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^2 Pmac Tuning Pro

1. Before entering the Regular PID auto tuning session for a particular motor make sure that the motor is under closed loop control Typically the default gains with which the PMAC boards are shipped are low enough and may be used as the initial gains for the start of a session Furthermore large offset bias signals and deadband characteristics between the amplifier and the PMAC s DAC outputs should be reduced to a minimum by the use of 1x29 and Ix68 variables see also Offset and Deadband Calibration above In the Auto Tuning window select the appropriate options prior to the start of an auto tuning session These include Type of amplifier used with the selected motor current mode or velocity mode Maximum excitation magnitude as of DAC output 100 represents a DAC value of 32767 increments or 10V nominal Note that depending on the type and the gain of the motor amplifier any given excitation as of maximum DAC output is equivalent to a certain current or voltage command to the motor Do not demand more current or voltage than the maximum recommended value as specified for any particular the motor amplifier by its manufacturer Excitation time in milliseconds This should be long enough to generate about 1 4 to 1 2 of motor revolution Number of test iterations Usually two times is sufficient Design goals in terms of bandwidth and damping Select Auto select Bandwidth if y a reasonable value for the closed
2. 14 PMAC Tuning Pro Software Reference Manual Current Loop Tuning PMAC Tuning Pro Software Reference Manual POSITION LOOP TUNING DAC Calibration The purpose of this option is to provide the ability to determine the DAC bias values gp m sm z imgur U PHL TTF i Seu TA LE Postion Loop Tramctory Toos Number of test erations Calibration step size Begin Calibration Done Help For a standard DC motor or a brushless motor which is commutated externally not by PMAC this option provides an optimum value for Ix29 For a stepper motor driven through PMAC s Acc 8D Option 2 the V F board this option provides optimum values for x29 and Ix79 When calibration begins a small PLC program is downloaded and executed in PMAC After the tests are completed the optimum values for Ix29 and Ix79 if a stepper motor was specified are displayed Select Implement Now to implement these bias gains in PMAC Do not use this option if PMAC is commutating the selected motor See also the special application note included in the PMAC Acc 8D Option 2 manual PMAC Setup for Stepper Motor Control Using Acc 8D Option 2 the V F Converter WARNING Regardless of the state of the selected motor s servo loop close or open it will be opened up by the Offset Calibration routines In a situation where the DAC bias voltage is known to be high the fact that the servo loop is open may lead to substantial motion during the Offset Calibr
3. SOFTWARE REFERENCE MANUAL Pmac Tuning Pro Release Version 1 x S RP gt Owes i an Se ie RR ee eh ee a AM TT T M ae Ber EI Paracas e Pit Ba ena a ET A TH difinan i ENNY jee F vl A Hil i mh il I MAY Mgnt Fy AANA 1 DELTA TAU Y7 Data Systems Inc NEW IDEAS IN MOTION Single Source Machine Control Power Flexibility Ease of Use 21314 Lassen Street Chatsworth CA 91311 Tel 818 998 2095 Fax 818 998 7807 www deltatau com Copyright Information 2003 Delta Tau Data Systems Inc All rights reserved This document is furnished for the customers of Delta Tau Data Systems Inc Other uses are unauthorized without written permission of Delta Tau Data Systems Inc Information contained in this manual may be updated from time to time due to product improvements etc and may not conform in every respect to former issues To report errors or inconsistencies call or email Delta Tau Data Systems Inc Technical Support Phone 818 717 5656 Fax 818 998 7807 Email support deltatau com Website http www deltatau com Operating Conditions All Delta Tau Data Systems Inc motion controller products accessories and amplifiers contain static sensitive components that can be damaged by incorrect handling When installing or handling Delta Tau Data Systems Inc products avoid contact with highly insulated materials Only qualified person
4. 2 Ifnecessary when in the Tuning menu enter the DAC Offset Deadband Calibrate option to adjust x29 and Ix68 For PMAC commutated motors x29 should not be implemented 3 Select the Auto Tuning simple option and enter its dialog box Select the correct amplifier type current or velocity loop 5 Enter the value of the desired bandwidth If not sure how to select the value for this entry check the Auto Select Bandwidth option Select a Damping Ratio between 0 8 and 1 0 6 Check the Auto Select Sample Period box if Auto Select Bandwidth is selected and or if the desired bandwidth is less than 20 Hz it is assumed the value of x60 0 prior to entry to this dialog box 7 For now leave the Include Low Pass Filter field and both Feedforward boxes unchecked Also select None for Integral Action 8 Adjust the values of the Max Excitation Magnitude Excitation Time and the Max Min Motor Travel fields so that the motor turns from 1 4 to 1 2 revolutions while accelerating during the open loop forward reverse motions a prolonged period of constant velocity motion should be avoided 9 Click the Begin Auto Tuning button and wait for the tuner to give the suggested values for some particular terms within the ESA If the numbers look reasonable accept them If the servo loop appears to behave in an unsatisfactory manner then click on the Kill button immediately This action issues to the addressed motor a PMAC KILL command Otherwise exit th
5. Excitation Time The period of time in milliseconds in which the DAC output is driven by the test signal is entered here Choose this period carefully It should be long enough for noticeable motion to take place at least equal to Minimum Motor Travel On the other hand too long a period of time may mean excessive travel and or excessive motor velocity In most applications excitation times between 50 to 100 milliseconds should be sufficient For motors having very large inertia loads large excitation times may be appropriate The default value is 50 ms Number of Iterations This refers to the number of backward forward motions in the testing phase of an auto tuning session If a number greater than one is chosen then the peak DAC output for the first iteration is determined from dividing the Maximum Excitation Magnitude by the Number of Iterations In this way the last iteration always corresponds to the Maximum Excitation Magnitude input The default value is 2 iterations which is sufficient for most applications WARNING Depending on the size of the excitation signal and the responsiveness of the servo loop implemented while tuning it 1s possible that the actual motor travel may go past the Maximum Motor Travel limit Maximum Motor Travel The maximum travel limit may be specified independently during the tests If this distance is reached the loop is immediately closed and the motor is commanded to jog back towards its original
6. The Gantry Interactive and Auto Tuning has been implemented for Regular PID Algorithm only For both Interactive and Auto Tuning the dialog boxes are identical to the Regular PID Algorithm described above except that a selected Second Motor has to be specified For Interactive Gantry Tuning the selected Second Motor position loop will be closed if open and it will be commanded to move the same distance It is recommended that prior to any commanded moves both motors be assigned with the same or similar x30 and Ix31 gains and that as the tuning proceeds towards stiffer servo higher gains for the primary motor the Second Motor gains are increased so that the dynamic response of both motors remains similar Position Loop Tuning 37 38 PMAC Tuning Pro Software Reference Manual Position Loop Tuning PMAC Tuning Pro Software Reference Manual TRAJECTORIES The trajectory menu allows the executing several pre defined as well as custom defined moves O37 O2926 2001 UMAC TURBO USB Port Position Step a Ls F Position Sep All of these moves and corresponding plots are explained in the following sections Position Step Feedback Tuning with Step Response Trajectories 39 PMAC Tuning Pro Software Reference Manual Step response is often used as a method of evaluating a feedback filter Many controls textbooks contain information on interpreting step responses for establishing proper feedback particularly for s
7. 1 1 93F O2f26f2001 UMAC TURBO USB Pork Position Loop Trajectory Tools Window Help DAC Calibration Open Loop Test Regular PID Extend serma algaritmi atch Fiter Gantry PID Low Pass Filter pasri Sapien A tee maah heuer la ar Mn kapethik tendon satel uo i oo poa e aeaa a no oO SS lailia Fallic Tiatira First select a motor using lt PgUp gt or lt PgDn gt Next enter the cutoff frequency and select either a first order or second order filter Now click the Implement Low Pass Filter button The low pass filter coefficients 1x38 and Ix39 will be calculated automatically and displayed on the left and these new coefficients will be downloaded to PMAC Cutoff Frequency This value is the actual cutoff frequency in hertz to use for the low pass filter in the servo loop To determine which frequency this is do a step move from the tuning screen and measure this frequency from looking at the plot of the step response First Order Filter With this radio button specify a first order low pass filter Typically first order filters introduce little lag to the servo but do not exhibit a steep cutoff for the pass band Second Order Filter This radio button allows you to specify a second order low pass filter Typically second order filters introduce more lag to the servo but do exhibit a good steep cutoff for the pass band Position Loop Tuning 35 PMAC Tuning P
8. Auto Calculate Frequency Specifications checkbox selected Remove Notch Filter This button removes the notch filter for the selected motor by zeroing out the coefficients 1x36 Ix39 and restoring x30 to its near original value before the notch filter was implemented Calculate Notch Filter Gain This button calculates the coefficients for the notch filter for the selected motor and displays the values on the left side of the screen The new values are not downloaded to PMAC When a notch filter is calculated the proportional gain 1x30 changes to a higher value This is necessary to maintain the same DC gain with the new notch filter implemented The amount Ix30 changes will depend on the values of the notch filter coefficients 34 Position Loop Tuning PMAC Tuning Pro Software Reference Manual Implement Notch Filter This button calculates the coefficients for the notch filter for the selected motor and displays the values on the left side of the screen The new values are downloaded to PMAC When a notch filter is implemented the proportional gain 1x30 changes to a higher value This is necessary to maintain the same DC gain with the new notch filter implemented The amount x30 changes will depend on the values of the notch filter coefficients Low Pass Filter Addition to PID Feedforward PMAC Tuning allows the set up of a low pass filter easily without the need to understand how a low pass filter works 0 PMAC
9. In general low damping ratios ratios well below one lead to large overshoots and long periods of transient oscillations leading towards instability On the other hand high damping ratios ratios well above one lead to very sluggish motion Typical damping ratios should range from 0 6 to 1 Note that the higher the value of the damping ratio the higher the computed derivative action from the ESA controller and consequently the higher the quantization noise amplification leading to possible motor jitters In most applications a damping ratio of 0 7 to 0 8 provides a good trade off between transient response requiring more derivative action and quantization noise reduction requiring less derivative action If integral action is included even if the specified damping ratio is unity or above some overshoot may occur in response to a step input In addition if the Auto select bandwidth option is chosen the damping ratio is set to unity The default value of this entry is 1 Position Loop Tuning 23 PMAC Tuning Pro Software Reference Manual Auto Select Bandwidth This option is useful in situations in which the range of acceptable values of bandwidth is not known When this box is checked based upon the results of the auto tune tests a safe bandwidth is determined This in turn selects the ESA terms and their numerical values Typically the safe bandwidth is lower than the maximum achievable bandwidth but is more likely to lead to a jitter f
10. PMAC Choose which PMAC card to tune or to test the terminal window The terminal window will open automatically When the program closes the device number is written to INI file The next time PmacTuningPro is opened the program will try to open that device number CEN ATE TTE A Open This function opens PMAC type file such as Ivar a D and Pmac file u pmc and all text type files Cimer Lon Pomi Sal Prac P Save The Save function saves any open text file without changing the filename SrL TEN Menu Overview PMAC Tuning Pro Software Reference Manual Save As This function saves any open text file with a new filename Print This function sends any open text file to the printer ima lt scorer Pett Patio pe a ee kf Exit This function saves the configuration to INI file and exits the eee Window Menu This menu is used for managing the position and arrangement of all windows currently displayed The Vertcaby Minimize Al Arrange All 2 Sirip Potting Motor 1 SPMACIOVISS 01 16 2001 PHACI TURBO ISA BUS 6 Menu Overview PMAC Tuning Pro Software Reference Manual CURRENT LOOP TUNING Digital Current Loop Tuning for PMAC2 Turbo PMAC2 and UMAC This feature has been added to the PMAC Tuning Pro to provide a quick tool in case re tuning of the Current Loop is needed after the initial setup of the Current Loop using the P2setup program for PMAC2 or the Turbosetup
11. Parabolic Move with too muon Kvff fira x i C _ FTES TE LEDS Aty QQB ask Motor 2 Parabote Mowe Plot Result Executed at 3205 06 PM TIZA REIT 7 i LEI i Die l Ft ihia i TE ye iy j pij il ii A ign a 1 a i I i i ij i ws 5 IT J 4 jt I LE E i E 1iLFJ hy a eit r F i lf TE ri 1 E l I i d bp E T E i p i ATIT j FL i j i i CE f l 5 i i i Lr oe i D i g ami lj ii i ice 4 j 1 4s i i om Whi i Ik ra el IF i MA r FEI re a i i ty a ee ee F N AA Nf Ni han ree j amp ji 4 8 EEEo i ie i a ian i fi E EJ aj ET Ei ma Ge ij as FELE i Fi perea ees fhe ee pe a ee Pe pe eee hy PF pee Cee j e N Ree ee ee ee ee ee cee Peet eed ee i EP Conrad teed cod ee Oca Lak be Seo ci bian a dea ed ser le dF ee eg ee Li eee i E a tn ha ee ee 48 Trajectories PMAC Tuning Pro Software Reference Manual Modified Parabolic Move with Some Kaff Hey Pico BT lbt de WE BRA AGr CA AGE Waor Er Parabolic Move Pict Result Ececuted af 3 05 25 PM Tree Finally a bit of acceleration feedforward Kaff 1x35 gives us an almost perfectly tuned motor Trapezoidal Velocity Trapezoidal elocity Move Distance cta 10000 Velocity cts sec fi 0000 Acceleration cts mzec 100 Humber of Repeats 1 Do A Trapezordal Move Kill Motor After Trapezoidal Move Move in only one direction Dwell Tim
12. Profiled Parabolic Response Parabolic Move 4000 500 Move Size cts Hove Time ms Do A Parabolic Hove Kill Motor After Parabolic Move Move in only one direction Dwell Time After Move fo ims In a position servo system without feedforward or dynamic error integration there must be a continual error between the commanded position and the actual position in a profiled move known as following error to produce a motor command These following errors will usually be proportional well correlated to the velocity and or the acceleration The velocity and acceleration feedforward terms can be used to reduce these following errors virtually to zero These parameters add terms to the torque command that are proportional to the commanded velocity and acceleration respectively in each cycle of the profiled move Mathematically speaking if two sets of data such as velocity and following error vary in complete proportion to each other they have a correlation of 1 0 perfect correlation If they vary completely independently of each other they have a correlation of 0 0 no correlation The more they vary in proportion to each other the closer their correlation will be to 1 0 In graphical terms the more two curves are shaped like each other the better they will be correlated Another important figure is the constant of proportionality between the two sets of data which is the average ratio between matching points in th
13. When satisfied with the signal to noise ratio of the step response click on the Implement and Check Response button There should be a step response that shows a numerical value for the natural frequency This number should be close to the bandwidth selected by the Auto Tuner If it is to within 10 to 20 of the selected bandwidth in Hz consider that the Auto Tuner has a good estimate of the current loop dynamics ment Loop fubo Tuning Hauks all Precent gare Recommended Game Ki cumenti poria monesi Ep Cumeni COO OOOO Epi Curent V6 LoS alti lea ep emle hie a Le La eae lnplument Mew Gains and Check Aespene Typical Current Loop Auto Tune Message Box 5 Now uncheck the Auto Select Bandwidth option and gradually increase the Bandwidth entry and repeat the above procedure until a message appears indicating saturation of the gains At that time reduce the bandwidth entry and try to converge to the highest bandwidth that just avoids causing saturation This will be the highest achievable bandwidth using the Auto Tuner with the proportional gain in the feedback path Kp1 If a higher value of bandwidth is desired try to use the proportional gain in the forward path Kp2 Once a satisfactory current loop response is achieved for all motors the current loop gains save within PMAC2 Usually the next step is the setup procedure for PMAC2 s commutation I variables and finally position loop tuning Current Loop Tuning 13
14. causing saturation Maximum Excitation Magnitude This is the maximum step size of the commanded direct magnetizing current Ig used within the identification tests the numerical range of this entry is the same as Ix77 For the first iteration of the identification process this number is divided by the Number of Iterations to form the first step size The last iteration has a step size equal to the Max Excitation magnitude Select this entry very carefully If the Max Excitation magnitude is selected to be too large it may cause sudden motion of the motor or possibly damage the amplifier If the numerical value of Max Excitation magnitude is set to be too small the current feedback noise to signal ratio may be unacceptably high for the correct identification of the motor winding impedance Usually a numerical value of 5000 is a good starting point If too much noise to signal ratio is observed in the step response progressively increase this number Excitation Time This is the period of time for the direct Ig current step test A period of 50 ms should be sufficiently long to achieve steady state values In general this period should be made as short as possible and yet long enough for the current response to reach its steady state Number of Iterations This is the number of step stimulus tests during an auto tuning cycle Ifa number greater than 1 is chosen then the commanded step size at the first iteration will be the Maximum Exc
15. first order low pass filter to attenuate high frequency noise which may otherwise cause a noticeable motor jitters After completing the above selection select the Begin Auto Tuning button This prompts the simple auto tuner to start the testing sequence Depending on the number of iterations selected there will be a number of backward and forward motions If the Pause between iterations option is checked the actual distance moved in each iteration will display If the box is not checked the auto tuner will continue testing the system as many times as selected in the Number Of Iterations Input option After the completion of tests the auto tuner computes the relevant terms of the PID Algorithm and displays them on the screen together with the existing terms for the selected motor The new terms may be discarded or accepted If accepted they are downloaded to PMAC automatically If undesirable behavior from that particular servo channel is noticed use the Kill button to open the loop and disable the amplifier If the motor appears stable and jitter free then exit the Tuning menu and go to the Trajectory menu In the Trajectory menu examine the response of the system under the new set of servo controller parameters selected by the auto tuner Many types of moves including sinusoidal and sine sweep are available Note that without feedforward and or integral action there may be a considerable amount of following errors during faster moves particu
16. loop bandwidth cannot be chosen This gives a safe lower bound value for the bandwidth Then increase the bandwidth gradually from the bandwidth automatically estimated to increase servo stiffness and auto tune again etc The maximum and minimum travel limits for the tests This should be long enough to generate 1 4 to 1 2 of motor revolution and yet short enough to avoid uncontrolled travel beyond a safe limit for a particular setup Position Loop Tuning 21 PMAC Tuning Pro Software Reference Manual e Choice of including feedforward action Include velocity and acceleration feedforward to minimize tracking or following errors e Choice of no integral action soft integral action or hard integral action Note that hard integral action should not be selected unless low bandwidth relative to auto select bandwidth is selected for closed loop system In general select soft integral action if you need zero steady state following error and a previous tuning session without the integral action could not satisfy your requirement e Choice of automatic selection of a safe bandwidth based upon the test results Select this option if the desired closed loop bandwidth cannot be chosen e Choice of automatic selection of the servo sampling period extension I variable Ix60 for a particular servo design goal It is useful to check this option particularly when the selected closed loop bandwidth is below 20 Hz e Choice of inclusion of a
17. program for PMAC2 Turbo and UMAC Preparatory Hardware and I Variable Set Up When PMAC2 s digital current loop is used usually the format of the output commands is digital pulse width modulated PWM signals For each machine interface channel PMAC72 has three pairs of top and bottom PWM signals which can be used for the half bridges of a 3 phase motor Each of the six output signals is a differential line driver pair for a total of 12 PWM pins which must be correctly connected to the amplifier The analog current feedback signals from two of the motor phase windings are also required and must be correctly connected to PMAC2 for more details see the appropriate sections of the applicable amplifier manual and the PMAC2 User Manual In addition to the need for correct interconnection wiring between the PMAC2 and the Digital Amplifier some global per channel and per motor I variables must be preset prior to any attempt to tune the current loops These I variables include the global variables 900 17m00 for Turbo and 1906 for PWM frequencies 1901 17m01 for Turbo for Phase Clock frequency 1902 I7m02 for Turbo for Position loop Servo Clock frequency 1903 I7m03for Turbo and 1907 for the ADC Clock frequencies 1904 I7m04 for Turbo and 1908 for the PWM deadtime between top and bottom signals for machine interface channels to 8 The factory default values for the per channel PWM I variables 19n6 I7mn6 for Turbo and I9n7 shou
18. reset or power down When a satisfactory set of gains has been reached save them within PMAC by opening up the PMAC Terminal under the Utility menu and issuing the SAVE PMAC online command Choices and Options in ESA Auto Tuning Amplifier Type This selects the type of amplifier used The default value is for a current loop amplifier If either an analog tachometer loop is closed within the amplifier or the amplifier operates without current feedback in voltage mode the Amplifier Type should be changed to velocity loop CAUTION Do not exceed the safe limit for DAC output specified in Maximum Excitation Magnitude for your particular setup Otherwise the power amplifier the motor and the mechanical structure connected to the motor may be damaged Maximum Excitation Magnitude This is the size of the largest DAC signal given as a percentage value of 10V For example if only two iterations are chosen for the Number of Iterations and the Maximum Excitation Magnitude is 100 then in the first iteration the maximum DAC output will be 5V in the second iteration it will be 10V Choose this parameter carefully In general it should be large enough to overcome friction and other disturbances so that actually some motion does occur On the other hand it should not be too large to cause amplifier motor or mechanical damage because of excessive torque command Consult the amplifier and motor specification The default value is 30
19. the response is too noisy reduce the desired bandwidth and auto tune again until a satisfactory response is obtained A good trajectory to try first is the Parabolic Velocity If there still exists some noticeable ringing at a fairly constant period which appears to decay with time and has a frequency not more than 10 times the closed loop bandwidth try the Notch Filter option to implement a notch filter On the other hand if there are persistent high frequency jitters buzzing try to reduce the Bandwidth and or the Damping Ratio and re tune again in order to decrease the servo response to this noise CAUTION Depending on the controller gain for even small amplitudes of the sine wave the DAC output under closed loop control may oscillate at its maximum magnitude during the sine sweep particularly at higher frequencies This may cause motor amplifier and or mechanical structure damage Do not execute a sine sweep trajectory with a high max frequency if uncertain about the ability of the electromechanical hardware to withstand the current or torque demands generated by the sine sweep at high frequencies Finally the frequency response of the closed loop system may be obtained by selecting the Sine Sweep Trajectory option in the Trajectory menu Select a maximum frequency not more than five times the close loop bandwidth with a magnitude not greater than 1 4 of revolution of your motor with a period not more than 10 seconds After the end of
20. the sweep go to the Plotting menu select Bode Plot and then plot the frequency response for both magnitude and phase Once a satisfactory set of servo parameters is obtained they may be saved on PMAC with the on line SAVE command via the PMAC Terminal Position Loop Tuning 25 PMAC Tuning Pro Software Reference Manual Extended Servo Algorithm Sp Baa valet lnc ESA interacio Tuning Pomian Si hta Titi te 26 Position Loop Tuning PMAC Tuning Pro Software Reference Manual ESA Siructure Whenever a PMAC is ordered with its option 6 or a Turbo PMAC s Iyy00 is set to 1 the standard PID servo algorithm for each of the servo channels is replaced by ESA There are two feedback loops and one feedforward loop Typically in a dual feedback application the data from the sensor connected to the load would be directed via PMAC s Encoder Conversion Table to the feedback loop 1 The data from the feedback sensor connected to the actuator would be brought into the loop through loop 2 There are two feedforward paths The dynamic feedforward path operates directly on the reference commanded motor position which includes the hand wheel input This path can be used to compensate for dynamic lags which may otherwise cause following tracking errors The second feedforward path contains a simple sign of commanded velocity nonlinear operator which is intended to be used for dry static and or sliding friction compensation
21. value of this quantity is often non zero However it should be a small number if a responsive closed loop performance is desired If a large deadband is reported say larger than 500 bits there may be a potential for imperfect servo performance particularly when the gains are low However do not set x29 equal to the deadband The value of Ix29 should be set equal to the offset value Re DAC Offset Result Present Offset Suggested Offset Tet DAC Offset 129 2488 129 312 The measured open loop deadband ts 1864 DAC bits Graphical Offset Illustration Motor Velocity Open loop Deadband DAC Bits Calibrated Ix29 Value Open Loop Test This button opens to perform a repetitive sequence of open loop moves according to the values set in the Open Loop Magnitude Open Loop Time and Number of Repetitions fields The open loop move will be performed when the Open Loop Test button is clicked Press lt x gt to close this screen sas mac Tuning V1 0 PMAC 1 Wigs O2f2672001 Lb File aurrene loop Position Loop Trajectory Tools DAC Calibration Open Loop Test Regular PID Extend serva cl qarichn Filters Gantry PID Tr r F F 16 Position Loop Tuning PMAC Tuning Pro Software Reference Manual ee Open Loop Test This section of the program allows a repetitive sequence of open loop outputs from PMAC using its O command feature to be programmed This is useful for tuning amplifiers particu
22. 19 a TD Ii NEE AANE E E A A O E A A E EA E A E A 19 Regidlar PID Auo TUNNE aioe sictoa ea vdcisdg oSieasoa i EEEREN 20 Choices and Options in Auto Tuning osoooseeeeeeesessssesssssssseseeerrrsssssssssssssseeerrrresessssssssssseeerrerereessssssssseeeeeeresesse 22 D me an Aulo Tune SESSION ccas aE E E A ANS 24 Extended Servo Algorithm sii isivcconea sun tousudeveousranedoneednaceubacsiedbowedasdiarebeeedonne le avouleationlenshdeadeuudunnccesuusdnobinsdeassdadsoceiewslawnie 26 ESA Tnteracive TUUN icici thsi tn eck stadia snag na acdc cn oa wi cnc seals can TEENE EVOA EO Ghia tn ee ead 26 PEA TC cha oa cs erage ae stn sac ose oe cic cara sn NE E ches alee et soe eee see sates tense eee Lt SE ICTT O T DOC III sesh se Sorc el dasa na MN os aloctnc eee ens cag halon eas Some iadeds eb aasstepe tee oat emta eo aiganest 27 I variable Assignment and Numerical Specification of PMAC s ESA Controller ccccccccccccccssseeeececcceeecaaeeseeeees 28 PES POT IG esses otis EE cashes ee AOE estos ote EAE E at seas IE E a laa E E AE 28 Choices and Options in ESA AvUtO T UNI xsivasesiucwesdserssesersvndsviviasessoewasdedssesaosued essbavivlandssuswasthedtedegavsdaverendiessndees 30 Domne ank T SAI 1 UNE CS SIO ss inissipsian ines oh estensaeinsia ea pies TE rd eA OWS NUR OO 32 UCT EI sess serene pen ee ate ETE A OA TEE sence tect sunbeds ON IE A EN I E T T ON A E NS 33 Notch Filter Addition to PID Feedforward ooo00000nnnnnnnnenenseenennnnesseeeennnss
23. A A E OET S O AET 59 PRAC TOn H a E E E E ace 59 ADOD n S E E 59 ii Table of Contents PMAC Tuning Pro Software Reference Manual OVERVIEW Introduction Welcome to the PmacTuningPro Delta Tau s tuning utility The PmacTuningPro is part of the Delta Tau software suite With PmacTuningPro the different control loops in PMACs can be controlled and improved PmacTuningPro is a configuration tool as well as a diagnostic tool to help create and manage the various aspects of tuning the motors With PmacTuningPro the digital current loop gains can be configured and optimized the open loop operation of the motor can be verified servo command offsets can be calibrated position loop gains can be configured and optimized for standard PID loop as well as Extended Servo configurations for single motors and gantry systems and implement various position and velocity filters The position and velocity loop configuration can be tested using various trajectories In addition to the tuning functions PmacTuningPro provides real time plotting utilities motor status screen watch window position window and a simple terminal to help monitor and perform different tasks on a system Features PmacTuningPro provides basic tools for current loop tuning PID tuning extended servo algorithm tuning trajectories DAC calibration open loop test notch filter and low pass filter and real time motor status display Manual Layout This manual explains ho
24. After completing the above selection select the Begin Auto Tuning button This prompts the simple auto tuner to start the testing sequence Depending on the number of iterations selected there will be a number of backward and forward motions If the Pause between iterations option is checked the actual distance moved in each iteration will be displayed If the box is not checked the auto tuner will continue testing the system as many times as selected by the value in the Number Of Iterations Input option After the completion of tests the auto tuner computes the relevant terms of the ESA and displays them on the screen together with the existing terms for the selected motor The new terms may be discarded or accepted If accepted they are downloaded to PMAC automatically If undesirable behavior from that particular servo channel is noticed use the Kill button to open the loop and disable the amplifier Position Loop Tuning 29 PMAC Tuning Pro Software Reference Manual In the Trajectory menu the response of the system under the new set of servo controller parameters selected by the auto tuner may be examined Many types of moves including sinusoidal and sine sweep are available Note that without feedforward and or integral action there may be a considerable amount of following errors during faster moves particularly if the selected bandwidth is relatively low The new ESA parameters are not saved permanently within PMAC and will be lost upon
25. Fat l A UEBB Att AaS A oO Motor 1 Open Loop Test Plot Result Excuted at 2 40 45 PM 7232001 Ba 00 man w Se a a i zX i i l 0 i TE R E a l A ADD 00 AE 6008 05 0 40 a 1 150 JTE 2H a hpn HI Amn Tine mec YO oh oe an ine ene cure Gling re dee mage of the curren command and s deca seociy cure aunty Fa Pegler Styrene curred Garter TOR FEOIR E ECODOR CORRECTLY Commanded Curent Veini es DELTA TAU ryebems Mt ii Petit Position Loop Tuning PMAC Tuning Pro Software Reference Manual Regular PID Interactive Tuning Using interactive Position Loop Tuning in PMAC Tuning ideally should be only for fine tuning after automatic tuning generates the ball park figure for required gain settings In this section a simplified explanation of each gain and parameters will be done so that intelligent guesses can be made O 7 Ell Motor Aiai Step Hove iso 22767 M SCune Valonty Mowe in one denteon Fev P P Sinarcas pou Present PID Terms Ixx30 Kp Proportional Gain Increasing proportional gain stiffens the servo loop and increases the natural frequency of the closed loop system Theoretically increasing the proportional gain will result in improved positioning and tracking However often for real systems increasing the proportional gain increases their sensitivity to the noise and disturbances If skipping the auto tuning begin tuning with the low prop
26. Ix76 Current Loop Tuning 7 PMAC Tuning Pro Software Reference Manual Whenever a motor is being electronically commutated using the PMAC2 s field oriented commutation algorithm one of the first steps would be to tune the current loops A stable and responsive current loop is a prerequisite for a satisfactory motor torque control and subsequently motor velocity and position control Usually the process of tuning the current loop is carried out prior to setting up the PMAC2 commutation I variables i e Ix70 x79 Therefore it is important to note that the correct setup of the PMAC2 s commutation I variables Ix70 Ix 79 and Ix83 is not required for current loop tuning PmacTuningPro has two current loop tuning aids the Interactive Tuning and the Auto Tuning options Each option is discussed below Interactive Current Loop Tuning Eal Prmac Tuning v1 0 PMAC 1 1 937 D2 28 21 fee Prac Tuning 1 0 PMAC 1 Y1 937 d2f26f2001 Una File Current Loop Position Loop Trajectory Tools oC of AJTO INTER oP oP AUTO INTER Hoo Bl ea taht Cusrent Loop Ki he Curent Loop Epl 1n23 Fant Phose OfSet jo 00 Devel Time jarre moo o In79 Second Phase OS 64 Do A Curent Loop Slep fi Clore Kal Motor To tune the current loop adjust the gains x61 x62 and or Ix76 and then execute a step current command This step in current command is in fact a step in
27. Structure of ESA Diagram The following table specifies the corresponding I variable assignment and the numerical range of the discrete time polynomials within ESA 1x45 TS 2 to 2 1 stat 1010 0 909588 yf Ret 1010 0 999958 550 ff Ret 1010 099099588 1 0 to 0 99999988 23 1 0 to 0 99999988 Position Loop Tuning 27 PMAC Tuning Pro Software Reference Manual l variable Assignment and Numerical Specification of PMAC s ESA Controller Other scaling factors include the usual 32 Ix08 multiplied by the commanded position and loop 1 actual position 32 Ix09 multiplied by the Loop 2 actual position 32 Ix07 multiplied by the master hand wheel input In addition the DAC scale factor is 1x69 2 Note that the control effort is limited to 16 bits prior to final 1x69 2 scaling As a result x69 is now essentially a scale factor which also limits the control effort Therefore the function of x69 is somewhat different in relation to the standard PMAC PID servo loop For example if x69 is set equal to 16384 then the maximum magnitude of the DAC value is limited to 16384 5 volts and the numerical value of the control effort is multiplied by 0 5 prior to updating the DAC output or the commutation algorithm input whenever it is active In addition the servo cycle extension I variable Ix60 is no longer restricted to numerical values defined by 2 1 In fact Ix60 can be any integer number This feature allows evenly adjusta
28. This entry specifies the desired closed loop system s decay rate of transient oscillations In general low damping ratios ratios well below one lead to large overshoots and long periods of transient oscillations leading towards instability On the other hand high damping ratios ratios well above one lead to very sluggish motion Typical damping ratios should range between 0 6 to 1 Note that the higher the value of the damping ratio the higher the computed derivative action from the ESA controller and consequently the higher the quantization noise amplification leading to possible motor jitters In most applications a damping ratio of 0 7 to 0 8 provides a good trade off between transient response requiring more derivative action and quantization noise reduction requiring less derivative action If integral action is included even if the specified damping ratio is unity or above some overshoot may occur in response to a step input In addition if the Auto select bandwidth option is chosen the damping ratio is set to unity The default value of this entry is 1 Auto select Bandwidth This option is useful for situations in which the ranges of acceptable values of bandwidth is not known When this box is checked based upon the results of the auto tune tests a safe bandwidth is determined This in turn selects the ESA terms and their numerical values Typically the safe bandwidth is lower than the maximum achievable bandwidth but is more
29. Y ciis weer ede acces ce en cence dcbconeteceee E aE 5 ERE a A dere gocher A peice E E E ee seve Sloep wee EE AT E A A waren eewiaees 5 Select PMAC oeennnssssssssnnneeeeeesssssssssssssseecereesssssssssssssssseseceereresssssssssrssseceeeerssssssssssseseeceeeeessssssseeeeeeeerssssssssseeeeeeeeeeee 5 ODD SI PEEN NEEESE E S EEE A E SE E A AEN E N E 5 IY a E E E EE phe ae E A EAE E T E E O E A E E E EE E 5 VAL D CE 6 DOIG EIEEE EE AN E A E E AEE A A E EE 6 D E E E E E E E E aaceeeeee 6 ON e301 a T 6 CURRENT LOOP Wl Oi 0 Cee en ee ee er 7 Preparatory Hardware and I Variable Set Up c cccccccsseeeccecccccecccaeeaeeessseeeeececccceeeeeeeesaaaaaaassssseeeeeeeeeseeeseeeaaaaegees 7 Overview of PMAC2 Turbo PMAC2 and UMAC Digital Current Loop cc ccccccsnccccnsesseeeseeeeeeeeeeeeeeeeeaaas J Mipeacti Ve C rent Loop TONNE sas cxcaatce yacasaentcessoos sacausanaccesaeeantertdanateseuse vase sucesas aneia o aoia 8 A Typical Interactive Current Loop Tuning S SSION 1cccccccccccssseesceecceeecn ae eseeeeeeeeeaaeeseeeeeeesaaaesseeeeceseeaaaeeeeeeeaaas 9 Current Loop Anto Tumi orosesecdcenecensieasveseuasveasessaiiesdeensinasenon towusudneneddkarnnendronsuond ved Ea EA EEEa EEE Sae raai 10 Current Loop Auto Tuning Dialog BOX ccccccccccccccccssssseseeeeeeeeeeeeeeeeeeeeeaaaeeeeeeseeeeeeeeeeeeeeeeeeeaeeasaaaasseeseeeeeeeeeeeaaaas 1 Typical Automatic Current Loop Tuning Session ccccccccccsssscccccccccccnessseecceeeaeeaeseeseceeee
30. agnitude bets Damping fata e7 Eecdtethon Jime jma fan Lign Tayi Scale Facini nl fra Aig Select Dandeidits lor me Kind fir fnrwand paih C Goth Epi and Kp 10 Current Loop Tuning PMAC Tuning Pro Software Reference Manual The objective of the current loop Auto Tuner is to set up the PI gains automatically according to the desired values of natural frequency bandwidth and damping ratio The Auto Tuner carries out a number tests with a step stimulus fed into the direct magnetizing current loop During these tests the integral gain Ix61 is not used and the proportional gain x76 is set to a fixed value Based upon the result of the tests the program attempts to estimate the impedance of the motor winding and subsequently it calculates the required PI gains to achieve the desired natural frequency bandwidth and damping ratio Current Loop Auto Tuning Dialog Box l Bandwidth This parameter specifies the desired natural frequency of the current loop The specified desired current loop bandwidth should be at least 10 to 15 times the desired position loop bandwidth the position control loop should be tuned once the current loop tuning is completed and the commutation I variables are correctly set and the load is connected to the motor Furthermore a current loop natural frequency bandwidth of less than 100 Hz usually is not acceptable for a smooth low cog torque generation The attainable bandwidth
31. and repetition is selected After adding movement all motion programs code is available in the EditBox Select the blend mode or not then download the motion program to PMAC and run from the trajectory window 52 Trajectories PMAC Tuning Pro Software Reference Manual TOOLS Configuration This command displays Configuration Windows In this window set P variables range M variables range PLC Number Motion Program Number to use the PmacTuning Program and enable other PLCs or disable PLCs when tuning with PmacTuningPro 02 28 2001 UMAC TURBO USB Port Trajectory Tools Window Help ools Position Tools Window Help UMAC TURBO USB Port Configuration Terminal StripPlot Report Motor Status Position ae ad al INTER f Configuration While using this program many l P and M varnables will be modified Also a few PLO and motion programs will be created temporarily to perform necessary tests By default this program will use P6100 through P8191 M8100 through M8191 PLOSO and 31 and motion program 999 ou may however specify your own range of these variables if the defaults conflicts with Your configuration Tou may also speciy if you would like to keep your PLC s active during the test procedures Configuratio P varables M varlables B o0 to B 71 Pics jo Of Motion Program 999 Disable PLC s while testing Gherk sum Brable Save Coordinate Definition Can
32. and the maximum following error automatically These will be displayed on a plot of the position and the following error The feedforward terms are increased from zero working first with velocity feedforward until the ratios and hopefully the correlations are as close to zero as possible without going strongly negative If either correlation goes very far negative there will be overshoot at the end of a move To get meaningful correlation information particularly about acceleration push the system hard Increase the length and or decrease the time of the move to obtain higher velocities and accelerations Decreasing time is appropriate if increasing the length would cause problems with maximum travel or top velocity In a system without a tachometer set the velocity feedforward equal to the derivative gain or slightly greater In a system using a tachometer the velocity feedforward should be greater than the derivative gain When the parabolic move is processed without any feedforward there will be a very high correlation to velocity 1 0 and almost no correlation to acceleration 0 0 Usually there is a real correlation to acceleration but it is swamped out by the velocity correlation As the velocity correlation is reduced there should be increased acceleration correlation When the acceleration correlation is reduced the correlation to velocity may increase again but the actual ratio and magnitude of the following error should be very
33. at the motor amplifier connections and PMAC2 amplifier connections are correctly wired Select the Current Loop Auto Tuning option in the Executive program and select the desired motor number to be auto tuned Click on the Check Current Loop Polarity option If the result is positive feedback incorrect current feedback polarity stop Reverse the current feedback signal polarity and check again for the correct negative feedback sense before proceeding further Check the Auto Select Bandwidth option and select a safe Maximum Excitation Magnitude value see above The other options can be left at the default values A Damping Ratio entry between 0 7 to 1 0 should be used throughout the auto tuning activities Select the Plot Current Curves option and click on the Begin Current Loop Auto Tuning button There should be a number of step response curves depending on the selected number of iterations During these tests the integral gain is set to zero which means that there will be a steady state error between the desired and the actual step size This is intentional Finally a message box will appear displaying the calculated gains based on the bandwidth that the Auto Tuner has selected If during the auto tuning cycle the responses indicate excessive noise Current Loop Tuning PMAC Tuning Pro Software Reference Manual click on the Cancel button Try a larger value for the Maximum Excitation Magnitude entry and repeat the auto tuning cycle
34. ate servo loop numerically and servo stability concerns an excessively high value of the integral gain is discouraged Begin tuning with a lower value and observe the improvements If no integral action is desired set it to O Ixx34 IM Integral Mode Setting this value to O enables the integrator all the time and setting it to 1 enables the integrator only when commend velocity is zero Ixx35 Kaff Acceleration FF feed forward Gain This gain helps the tracking effort of the system Determination of this gain involves somewhat complex calculations but there are intuitive ways to apply this gain If your velocity plot try parabolic move for checking velocity following of the system shows bad tracking at initial acceleration or deceleration applying this gain will help Ixx29 DAC Offset If for some reason the amplifier or PMAC has DAC offset it is recommended for the first step that the DAC offset in hardware is zeroed manually enter o0 command in the terminal window and the adjust the voltage of the amplifier to zero volts by manipulating the potentiometer on the amplifier For the second step whatever offset cannot be corrected by hardware adjustment may be corrected in software level by setting the DAC offset Ixx69 DAC Limit If the amplifier has more power than the motor can handle make sure that the DAC limit is set so that excessive current will not burn the motor Ixx60 Servo Cycle Extension If the the l
35. ation procedure Therefore make sure that the motor 1s free to rotate an unknown number of revolutions during the calibration Number of test Iterations This is the number of backward and forward open loop motions in the testing cycle Value values are from 1 to 10 and the default value is 4 The calibration program averages the results automatically Begin Calibration Selecting this button begins the calibrating procedure Depending on the number of iterations selected and the motor s friction and open loop deadband characteristics the time necessary to complete offset calibration will vary What the procedure does is increment the DAC in small positive steps until positive motion is detected The DAC is then decreased in small negative steps until negative motion is detected This completes one iteration Position Loop Tuning 15 PMAC Tuning Pro Software Reference Manual After the test is complete the results of the calibration are presented showing the current and suggested values for Ix29 and the open loop deadband size in encoder counts This quantity is not the programmable PMAC deadband set by Ix65 but rather the hardware or open loop deadband resulting from the imperfections in the amplifier motor load combination This quantity equates to twice the number of DAC bits that need to be added to or subtracted from x29 to provide a noticeable motion in either direction Due to amplifier deadband and or friction in the drive the
36. ble servo sampling selection in sub multiples of the base servo interrupt frequency For example when I160 0 260 1 and I360 4 then the servo loop for channel runs at the servo interrupt frequency the servo loop for channel 2 is executed at half the servo interrupt frequency and the servo loop for channel 3 runs at 1 5 of the servo interrupt frequency The servo interrupt frequency is itself hardware jumper selected refer to the PMAC Hardware Reference manual The Deadband dry friction compensation I variable 1x68 may be set to a positive integer number in the range of 0 to 65535 At every servo cycle the magnitude of x68 is simply added or subtracted from the instantaneous control effort depending on the sign of the commanded velocity Finally other auxiliary servo parameter I variables of the standard PMAC PID in the range of Ix63 to x67 are not implemented in the ESA version ESA Auto Tuning Miadi Motor Traral felts poo Damping Patio 57 Minimum Motor Travel iced ecn it Be hy ie he a a r prec ESA Advance Dolket f lnclude Low Pees Filet TV Wetec feod Fiona T Acciona Fed Fora ESA AuboT ene 28 Position Loop Tuning PMAC Tuning Pro Software Reference Manual The Auto Tuning option opens the dialog box shown above The inputs check boxes and options within this dialog box are similar to the Auto Tuning dialog box of the Regular PID algorithm Prior to entering th
37. cation moves Execute it and plot the response If the response is not satisfactory due to unacceptable following errors re enter the tuner and increase the desired bandwidth Alternatively if the response is too noisy reduce the desired bandwidth and auto tune again until a satisfactory response is obtained A good trajectory to try first is the Parabolic Velocity The features of this trajectory are identical to the parabolic option in the PID tuning dialog box of the PMAC Executive program If there still exists some noticeable ringing at a fairly constant period which appears to decay with time and has a frequency not more than 10 times the closed loop bandwidth select the Notch Filter option to implement a notch filter On the other hand if there are persistent high frequency jitters buzzing reduce the Bandwidth and or the Damping Ratio and re tune again in order to decrease the servo response to this noise CAUTION Depending on the controller gain for even small amplitude of the sine wave the DAC output under closed loop control may oscillate at its maximum magnitude during the sine sweep particularly at higher frequencies This may cause motor amplifier and or mechanical structure damage Do not execute a sine sweep trajectory with a high max frequency if uncertain about the ability of the electromechanical hardware to withstand the current or torque demands generated by the sine sweep at high frequencies Finally obtain the frequ
38. cel Ok P variables Set at least 50 variables between Start P variables and End P variables M variables Set at least 50 variables between Start M variables and End M variables PLC number Set 2 legal plc numbers to use in PmacTuningPro Motion Program Set legal motion program number to use in PmacTuningPro Disable PLCs while testing Checkbox Enable or disable any other currently running PLCs whole doing auto tune or trajectories Check Sum Enable Checkbox Set enable or disable when data is uploaded using check sum or not in serial communication mode Save Coordinate Definition Checkbox Set enable or disable when trajectories are performed to save the coordinate definition and restore the coordinate definition after done trajectories Tools 53 Terminal PMAC Tuning Pro Software Reference Manual This button calls a terminal window that can be used to send on line commands and to query variables from PMAC 02 26 2001 UMAC TURBO USB Pork Trajectory Tools Window Help P Configuration of 7 a StripPlot Report Motor Status Position M611 3 MG113 P6107 Mel 21 Mb102 WHILE M81 02 Ma1 21 lt P8106 ENDYY Ml 13 81 13 P107 M8l22 W8102 WHILE M81 02 M8122 lt P8106 END M81l19 0 DISPLC3I Pa101 123 RET 7419 2001 12 12 40 PM 1 100 Previous Command list ple 31 ve Send any command or see return value by return key See the current motor number coordinate n
39. commanded position as a sine wave of a given frequency The option is very useful for testing the frequency response of the closed loop system at a particular frequency The Amplitude size is incremental from the present command position The Frequency is in units of Hz and the number of sinusoidal cycles is specifed Sine Sweep Trajectories CAUTION Depending on the controller gain for even small amplitude of the sine wave the DAC output under closed loop control may oscillate at its maximum magnitude during the sine sweep particularly at higher frequencies This may cause motor amplifier and or mechanical structure damage Do not execute a sine sweep trajectory with a high max frequency if uncertain about the ability of the electromechanical hardware to withstand the current or torque demands generated by the sine sweep at high frequencies Sine Sweep Amplitude cts fio Start Frequency Hz fo End Frequency Hz fo Sweep Iimelsec fio Do A Sine Sweep Move Kill Motor After Sinusoidal Move Sweep Method Domain gt Logarithmic Time Frequency i Linear 51 PMAC Tuning Pro Software Reference Manual The Sine Sweep dialog box allows the entry of commanded position as a sine wave of varying frequency This option is useful for testing the frequency response of the closed loop system through a range of frequencies From the resulting sine sweep a bode plot may be obtained within the Plot
40. continue however until the specified number of iterations is completed subject to the specified travel limit The default value is 4000 feedback counts Minimum Motor Travel This entry allows checking if in fact a detectable motion took place If the Max Excitation magnitude is relatively low and the Number of Iterations is relatively high the first iteration s peak DAC output may become too small As a result no detectable motion may take place during the excitation time By selecting an acceptable number of counts for the Minimum Motor Travel erroneous gain estimations can be avoided In general this entry should correspond to at least 30 degrees of motor rotation The default value is 400 feedback counts Bandwidth This entry allows specifying the closed loop system s speed of response and servo stiffness In general the higher the value of the bandwidth the higher those computed terms of the ESA which correspond to the error proportional gain In practice typical closed loop bandwidths range from 4 Hz for very large motor load inertia systems to 100 Hz for very high gain amplifiers driving extremely light motor load inertia systems Note that if the Auto Select Bandwidth option is checked the program selects a lower bound safe bandwidth automatically which will appear in this box after the tests The default value is 20 Hz Damping Ratio This entry specifies the desired closed loop system s rate decay of transient oscillations
41. does depend on the amplifier and the motor phase winding impedance For low impedance motors bandwidths as high as 500 Hz or more may be achievable without saturating the gains For high impedance motors saturation limits may be experienced 1f the desired bandwidth is set too high Usually bandwidths in the range of 200 to 500 Hz are acceptable for most applications Damping Ratio This parameter specifies the desired damping ratio which is a measure of how fast the current loop transients settle down or dampens out A suitable numerical value for the desired damping ratio is between 0 7 and 1 0 Auto Select Bandwidth When this box is checked the Auto Tuning algorithm selects a conservative lower bound bandwidth automatically replacing the Bandwidth entry above This option is useful for providing a shortcut in the convergence process to the maximum achievable current loop bandwidth for a given amplifier motor combination When this box is checked the Auto Tuner uses internal calculations on the results of the step stimulus tests to determine a conservative bandwidth The recommended procedure is to check this box and carry out an auto tuning cycle noting the automatically calculated bandwidth displayed in the Bandwidth entry Then uncheck this box and gradually increase the Bandwidth entry Carry out another auto tuning cycle until one of the gains saturates The final selected gains should be those that provide the highest bandwidth without
42. e After Hove 500 ms The Trapezoidal Velocity input test profile provides a forward reverse trajectory with a constant acceleration rate You select a desired acceleration time as well as the peak velocity If the peak velocity could not be reached due to the indirectly specified acceleration rate then a triangular velocity profile will be generated After the Velocity Feedforward gain has been fine tuned with either the Parabolic Input or the Ramp input use this trajectory in order to fine tune the Acceleration Feedforward gain 1x35 during the acceleration deceleration phase of the trajectory Trajectories 49 PMAC Tuning Pro Software Reference Manual pent ey bee at ay P z ing x Ft A EBRE oP Ce AGE ptor Al Trapezoidal Move Flot Resa gt Executed at 1239 55 PM Sedo E f i zem eet n am aD ns al E papai Te pe I F aiie Cea lid I ae eee re Cire Lord re ee eee l T i BS ae ar TE T I as a ri i S Curve Velocity 5 Curve Yelocity Move Distance cts 10000 Velocity cts sec fi 0000 Acceleration cts msec 100 Humber of Repeats 1 Do 5 Curve Move Kill Motor After 5 Curve Move Move in only one direction Dwell Time After Move 500 ms The S curve Velocity input test profile provides a forward reverse trajectory with a constant rate of change of acceleration or constant jerk Select a desired acceleration time as well as the peak velocity If the pea
43. e ESA auto tuning session for a particular motor make sure that the motor is under closed loop control Typically the default gains with which the PMAC boards are shipped are low enough and may be used as the initial gains for the start of a session Furthermore large offset bias signals and deadband characteristics between the amplifier and the PMAC s DAC outputs should be reduced to a minimum by the use of Ix29 and x68 variables When the ESA Auto Tuning dialog box is opened select the appropriate options prior to the start of an auto tuning session These include e Type of amplifier used with the selected motor current mode or velocity mode e Maximum excitation magnitude as of DAC output 100 represents a DAC value of 32767 increments or 10 volts nominal Note that depending on the type and the gain of the motor amplifier any given excitation as of maximum DAC output is equivalent to a certain current or voltage command to the motor One should not demand more current or voltage than the maximum recommended value as specified for any particular motor amplifier by its manufacturer e Excitation time in milliseconds Should be long enough to generate about 1 4 to 1 2 of motor revolution e Number of test iterations Usually two times is sufficient e Design goals in terms of bandwidth and damping Select Auto select Bandwidth if a reasonable value for the closed loop bandwidth cannot be chosen This gives a safe lowe
44. e PWM output the current feedback signals and if necessary Amplifier Enable signal are all correctly connected between the motor and the Digital Amplifier WARNING It is both unnecessary and possibly dangerous to have any mechanical load connected to the motor during a current loop interactive tuning session During the execution of the current loop step the Executive program has to increase the servo frequency to be the same as the phase frequency for data gathering purposes In addition all other motor channels are disabled momentarily I x00 is set to zero for all motors other than the one being tested until the end of the step test It is therefore most important that no load is connected to any of the motors being controlled by a PMAC2 while any other motor s current loop is being tuned Current Loop Tuning 9 PMAC Tuning Pro Software Reference Manual Select a Step Size equal to the size of the magnetizing current I variable x77 used in the test The size of the step should be sufficiently large to overcome any possible amplifier deadband and other low amplitude non linearity and noise On the other hand it should not be too large to avoid any possible inadvertent motion of the motor due to incorrect setting of the commutation parameters A Step Size of 5000 bits is usually a good starting point In most cases a Step Time of between 50 to 100 milliseconds should be sufficiently long for this test By clicking on the Current Loop Ste
45. e aa Cal a i in on 600 004 a l Ba H i ra E gwi i a E Th x H E Hi ac i Tare rie se Tie Penk Tiresa A 9 Baha Pee ed He Cee Sede Se herr i Tir fl Ceneri Leop Gera indeed Gann Fae ee 0H ee Posed Pei Proportional Gam Ap ot pe Dniem Pah Proprio Gain Red ETE 1 a See Se lars A Typical Current Loop Step Response In summary increasing the integral gain x61 increases the natural frequency speed of response but also reduces the damping ratio increases the settling time To compensate for the reduction in the damping ratio one should increase either or both of the proportional gains 1x62 and or Ix76 The choice between the two proportional gains is often dictated by a trade off the noisiness of the current sensor verses the resolution of the velocity sensor pointed to by Ix04 For systems with low resolution velocity sensors it is best to use Ix76 the feedback path proportional gain instead of x62 the forward path proportional gain For systems with noisy current sensors it is best to use x62 instead of Ix76 In general for a given numerical value of the proportional gain when it is implemented through Ix62 a faster response is achieved However the response may have somewhat more overshoot A Typical Interactive Current Loop Tuning Session Prior to using the Interactive Current Loop tuning option make sure that the pertinent I variables see above have been set up and that th
46. e following error curve it no longer resembles the velocity curve correlation of 0 211 Also the maximum following error is reduced from 112 to 9 6 counts Modified Parabolic Move with Increased Kvff 1x32 mili bees HIE A RBA wee CAs AGE itor Er Parabolic Move Pict Result beecuted af 2 50 40 FPH Tree J ae ae rere See i Lari aripa JEEE Lai Foi arey Erra i Pai Trajectories 47 PMAC Tuning Pro Software Reference Manual Modified PORRE Move with Ix34 Sei 3 Ae EIB TS ace dag sen j Motor ne ra meas Executed si Fa 5 Pe Tasan Eer TET Erala j Tet iain ce il fF wee ice lim rity ifi lida i i s i TE j Fit Hi WT i F amir fll TRY pih E ii i J5 i i 7 I k Cimi ri ANIN AA i i E Ty Lo A gi l i LF it TE 2 PRUIM a p Tin iff es ica m r a ii am EN wN Ln EJ DEI ET E Jia Pra Cir el er a Cae a eG emits kaa Seen ch ee THp Pe eee ee ory Bee ee r F ar te tare Cees Ue se eel ed ee ES Pee Cpe eee ie Prim Fee rel ey i Teki Peiqerineg Some Les Ber Tie Command Yalocty Lat ach aoc Lat Paing Er Pint min Now we instruct the integration in the servo loop to be active only when the motor is not be commanded to move To do this set Ix34 the integration mode equal to 1 The improvement is seen above If Kvff is increased more then the following behavior will exhibit where the following again resembles the velocity curve but in an inverted manner Modified
47. e on a small DC laboratory motor with virtually no load so the response is faster than it would be in almost any real world application The actual times are not important However the shapes of the response curves are This system has a current controlled amplifier with no tachometer The goals of this system are critically damped step response the quick elimination of steady state errors at rest and the minimization of following errors Initial Step Move Response The screen below shows the step response with very little damping added derivative gain Kd 500 The large amount of ringing is unacceptable therefore some more Kd is needed The next figure shows the response with an increased Kd of 1100 The ringing is largely eliminated there is an overshoot of 54 and a rise time of 24 msec Try to make the quicker which means a es system at tech e WE Eb avana AGE Motor 2 Step Moye Plot Result Executed 2 10 47 PM Tao Pb ett Trajectories 4 PMAC Tuning Pro Software Reference Manual Modified Step jjj lee with al J Kd 1x31 TIESAI ahe ren histor 2 Sep Move Plot Result Executed at 2 12 i Pr Tivo x z E 1h AE wt Sal PL ME HAI H lim i d aa Pee Tep p ee e hea real A ee Teee eee ee iee E a Aomori Caan Le e Geen n ih e Fi le a Gam eD Wg a a Ee Te e fa pe L Fa a a fa E ei l Creed id h e r Dee ee TE Ree ee eee el Moen Peete a amr eiet Papas are per Lead Rat fa C
48. e sets Even if two sets of data are very well correlated the ratio may be so low that one of the sets is negligible in practical terms Trajectories 45 PMAC Tuning Pro Software Reference Manual For each move done the program will calculate the correlation between velocity and following error and between acceleration and following error It will also calculate the average ratio between following error and both velocity and acceleration As a feedforward gain is increased the ratio of following error to that quantity will decrease linearly e g if a gain of O produces a ratio of 12 0 and a gain of 5000 produces a ratio of 6 0 then a gain of 10 000 can be expected to drive the ratio to zero The ratio will decline even as the correlation stays high When the ratio gets small enough the correlation should decrease as some other factor becomes the dominant cause of following error e g noise or the other feedforward gain Ideally the correlation will be brought near zero as well as the ratio PMAC has two feedforward terms 1 Kvff Velocity Feedforward gain 1x32 2 Kaff Acceleration Feedforward gain 1x35 The strategy in this section is to do a series of parabolic moves cubic in position parabolic in velocity linearly varying in acceleration while adjusting the feedforward terms to reduce the following error and its correlation to velocity and acceleration After each move the program will calculate the correlations and ratios
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50. econd order systems Current controlled motors driving inertial loads are second order systems In a step response a sudden change is made to the command position and the feedback filter attempts to bring the system to this new position In observing how the system gets to the new position we can deduce a great deal about the properties of the system It does not matter that such a large instantaneous step in position in the actual operation of the system will ever be created The purpose of this jolt to the system is to bring out system characteristics that might otherwise not be obvious This detailed information on the PID filter is not essential to performing the tuning but is included here for reference PMAC has three feedback parameters to be adjusted in this process 1 Kp Proportional gain 1x30 2 Kd Derivative gain 1x31 3 Kai Integral gain 1x33 We will be looking at three key step response parameters to set the feedback Rise Time The time it takes the system to go from 10 to 90 of the commanded step Natural frequency is directly related to this Overshoot The percentage past the commanded step that the system travels Damping ratio is directly related to this Settling time The time it takes the system to get and stay within 5 of the commanded step Typically what is desired is a quick rise time with little or no overshoot and quick settling time The case of critical damping which is the fastest poss
51. ency response of the closed loop system by selecting the Sine Sweep trajectory under the Trajectory menu Select a maximum frequency not more than five times the close loop bandwidth with a magnitude not greater than 1 4 of revolution of the motor with a period not more than ten seconds After the end of the sweep go to the Plotting menu select Bode Plot and then plot the frequency response for both magnitude and phase Once satisfactory servo parameters are obtained save them on PMAC using the on line SAVE command via the PMAC Terminal option under the Utilities menu and or backup the I variables on the host PC via the Back Up PMAC I Variables option under the Utilities menu Filter Notch Filter Addition to PID Feedforward PMAC Tuning allows the setting up of a notch filter easily without the need to understand how a notch filter works 0 PMAC 1 1 93F 02 28 2001 UMAC TURBO USB Port Position Loop Trajectory Tools Terminal Tools Wind DAC Calibration Open Loop Test Regular PID H Extend sera aganti F Filters Gantry PID d Motch Filter Low Pass Filter Position Loop Tuning 33 PMAC Tuning Pro Software Reference Manual reo Hemove Noleh File all Watne dI First select a motor using lt PgUp gt or lt PgDn gt Next enter the frequency of the mechanical resonance to notch out If the Auto Calculate Frequency Specifications checkbox is selected then select Implement Notch Filter The notch f
52. g errors proportional to motor acceleration caused by inertial lags If such lags are acceptable then there will be no need for the use of this particular action and the check box may be left empty Integral Action In general integral action is required only if the existing amount of friction and or torque force disturbances cause an unacceptable level of steady state following errors If this happens to be the case for a particular application then try a small amount of Integral Action value of Ix33 and gradually increase the amount of Integral Action for faster rise time Pause Between Iterations Check this box interested in seeing the distance traveled during each iteration step Usually the first time in an auto tuning session this box is activated Once the optimum values for the Excitation Time and the Minimum Maximum Travel Limits are set there will be no need to pause between test cycles or iterations Doing an Auto Tune Session The following provides some guidelines for typical auto tuning activities when using the Regular PID auto tune method 1 Use the JOG command or otherwise move the motor to a safe position where both forward and reverse motions of at least twice the size of the Maximum Travel Limit are acceptable 2 Ifnecessary in the Tuning menu select the DAC Offset Deadband Calibrate option to adjust x29 and Ix68 note that for PMAC commutated motors Ix29 should not be implemented 3 Next select the Auto Tu
53. g if need be Read the readme32 txt file for last minute additions to this manual Setting up Communications with PMAC No applications including PmacTuningPro will be used to add remove or configure PMACs in the system Rather communication settings have been centralized in the operating system making the set up of each PMAC much like other devices in the computer i e video card sound card etc All setup is done through the Control Panel s Add New Hardware wizard Installation steps as provided in the Pcomm32 Pro Installation manual will help with installing and registering the newly installed devices Before running this application it is important that all applications that use PComm32 the Delta Tau 32 bit communication driver be shut down This includes PmacTuningPro Pewin32Pro NC for Windows and any applications developed with PComm32 or PTalkDT Getting Started 3 PMAC Tuning Pro Software Reference Manual Getting Started PMAC Tuning Pro Software Reference Manual MENU OVERVIEW This chapter describes the File menu and the Window menu All other menu items are explained in the respective chapters Ea Prac Tuning 1 0 PMAC 1 1 937 O2 26f2001 UMAT TURBO USB Pork File eurent laap Position Loop Trajectory Tools Window Help mrs DAC Calibration Open Loop Test A PS oy Regular PID Auto Tuning Extend serma Slgarithinm F Interative Tuning Filters Gantry PID File Menu Select
54. i OFF Amplifer is Enabled Positrve Limit is Off Negative Limit i OFf Motor Position Loop i closed The current motor status is shown in real time Current motor activated or not 1x00 Current motor commutation enable or not 1x01 Current motor current loop feedback address 1x82 PMAC2 type only A zero value for x82 tells PMAC2 not to close the current loop for this motor Current motor amplifier fault bit is on or off Current motor amplifier enable bit is on or off Current motor positive limit bit is on or off Current motor negative limit bit is on or off Current motor position loop mode is killed opened or closed 56 Tools PMAC Tuning Pro Software Reference Manual Position This button calls a position window that can be used to show current position value in real time alp 8 Ex 02 28 2001 UMAC TURBO USB Port Configuration Terminal StripPlot Report Motor Status Position PMACIV1 937 oz za z001 UmMac Bim Ea Select which motor position value to display by clicking the right mouse button and opening Select Motor Command Set Font Size Color and Background by clicking right mouse button and Selecting Open Command Tools 57 58 PMAC Tuning Pro Software Reference Manual Tools PMAC Tuning Pro Software Reference Manual HELP PMAC Tuning Help This button opens a Help window that can be used to help using PmacTuning Program URBO USE Port
55. ible rise time that creates no overshoot is often the goal There are usually tradeoffs between these parameters particularly between fast response and low overshoot If the amplifier has a tachometer the tachometer is providing derivative gain and therefore damping within the amplifier itself If the amplifier has been well tuned it is not necessary to add more derivative gain in the digital filter but can be if desired On PMAC it is possible to have the error integration active at all times by setting x34 to 0 or to have it active only when the motion is stopped by setting x34 to 1 While the step response for these two cases will look essentially identical the behavior on real moves will be very different Error integration that is active at all times can reduce following error on an extended profiled move but at the cost of reduced system stability and of overshoot at the end of the move which makes up for the lag at the beginning of the move In a system without feedforward the close following may be worth these costs But the velocity and acceleration feedforward terms in PMAC can virtually eliminate following error without these drawbacks For this reason most PMAC customers use error integration only when motion is stopped where it can eliminate steady state errors due to static friction or net torque loads Proportional gain term Kp x30 also affects derivative and integral gains and is not strictly speaking a true proportiona
56. ilter coefficients 1x36 Ix39 will be calculated automatically and displayed on the left and these new coefficients will be downloaded to PMAC Resonant Frequency This value is the actual frequency in hertz to notch out in the servo loop To determine which frequency this is do a step move from the tuning screen and measure this frequency from looking at the plot of the step response Auto Calculate Frequency Specifications This checkbox allows the Executive to determine the necessary other frequencies and their respective damping ratios in order to calculate the notch filter coefficients In most cases this option should be selected Lightly Damped Zero Frequency In practice typically this frequency is a value 90 of the resonant frequency Remember that this value is calculated if the Auto Calculate Frequency Specifications checkbox selected Lightly Damped Zero Frequency Damping Ratio In practice typically this damping ratio is a value of 0 2 Remember that this value is calculated if the Auto Calculate Frequency Specifications checkbox selected Heavily Damped Pole Frequency In practice typically this frequency is a value 145 of the resonant frequency Remember that this value is calculated if the Auto Calculate Frequency Specifications checkbox selected Heavily Damped Pole Frequency Damping Ratio In practice typically this damping ratio is a value of 0 8 Remember that this value is calculated if the
57. indaw Help About This button opens an About window that can be used to show version of PmacTuningPro and copyright TURBO USB Port vindow Help PriacTuning Helo Fi DELTA TAU Data Systems Inc RER DEAS M MOTICIL Pmac Tuning Version 1 0 0 0 Beta Jul 19 2001 ww Celtatau com Copag c 2000 2001 Dela Tau Date Spiere INC Ths pogam i paesed by US and intamationsl copyright laers jo Help 59
58. ing dialog box again and check and record the value of bandwidth selected by the tuner This will appear in units of Hz in the Bandwidth box Then exit this dialog box Now go to the Trajectory menu and select Step In the Setup dialog box choose a reasonable step size typically between 1 4 to 1 2 of motor not necessarily load revolution Execute the step move Now go to the Plotting menu and select Actual position and Commanded Position both on the left hand side and plot If the natural frequency evaluated from the step response is within 10 to 20 of the selected bandwidth the tuner has done a good job If the reported natural frequency is not close enough say within 10 to 20 to the desired bandwidth selected in the auto tune dialog box try tuning with more less excitation magnitudes and excitation times If the step response is satisfactory go back to the Auto Tune simple dialog box and if there is a constant following error add some Integral action Check the feedforward actions if tracking errors are to be minimized and Low Pass Filter if noise induced jitters are noticeable Re tune and implement the new controller then exit the dialog box Now go back to the Trajectory menu and this time choose a trajectory which is typical of the application moves Execute it and plot the response If the response is not satisfactory due to unacceptable following errors re enter the tuner and increase the desired bandwidth Alternatively if
59. ion sensors are used Kp1 and Kp2 When this radio button is selected the required proportional gain determined by the Auto Tuner will be implemented partially in the forward path and partially through the feedback path Here an attempt is made for the trade off between a low resolution position feedback signal and a noisy current feedback signal in selecting these gains Typical Automatic Current Loop Tuning Session Prior to any attempt to use the Auto Tuner for the Current Loop make sure that the pertinent I variables see above have been set up and that the PWM output and the current feedback signals and if necessary Amplifier Enable signal are all correctly connected between the motor and the Digital Amplifier 12 WARNING It is both unnecessary and possibly dangerous to have any mechanical load connected to the motor during a current loop auto tuning During the execution of the auto tuning tests the Executive program has to increase the servo frequency to be the same as the phase frequency for data gathering purposes In addition all other motor channels are disabled momentarily 1x00 is set to zero for all motors other than the one being tested until the end of the step test Therefore it is important that no load is connected to any motor being controlled by a PMAC2 while any other motor s current loop is being auto tuned Make sure that no load is connected to any of the motors being controlled by the PMAC2 board and th
60. is dialog box 10 If the Auto Select Bandwidth box was checked enter the simple auto tuning dialog box again and check and record the value of bandwidth selected by the tuner this will appear in units of Hz in the Bandwidth box Then exit this dialog box 11 Now go to the Trajectory menu and select Step Enter the Setup dialog box and choose a reasonable step size typically from 1 4 to 1 2 of motor not necessarily load revolution Execute the step move 12 Now go to the Plotting menu and select Outer loop position and commanded position both on the left hand side and plot If the natural frequency evaluated from the step response is within 10 to 20 of the selected bandwidth the tuner has done a good job 13 If the reported natural frequency is not close enough e g within 10 to 20 to the desired bandwidth selected in auto tune dialog box try tuning with more less excitation magnitudes and excitation times 14 If the step response is satisfactory go back to the Auto Tune simple dialog box and if there is a constant following error add Soft Integral action Check the feedforward actions if tracking errors are to be minimized and Low Pass Filter if noise induced jitters are noticeable Re tune and implement the new controller Then exit the dialog box 32 Position Loop Tuning PMAC Tuning Pro Software Reference Manual 15 16 17 Now go back to the Trajectory menu and choose a trajectory that is typical of the appli
61. is driven by the test signal is entered here This period should be chosen carefully It should be long enough for noticeable motion to take place at least equal to Minimum Motor Travel On the other hand too long a period may result in excessive travel and or excessive motor velocity In most applications excitation times between 50 and 100 milliseconds should be sufficient For motors having very large inertia loads large excitation times may be appropriate The default value is 50 ms Number of Iterations This refers to the number of backward forward motions in the testing phase of an auto tuning session If a number greater than one is chosen then the peak DAC output for the first iteration is determined by dividing the value in the Maximum Excitation Magnitude field by the value in the Number of Iterations field In this way the last iteration always corresponds to the value in the Maximum Excitation Magnitude Input field The default value is two iterations which is sufficient for most applications WARNING Depending on the size of the excitation signal and the responsiveness of the servo loop implemented while tuning it 1s possible that the actual motor travel may go past the Maximum Motor Travel limit Maximum Motor Travel Specify independently the maximum travel limit during the tests If this distance is reached the loop is immediately closed and the motor is commanded to jog back towards its original position The test will
62. isible in the right side plot Timer Set the data update time interval Report This button calls a report window that can be used to see tuning related I variables n2i26 2001 UMAC TURBO USB Port Report Tools 55 PMAC Tuning Pro Software Reference Manual Peas Vi O37 OF fi UMAC TULED USA Pes 7AL2 12 77 17 PH l ELOD i Horari Activation Control MTOI Pmarc Commint ate Enable Matari Current Lop Feedback Address atari Fatal Following Error Limit rida pla MOTOFI GurputT or Flrat Phasge PAC mM OTOP PID Proportional cain eOToOrL FIO Ger ival ive Gain SeoTOrL PIO Welocity Feedforward cain OTOL PID Tategral Gain MOTOFI PIO Acceleration Feedforward Ga stor Motch Filter Coefficient Wi i t ri K tih Filter Coefficient HZ sMotorl Hotch Filter CoefFictent Di Motarl Ketch Filter Coefficient be Integrated Current Limit Serva Cycle Extension Period Friction Feedforwar Cutput Command Limit scale Second Phase Output 145 mi i i i ir A SSS e5 rr The I variables that relate PMAC tune values can be viewed and the report can be printed or saved to a file Motor Status This button calls a motor status window that can be used to show current motor status in real time Configuration Terminal StripPlot Report Motor Status Position as Motor Setup Summary Motor 1 is enabled and 1100 1 Motor 7 is nor cormmutated and 1101 0 Motor 1 s 182 0 Digital Current Loop inactive Aroplifer Fault bit
63. itation Magnitude entry divided by the Number of Iterations entry In most cases one or two iterations should be sufficient for a successful identification of the current loop parameters Current Loop Tuning 11 10 PMAC Tuning Pro Software Reference Manual Plot Current Curves When this option is checked the results of the direct current test stimuli for each iteration step are shown graphically Note that since all the test stimuli use only the proportional gain the steady state response is likely to show a value that is smaller than the desired step Kp1 in feedback Path When this radio button is selected the required proportional gain determined by the Auto Tuner will be implemented in the feedback path through the use of Ix76 Choose this option if there is a low noise current feedback signal This implementation of the proportional gain in the feedback path helps reduce the quantization noise effects from the position sensor It is useful particularly when low resolution position sensors are used Kp2 in forward Path When this radio button is selected the required proportional gain determined by the Auto Tuner will be implemented in the forward path through the use of Ix62 Choose this option if excessive noise is observed in the current feedback signal This implementation of the proportional gain in the forward path may amplify the quantization noise effects from the position sensor Avoid this option when low resolution posit
64. k velocity could not be reached due to the indirectly specified acceleration rate then a parabolic velocity profile will be generated After the Velocity Feedforward gain has been fine tuned with either the Parabolic Input or the Ramp input use this trajectory in order to fine tune the Acceleration Feedforward gain 1x35 during the acceleration deceleration phase of the trajectory Note that the S curve Velocity input does provide a controlled rate of change of acceleration deceleration which in turn reduces the mechanical stress on the drive system However for the same acceleration time and final speed the peak value of acceleration will be twice the Trapezoidal input 50 Trajectories PMAC Tuning Pro Software Reference Manual Sinusoidal CAUTION Depending on the controller gain for even small amplitude of the sine wave the DAC output under closed loop control may oscillate at its maximum magnitude during sine trajectory particularly at higher frequencies This may cause motor amplifier and or mechanical structure damage Do not execute a sinusoidal trajectory with a high frequency if uncertain about the ability of the electromechanical hardware to withstand the current or torque demands generated by the high frequency sinusoidal input Sinusoidal Amplitude cts fi 000 Frequency Hz fo Number of Repeats fio Do A Sinusoidal Move Kill Motor After Sinusoidal Move The Sinusoidal dialog box allows the entry of
65. l gain For this reason if Kp is modified when Ki 1x33 or Kd 1x31 is not equal to zero the effective integral or differential gain is changed also The shape of the response curve will not change much although the timing will Change Ki and or Kd in the opposite direction from Kp to keep their effective gains constant Feedforward will affect step response even though it has no effect on the system stability we are really evaluating Be sure that both acceleration and velocity feedforward are set to zero while processing the step responses The default step size of 100 encoder counts may or may not be adequate The guidelines are to make the step large enough so that the granularity of the position measurement is not a nuisance but small enough so that the filter does not saturate on the step the step size times proportional gain should be less than 178 950 000 with some margin for instance a step size of 3000 with a proportional gain of 60000 will saturate giving a misleading response Some systems will have mechanical resonances in the coupling of the motor to the load The PID filter cannot compensate for these resonances if their presence is not tolerable keep the gains low enough not to stimulate them or preferably stiffen the coupling to reduce the resonances 40 Trajectories PMAC Tuning Pro Software Reference Manual ang the Step Response Set a safe starting filter with a little proportional gain with no or almost no deri
66. larly if the selected bandwidth is relatively low Choices and Options in Auto Tuning Amplifier Type This selects the type of amplifier used The default value is for a current loop amplifier If either an analog tachometer loop is closed within the amplifier or the amplifier operates without current feedback in voltage mode the Amplifier Type should be changed to velocity loop CAUTION Exceeding the safe limit for DAC output specified in Maximum Excitation Magnitude for a particular setup could damage the power amplifier the motor and the mechanical structure connected to the motor Maximum Excitation Magnitude This is the size of the largest DAC signal given as a percentage value of 10V For example if only two iterations are placed in the Number of Iterations field and the Maximum Excitation Magnitude field is 100 then in the first iteration the maximum DAC output will be 5V and in the second iteration it will be 10V Choose this parameter carefully In general it should be large enough to overcome friction and other disturbances so that some motion actually does occur On the other hand it should not be so large as to cause amplifier motor or mechanical damage because of excessive torque command Consult the amplifier and motor specification The default value is 30 22 Position Loop Tuning PMAC Tuning Pro Software Reference Manual Excitation Time The period of time in milliseconds in which the DAC output
67. larly those with tachometer feedback It can take the place of special hardware devices that perform the same purpose In addition it has safety features that no hardware device can have automatic shutdown on exceeding programmable velocity and position limits It also uses data gathering and plotting to display the results of the stimulation velocity position and acceleration versus time eliminating in many cases the need for an oscilloscope to do the tuning Set the open loop magnitude which is expressed as a percentage 0 100 of the value stored in Ix69 Ix69 holds the maximum allowable output magnitude in binary bits which can range from 0 to 32767 corresponding to 0 to 10 volts The factory default for Ix69 is 20480 which is about 6 3V but many users reset this to the full 32767 The open loop time specifies the time duration of the on state when a positive or negative value is written to the DAC output for the open loop move The Open loop zero time specifies the time duration of the off state when a value of zero 0 is written to the DAC output for the open loop move No of reps specifies the number of repetitions for the open loop move cycle A value of zero 0 indicates infinite repetitions until the space bar is pressed When the open loop program is executed the moving motor s velocity will be limited to the velocity limit as specified by Ix16 This is intended to protect the system by preventing it from moving too fas
68. ld also be inspected and if necessary modified accordingly The relevant per motor I variables are Ix00 Ix01 Ix02 x66 and Ix82 which should all be set up correctly Overview of PMAC2 Turbo PMAC2 and UMAC Digital Current Loop The field oriented electronic commutation algorithm used on PMAC2 requires the closure of two feedback loops around the motor current vector in the field frame This algorithm transforms the digitized values of the motor phase currents to a current vector in the field frame and then resolves the vector into two components the torque producing quadrature current Iq and the field producing direct magnetizing current Ig Each component of the feedback signal is independently utilized for the regulation of Ig and Iq using a Proportional plus Integral PI control algorithm The pertinent motor I variables for current loop tuning are Ix61 the current loop integral gain K Tx62 the current loop forward path proportional gain Kp x76 the current loop feedback path proportional gain Kp1 Ix66 the PWM Scale factor Ix66 the PWM Scale Factor must be set correctly according to the chosen PWM frequency i e x66 should be set to a value slightly greater than 1900 or 1906 Once Ix66 is set to a reasonable value it should not be altered as any modification of this variable will affect the loop s dynamic response To tune or re tune the current loops only alter the values of Ix61 x62 and or
69. least 16 MB of free disk space and 32 48 MB of RAM 32 MB for Windows 98 ME or 48 MB for Windows 2000 e A free serial communications port or USB port or Ethernet port or PCI BUS slot or ISA BUS slot to talk to PMAC for on line processing e Any monitor with VGA resolution 800x600 suggested but 640x480 works fine 2 Overview PMAC Tuning Pro Software Reference Manual GETTING STARTED Installing PmacTuningPro Before installing PmacTuningPro read the license agreement included in this manual behind title page and make a backup copy of the installation disks To install PmacTuningPro from the Delta Tau Software CD insert the CD into the CD drive Auto install menus will open Click on PmacTuningPro from the Suite to launch the PmacTuningPro installation To install PmacTuningPro from floppy disks put the PmacTuningPro distribution disk labeled Disk 1 into a floppy drive and choose File and Run from the Program Manager Enter A SETUP EXE or substitute A for the letter of the floppy drive PComm3 drivers were rewritten to accommodate the addition of PCI USB and Ethernet communication modes It is therefore important to uninstall all old Delta Tau software products before installing PmacTuningPro The installation program will suggest a directory path where the program files should be copied Use the suggested directory location for the installation for the purposes of uniformity among all PmacTuningPro users and trouble shootin
70. likely to lead to a jitter free stable feedback loop Auto select Sample Period This option if checked selects the appropriate value of Ix60 the servo period extension I variable suitable for the chosen bandwidth automatically It is advisable to check this option if a low bandwidth less than 20 Hz is recommended by the Auto select Bandwidth option When this option is selected the servo period is extended appropriately to minimize the adverse effects of quantization noise Include Low Pass Filter This option augments a first order low pass filter to the control law which helps in the attenuation of quantization noise particularly when higher bandwidths are required and the open loop system is relatively low gain low encoder resolution large inertia low amplifier gain etc Velocity FeedForward Check this box if velocity feedforward action is required The auto tuner will determine automatically the terms in the ESA feedforward filter that would generate this action In general velocity feedforward is needed to overcome following errors proportional to motor velocity resulting from back emf viscous damping and velocity feedback If such lags are acceptable then there will be no need for the use of this particular action and the check box may be left empty Acceleration FeedForward Check this box if acceleration feedforward action is required The auto tuner will determine automatically the terms in the ESA feedforward filter that
71. nel should be allowed to handle this equipment In the case of industrial applications we expect our products to be protected from hazardous or conductive materials and or environments that could cause harm to the controller by damaging components or causing electrical shorts When our products are used in an industrial environment install them into an industrial electrical cabinet or industrial PC to protect them from excessive or corrosive moisture abnormal ambient temperatures and conductive materials If Delta Tau Data Systems Inc products are directly exposed to hazardous or conductive materials and or environments we cannot guarantee their operation PMAC Tuning Pro Software Reference Manual Table of Contents OVERYVIEY ais sa ssc nce ceecesecgn eee ec cca ces eaecatenececaeessastesenieeescaatneaeeetenessteeeeeestecees 1 AMI oduc OR Naser dyee ees E cof wee E E ie ntcedw E EE EE E T EE l E UU SS e E ET A E E E E EA E E E EAEE AEE EE l Moak AY O e E E E T E E EE E EE E E T E E ana denteeemaateens l TOV S M TS O T T a E O S E l Hardware and Solltwae Reguire menis eeii iiin a AEE EEEE 2 GCE TIING STARTED ssr E EE 3 installing PmacTuningPro esis ciescineacnaseusndanensbsanacanesdainatemad debieda adevabanbinneddeadawsawoeausbiencauevannddioesdainsedabeebawndguevdeeconstueadobeiane 3 Setting up Communications With PMAC 10 0 ccccccccccsssssseseeeseeeeeeeeeeeeeeeeaaaaeeessseeeeeeeeeeeeeeeeeaaaeaesssseeeeeeeeeeeeeeeeaqags 3 MEAVOVYERVIE Y
72. ning simple option and enter its dialog box Select the correct amplifier type current or velocity loop 5 Enter the value of the desired bandwidth If not sure how to select the value for this entry check the Auto Select Bandwidth option Select a Damping Ratio between 0 8 and 1 0 6 Check Auto Select Sample Period if Auto Select Bandwidth is also selected and or if the desired bandwidth is less than 20 Hz it is assumed the value of Ix60 0 prior to entry to this dialog box 7 For now leave the Include Low Pass Filter and both Feedforward Boxes unchecked Also select None for Integral Action 24 Position Loop Tuning PMAC Tuning Pro Software Reference Manual 10 11 12 13 14 15 16 17 Adjust the values of the Max Excitation Magnitude Excitation Time and the Max Min Motor travel fields so that the motor turns between 1 4 to 1 2 revolutions while accelerating during the open loop forward reverse motions a prolonged period of constant velocity motion should be avoided Select the Begin Auto Tuning button and wait for the tuner to give the suggested values for some particular terms within the ESA If the numbers look reasonable accept them If the servo loop appears to behave in an unsatisfactory manner then click on the Kill button immediately this action issues to the addressed motor a PMAC KILL command Otherwise exit this dialog box If Auto Select Bandwidth was checked enter the simple auto tun
73. ntry Auko Tuning Gantry Interactive Tuning kni at ee ee hiia Ta PE PA LA P F Ampi hl lie Tr Pa Curent callers iarri fia 7 Neinelty Loop Mae Esciyton bagnata Bardivicth Pzt a Excilation Tire pnt 5a a Masimism Motor Travel feta 2900 Damgirg Ratio o r O Minimum boier Travel fete E I AntoSielnct Hande idih M Auti eiect Sample Period J malra lea 36 Position Loop Tuning PMAC Tuning Pro Software Reference Manual Gantry Interactive Tuning D PMATC W195 O2f2872001 UMAC TURBO USB Pork Position Loop Trajectory Tools Window Help DAC Calibration Open Loop Test Regular PID Extend serma Gigantin Filters Gantry PID a T F YF Gantry Auto Tuning Gantry Interactive Tuning s iritira Aa iiny bier Teei Chin Gas Bins Slaw siin i hati Ed feo i i ie ATH 13iF Simp Ties best oo meeiz Kvn fa Blaha win 000 fe paninon Sap hji fi f Postion Ramp CoA Sep Mowe aani ad L T Parabole Vestn f boat zan PT D Gal Mote Alter Sep Mowe npercidal waiocity bei PA T Mom in onn deection cci paaa F Gn soidei 9 C Sne Sweep CAUTION If the selected second motor is not well tuned relative to the motor being tuned the response of the Gantry system may be unsatisfactory to the extent that physical damage may occur due to mechanical interaction
74. oad is moving very slowly that is if the encoder counts relative to the servo cycle is low all the time it may be a good idea to extend the servo cycle By increasing the servo cycle extension PMAC will try to close the loops less frequently This is desirable since PMAC will use less time for servo calculation More calculation power would be reserved for PLCs and other housekeeping chores The default value is O and this will update the servo loop every servo interrupt cycle If this value is set to 1 the servo loop will be updated every two servo cycles If set to 4 the servo loop will be updated every five servo cycles Ixx68 Friction FF feed forward Gain This gain acts when the position of the servo is not within in position limits at zero velocity state steady state according to the direction needed to be compensated Use moderation in setting this gain Ixx11 Fatal Following Error Limit When the magnitude of the following error exceeds Ix11 motor x is disabled killed Regular PID Auto Tuning Open boop Tast Regus PII 20 Position Loop Tuning PMAC Tuning Pro Software Reference Manual E yaco Cauton See manua Erch ion Time m 50 Masinum Motor Travel iets 1000 Mirimum Motor Travel feta 400 AD Advance Option I jdubo Helack Sampii Period T elude Low Pan Filter M Welociy Feed Freid Accelniaton Feed Forwaid AutoTune iega Action fe Hore 1_
75. ortional gain setting The default value is a very conservative value for most systems and is a good starting point Ixx31 Kd Derivative Gain Derivative gain works like damper Higher the derivative gain higher the damping action This gain prevents overshoot but makes the system sluggish Also in digital system the quantization noise is amplified when derivative gain is applied and in slow moving low counts per second system this noise might contribute significantly to the error If skipping the auto tuning it is always wise to begin the tuning with the low derivative gain setting Default value is conservative value for most systems and is a good starting points Position Loop Tuning 19 PMAC Tuning Pro Software Reference Manual Ixx32 Kvff Velocity FF feed forward Gain Velocity feed forward gain will help the system with steady state error reduction But whereas PID is feedback gain causal velocity feed forward gain is feed forward gain non causal Setting it to an unreasonable value will destabilize the system Using the derivative gain is recommended Often the optimal result is obtained by setting this value equal to the derivative gain value Ixx33 Ki Integral Gain Integral gain acts to correct the system according to the accumulated following error of the system Itis effective particularly to counter the steady state error caused by friction However for numerical reasons too high integral gain will satur
76. p Response with High Ki cccccccccccsssessscccceeeceeeseseeceeeeeaeeeeeeeeeeeeaaeeseeeeeeeeeaaaeeeeeeeeeaaaaeseseeeeesaaaaseeseess 44 MPS OM RA cs ach occ esgic cedetananeceseunnee ae snadeagsanadansn a E E Aiaia 44 PPE AO y eO ee E E E 45 Doing the Parabolic MOVE vosiasccennstnasnsasesaznonsdantaears Guedserteasesnodvaiventnnswansasarisandscswoesisassoardeadeseiabaisonedentsseetoatoessoages 46 Modified Parabolic Move with Increased Kvff IX32 ccccssccccccccccccccssssscececeeceaessseseeeeeesaeseeeeeeeeeeaaaeeeeeeeeeesaaaeeeeess 47 Modified Parabolic Move with x34 L nooeeennnnnnnnnnnnnnnsssssennnnsssseeeronssssserenssssssserrosssssseeresssssssereessseerreesssseeereo 48 Modified Parabolic Move with too much KVff cccccccccccccsseessscsccceceecaeeseseeeeeeeeaeseseeeeeeeeaaaeeeeeeeeeesaaaeeeeeeeeesaaaneeeess 48 Modified Parabolic Move with Some KAff iccccccccccsssccccccccccccnssssecceeeeeaesseeeeeeeeeaeeaeeseeeeeeeeeaaeeeeeeeeeeseaaasseeeeeesaaaaseeees 49 Tatras ZOLA WC OCU YE ssc sca E E EE 49 OSV C1 arce cere A A E ease tian ET A A A E E T E S 50 O a E E E RS 5I TS 9 E ceucasansansuesasn wi arenansetonuesersanemaneconees 51 Set E E E 52 TOOLS e a E E S ce iessatseeosecvasieesctcsetsteresiees 53 OMIT ALON eeen e E E E E E 53 Tl E S E 54 P eea e E E tumcondsneebtoueptenicuantesieuenteatasen 54 ECE D a NE EE A SE EN ante TAE E PET TE A E T EE E 55 MOES N ea E E E E a tovent 56 POO E E E T O 57 E i E EAE AONE A S EN E OEIT A T O T ONE E
77. p button a step stimulus is injected in the direct Ig component of the current loop the response data is then gathered within PMAC2 and it is plotted on the screen Since the non torque producing component of the current vector is stimulated there should be almost no or a very small amount of motion If the commutation I variables were set correctly no motion should be detected The numerical value of the natural frequency should be noted from the step response screen The general aim is to increase it to as high a number as possible while keeping the damping ratio between 0 7 to 1 0 see above Numerically aim for a natural frequency of at least 150 to 200 Hz for a motor with a high winding impedance For a motor with small winding impedance the attainable value of natural frequency may be as high as 400 to 500 Hz In general the current loop should be tuned to have a natural frequency that is 10 to 15 times higher numerically than the desired position loop s natural frequency Furthermore a current loop natural frequency of less than 100 Hz is usually not acceptable for a smooth low cog torque generation even when the required position loop natural frequency is below 10 Hz No attempt should be made to tune the position loop until the current loop tuning is completed the commutation I variables are set up and the mechanical load is connected to the motor Current Loop Auto Tuning Auto Tune Parameters eee EAL that Earitatinn M
78. position The test will continue however until the specified number of iterations is completed subject to the specified travel limit The default value is 4000 feedback counts 30 Position Loop Tuning PMAC Tuning Pro Software Reference Manual Minimum Motor Travel This entry allows checking if in fact a detectable motion took place If the Max Excitation magnitude is relatively low and the Number of Iterations is relatively high the first iteration s peak DAC output may become too small As a result no detectable motion may take place during the excitation time Safeguard against erroneous gain estimations by entering an acceptable number of counts for the Minimum Motor Travel In general this entry should correspond to at least 30 degrees of motor rotation The default value is 400 feedback counts Bandwidth This entry allows specifying the closed loop system s speed of response and servo stiffness In general the higher the value of the bandwidth the higher those computed terms of the ESA which correspond to the error proportional gain In practice typical closed loop bandwidths range from 4 Hz for very large motor load inertia systems to 100 Hz for very high gain amplifiers driving extremely light motor load inertia systems Note that if the Auto Select Bandwidth option is checked the program select a lower bound safe bandwidth automatically which will appear in this box after the tests The default value is 20 Hz Damping Ratio
79. r bound value for the bandwidth Then increase the bandwidth gradually from the bandwidth automatically estimated to increase servo stiffness and auto tune again etc e The maximum and minimum travel limits for the tests This should be long enough to generate 1 4 to 1 2 of motor revolution and yet short enough to avoid uncontrolled travel beyond a safe limit for a particular setup e Choice of including feedforward action Include velocity and acceleration feedforward to minimize tracking or following errors e Choice of no integral action soft integral action or hard integral action Note that hard integral action should not be selected unless low bandwidth relative to auto select bandwidth is selected for closed loop system In general select soft integral action if zero steady state following error is needed and a previous tuning session without the integral action could not satisfy the requirement e Choice of automatic selection of a safe bandwidth based upon the test results Select this option if the desired closed loop bandwidth has not been chosen e Choice of automatic selection of the servo sampling period extension I variable 1x60 for a particular servo design goals It is useful to check this option particularly when the selected closed loop bandwidth is below 20 Hz e Choice of inclusion of a first order low pass filter to attenuate high frequency noise which may otherwise cause a noticeable motor jitters
80. rai Pombori Ladi g Achai Pomin Lai Modified Step Response with Higher Kp Ix30 The next figure below shows the response with Kp increased from 80000 to 1000000 Note that the shape of the curve has not changed much this is because the effective derivative gain is increasing with Kp but the rise time has improved slightly to 13 ME We turn now to Kd mi iee faa n i 2 Step Move Plot Resuh Executed at 2 id 28 PM TDD Tl iel am eral to am Ls 1m Ep Ag AD An p Fi toe Sor mm Bee e 2 p Pee ee Fem ee D eee a Prep ee On Dee ee Geen eid aes a Ge i ee et Bie jeli i or er ie to Coe ed ee eee Lee ee Te ee ee Bere ee Frien eet Geer ttt Piai ing Esa Limi adh I PIT Commenced Patan Laf Aun Boker Lat 42 Trajectories PMAC Tuning Pro Software Reference Manual Modified Step Response with Increased Kd Again The figure below shows the step response with a Kd of 2500 This is the critically damped case 1 e fast response with no overshoot With Kd any smaller we get some overshoot And with it any larger we just slow down the response The tendency of the system to settle slightly off from the target position is due to a net torque or static friction We will eliminate this with integral gain Eth H a LE RDB ater Ohne AE s Step Move Pict Result Eeecuted af 2 1602 PM TA Lg u EE aul sti dl I RNI a8 liE r ee Pip ea a Pee ira ole Prep Be Gee Sed en p eee raa A e Fige Gan e D Cere
81. ree stable feedback loop Auto Select Sample Period This option if checked automatically selects the appropriate value of Ix60 the servo period extension I variable suitable for the chosen bandwidth It is advisable to check this option if a low bandwidth less than 20 Hz is recommended by the Auto select Bandwidth option By selecting this option the servo period is extended appropriately to minimize the adverse effects of quantization noise Include Low Pass Filter This option augments a first order low pass filter to the control low which helps in the attenuation of quantization noise particularly when higher bandwidths are required and the open loop system is relatively low gain low encoder resolution large inertia low amplifier gain etc Velocity FeedForward Check this box if velocity feedforward action is required The auto tuner will determine x32 automatically that would generate this action In general velocity feedforward is needed to overcome following errors proportional to motor velocity resulting from back emf viscous damping and velocity feedback If such lags are acceptable then there will be no need for the use of this particular action and the check box may be left empty Acceleration FeedForward Check this box if acceleration feedforward action is required The auto tuner will determine Ix35 filter automatically that would generate this action In general acceleration feedforward is needed to overcome followin
82. ro Software Reference Manual Remove Low Pass Filter This button removes the low pass filter for the selected motor by zeroing out the coefficients 1x38 and x39 and restoring x30 to its near original value before the low pass filter was implemented Calculate Low Pass Filter This button calculates the coefficients for the low pass filter for the selected motor and displays the values on the left side of the screen The new values are not downloaded to PMAC When a low pass filter is calculated the proportional gain 1x30 changes to a lower value This is necessary to maintain the same DC gain with the new low pass filter implemented The amount Ix30 changes will depend on the values of the low pass filter coefficients Implement Low Pass Filter This button calculates the coefficients for the low pass filter for the selected motor and displays the values on the left side of the screen The new values are downloaded to PMAC When a low pass filter is implemented the proportional gain 1x30 changes to a lower value This is necessary to maintain the same DC gain with the new low pass filter implemented The amount x30 changes will depend on the values of the low pass filter coefficients Gantry PID Gantry Auto Tuning 0 PMAC 1 1 93F 02 28 2001 UMAC TURBO USB Pork Position Loop Trajectory Tools Window Help DAC Calibration Open Loop Test Regular PID Extend serva ganiem Filters Gantry PID a T F iF Ga
83. s 46 Trajectories PMAC Tuning Pro Software Reference Manual 5 Increase Kaff Accel FF Gn Ix35 Do another move and evaluate the correlation and FE to Accel ratio again Repeat until the maximum Kaff is reached that retains any positive correlation At this point there should be minimal following error and most of what remains should be caused by noise or mechanical friction If mechanical friction is the cause there should be a fairly strong velocity correlation because the friction causes the following error related to the sign of the velocity However each half of the following error curve should be quite flat if friction is the primary cause In the first figure below we see the plot of a parabolic move using a step size of 4000 counts and a step time of 500 milliseconds Here position is plotted against time with the statistics of the following error shown The following error gets as large as 112 counts and it is almost perfectly correlated to velocity Vel corr 0 913 It shows very low correlation to acceleration Acc corr 0 226 The next two figures show the plot of position and velocity and following error versus time for the same move Note that the velocity and following error curves are shaped almost exactly alike This is a ramification of their high correlation Now we will introduce some velocity feed forward As a rule of thumb choose Kvff 1x32 to be equal to Kd Ix31 In this case Kvff 2500 By looking at th
84. s n nib ed ip d an Lea Flip k lba jepi e EEk ib Hel irte a F aa ie d e i l d 2 are hA h eel ed Pe eee r aa PP ll Priim fee ee Gen ee Pd Pere Eo Lee ble eo Careers Pariuri Lar ec Acne ibe ao SS M la OO ll Modified Step eusecen with Increased Ki 1x33 The figure below shows what happens with a little bit relatively speaking of integral gain Ki 10000 the steady state error is gone but the nature of the curve has not really changed Jat TEN LUE m ae er qang yok Motor j Step Move Pict Result Executed af 2 18 02 Pid Tres a os I Tet ren pa aE FHE FIE ANI an a a Be Tree UE ee eel a ar Pee ee Cee Se Cee Fee Trelis a Pimp Gain 1 eee Cee Se diode eo eds Pearce a lol ed Pegs ad te Dd pe Ep a ee i ee i el ee Se ee eel eed eT Gee eee eee Pel Frie Peel ee ee eel Pe Bro Led fort T je pA Cornea Sie Lae irja Poin Lee Trajectories 43 PMAC Tuning Pro Software Reference Manual Modified Step Response with High Ki The figure below shows the response curve for a substantially increased Ki 100000 This curve demonstrates how quickly the system would respond to a disturbance while in position Remember that we are using integral gain only when in position so changing integral gain does not affect the actual dynamic response although it will change the shape of the step response here We still have the stability characteristics of critical damping while on the move Even the higher value of Ki does not res
85. small Parabolic moves were chosen for this procedure because their acceleration and velocity vary continually and are uncorrected to each other making them ideal for this type of analysis For further examination of the move you may plot the velocity curve the acceleration curve or the following error curve These are automatically scaled to fill up the plot window for maximum resolution The move statistics are re displayed with these plots Doing the Parabolic Move 1 Do a parabolic move and observe the plotted response and the calculated statistics for the move 2 Presuming there is a high correlation between following error and velocity the velocity and following error curves have the same shape and a relatively high maximum following error as shown on the plot increase Kvff Velocity FF Gn Ix31 3 Do another parabolic move If there is still inadequate Kvff there will still be a high correlation but the FE to Vel ratio and the maximum FE will be reduced Repeat steps 2 and 3 until the maximum Kvff that produces a square wave looking shape for the following error is reached 4 At this point there should be noticeable correlation between acceleration and following error Notice this through the numerical correlation value or by plotting the acceleration and the following error and noticing the similarity in shape If there is no correlation try increasing the length or decreasing the time of the move to get higher acceleration
86. ssseeeossssseeeenossssseeerossssssseeessssseseeeo 33 Table of Contents i PMAC Tuning Pro Software Reference Manual Low Pass Filter Addition to PID Feedforward wicccccccccsssseccccccccccnneeescceeeeeeneeesseeeeeeeaaaeeeeeeeeeeeaaaeeseeeeeesaaaaaseeeess 35 Ganmo Ng sacsc ates cctnce E E E 36 Ganiry AWO T UnA D eisni nia S E A RR 36 Goni ry Lae Cas TUNE ae eR ONe ORTREEE TOE ea T E E rrre 37 Ce essa caesar a gachcs ctcccaccac ce cece E E wexteeuivestneees 39 PoS OS wheres niente E tate bros erann AE AE attend ane EAE EE EA AEE 39 Dome thestep Res pOn E sse E E E e EEE a Ae Er eSt 4 initi l Step Move Response serssctancseneesismesesoowsnstesvinnieveseraseiniadeiehwencuaabinedeiisensiceebedelsincuaavineledawevesmersennpeeoeneieses 4 Modified Step Response with Higher Kd 1X31 ccccccccccccssssecccccceceeecneseeseceeeeeaaeseeeeeeeeeaaaeeeeeeeesaaaaeeeseeeeessaaaseseess 42 Modified Step Response with Higher Kp IX30 cccccccccccsesseccccceceeecnesseeeeceeeeaaeseeeeeeeeeeaaaeeeeeeeeeesaaasseeeeeeeeaaaaeeeeeess 42 Modified Step Response with Increased Kd Again viccccccccccssseeccccccccecnneseeeceeeeeaenaseseeeeeeeeaaeeeeeeeeeeseaaaaeseeeeesaaaaeseeess 43 Modified Step Response with Increased Kd Again viccccccccccsssecccccccccccneseesececeeeneeaeseseeeeeeeeeaeeeseeeeeeeeaaaesseseseeaaaseeeees 43 Modified Step Response with Increased Ki 1X33 cecccccccccsssscccccccccecnssessecceceeeeeassseeeeeeeeaaaeeseeeeeeeeaaaaeseceeessaaaeeeeess 43 Modified Ste
87. t This feature depends on having proper encoder feedback to the card The open loop program is terminated if the velocity limit is exceeded in either the positive or negative direction In addition if either the hardware or the software position limits are exceeded the open loop program will stop The hardware limits are the external limit switches connected to PMAC The software limits are defined by Ix13 and Ix14 for the positive and negative position limits respectively Open Loop Magnitude Here you specify the magnitude maximum voltage in one direction for the open loop move This is expressed as a percentage 0 100 of the value stored in Ix69 which holds the maximum allowable output magnitude in DAC bits This can range from 0 to 32767 corresponding to 0 to 10V The factory default for x69 is 20480 which is about 6 3V but this is usually reset to the full 32767 10V Open Loop Time ms The open loop time specifies the time duration of the on time when a positive or negative value is written to the DAC output for the open loop move Position Loop Tuning 17 PMAC Tuning Pro Software Reference Manual Number of Repetitions This specifies the number of repetitions for the open loop move A value of zero indicates infinite repetitions until the space bar is pressed Plot Response This option displays the last response plot without redoing the move Regular PID Tuning Bal Prres pan Loop Tash Result Motor FI E
88. the direct or the magnetizing current which should produce little or no torque and hence a very small amount of motion if any A time trace as shown in the example below provides numerical values of the pertinent characters of the step response including the natural frequency and damping ratio As the integral gain Ix61 is increased the natural frequency will be increased manifested by a faster rise time However the dampness characteristic of the response will be reduced This is shown by longer settling time and increased overshoot To provide the required damping typically a damping ratio between 0 7 to 1 0 either or both of the proportional gains x62 and Ix76 may be increased 8 Current Loop Tuning PMAC Tuning Pro Software Reference Manual The iterative process of increasing the integral gain to produce faster rise time higher natural frequency and increasing the proportional gains to produce less overshoot and faster settling damping ratio between 0 7 to 1 0 could be continued until the closed loop current response exhibits either no further rise time improvements due to saturation or noise induced buzzing due to ADC quantization of the current signal In either case one must reduce the gains and test for a satisfactory behavior via the step response test again 3 1 y pin 1 e Eeg Hl Stee eee eam e WEBak Aer Qanga dr Orra Loon kimmie fki fread paaie at lle 30 BA Be 7TH a oe x wo es pe ee ee e
89. ting menu The entries include the Amplitude of sinusoidal input the Starting and Ending Frequencies in Hz the sweep time In addition whether a linear or logarithmic method should be used for the frequency increase The data gathering parameter I19 is adjusted automatically so that the highest frequency is sampled at least eight times As a result a long sweep time should be avoided when a wide frequency range is chosen that ends at a high frequency since the number of data gathering storage area within PMAC is limited to approx 10000 points The linear sweep changes the frequency from the minimum to maximum as a linear function of time which provides more cycles at higher frequencies The logarithmic sweep changes the frequency from the minimum to the maximum as log 10 function of time provides more cycles at lower frequencies In theory the linear should lead to more accurate high frequency bode plots and the logarithmic to more accurate low frequency bode plots User Defined i LIN C Spline C PYT Run Program Kill Motor After Hove TL Tims Distance cts Chack 416 el Dwell me 0 I Blend Mode User Dered Prague lor Linear Move WAV 2 52 47 PH DELETE GATHER UNDEF ALL 1 A RTA MEI 08 908 79 sosther OM bi Deen PROG 399 CLEAR El F The User Defined input test profile provides a forward reverse trajectory with Leaner Mode Spline1 Mode and PVT Mode The desired TA TM TS Distance and Dwell Time
90. ult in oscillations so we will use that We have achieved what we wanted with feedback wei b Se LE BRB wer Une AGE Motor i2 Step Move Plot Result Executed a 2 19 79 PM Tie 3 Eh anl Ege me j on ksime tiki INE ken Ler Position Ramp The Ramp Position input test profile provides a forward reverse trajectory with almost zero acceleration time very large acceleration rate and a constant velocity Position Ramp Move Distance cts 10000 Velocity cts sec 10000 Humber of Repeats fi Do A Ramp Move Kill Motor After Ramp Move Move in only one direction Dwell Time After Move 500 mz This trajectory is suited best for the tuning of the Velocity Feedforward gain 1x32 in order to reduce the steady state following errors at a constant velocity Note that a too high value for the velocity input may cause unacceptable mechanical stress even vibrations on the drive system and its load In addition there may be unacceptable overshoot at the end of motion if the velocity input value is too large 44 Trajectories PMAC Tuning Pro Software Reference Manual hg lee hae TETP bet en Fi i Pals zi wei bes LE DMR wa oe Che AaE Motor 41 Ramp Move Pilot Result Executed af 4 16 27 Fh Sono 5 F Chart sare PFTS De a r ao CIH idon Feed Gene eo Pel Poison Br Lard i Oomer Poor Lei Arim Poin Sui Parabolic Velocity Feedforward Tuning with a
91. umber and feedrate override value 1 2 3 Use up arrow or down arrow to catch the previous command history 4 Set Font or Background setting by clicking Terminal Tools from main menu Strip Plot This button calls a Strip Plot window that can be used to see real time data from PMAC 54 a200i UMAC TURBO USB Port UMAC TURBO USB Pork tory Tools Window Help fools Position Tools Window Help Configuration mii S25 x a Terminal Report Motor Status Position he r jel Tools PMAC Tuning Pro Software Reference Manual Commanded Velocity The commanded velocity from PMAC is visible in the left side plot Actual Velocity The actual velocity value from PMAC is visible in the left side plot Commanded Position The commanded position value from PMAC is visible in the left side plot Actual Position The actual position value from PMAC is visible in the left side plot M Variable The user defined M variable value from PMAC is visible in the left side plot Commanded Acceleration The commanded acceleration value from PMAC is visible in the right side plot Actual Acceleration The actual acceleration value from PMAC is visible in the right side plot Following Error The following error value from PMAC is visible in the right side plot Command DAC Current The command DAC Current value from PMAC is visible in the right side plot Actual DAC Current The actual DAC Current value from PMAC is v
92. vative or integral gain and no feedforward The current values for Kp Ki and Kd are displayed on the screen 2 Do a step move and observe the plotted response displayed on the screen along with the calculated statistics 3 Adjust probably increase Kp Proportional Gn to get the fastest rise time possible without a huge amount of overshoot Allow more overshoot here than in the final response 4 Once there is a fast response increase Kd Derivative Gn to bring down the overshoot to the desired value Note that this will also increase the rise time It may be necessary for further tradeoffs between Kp and Kd to get the desired response Note It may be necessary to change the size and or the duration of the step to be able to observe the response better The default values are 1000 counts step with 500 milliseconds dwell time 5 Once Kp and Kd have been set the dynamic step response has been taken care of provided error integration is used only in position Now add integration to improve the static holding properties of the system As Ki Integral Gn is increased and the step response is observed notice that it increases overshoot but comes back to the command position more quickly A good value for Ki is one that brings the response back down to the command position as quickly as possible without going back past it The following figures are taken from the actual tuning procedure for a motor using this program They were don
93. w to use PmacTuningPro to communicate with and Tune motors using the PMAC motion control card Knowledge of the basic use of the Windows operating system is assumed How this Manual is Organized e Chapter 1 Getting Started Covers installing the software and setting up communication with PMAC Provides Delta Tau support information e Chapter 2 Menu Overview Gives a brief description of each of PmacTuningPro s menus e Chapter 3 Current Loop Tuning Provides a quick tool for tuning of the Current Loop This is a repetition of initial setup of the Current Loop Tuning using the P2setup program for PMAC2 or the Turbosetup program for PMAC2 Turbo and UMAC e Chapter 4 Position Loop Tuning Details all of the PID and Extended Servo Algorithms steps including DAC calibration Open Loop test Filters and Gantry Tuning e Chapter 5 Trajectories Provides several pre defined as well as custom defined moves e Chapter 6 Tools Allows viewing several diagnostic and static tools including Terminal windows Position and status screens e Chapter 7 Help Details PmacTuningPro s help information routines Overview I PMAC Tuning Pro Software Reference Manual Hardware and Software Requirements PmacTuningPro will run on any computer capable of running Windows 98 ME or 2000 TM 266 MHz Pentium MMX and up recommended In addition the following is needed e Microsoft Windows 98 ME or Windows 2000 loaded on the computer e At
94. would generate this action In general acceleration feedforward is needed to overcome following errors proportional to motor acceleration caused by inertial lags If such lags are acceptable then there will be no need for the use of this particular action and the check box may be left empty Position Loop Tuning 31 PMAC Tuning Pro Software Reference Manual Integral Action In general integral action is required only if the existing amount of friction and or torques force disturbances cause an unacceptable level of steady state following errors If this happens to be the case for a particular application then try first the soft integral action Use the hard integral action only if the selected bandwidth is low relative to the value recommended by the Auto select Bandwidth option Pause Between Iterations Check this box to see the distance traveled during each iteration step Usually the first time in an auto tuning session this box is activated Once the optimum values for the Excitation Time and the Mintmum Maximum Travel Limits fields are set there will be no need to pause between test cycles or iterations Doing an ESA Auto Tune Session The following steps provide some guidelines for typical auto tuning activities when using the simple auto tune method 1 Using the JOG command or otherwise move the motor to a safe position where both forward and reverse motions of at least twice the size of the Maximum Travel Limit are acceptable

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