loop Automobile Driving IEEE Transactions on Systems Man and Cybernetics Vol 11 June 1981 2 MacAdam C C An Optimal Preview Control for Linear Systems Journal of Dynamic Systems Measurement and Control ASME Vol 102 No 3 Sept 1980 325 Appendix J Model Input and Output Variables The main output of the vehicle solver programs in CarSimEd is a pair of files extensions ERD and BIN with time histories of variables computed during the simulation By convention the two files together are called an ERD file See Appendix C for a full description of the ERD format The simulation is performed by calculating new values of vehicle variables as functions of simulated time The ERD file contains a large table of numbers where each column corresponds to a dif
405. tical movem Steer vs Fy 0 13 degM a i Steer vs Mz degMim To measure compliance apply Fx Fy and Mz to the Ratio is positive if wheelbase increases when eee le PEE tel Ad sD aa TE ihe SI Fx Fy Opposite directions suspension is compressed Susp Steer and Toe Kinematics End Yiew f Top Yiew Toe ounce lt deginm camber toe Camberfounce o 6 degimm 4 aS BE GO shows a pull down menu of data libraries Takes you to the library selected Figure 9 12 Independent suspension screen User Settings Unsprung mass keyword MUS IAXLE Mass of wheels tires brakes and all parts that generally move vertically with the wheel as the suspension deflects For parts such as driveline components and suspension linkages that have one end attached to the moving wheel and the other to the sprung mass you can add about half their masses to the overall unsprung mass This value includes both wheels in the suspension 2 Track width keyword LTK IAXLE Lateral distance between centers of tire contact at the simulation load condition G Height of axle roll center above ground at the simulation load condition keyword HRC IAXLE This is typically a value between 0 and 200 mm for independent suspensions The mathematical models in CarSim do not include an actual roll center point the wheels are assumed to move in a straight line as shown by the lines of motion in the kinematics s
406. time t F t C eAt fi 2 5 t i RO 5 A control response scalar g is also defined to relate the control input u over the interval t to the output variable y at time t dy t crl eA st AS a t C Anan B n gt 6 Note that g t is related to F t by integration e tf CeAN ani B f Fm dnl B 7 The response equation re written using the newly introduced terms is y t F t xo g t u 8 To determine the optimal control a quadratic performance index J is defined T 2 i f uO OF Wood where W t is an arbitrary weighting function A control u is considered optimal if it minimizes J the squared deviation of response variable y t relative to the target function Ytarget t Because J is quadratic the minimum occurs when the derivative dJ du is zero The value of u which minimizes J can be found by substituting Equation 8 into 9 and taking the partial derivative of J with respect to u 1 J T J F x g t u Yarga Of W t dt fim 2 T T H F t x g t u Yarra t f t W t dt 11 Solving for u gives the following ad Yarga FO x fo ty W t dt ees 12 g t W t dt 319 Appendix I The CarSimEd Steer Controller In practice the integrals over T can be replaced with finite summations Yearget F xolg iW Tha a ee 13 L gW i l where the time dependencies of Equation 12 are replaced with an index i The meaning here is that index i applied to F g W a
407. tions If you want to use CarSim to determine stopping distance or other measures of braking performance it is convenient to have the simulation stop when the absolute speed is close to zero A typical value for this purpose would be V_STOP 0 1 km h Set V_STOP 1 km h To keep the simulation running after the vehicle has come to a complete stop If the stop time continues after the vehicle comes to rest the bouncing and other motions as the vehicle can be seen as it settles into equilibrium Location in CarSimEd CarSimEd Startup Runs 3D Handling Input Braking File Location Input Braking Braking tbk Input Road Profile Use this screen to specify the road input for a 2D ride run This screen is only used for a 2D ride run If it is linked to a 3D car or suspension analysis run the data are ignored 164 Chapter 9 Alphabetical Library Reference Discussion This data screen is used both to specify the longitudinal profile for the ride model and also to specify an optional wire frame description for viewing the input 4m Input Road Profile of x File Edit Text Page Tools Data set Big bump 41 I gt Hew Detete GOY i Back Changed ID 52 CO Hotes 12 46 03 Category dE H Locked 7 9 88 Road sievahori m Update Plot Tidy Table_ A Road Profile m m 09 08 OF 06 05 04 03 02 01 0 0 5 10 15 Longitudinal distance m Ani
408. tle is Default Settings Note By doing this all subsequent plots will be made using these modified settings You can make a new data set but it will only be used if you set links to it from the Plot Setup screen 225 Chapter 10 Advanced Topics Creating Offset Plots When comparing many similar variables it is sometimes convenient to offset the plots vertically For example the figure below shows four plots that are offset by 5 units Alphas with Offsets DLC Slip angle deg 5 LF wheel LR wheel RF wheel RR wheel 10 10 20 Time sec Making One Plot With Offsets 1 Make a plot of the variables of interest in WinEP Make sure the window with the plot of interest is the active one by clicking on it Click on it even if it is highlighted 2 Use the Data menu command Offsets to bring up the Offsets dialog box 3 Enter values for the offsets in the dialog box 4 Click the OK button to view the revised plot Routinely Making Plots With Offsets 1 Goto the Plot Setup library by clicking the plot setup icon in the ribbon bar b or use the Plot Setup command from the Tools menu 2 Go to the Data Transforms library by following the link see 9 in Figure 9 7 on page 181 Note Another way to get to the library is through the GO menu Look for the menu item Plot Transfrm Transfrm tbk 3 Refer to the description of the Plot Data Transforms screen in Chapter 9 for information
409. tter followed by the printed values of all output variables These files can be imported into other programs with some editing of the header information and they can also be viewed within CarSimEd using the standard CarSimEd controls Note Text ERD files are not recommended for routine use of CarSimEd The solver programs take longer to write them and the plotter and animator programs take significantly longer to read them Also they occupy about three times as much disk space as the binary files Location in CarSimEd CarSimEd Startup Runs Computation Parameters File Location Comp_par Comp_par tbk Generic 2D Table Use this screen to store and display tabular data involving two independent variables for custom models This library is not used with the standard CarSimEd models but is provided in case you create a new solver programs with AutoSim and want to run it from the CarSimEd database Discussion All tables in the standard CarSimEd models are associated with libraries in the CarSimEd data base However AutoSim users can create new models with the same architecture as those in CarSimEd If these new models involve tabular data with two independent variables then this library can be used to store the data 157 Chapter 9 Alphabetical Library Reference 4m Generic 2 D Table Iof x File Edit Text Page Tools Data set 41 vow etete cow Back chsrsed 5 O N
410. tton is selected the animator accesses the computer clock and waits if necessary to avoid running the animation faster than real time Chapter 6 The Animator Radio button for maximum speed animation When this button is selected the animator does not access the computer clock allowing maximum display speed Select this button if the animation is running slower than real time End of run pause The animator delays this amount of time at the end of a run before looping to start over A pause of 0 5 sec or more gives a visual indication that the run has ended Log file Enter a name for an optional file written by the animator as it processes the inputs use the adjacent button to select a destination folder The log file is sometimes helpful for debugging but it is not needed for normal operation Browse button Click to bring up the Windows file dialog box to locate a destination folder for the log file 7 OK button Click to close the dialog box and apply the new preferences Cancel button Click this to close the dialog box without changing anything keep the previous preferences Animation Menu The animation menu serves mainly to remind you of keyboard commands that control animation Although the menu items are functional you will usually find it quicker to use the indicated keyboard commands From Beginning Continue From Current Position Ctrl D Stop space Step Forward Step Back
411. types are provided in Appendix F along with some examples Short summaries are provided below Simfile Simfile is the batch control file Whenever you click the Run button anew Simfile is created in the same folder as the solver program by convention this is the folder Programs If a file named Simfile already exists it is overwritten Because Simfile is automatically re generated before each run it can be deleted at any time without loss of information The Programs folder contains the Simfile used for the most recent run Therefore if you run a solver program independently of CarSimEd it will repeat the last run made if it is still in the Programs folder To run a program in the interactive mode you must delete or rename Simfile or launch the solver program from outside the Programs folder Chapter5 The Solver Programs Table 5 1 Standard files created when a simulation is run SGUI Batch control file taken from the Runs screen lt id gt LPO Runs Program List of parameters written as output by program Also contains initial conditions Can be used to repeat a run lt id gt LPF Runs Program List of parameters and final conditions written as output by program Can be used to continue a run animator programs IN B Runs Program Numerical values of output variables stored in binary form and used in association with ERD files PAR files PAR Files The PAR file lists input paramet
412. ue is not used by the solver programs Color of wheel object drawn by wire frame animator keyword set_color Select the button next to the field to access a pull down menu with the valid color names This information is not used by the solver programs Location in CarSimEd CarSimEd Startup Runs Vehicles Car Tires CarSimEd Model File Location Vehicles Tires_ed Tires_ed tbk Tires Cornering Stiffness Use this screen to define the cornering stiffness of a tire as a function of vertical load Discussion For small levels of lateral slip tires produce lateral force that is proportional to negative slip angle The coefficient is called cornering stiffness It is strongly dependent on load The CarSimEd model accounts for the load sensitivity with a tabular function For large slip angles the CarSimEd model reduces the lateral force to account for friction limits Details are provided in Appendix G 212 Chapter 9 Alphabetical Library Reference 4m Tires Cornering Stiffness of x File Edit Text Page Tools Data set Example Ky v 4l I gt Hew Delete GOY Back Changed ID 35 O Hotes 12 46 28 Cornering stiffness d Fy de Nideq Update Plot Tidy Table 1300 Load H Stiffness H deg 1200 1100 1000 cae 4000 1097 800 6000 1253 700 8000 1250 600 500 400 300 200 100 0 0 1000 2000 3000 4000 5000 6000 7000 8000 Yertical load N
413. up 220 mm range x Suspension Back View x Input Computation Parameters No library selected x Suspension model dt 0 01 x View Echo File All Parameters Input il 7 2J Multiple Plots No Library Selected x Plot J Overlay Runs Plot 1 Setup Moven l Plot 2 Setup x Plot 3 Setup No data set selected x Plot 4 Setup No plot setup selected x O Show More GO shows a pull down menu of data libraries Takes you to the library selected Discussion CarSimEd includes four Runs screens Three are for running the stand alone solver programs 3D Car 2D Ride and Suspensions Analysis and the other is for running with SIMULINK These screens are nearly identical in appearance and function The Suspension screen is nearly identical to the 3D Car screen see Figure 9 9 on page 189 The differences are 1 The suspension screen does not have yellow fields for speed and friction because those parameters are not used in the suspension model 2 The screen has a different title 3 The system label is Suspension rather than Vehicle Please refer to the section for the 3D Car version for descriptions of the controls and settings of this Runs screen Note The only meaningful input for the suspension model is the spindle height as a function of time Therefore discussions of other inputs do not apply when using the suspension model Location in CarSimEd The Runs Suspension Analyses screen can al
414. uring a test For most engineering applications data are stored in the computer memory in 4 byte floating point format also known as single precision floating point The 4 byte floating point format is commonly used for data generated by computer The maximum efficiency for data processing is usually obtained when the 4 byte floating point format is used The ERD file format is used on a variety of computer systems and for a variety of mass storage media On some systems binary data are stored in discrete records A computer program reading such a file needs to know how many bytes each record contains and how many records are in the file Thus the header contains these two parameters Disk files on workstations and desktop computers are not structured a binary file is simply a continuous stream of bytes that continues to the end of the file Thus technically correct parameter values for the header could be one record containing all of the bytes for the file Also there is a certain amount of overhead associated with reading a record The time needed to read the data for a file is minimized if a single read operation is performed for the entire file On the other hand if the file is large the memory needed to read the entire file in one chunk may not be available with some programs A second problem can occur if the true number of bytes in the file is less than the number as inferred by the parameters NBYTES and NRECS i e the total size
415. use the browse button 2 Browse button Click to bring up the Windows file browse dialog box to search your directory system for a suitable folder If you select a folder using the browser the resulting pathname is automatically entered into the file field G Save button Click to create the Parsfile Cancel button Click to exit this dialog box without creating a file Check box for shape and frame definitions If checked when you click the Save button all vehicle shape and frame data will be included in the file Check box for grid definitions If checked when you click the Save button the current grid information will be included in the file Check box for Path Definitions This refers to the path input when a closed loop driver model is used to steer the vehicle in a simulation If checked when you click the Save button the coordinates of the path will be included in the saved parsfile Check box for Camera definitions If checked when you click the Save button the current camera reference frame and point coordinates will be included in the file Check box for look point definitions If checked when you click the Save button the current look point reference frame and coordinates will be included in the file Exits the animator program To use the keyboard type the Windows standard sequence Alt F X or Ctrl Q 68 Chapter 6 The Animator Edit Menu The Edit menu supports the clipboard and sets preferences
416. used in this field are not sensitive to case x and X refer to the same variable Several examples are provided in the following Examples subsection to indicate how you might use this field Calculator input field Enter a mathematical expression then click the button 15 to see the result in the calculator output field 7 In addition to normal arithmetic operations the calculator has a number of built in functions that are described in a later subsection and which can be displayed by clicking the Help button 8 Calculate button Click to evaluate the expression in the input field and print the result in the output field 17 Calculator output format This field contains a format string used to control the round off in the calculator output 7 It is applied when you click the button 15 The syntax is the same as for the other format field 10 described previously Calculator output field This displays the results of the calculation performed when you click the button 15 The format can be specified using the format string 16 Plot This graphic is created by plotting values of columns 2 and higher on the Y axis against the values of column 1 on the X axis from G Thus the number of plots is N 1 where N is the number of columns The plot is not made automatically you must click the Plot button to create it or update it after modifying the tabular data G Calculate button Click to replace the
417. ve If the data include zero or negative values linear scaling is used even if the Log box is checked 1 X and Y Manual Scaling check boxes When one of these boxes is checked the corresponding axis is scaled to cover the minimum and maximum values specified below Otherwise scaling is performed automatically to include the full range 12 Minimum and maximum values for the axes These values are used only if the manual scaling box is checked AD For the X axis these fields are hidden when the manual scaling box is not checked For the Y axis they are always visible because in some versions of CarSimEd the values are needed for plotting software other than WinEP Location in CarSimEd This library is accessible from several places in CarSimEd e Accessed from the ribbon bar with the button e Accessed with the Tools menu e Accessed from the Plot Setup Batch screen e CarSimEd Startup Runs Plot Setup Single File Location Plot Setup Setup tbk Plot Transforms This screen is used for setting up plots in which the data transformed numerically The options are to apply offsets horizontally and vertically and filtering smoothing and un smoothing Discussion Offsets When comparing many similar variables it is sometimes convenient to offset the plots When you are viewing plots on the screen offsetting is probably not necessary because you can see the different colors and use the movable cursor to identify the differen
418. ve the animator automatically determine the range for the grid set the minimum and maximum values equal or leave them blank Maximum X and Y values covered by the grid keywords set_max_x set_max_y The units for these values are meters If not specified the default values are zero To have the animator automatically determine the range for the grid set the minimum and maximum values equal or leave them blank Note The X and Y directions are handled independently Even if the range is set manually in one direction the range for the other direction can be determined automatically Location in CarSimEd CarSimEd Startup Runs Animator Camera Setup File Location Animate Cameras Cameras tbk 132 Chapter 9 Alphabetical Library Reference Animator Groups The Animator Groups screen is used to group shapes reference frames and other groups Due to the versatility of the animator this library can be used for several purposes Discussion The Animator draws several kinds of objects a flat grid for the ground a 3D grid for the ground a target path on the ground multiple shapes and multiple wheels The multiple shapes can be fixed or moving The grid properties are specified in the Animator Camera Setup screen the target path display properties are specified in the Input Target Path For Closed Loop Steer Control screen and almost everything else is grouped using this screen Grouping Shapes Together Gr
419. vector vector describing the position of one point relative to a reference point Unless specified otherwise the reference point is the origin of the earth fixed coordinate system Vector an object that has a direction in 3D space and a magnitude The existence and meaning of a vector are not dependent on the choice of coordinate or axis system Velocity vector time derivative of the position vector of a point Angles An angle implies a rotation from a reference line to another line in the plane containing both lines about an axis that is perpendicular to both lines The direction of the axis defines the sign convention of the angle based on a right handed rotation Line up your right hand thumb with the axis direction and your fingers curl in the direction of a positive rotation Sometimes an angle is defined between a plane and a line In this case the angle is taken from a projection of the line into the plane as shown in Figure B 1 for an angle between plane ABC and line AD 246 Appendix B Vehicle Dynamics Terminology Angle of interest shaded Angle is between plane ABC and line AD plane containing lines AD and AE line AE is normal to plane ABC Figure B 1 Angle between a plane and a line Resultant Force and Moment Vectors All actions on a body that would cause it to accelerate in translation or rotation if not opposed by other actions can be combined into a single resultant force v
420. ver Programs Once a run starts the solver programs have three methods of stopping 1 A normal stop in which the simulated test is completed In this case the solver program quits at the end of the run returning you to the Runs screen where you can click a button to view an animation or inspect plots There are several parameters that are checked to see if the run should stop the stop time a minimum speed threshold a maximum roll angle and a maximum distance traveled A controlled stop due to an input error In this case the window for the solver program stays visible with an error message displayed This is usually due to a non existent file name and is corrected by going to the Startup screen and updating the text files as described on page 236 If this does not solve the problem locate and open the LOG file described in Chapter 5 and use it to determine how many input files were read and which file caused the problem An uncontrolled stop In this case a Windows system level error message is generated The problem is usually numerical causing an excessively large number to be passed to the CPU The problem is usually due to bad input parameter values that cause the system to become unstable To help track down the problem a View the echo file made prior to the start of the run The echo file has the extension LPO and is described in Chapter 5 Look over the parameters for something that is not right like a very low mass
421. verage lt list of numbers gt Returns the sum divided by the number of items in the list ceiling lt number gt Rounds up to nearest integer cos lt number gt Cosine number in radians cosh lt number gt Hyperbolic Cosine number in radians exp lt number gt Exponent 2 7182818 raised to power of number floor lt number gt Rounds down to nearest integer hypotenuse lt length gt lt length gt Length of hypotenuse In lt number gt Natural Log base e 149 Chapter 9 Alphabetical Library Reference log lt number gt lt base gt Log of number in base max lt list of numbers gt Highest value in list min lt list of numbers gt Lowest value in list round lt number gt Rounds to nearest integer sin lt angle gt Sine of an angle in radians sinh lt angle gt Hyperbolic sine of an angle in radians sqrt lt number gt Square root of a positive number sum lt list of numbers gt Sum of a list of numbers tan lt angle gt Tangent of an angle in radians tanh lt angle gt Hyperbolic tangent of an angle in radians truncate lt number gt Truncates to integer Location in CarSimEd Accessed from the Tools menu or the ribbon bar with the button tal File Location Sgui_lib Calc tbk CarSimEd Startup This screen appears immediately after CarSimEd has been started CarSimEd has three possible entry points and you use this screen to choose the type of simulation After sele
422. w steps 1 through 3 above 2 Use the GO button in the ribbon bar to go to the CarSimEd startup screen Startup tbk 3 Go to the data set named Install this is a data set included in the software as installed 4 Click the button Change Settings 2 This will hide the CarSimEd logo and reveal more buttons including the ones shown here Update All PAR Files Data Set for Start button No data set selected gt 2 Change Settings G san AT Chapter 4 The Basics of Using CarSimEd 4 Click the button Update All PAR Files Besides updating all PAR files the Locked buttons on every screen will be checked 5 After the update is complete return to the Runs screen by clicking the Start button G or by using the GO button Deleting Data Sets CarSimEd has several methods for deleting data sets To Delete the Current Data Set 1 Click the Delete button in the ribbon bar CarSimEd will display a warning asking you to confirm that you want to delete the data Notes You can by pass the warning message by holding the Control key down when you click the Delete button The Delete button cannot be used if the Locked button is checked The data set must be unlocked before you can delete it To Delete All Data Sets Except the Current One 1 Click the Delete button in the ribbon bar while holding down the Shift key CarSimEd will display a warning asking you whether you want to cancel delete
423. ward S Start From Beginning Select this command to restart the animation from the beginning of the simulation run The keyboard command is Ctrl S Continue From Current Position Select this command to continue the animation if it has been stopped The keyboard command is Ctrl D Stop Select this command to stop pause the animation This is like being able to freeze time While stopped you can still use the Coordinates menu to move the camera around zoom in and out and change the look point The keyboard command is the space key 70 Chapter 6 The Animator Step Forward Select this command to step forward one increment in time like a frame advance on a VCR The keyboard command is the s key Step Backward Select this command to step backward one increment in time The keyboard command is Shift S Coordinates Menu This menu serves mainly to remind you of keyboard commands that control the camera viewpoint Although the menu items are functional you will usually find it quicker to use the indicated keyboard commands Coordinates Coordinate Plus x x Coordinate Minus x Y Coordinate Plus y Y Coordinate Minus i zZ E Z Coordinate Plus Z Coordinate Minus v Camera Coordinates Look Point Coordinates L Increase Focal Length f Decrease Focal Length F The first six items are used to change the position of either the camera point or the look point depending on which is checked
424. ways be accessed from the GO menu and the CarSimEd Startup screen 200 Chapter 9 Alphabetical Library Reference CarSimEd Startup Runs Suspension Analyses The Tools menu and the button in the ribbon bar will take you to one of the Runs libraries in CarSimEd As installed these are shortcuts for getting to the stand alone Runs screen If you primarily use the suspension model you can change these shortcuts by Control clicking the E button in the ribbon bar This brings up the file browser dialog box which you can use to identify the file Runs_sus Runs_sus tbk as the default Runs library File Location Runs_sus Runs_sus tbk Runs Batch The batch runs screen is used to set up several runs ahead of time and make them all at once It also can be used to override parameters Discussion This screen is used to set up runs and then execute them in batch mode It is handy for redoing a group of runs say because a change was made in a vehicle parameter value It can also be used to change a parameter such as test speed and make a set of runs again using the new parameter The basic method is 1 Create a list of runs to be made G using existing data sets 2 from the Runs library 2 Define parameters and as necessary link to other data sets to override the conditions specified in the Runs data sets OX 3 Click the Make Runs button 8 201 Chapter 9 Alphabetical Library Reference
425. wever only two sequences are common for vehicle dynamics yaw pitch roll used for large body motions and yaw roll pitch used for the spinning wheels These are the only two allowed by the animator For the animator in CarSimEd the value must be either the text yaw_pitch_rollor the text yaw_roll_pitch These two options are selected from a pull down menu Location in CarSimEd Camera Setup CarSimEd Startup Runs Animator Camera Setup Animator Reference Frames Vehicle Definition CarSimEd Startup Runs Vehicles Car Animator Groups Animator Reference Frames File Location Animate Frames Frames tbk Animator Shapes This screen is used to define one or more wire frame shapes that are drawn by the animator 139 Chapter 9 Alphabetical Library Reference iol x m Animator Shapes File Edit Text Page Data set CAO LR Door w 41 I gt Hew Delete GO Back Changed ID 360 CO Hotes 12 25 32 EJ Locked 7 20 98 Coordinates 1 6218 0 8262 0 3213 1 6830 0 8568 0 5814 1 6983 0 7956 0 7650 1 6983 0 7191 0 8874 1 7901 0 5967 1 3464 2 2797 0 5967 1 3158 2 4021 0 6120 1 2546 2 7081 0 6885 1 0710 2 7234 0 7038 0 9945 2 7081 0 7191 0 9180 2 6469 0 7956 0 8109 2 5092 0 8568 0 5967 2 4174 0 8415 0 5355 2 3562 0 8415 0 4437 2 3256 0 8262 0 3213 1 6218 0 8262 0 3213 Coordinate Offsets Xoffset _______ offset 2 Zofftsett Coord
426. window with a menu bar The main window contains plot windows each showing plots made with a single set of X Y axes Figure 7 1 shows the main WinEP window with four example plot windows Each plot window contains a graphical representation of one or more X Y data sets An X Y data set is a series of X and Y values obtained from a data file The X Y data sets can come from the same file or from different files The X values in each data do not have to be the same and the data sets do not have to contain the same number of points WinEP reads the data from ERD and text files and has completely automated scaling formatting and labeling capabilities However labeling options are limited for non ERD text files Note If a file is not in ERD format it can be converted by adding several lines of text to the beginning of the file A description of the ERD file format is provided in Appendix C Once a plot window is created the X Y data sets can be transformed by subtracting offsets or by applying high pass or low pass filters However the data sets cannot be deleted or replaced If you create a plot with different data sets the new plot will have a new window Chapter 7 The Plotter FA winEP Ay lat accel of CG Braking in a turn File Edit Format Data View Window Help fl Ay lat accel of CG Braking in a turn Loix Fz vertical forces Braking in a turn Ay lat accel of CG Braking in a turn Fz vertical forces
427. words recognized by the solver programs in CarSimEd Chapter 4 The Basics of Using CarSimEd 6 Optionally use Links 1 2 and 3 7 to link to data sets that will override those specified in the selected runs For example to make all the runs with no braking input link to the braking input library and select the data set No Braking Click the Make Runs button to make the batch of runs am Runs Batch T_ jor x File Edit Text Page Tools O Hotes 5 07 33 category Bl C Locked 8 2198 Runs To Make Simulation Library Gi Data Sets from Runs Library lt Braking Base Car Brk split Car ax Brk split M2 Braking in a Turn Base Car Brk in Turn Overriding Data Parameter Set 1 Link 1 Parameter Set 2 Link 2 No library selected NY library selected merram Parameter Set 3 Link3 Make Runs lt Circle Test Base car Circle Y 0 to 200 lt Crosswind gt Base car No Steer CVV 40 1 Base car Path Cy 40 120 Z9 om Data Sets to Run Braking in a Turn gt Base Car Brk in Turn G Braking Base Car Brk split mu Car ax Brk split mu Braking in a Turn gt Figure 4 9 Batch run screen Notes You can view the results from the individual runs data sets or use the batch plot library If you specified any parameters or links in steps 5 and 6 then the individual run data sets are modified such that the link with the label Overriding Da
428. xternal brake torque input RF wheel INPT 5 INPT_TBRK_LR N m External brake torque input LR wheel INPT 6 INPT_TBRK_RR N m External brake torque input RR wheel INPT 7 INPT_THROTTLE External throttle input 195 Output Variables OUT 1 AAy_LF rev s2 LF wheel angular acceleration gen name Wheel angular acceleration rigibody name LF wheel OUT 2 AAy_LR rev s2 LR wheel angular acceleration gen name Wheel angular acceleration rigibody name LR wheel OUT 3 AAy_RF rev s2 RF wheel angular acceleration gen name Wheel angular acceleration rigibody name RF wheel 328 Appendix J Model Input and Output Variables OUT 4 AAy_RR rev s2 RR wheel angular acceleration gen name Wheel angular acceleration rigibody name RR wheel OUT S Alpha_LF deg LF wheel slip angle without lag gen name Slip angle rigibody name LF wheel OUT 6 Alpha_LR deg LR wheel slip angle without lag gen name Slip angle rigibody name LR wheel OUT 7 Alpha_RF deg RF wheel slip angle without lag gen name Slip angle rigibody name RF wheel OUT 8 Alpha_RR deg RR wheel slip angle without lag gen name Slip angle rigibody name RR wheel OUT 9 AVx deg s Body roll rate gen name Roll rate rigibody name Body OUT 10 AVy deg s Body pitch rate gen name Pitch rate rigibody name Body OUT 11 AVy_LF rev s LF whe
429. y to tidy the appearance of the table G Delete button Click to ensure that all numbers in a row are separated with white space only If commas exist they are removed If numbers are already separated only by white space this has no effect Flip Rows button Click to reverse the order of the rows of data in the tabular data field Flip Cols button Click to reverse the order of the columns of data in the tabular data field 3 Help button Click to bring up a window with a listing of functions that can be used in formulas in the calculators Format button Click to format the numbers in the tabular data field G according to the format string 10 Format field The text in this field specifies whether numbers are written with fixed decimal places or in scientific notation It also specifies how many digits are written to the right of the decimal point The format string has the form X X where the X s represent a series of place holders 0 place holder for a digit Same as 0 except the digit is not printed unless it is needed E or e Scientific notation with sign always used for the exponent The number of digits in the exponent is determined by the number of place holders If used you must put place holders 0 or before and after the E or E If the format field is blank then numbers are written to their full precision Following are some example format strings and the effect they have on three exa
430. ylinder It is generally used only to define the rods and the wheel in the five link suspension model Wheels on the vehicle are defined by the effective tire rolling radius from the Tires data screen Discussion The animator considers a wheel to be two polygons with a specified radius separated by a specified thickness In addition the corresponding nodes of the polygons are connected by lines 4m Animator Wheels ioj x File Edit Text Page Tools T EJ Hotes 12 45 35 category ds H Locked 7 9 98 Number of points ee Color ae v ON radial line to show wheel spin Coordinates of Center Scale Factor X coordinate E X scale EN Y coordinate HO Y scale a Q Z coordinate Zscale oS eo User Settings Thickness keyword set_thickness This should have units of meters Radius keyword set_radius This should have units of meters Number of points used for set_num_points polygon approximation of circle keyword Color of lines drawn by animator to show the wheel keyword set_color Valid colors are provided in a pull down menu 142 Chapter 9 Alphabetical Library Reference Radial line option keyword set_radial_line This check box determines whether a line is drawn from the center of one of the polygons to the first node The single line is useful for determining when wheels lock up during braking simulations The values a
431. ystems ASME Publication AMD Vol 108 1990 3 Segel L Theoretical Prediction and Experimental Substantiation of the Response of the Automobile to Steering Control The Institute of Mechanical Engineers London 1956 4 Jindra F Mathematical Model of Four Wheeled Vehicle for Hybrid Computer Vehicle Handling Program National Highway Traffic Safety Administration DOT HS 801800 1976 5 Wade Allen Henry T Szostak et al Vehicle Dynamic Stability and Rollover National Highway Traffic Safety Administration DOT HS 807 956 June 1992 6 Orlandea N and M A Chace Simulation Of A Vehicle Suspension With The Adams Computer Program SAE Paper No 770053 1977 7 Antoun R J et al Vehicle Dynamic Handling Computer Simulation Model Development Correlation and Application Using ADAMS SAE Paper No 860574 1986 8 Kort m W Sharp R S eds Multibody Computer Codes in Vehicle System Dynamics Lisse Swetz and Zeitlinger 1993 9 Sayers M W Symbolic Vector Dyadic Multibody Formalism for Tree Topology Systems Journal of Guidance Control and Dynamics Vol 14 No 6 Nov Dec 1991 1240 1250 10 Gillespie T D Fundamentals of Vehicle Dynamics SAE Warrendale PA 1992 306 Appendix H The Tire Model Figure H 1 Tire points and axes The interaction of each tire with the ground is modeled by a longitudinal force F a lateral force Fy a vertical force Fz

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