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RT3000 User Manual

1. Revision History B Changed Height EA AANA NA NA NA AA Ao ON VN SEN X8 EN P8 Date 22 05 2003 Part 14A0004B Document RT3000 Dimensions Sheet 1 of 1 Oxford Technical Solutions 77 Heyford Park Upper Heyford Oxfordshire OX25 5HD www oxts co uk Copyright Oxford Technical Solutions 2002 Confidential Information The information in this document is confidential and must not be disclosed to other parties or used to build the described components without the written permission of Oxford Technical Solutions 0 10 20 30 Print Size A4 Scale 1 2 Half Units mm Tolerances X X 0 1 Projection 3rd Angle Material HE30 Alu Finish Anodised Notes A M4 x 10 Tapped Hole B 2mm dia x 3 hole 14Cxxxx N NANA NA NA NANI NA NA AAAA
2. User cable drawn to show space required for the bend radius Edit History Date 08 11 01 Part 14A0007A Document RT3003 Outer Dimensions Sheet 1 of 1 Connector Boot Details Deutsch AS612 35SA 9 Way Male D type and shell 9 Way Male D type and shell 9 Way Male D type and shell BNC Socket crimp and inline 8 Way RJ45 10 Base T Plug Hellerman 154 42 G FEC 357 649 472 748 FEC 357 649 472 748 FEC 357 649 472 748 FEC 309 679 Suggested See Note A 14C0009A J1 Tail Lengths J2 Nav Data Supply 9 18 Volts DC Supply Return EMI Ground OX Oxford Technical Solutions 77 Heyford Park Z Fi Upper Heyford A amp Oxfordshire SN QT OX25 5HD www oxts co uk Copyright Oxford Technical Solutions 2002 The information in this document is confidential and must not be disclosed to other parties or used to build the described components without the written permission of Oxford Technical Solutions EPETASE EE ERET EEC SEVERI 0 10 20 30 Print Size A4 Not to scale mm 5mm J5 PPS OUT Length XX is denoted in the part ordered by the final digits of the part number in centimetres 300mm 300mm 300mm 2000mm 300m
3. For the Advanced Slip feature to work correctly the system needs to know the position of the rear wheels on a vehicle with front wheel steering Vehicles with rear wheel steering should use the front wheels vehicles with all wheels steering cannot use this feature reliably Minor steering of the rear wheels does not significantly affect the results A position at road height mid way between the rear wheels should be used The Advanced Slip feature also requires some knowledge of the road surface Three pre defined options are given Normal Low Friction Ice and High Friction The Other feature should not be used The CAN bus can be enabled or disabled In systems without the CAN option this should be set to Disabled g Oxford Technical Solutions Y 4 ry 7j RT3000 User Manual e Committing the Configuration to the RT3000 The changes to the RT3000 settings must be performed using Ethernet It is necessary to configure your computer s Ethernet settings so it is on the same network as the RT3000 If necessary ask you system administrator to help Figure 12 below shows the Commit screen Figure 12 RT3000C g Commit Screen RT3000 Configuration Wizard x E Commit RT3000 Commit configuration to the RT3000 Inertial LECHE IP address of RT3000 Measurement 1950017 Save the configuration in System iN the RT3000 Changes will take effect when the system restarts Step 7 of 8 Reset RT3000 after downloading fi
4. ww ow eww The schematic shows the layout for a dual antenna system the second GPS GPS2 and the second antenna are not fitted on single antenna systems The accelerations and angular rates are measured in the Inertial Measurement Unit IMU The accelerometers are all mounted at 90 degrees to each other so they can measure each direction independently The three angular rate sensors are mounted in the same three directions as the accelerometers A powerful 40MHz floating point DSP controls the ADC and through advanced signal processing gives a resolution of 20 bits Digital anti aliasing filters and coning sculling motion compensation algorithms are run on the DSP Calibration of the accelerometers and angular rate sensors also takes place in the DSP this includes very high precision alignment matrices that ensure EB Oxford Technical Solutions h Tins RT3000 User Manual that the direction of the acceleration and angular rate measurements is accurate to better than 0 01 degrees The sampling process in the Inertial Measurement Unit is synchronised to GPS time so that the 100Hz measurements from the RT3000 are synchronised to GPS The Navigation Computer is a 300MHz CPU Pentium class processor that runs the navigation algorithms more on this below Information from the DSP and the two GPS receivers is fed into the Navigation Computer The Navigation Computer runs a real time operating system QNX so that the outpu
5. E Oxford Technical Solutions lh Ims RT3000 User Manual A In current versions of the software the Strapdown Navigator will not leave Green and return to any other state This may change in future releases Position Solution Single Antenna only The Position Solution LED shows what type of GPS solution is currently being used by the Kalman filter to update the Strapdown Navigator Table 10 below gives the states of this LED Table 10 Position Solution LED States Colour Description Off The GPS receiver does not have a valid position Red Start up only The GPS receiver is sending data to the main processor This is an Flash operational check for the GPS receiver Red The GPS receiver has a standard position solution SA or a differential solution DGPS Yellow The GPS receiver has a kinematic floating position solution 20cm accuracy Green The GPS receiver has a kinematic integer position solution 2cm accuracy GPS Heading Solution Dual Antenna only The GPS Heading Solution LED indicates the state of the dual antenna receiver Table 11 below defines the states of this LED Table 11 States of the GPS Attitude LED Colour Description Off GPS receiver fault Valid only after start up pcr GPS receiver is active but has been unable to determine heading Flicker Red Integer uncalibrated heading lock Yellow The receiver has a floating poor calibrated heading lock Green The receiver has a
6. The system will start when it has estimates of all of these quantities Course over Ground will be used to as the initial Heading when the system exceeds 5m s 18kmh about 1 1mph If the system is mounted level in the vehicle then the Vehicle Level option will enable the system to start immediately Otherwise the system requires about 40s to find approximate values for Roll and Pitch For the initialisation process to work correctly the system requires the user to tell it which way it is mounted in the vehicle otherwise the Course over Ground will not be close enough to the Heading Real Time Outputs During the initialisation process the system runs 1 second behind so that the information from the GPS can be compared to the information from the inertial sensors After initialisation the system has to catch up this one second lag It takes 10 seconds to do this during the first 10 seconds the system cannot output data in real time the delay decays to the specified latency linearly over this 10 second period The user can identify that the outputs are not real time because the Strapdown Navigator State LED is orange When the system is running it real time this LED is green E Oxford Technical Solutions j i T RT3000 User Manual Warm Up Period During the first 15 minutes of operation the system will not conform to the specification During this period the Kalman Filter runs a more relaxed model for the sensors
7. 23 Latitude Byte 0 The Latitude of the IMU It is a double in units of radians 24 Latitude Byte 1 25 Latitude Byte 2 26 Latitude Byte 3 27 Latitude Byte 4 28 Latitude Byte 5 29 Latitude Byte 6 30 Latitude Byte 7 31 Longitude Byte 0 Longitude of the IMU It is a double in units of radians 32 Longitude Byte 1 33 Longitude Byte 2 34 Longitude Byte 3 35 Longitude Byte 4 36 Longitude Byte 5 37 Longitude Byte 6 38 Longitude Byte 7 39 Altitude Byte 0 Altitude of the IMU It is a float in units of metres 40 Altitude Byte 1 41 Altitude Byte 2 42 Altitude Byte 3 43 North Velocity LSB North Velocity in units of 10 4 m s 44 North Velocity 45 North Velocity MSB 46 East Velocity LSB East Velocity in units of 1074 m s 47 East Velocity 48 East Velocity MSB 49 Down Velocity LSB Down Velocity in units of 10 4 m s 50 Down Velocity 51 Down Velocity MSB 52 Heading LSB Heading in units of 10 6 radians Range r 53 Heading 54 Heading MSB E Oxford Technical Solutions Hin RT3000 User Manual Byte Quantity Notes 55 Pitch LSB Heading in units of 10 6 radians Range 7 2 56 Pitch 57 Pitch MSB 58 Roll LSB Heading in units of 10 6 radians Range n 59 Roll 60 Roll MSB 61 Checksum 2 This checksum allows the software to verify the integrity of the packet so far For a medium latency output the full navigation solution is avai
8. eight Offset I0 000 m a within n 100 m Confidently Height Offset o 000 n ta within fo 100 m Accurately IH ee fU m m ev ID 030724 14am Back b Cancel It is best to mount the two antennas on the top of the vehicle Although it is possible to mount one on the roof and one of the bonnet hood in reality the multi path reflections from the windscreen will degrade the performance of the system If the antennas are mounted at significantly different heights or if the mounting angle is not directly along a car axis forward or right then use the advanced settings Getting the angle wrong by more than 3 degrees can lead the RT3000 to lock on to the wrong heading solution The performance will degrade or be erratic if this happens The RT3000 does not estimate the distance between the two antennas It is essential to get this right yourself otherwise the system will not work correctly and the performance will be erratic Revision 030728 Ea ERO CITY i_ 4 CT Non Setting the Correct Options The options screen gives some settings that should be changed if you are experiencing trouble Figure 9 below shows the Options screen Figure 9 RT3000Cfg Options Screen RT3000 Configuration Wizard x E Options RT3000 Options to improve performance Inertial PPEP Option Setting EEC leita Vehicle Starts Level You can specify more SPC Vibration Normal specific information GPS E
9. 1 e after the IMU to Vehicle Attitude matrix has been applied It is a signed word in units of 107 m s Acceleration Y is the vehicle body frame acceleration in the y direction i e after the JMU to Vehicle Attitude matrix has been applied It is a signed word in units of 10 4 m s Acceleration Z is the vehicle body frame acceleration in the z direction 1 e after the MU to Vehicle Attitude matrix has been applied It is a signed word in units of 107 m s Angular Rate X is the vehicle body frame angular rate in the x direction i e after the JMU to Vehicle Attitude matrix has been applied It is a signed word in units of 10 radians s Angular Rate Y is the vehicle body frame angular rate in the y direction i e after the IMU to Vehicle Attitude matrix has been applied It is a signed word in units of 10 radians s Angular Rate Z is the vehicle body frame angular rate in the z direction i e after the IMU to Vehicle Attitude matrix has been applied It is a signed word in units of 10 radians s See Table 1 below This checksum allows the software to verify the integrity of the packet so far For a low latency output the accelerations and angular rates can be used to quickly update the previous solution Contact Oxford Technical Solutions for source code to perform this function Revision 030728 EI Y wit EN A QN e Ori Table 21 NCOM Packet Definition Batch 2 Byte Quantity Notes
10. FTP User user FTP User Password user For details on the output packet format of the UDP broadcast contact Oxford Technical Solutions Connection Details The RJ 45 connector on the 14C0009x User Interface Cable is designed to be connected directly to a network hub To extend the cable it is necessary to use an In Line Coupler This is two RJ 45 sockets wired together in a straight through configuration Following the In Line Coupler a normal straight UDP Cat 5e cable can be used to connect the coupler to the hub The RT3000 can also be connected directly to an Ethernet card in a computer To do this a Crossed In Line Coupler must be used The connections in the crossed coupler are given in Table 15 below Note that this is not the normal configuration sold and it may be necessary to modify an existing coupler to suit Revision 030728 a Table 15 In Line Coupler Connections Socket 1 Pin 1 Pin 2 Pin 3 Pin 4 Pin 5 Pin 6 Pin 7 Pin 8 Straight Socket 2 Pin 1 Pin 2 Pin 3 Pin 4 Pin 5 Pin 6 Pin 7 Pin 8 Crossed Socket 2 Pin 6 Pin 3 Pin 2 A typical In Line Coupler is shown in Figure 14 below Figure 14 In Line RJ 45 Coupler Uu Oxford Technical Solutions RT3000 User Manual Laboratory Testing There are several checks that can be performed in the laboratory to ensure that the system is working correctly The most fragile items in the system are the accelerometer
11. Introduction 6 RT3000 Family Variants 8 Single Antenna Models 8 Dual Antenna Models 8 Scope of Delivery 10 Warranty 12 Specification 13 Environmental Protection 17 Quick Guide to Operation 18 Initialisation Process 20 Real Time Outputs 20 Warm Up Period 21 System Outputs 22 Co ordinate Frame Conventions 22 LED Definitions 24 Strapdown Navigator LED States 24 Position Solution Single Antenna only 25 GPS Heading Solution Dual Antenna only 25 Self Test LED 26 Power Comms LED 26 Fitting the Secondary Antenna 21 Multipath Effects on Dual Antenna Systems 28 Setting up the Base Station 29 Using the RT Base 29 Using the Novatel Power Pak 29 Changing the RT3000 s Configuration 32 Overview 32 Revision 030728 Bl X i S Oro Reading the Initial Configuration 32 Orientation of the RT3000 in the vehicle 34 Specifying the Position of the Primary Antenna 35 Specifying the Orientation of the Secondary Antenna 37 Setting the Correct Options 38 Committing the Configuration to the RT3000 41 Saving a copy of the settings locally 42 Ethernet Configuration 43 Connection Details 43 Laboratory Testing 45 Accelerometer Test Procedure 45 Gyro Test Procedure 46 Testing the Internal GPS and other Circuitry 47 Deriving further Measurements 48 Computing a Velocity at a remote point 49 Computing the Slip Angle 50 Computing Forward and Lateral Velocities 51 Computing the Forward Lateral and Down Accelerations 51 Using a Flat Metric Grid 5
12. Note the range of Heading is 0 to 360 degrees the range of pitch is 90 degrees the range of roll is 180 degrees u Oxford Technical Solutions I mw RT3000 User Manual g Table 51 Identifier 608h Body X Y Z Angular Rates Description 0 16 S deg s 0 01 0 Body X Angular Rate Roll Angular Rate 16 16 S deg s 0 01 0 Body Y Angular Rate 32 16 S deg s 0 01 0 Body Z Angular Rate Table 52 Identifier 609h Vehicle Angular Rates Description 0 16 S deg s 0 01 0 Forward Angular Rate 16 16 S deg s 0 01 0 Pitch Angular Rate 32 16 S deg s 0 01 0 Yaw Angular Rate See message 608h for Roll Angular Rate The definition of roll rate used in this manual is consistent with the Euler Angles used to output Roll Pitch and Heading therefore the Roll Angular Rate is the same as the pitched X Angular Rate or the Body X Angular Rate The Forward Angular Rate is the rotation about the axis which is horizontal Table 53 Identifier 60Ah Track Slip Angles Description 0 16 S degrees 0 01 0 Track Angle 16 16 S degress 0 01 0 Slip Angle Note that the Slip Angle will be close to 180 degrees when driving backwards Revision 030728 a Description 0 Distance with Hold m ten 0 Distance cie M c Note The Distance with Hold will not increase when the RT3000 measures a speed less than 0 2m s whereas the Distance field will drift by the noise of the RT3000 when stationary The d
13. Table 56 List of Available Drawings Drawing Description Single Antenna RT3000 System Outer Dimension Drawings Available as an 14A0004x option for single antenna systems 14A0007x RT3000 System Outer Dimension Drawing 14C0009x RT3000 User Interface Cable 14C0016x RT3000 Radio Modem Interface Cable 14C0021x RT3000 User Interface Cable 14C0023x RT3000 User Interface Cable 14C0019x Base Station Radio Modem Power Cable 14C0018x M12 Power Cable PowerPak I Base Station GPS Receiver GPS 600 GPS Antenna AT575 70B GPS Antenna u Oxford Technical Solutions Oxford Technical Solutions 7 77 Heyford Park Upper Heyford 2 S Oxfordshire NW 0X25 5HD Mm www oxts co uk Copyright Oxford Technical Solutions 2003 Confidential Information The information in this document is confidential and must not be published or disclosed either wholly or in part to other parties or used to build the described components without the prior written consent of Oxford Technical Solutions is EA z A A l 0 10 20 30 Print Size A4 Scale 1 2 Units mm Tolerances All 0 1 Material Finish CN CON IC CN CS DDD IOS KV ESIS IMS POGUE NA NA KANA NANANA D Projection 3rd Angle Notes
14. e g 2 during year 2002 8 8 U year 100 0 Century e g 20 during 2002 16 8 U month 1 0 Month 24 8 U day 1 0 Day 32 8 U S 0 01 0 Hundredths of a Second 40 8 U S 1 0 Seconds 48 8 U min 1 0 Minutes 56 8 U hour 1 0 Hours Note Time is always reported as GPS time Currently this is 13 seconds different from UTC Table 44 Identifier 601h Latitude and Longitude Description 0 32 S degrees le 7 0 Latitude 32 32 S degrees le 7 0 Longitude a Oxford Technical Solutions RT3000 User Manual Table 45 Identifier 602h Altitude Description 0 32 S m 0 001 0 Attitude Table 46 Identifier 603h Velocity Description 0 16 S m s 0 01 0 North Velocity Down Velocity The Horizontal Speed is the vector addition of North and East Velocities For Forward Speed which can go negative see message 604h Table 47 Identifier 604h Velocity in Vehicle Frame Description Forward Velocity The Forward Speed can go negative when driving backwards Revision 030728 8 Description 0 16 S m s 0 01 Body X Acceleration 32 16 S m s 0 01 0 Body Z Acceleration Table 49 Identifier 606h Vehicle Accelerations Description 0 16 S m s 0 01 0 Forward Accelerations 32 16 S m s 0 01 0 Down Acceleration Table 50 Identifier 607h Heading Pitch Roll Description o am S ec E oa 0 16 U degrees 0 01 32 16 S degrees 0 01 0 Roll
15. omi of mounting angle change throughout the testing If the RT3000 is shock mounted then the RT3000 mounting will change by more than 0 05 degrees this is acceptable but the hystersis of the mounting may not exceed 0 05 degrees When shipped the antenna separation is set to 1000mm exactly It is possible to change the antenna separation distance either for ease of use or to change the performance a larger distance will improve performance Contact Oxford Technical Solutions for details on how to change the antenna separation Multipath Effects on Dual Antenna Systems Dual antenna systems are very susceptible to the errors caused by multipath This can be from buildings trees roof bars etc Multipath is where the signal from the satellite has a direct path and one or more reflected paths Because the reflected paths are not the same length as the direct path the GPS receiver cannot track the satellite signal as accurately The dual antenna system in the RT3000 works by comparing the carrier phase measurements at the two antennas This tells the system the relative distance between the two antennas and which way they are pointing the heading For the heading to be accurate the GPS receivers must measure the relative position to about 3mm The level of accuracy can only be achieved if there is little or no multipath In an ideal environment with no surrounding building trees road signs or other reflective surfaces the only mu
16. 0 1mm s at 100Hz nearly 2000 times better than the gravity caused by a 1 rotation To compute the accelerations in a level co ordinate frame where gravity does not affect the acceleration measurements use the following rotation Revision 030728 E nw 2 S A a Oy cos 0 0 sim0 0 0 ApzCppAgs 0 1 0 ffo cos 0 sin o fA si 0 o cos 0 0 sio cos where Ar is the vector containing the Forward Lateral and Down accelerations C rb is the rotation from the body co ordinate frame to the level co ordinate frame and A y is the vector of accelerations on the body co ordinate frame Using a Flat Metric Grid Because the earth is elliptical it is not possible to have distance in metres that make sense on the whole globe Over a small local area for example 10km the effects of earth curvature can be ignored and a local square grid can be used When working on a local grid the measurements for position will be expressed as Northings and Eastings 1 e the number of metres North of an origin and the number of metres east of an origin It is necessary to choose an origin where the Northings and Eastings are zero we will call this the base latitude and the base longitude Then we can compute the Northings and Eastings using the following equations n Northinge Latitude Base Latitud 63 TS P T T Fastings Longitude Base Longitud9 6378137 cos Base Latitude In each of these equations the La
17. By running a more relaxed model the system is able to 1 Make better estimates of the errors in the long term if it does not get these correct then they become more difficult to correct as time goes on 2 Track the errors in the inertial sensor during their warm up period when their errors change more quickly than normal During this period it is necessary to drive the vehicle otherwise the errors will not be estimated and the specification will not be reached The NCOM output message and the CAN outputs includes status information that can be used to identify when the required specification has been met Revision 030728 El nw 4 S CN e Von System Outputs The system can output data on two serial ports and over Ethernet if the CAN bus option is selected then the second serial output is replaced by the CAN bus output The outputs are available on the standard cables as follows Table 6 Output Connector functions Connector Function J2 RS232 Serial Output normally NCOM RS232 Serial Output normally NCOM Optionally CAN bus output J6 10T or 100T Ethernet The standard serial output of the RT3000 is a proprietary binary format referred to as NCOM this 1s described in detail at the end of the manual Oxford Technical Solutions offers C and C code that will interpret the packet This can be used freely in user s programs to interpret the output of the RT3000 For those who wish to interpret the packet direc
18. antenna in the same direction See Figure 4 below Figure 4 Dual Antenna Orientations e COMI Rn Correct Wrong 4 For good multipath rejection the antennas must be mounted on a metal surface using the magnetic mounts provided no additional gap may be used Multipath affects stationary vehicle more than moving vehicles and it can lead to heading errors of 0 5 degrees RMS if the antennas are mounted poorly on the vehicle CA For both single antenna systems and dual antenna systems it is essential that the supplied GPS antenna cables are used and not extended shortened or replaced This is even more critical for dual antenna systems and the two antenna cables must be of the same specification Do not for example use a 5m antenna cable for one antenna and a 15m antenna cable for the other Do not extend the cable even using special GPS signal repeaters that are designed to accurately repeat the GPS signal Cable length options are available in 5m 15m and 30m lengths 6 Mount both antennas where they have a clear unobstructed view of the whole sky from all angles 7 It is critical to have the RT3000 mounted securely in the vehicle If the angle of the RT3000 can change relative to the vehicle then the dual antenna system will not work correctly This is far more critical for dual antenna systems than for single antenna systems The user should aim to have no more than 0 05 degrees Revision 030728 a nw 2 S UN e
19. data for example if heading is 0 1 and Course over Ground is 359 8 then you need to add 360 to your result Computing Forward and Lateral Velocities Speed is the total rate of travel in any given direction It can be expressed as a horizontal speed or a 3D speed Forward Velocity is usually very close to speed except when the vehicle skids The Lateral Velocity is usually very close to zero except when the vehicle skids The Forward and Lateral Velocities can be found by rotating the velocities in the navigation co ordinate frame to be in the direction of the vehicle using the heading angle The rotation required to compute the Forward and Lateral Velocities are cos y sin 0 VrjsCp VgQ7 siwv cos y o V n 0 0 1 where Vr is the vector containing the Forward and Lateral Velocities and Down Velocity C p i5 the rotation matrix from the navigation co ordinate frame to a level co ordinate frame where the X axis is aligned to the heading of the vehicle and V a is the velocity in the navigation co ordinate frame Computing the Forward Lateral and Down Accelerations When the vehicle rolls the Y Acceleration measured in the body co ordinate frame contains a component of gravity because the Y direction is no longer at right angles to gravity A roll angle as small as 1 gives a Y acceleration of 0 171m s just from the coupling of gravity The RT3000 can measure acceleration to 10mm s and has a resolution of about
20. situation even though no sensor measures velocity directly The Kalman filter could also be used to measure the bias or offset of the accelerometer thereby improving the system by providing on line calibration The bias of the accelerometer might mean that the system always believes that the lift arrives early at each floor by changing the bias on the accelerometer the measurement of lift position can be made to correlate with the floor sensor more accurately The same principles are used in the RT3000 Position and Velocity are compensated directly but other measurements like accelerometer bias have no direct measurements The Kalman filter tunes these so that the GPS measurements and the inertial measurements match each other as closely as possible The Kalman filter in the RT3000 has 23 states These are position error north east down velocity error north east down heading error pitch error roll error gyro bias X Y Z gyro scale factor X Y Z accelerometer bias X Y Z GPS antenna position X Y Z and GPS antennas orientation heading pitch The errors are applied smoothly to the states For example if the Kalman filter wants to correct a position error of 5cm in the north direction then this is applied slowly rather than jumping directly to the new position This helps applications that use the RT3000 for control since any differential terms in the control algorithm do not have large step changes in them Rev
21. the Orientation Angle Accuracies are le 4 radians Table 38 Status Information Channel 16 Bytes Format Definition Valid When 0 1 Short Heading of the vehicle in the RT3000 co ordinate frame Byte 6 0 2 3 Short Pitch of the vehicle in the RT3000 co ordinate frame Byte 6 0 4 5 Short Roll of the vehicle in the RT3000 co ordinate frame Byte 6 0 6 UChar Validity 7 Char Bits 1 7 UTC Time Offset Bit0 1 Note The units of the Orientation Angles are 1e 4 radians To compute UTC Time from GPS Time add the offset Currently the offset is 13 seconds The offset is always an integer number of seconds UTC Time slips or gains a second occasionally whereas GPS Time does not Oxford Technical Solutions Y Mine RT3000 User Manual Table 39 Status Information Channel 19 Bytes Format Definition Valid When 0 7 8x Char This is the Software Version or Development ID that is running in the RT3000 in ASCII format Table 40 Status Information Channel 20 Bytes Format Definition Valid When 0 1 Short Age of the Differential Corrections from the Base Station DE Reserved Note The unit of the Differential Corrections is 0 01 seconds Table 41 Status Information Channel 21 Bytes Format Definition Valid When 0 3 Long Disk Space Remaining on RT3000 Note that the RT3000 Value gt 0 always leaves about 20K spare on the disk 4 7 Long Size of current logged raw data file When there is Value gt 0 insufficient spac
22. this procedure 1 Ifthere is a mobile vat file in your system to convert from the RT3000 co ordinate frame to the vehicle s co ordinate frame then it needs to be removed and the system needs to be restarted 2 Connect power to the system connect the system to a laptop computer and run the visual display software ENGINUTIY EXE 3 Rotate the RT3000 according to Table 17 below and check that the angular rate measurements occur 4 With the unit stationary check that all the angular rates are within 5 s In general they will be within 0 5 s but the algorithm in the RT3000 will work to specification with biases up to 5 s Table 17 Angular Rate Measurement Specifications Rotation Angular Rate Measurement ve Zero Zero X direction should indicate positive rotation others are small ve Zero Zero X direction should indicate negative rotation others are small Zero ve Zero Y direction should indicate positive rotation others are small Zero ve Zero Y direction should indicate negative rotation others are small Zero Zero ve Z direction should indicate positive rotation others are small Zero Zero ve Z direction should indicate negative rotation others are small It is hard to do a more exhaustive test using the angular rate sensors without specialised software and equipment For further calibration testing it is necessary to return the unit to Oxford Technical Solutions Note that the RT300
23. v v 1 User Cable v v v v v v v v v 1 GPS Antenna AT575 70B v v x XO v 1 GPS Antenna AT2775 12 v x2 1 GPS 600 LB Antenna v v 1 5m TNC SMA Cable v x2 v v 1 Null Modem Serial Cable v v v v v v v v v Base Station Components 1 Base Station GPS Receiver v v v v 1 15m Antenna Cable v v v v 1 GPS 600 L1 Antenna v v 1 GPS 600 L1 L2 Antenna v v 1 Null Modem Serial Cable v v v v 1 Base Station Power Cable v v v v Accessories 1 CD ROM with Manual and Software v v v v v v v v v 1 RT3000 User Manual v v v v v v v v v Note 1 Several different user cables are available A different cable may be chosen by the customer Custom cables are also made See drawings at the end of the manual for cable specifications Note 2 The Base Station is an optional extra and must be purchased separately or as part of a bundle New systems can be supplied with an optional RT Base unit which is covered by a separate manual In addition to the components supplied the user will require a laptop computer and for systems that include a base station radio modems For line of sight operation within a 2km range the optional SATEL radio modems can be purchased m Oxford Technical Solutions RT3000 User Manual dl Figure 1 Typical RT3000 system in transit case n Pe 73 Note that the antenna style has changed since this picture was taken Revision 030728 ls nw 2 S UN e omi Warranty Oxford Technical Solutions Limited warra
24. vector measured in the navigation co ordinate frame to the body co ordinate frame The navigation co ordinate frame is the orientation on the earth at your current location with axes of North East and Down If E is vector V measured in the navigation co ordinate frame and V b is the same vector measured in the body co ordinate frame the two vectors are related by Vin C bn V b cos y sin y 0 cos 0 0 sin 0 0 0 V siy cos y of 9 0 49 cos 6 sin gt V 0 0 1 sin 0 0 cos 0 0 sio cos o n Oxford Technical Solutions RT3000 User Manual ey where y is the heading angle 0 is the pitch angle and is the roll angle Remember heading pitch and roll are usually output in degrees but the functions sin and cos require these values in radians Computing a Velocity at a remote point You can use the outputs of the RT3000 to compute the velocity at any other point on the vehicle assuming that the vehicle is rigid Velocity measurements from the RT3000 are expressed in the navigation co ordinate frame whereas the remote point is expressed in the body co ordinate frame The following formula relates the outputs of the RT3000 to a velocity at a remote point Y2n V nt Con b P p where V2 is the velocity at the remote point V is the velocity at the RT3000 C bi is the rotation matrix above Q p is the angular rate vector in the body co ordinate frame and Pob is the distance from the RT3000 t
25. 0 is capable of correcting the error in the angular rate sensors very accurately It is not necessary to have very small values for the angular rates when stationary since they will be estimated during the initialisation process and warm up period This estimation process allows the RT3000 to go for long periods without requiring recalibration 6 Oxford Technical Solutions RT3000 User Manual Testing the Internal GPS and other Circuitry To check that all the internal circuits in the RT3000 are working correctly and that the navigation computer has booted correctly use the following procedure 1 Connect power to the system connect the system to a laptop computer and run the visual display software ENGINUTIY EXE 2 Use Table 18 below to check that the status fields are changing Table 18 Status Field Checks Field Increment Rate IMU Packets IMU Chars Skipped GPS Packets GPS Chars Skipped GPS2 Packets GPS2 Char Skipped 100 per second Not changing but not necessarily zero Between 2 and 20 per second depending on system Not changing but not necessarily zero Between 2 and 20 per second only for dual GPS systems Not changing but not necessarily zero These checks will ensure that the signals from the GPS and from the Inertial Sensors are being correctly received at the navigation computer Revision 030728 jar nw EN S A C e Opi Deriving further Measurements Th
26. 000 e The orientation of the Dual antennas compared to the RT3000 e Some environment parameters Many of these parameters the RT3000 can figure out by itself but this takes time Measuring the parameters yourself and configuring the RT3000 shortens the time before full specification can be met If the RT3000 has been running for some time it will have improved the measurements that you have made It is possible to read these improved measurements into RT3000Cfg commit them to the RT3000 and then use them next time you start the system If you move the RT3000 from one vehicle to another it is essential that you return to the default configuration rather than using a set of parameters that have been tuned for a different vehicle Reading the Initial Configuration The first page of RT3000C g gives several options for reading the configuration from different places Figure 5 below shows RT3000C fg just after it is started E Oxford Technical Solutions lh oy RT3000 User Manual g Figure 5 RT3000Cfg Initial Screen t T3000 Configuration Wizard x Read Configuration RT3000 Choose where the initial settings should be read from Inertial SUE Use Default settings Measurement Start with the default LLE Read from a folder values or load a configuration from a directory a stored Step 1 of 8 C Read from an NCOM file NCOM file or the RT3000 system gt Orientation C Read initial settings
27. 000 recognises jumps in the GPS position and ignores them e The position and velocity measurements that the GPS makes are smoothed to reduce the high frequency noise e The RT3000 makes many measurements that GPS cannot make for example acceleration angular rate heading pitch roll etc The standard RT3000 system processes the data in real time The real time results are output via an RS232 serial port over 100 Base T Ethernet using a UDP broadcast and optionally on CAN bus Outputs are time stamped and refer to GPS time a 1PPS timing sync can be used to give very accurate timing synchronisation between systems The inertial measurements are synchronised to the GPS clock Internal data logging enables the data to be reprocessed post mission Data can be collected in the unit downloaded using ftp processed on the PC and viewed using customer s software Installation and operation of the RT3000 could not be simpler A single unit contains the inertial sensors GPS receiver data storage and CPU One or two antennas need to be mounted outside the vehicle where they have a clear view of the sky 9 to 18Vd c power can be obtained from most vehicles power supplies A laptop computer allows real time viewing of the results a Oxford Technical Solutions EROS 4 1 RT3000 User Manual ws Taking the time to thoroughly read and understand the manual will inevitably lead to achieving the best results with the RT3000 syste
28. 1cm or better in a straight line It is much harder to measure to 1cm through a car roof and it is much harder to measure to 1cm if the RT3000 is slightly misaligned in the vehicle Any alignment errors should be included in the accuracy that you believe you can measure to Telling the RT3000 that you have measured the distances to 1mm may lead the RT3000 to believe its results are better than they really are You may be impressed by the accuracy that the RT3000 reports but in reality it will not be that accurate It is better to overestimate the accuracy than to underestimate it E Oxford Technical Solutions B S RT3000 User Manual A Specifying the Orientation of the Secondary Antenna If your system has two antennas then it is necessary to tell the RT3000 the orientation of the two antenna system compared to the vehicle It is critical to tell the RT3000 the exact distance between the two antennas to 5mm or better Figure 8 RT3000Cfg Secondary Antenna Screen RT3000 Configuration Wizard x a Secondary Antenna RT3000 Specify the Secondary GPS Antenna position on the vehicle Inertial and GPS Secondary antenna Behind Measurement Compare the position of System Separation 1 000 m the Secondary bottom antenna to the Primary Step 5 of 8 Antenna Read Configuration Orientation Primary Antenna Dual Antenna gt Use advanced settings Options Commit Orientation 1180 00 deg to within Finish thin f 00 deo E
29. 2 Computing Performance Metrics 52 Operating Principles 54 Internal Components 54 Strapdown Navigator 55 Kalman Filter 57 NCOM Packet Format 58 Status Information 62 CAN Messages and Signals 70 Termination Resistor 70 CAN DB File 70 CAN Bus Messages 70 E Oxford Technical Solutions RT3000 User Manual 4 e Oy Table Heading Definitions 71 Signals 72 Revision History 71 Drawing List 78 Revision 030728 8 nw EN S A C e Opi Introduction The RT3000 family of Inertial and GPS Navigation Systems from Oxford Technical Solutions are instruments for making precision measurements of motion in real time The RT3000 uses mathematical algorithms developed for use in fighter aircraft navigation systems An inertial sensor block with three accelerometers and three gyros angular rate sensors is used to compute all the outputs A WGS 84 modelled Strapdown Navigator Algorithm compensates for earth curvature rotation and Coriolis accelerations while measurements from high grade kinematic GPS receivers update the position and velocity navigated by the inertial sensors This innovative approach gives the RT3000 several distinct advantages over systems that use GPS alone e The RT3000 has a high 100Hz update rate and a wide bandwidth e The outputs are available with very low 3 9ms latency e All outputs remain available continuously during GPS blackouts when for example the vehicle drives under a bridge e The RT3
30. 376 Date 29 05 02 Part 4 14C0019C Document Radio Modem Base Sheet 1 of 1 Oxford Technical Solutions 77 Heyford Park Upper Heyford Oxfordshire OX25 5HD www oxts co uk Copyright Oxford Technical Solutions 2002 Pin Definitions Brown Positive 12V Power supply 9 18 d c White Not Used Blue OV GND Confidential Information View from front Black Earth Case The information in this document of plug is confidential and must not be disclosed to other parties or used to build the described components without the written permission of Oxford Technical Solutions ail 14C0018A FEREFFTTT TETTFTTTTEUTETTTEETT 0 10 20 30 Print Size A4 Scale 1 1 Units mm 1 1 1 2 1 3 1 4 serene See ERY 9 i o 7 NEN o ON T dene w ex Ress BESS em m Tolerances 100mm Parts Connections RS290 6512 M12 4w 2m PUR straight Connector 1 1 Brown J2 1 RS266 0250 Car Cigarette Lighter Plug 1 2 White Not Connected RS399 524 Yellow Heat Shrink 6 4mm 1 3 Blue J2 2 RS399 934 Clear Heat Shrink 6 4mm 1 4 Black J2 2 Date 07 12 01 Part 4 14C0018A Document M12 Power Cable Sheet 1 of 1 Oxford Technical Solutions 77 Heyford Park Upper Heyford Oxfordshire OX25 5HD www oxts co uk Copyright Oxford Technical Solutions 2002 C
31. 80 mm 2 3 kg 10 to 50 C 0 1 g Hz 5 500 Hz 100G 2ms sine Yes 512 MB No Yes RT3060 WAAS 1m CEP 0 1 km h RMS 10 mm s lo 0 01 0 1 lo 100 m s 0 05 lo 0 2 1o dynamic 0 01 s lo 0 1 lo 100 s 0 2 RMS 0 25 RMS 0 4 100 Hz 3 9 ms 9 18 V d c 20W 234 x 120 x 80 mm 2 3 kg 10 to 50 C 0 1 g Hz 5 500 Hz 100G 2ms sine No 512 MB No Yes Note 1 For OmniStar HP continuous sky may be required for a long period of time 30 minutes or more before the accuracy achieves 10cm The OmniStar HP service can achieve this in complete open sky and airborne applications Revision 030728 0 MRS 3 QN e Ori Table 4 Performance Specification for the RT3000 Dual Antenna Systems Product Positioning Position Accuracy Velocity Accuracy Acceleration Bias Linearity Scale Factor Range Roll Pitch Heading Angular Rate Bias Scale Factor Range Track at 50km h Slip Angle at 50 km h Lateral Velocity Update Rate Calculation Latency Power Dimensions Weight Operating Temperature Vibration Shock Survival Base Station Included Internal Storage Twin Antenna Upgradeable GPS RT3003 L1 L2 Kinematic 2cm 16 open sky 0 05 km h RMS 10 mm s lo 0 01 0 1 lo 100 m s 0 03 lo 0 1 lo 0 01 s lo 0 1 lo 100 s 0 07 RMS 0 15 RMS 0 2 100 Hz 3 9 ms 9 18 V d c 20W 234 x 120 x
32. 80 mm 2 4 kg 10 to 50 C 0 1 g Hz 5 500 Hz 100G 2ms sine RT3022 L1 Kinematic 20cm 16 open sky 0 08 km h RMS 10 mm s lo 0 01 0 1 lo 100 m s 0 04 lo 0 1 lo 0 01 s lo 0 1 lo 100 s 0 1 RMS 0 15 RMS 0 2 100 Hz 3 9 ms 9 18 V d c 20W 234 x 120 x 80 mm 2 4 kg 10 to 50 C 0 1 g Hz 5 500 Hz 100G 2ms sine RT3102 Stand Alone DGPS 1 8m CEP Stand Alone 0 4m CEP DGPS 0 1 km h RMS 10 mm s lo 0 01 0 1 lo 100 m s 0 06 lo 0 1 lo 0 01 s lo 0 1 lo 100 s 0 2 RMS 0 25 RMS 0 4 100 Hz 3 9 ms 9 18 V d c 20W 234 x 120 x 80 mm 24 kg 10 to 50 C 0 1 g Hz 5 500 Hz 100G 2ms sine No Oxford Technical Solutions E ov RT3000 User Manual Environmental Protection The RT3000 is rated to IP65 To achieve IP65 it is necessary to have connectors fitted to both TNC Antenna Connectors and to use self amalgamating tape over the TNC connectors Revision 030728 Li Quick Guide to Operation The basic operation of the RT3000 products is simple The following steps should be taken to operate the units 1 Fit the RT3000 system to the vehicle with the cable connections facing the rear of the vehicle The LEDs should be to the left and the antenna connections to the right for normal level operation 2 Connect the User Cable 14C0009A to the RT3000 Figure 2 RT3000 System in vehicle 3 Connect the GPS Cable t
33. Accuracy 3 Orientation Accuracy Since the Heading specification and the Pitch Roll specifications are not the same it is best to monitor the Orientation accuracy as a combined Pitch Roll attitude accuracy and a separate Heading accuracy To combine the Pitch Roll accuracy use the formula i hA RollA AttitudeAccuracy 2 RAce Roce 2 The Heading accuracy is output directly by the RT3000 Revision 030728 E nest 2 DAS O NOn Operating Principles This short section gives some background information on the components in the RT3000 and how they work together to give the outputs A short overview of the algorithm is given and some explanation of how the software works The section is provided as interesting information and is not required for normal operation Internal Components Figure 16 below gives a schematic view of the components in the RT3000 system Figure 16 Schematic showing the internal components of the RT3000 Accelerations Angular Rates 40MHz DSP 20 bit resolution ax dy ay Wx Dy Wy Differential Corrections Radio Modem dui adu MG Serial e g SATEL 3ds or cellphone 300MHz CPU 64MB Storage Ethernet Sync 1PPS 100Hz out or event in Power Power Supply 9 18Vdc 4 RT3000 a em www ewww ww
34. Copyright Oxford Technical Solutions 2002 J3 RADIO Confidential Information 14C0021A J1 Tail Lengths 300mm 300mm 300mm 2000mm 300mm 300mm centimetres Connection Cable Details Description Supply Blue 16 0 2 Supply Return Black 16 0 2 Nav Data RS232 TX Nav Data RS232 RX N C Radio Data RS232 TX Radio Data RS232 RX N C Aux Data RS232 TX Aux Data RS232 RX PPS out Centre Conductor Nav Data RS232 Common Ethernet ETX Ethernet ERX N C Radio Data RS232 Common Aux Data RS232 Common PPS out GND Screen N C Ethernet ETX Ethernet ERX EMI Ground Green 16 0 2 JO mE mA i chon mak anb mal ami nubi COANDUNARWN O NNK po Length XX is denoted in the part ordered by the final digits of the part number in For example 14C0021x 100 specifies a cable length of 100cm x is the revision Connections J3 1 J3 14 J3 15 PWR Blue J3 7 J3 8 PWR Black J2 3 J2 2 N C J3 11 J3 9 N C J4 3 J4 2 J5 CORE J2 5 J6 2 J6 6 N C J3 7 J4 5 J5 SCREEN N C J6 1 J6 3 PWR Green Supply 9 18 Volts DC Supply Return EMI Ground J5 PPS OUT Special Notes Cable outers braided and connected to EMI Ground J1 13 20 Twisted see NOTE A J1 14 21 Twisted see NOTE A J6 Network 10B T Power c
35. Float 32 bit IEEE float Double 64 bit IEEE float Note If a U precedes the value then it is unsigned otherwise it is signed using 2 s complement The definition of the packet is given in Table 20 Table 21 and Table 22 below Note that to reduce the latency the SYNC character listed as the first character of the packet is transmitted at the end of the previous cycle On the communication link there will be a pause between the transmission of the SYNC and the next character It is not advised to use this pause to synchronise the packet even though the operating system should guarantee the transmission timing of the packet E Oxford Technical Solutions RT3000 User Manual Din 4 Qu mih Table 20 NCOM Packet Definition Batch 1 Byte 0 Quantity Sync Time Time Acceleration X LSB Acceleration X Acceleration X MSB Acceleration Y LSB Acceleration Y Acceleration Y MSB Acceleration Z LSB Acceleration Z Acceleration Z MSB Angular Rate X LSB Angular Rate X Angular Rate X MSB Angular Rate Y LSB Angular Rate Y Angular Rate Y MSB Angular Rate Z LSB Angular Rate Z Angular Rate Z MSB Nav Status Checksum 1 Notes Always E7h Time is transmitted as milliseconds into the minute in GPS time Range is 0 to 59 999 ms The packets are always transmitted at 100Hz use this quantity to verify that a packet has not been dropped Acceleration X is the vehicle body frame acceleration in the x direction
36. Ground OR Oxford Technical Solutions 77 Heyford Park J2 Nav Dat Upper Heyford A S i A S Oxfordshire QNS My OX25 5HD uaa www oxts co uk Copyright Oxford Technical Solutions 2002 The information in this document is confidential and must not be disclosed to other parties or used to build the described components without the written permission of Oxford Technical Solutions J3 RADIO 0 10 20 30 Print Size A4 Not to scale J5 PPS OUT J6 Network 10B T 300mm Connection Cable Details Description Supply Blue 16 0 2 Supply Return Black 16 0 2 Nav Data RS422 TX Nav Data RS422 RX Nav Data RS422 TX Radio Data RS232 TX Radio Data RS232 RX N C Aux Data RS232 TX Aux Data RS232 RX PPS out Centre Conductor Nav Data RS422 Common Ethernet ETX Ethernet ERX Nav Data RS422 RX Radio Data RS232 Common Aux Data RS232 Common PPS out GND Screen N C Ethernet ETX Ethernet ERX EMI Ground Green 16 0 2 JO mE mA i chon mak anb mel ami nubi QOdoQo oo 0iROonPnMN o NNK po Connections J3 1 J3 14 J3 15 PWR Blue J3 7 J3 8 PWR Black J2 2 J2 7 J2 1 J3 11 J3 9 N C J4 3 J4 2 J5 CORE J2 5 J6 2 J6 6 J2 6 J3 7 J4 5 J5 SCREEN N C J6 1 J6 3 PWR Green Special Notes Cable outers braided and connected to EMI Ground J1 13 20 Twisted see NOTE A J1 14 21 Twis
37. I omy e nmi Figure 17 Schematic of the Strapdown Navigator Angular Rates amp 8 8 J Bias Correction Scale Factor Correction Heading Pitch Roll Earth Rotation Rate Transport Rate Accelerations m x 1 x Velocity Bias TEX Gravity bM Coriolis Acceleration L Q People familiar with Inertial Navigation Systems will note that Angular Rates and Accelerations are labelled as the inputs In reality the DSP in the RT3000 converts these to Change in Angle and Change in Velocity to avoid problems of coning and sculling Some other rotations are also missed in the diagram The RT3000 does not use a wander angle so it will not operate correctly on the North and South poles The Angular Rates have their bias and scale factor corrections from the Kalman Filter applied Earth Rotation Rate is also subtracted to avoid the 0 25 degrees per minute rotation of the earth The Transport Rate is also corrected this is the rate that gravity rotates by due to the vehicle moving across the earth s surface and it is proportional to horizontal speed Finally the Angular Rates are integrated to give Heading Pitch and Roll angles These are represented internally using a Quaternion so the RT3000 can work at any angle and does not have any singularities The Accelerations have their bias corrections from the Kalman Filter applied Then they are rotated to give accelerations in th
38. M12 Moulded Plug Wire Hellerman 154 42 G Farnell 463 050 472 748 Farnell 463 061 472 750 Farnell 463 050 472 785 See Note A Farnell 723 3863 J4 missing to maintain compatibility with other cables N 14C0016A J1 Tail Lengths 300mm 300mm 300mm 300mm 2000mm Connection Cable Details Description Power Supply 10 to 18V D C Power Return Ov Ground Nav Data RS232 TX Nav Data RS232 RX N C GPS Data RS232 TX GPS Data RS232 RX N C DSP Data RS232 TX DSP Data RS232 RX PPS RS422 A Nav Data RS232 Common Ethernet ETX Ethernet ERX N C GPS Data RS232 Common DSP Data RS232 Common PPS RS422 Common PP2 RS422 B Ethernet ETX Ethernet ERX Case Earth OONOORWN HG 24 mm XX Length XX is denoted in the part ordered by the final digits of the part number in centimetres For example 14C0016x 100 specifies a cable length of 100cm x is the revision Connections J7 1 Brown J3 14 J3 15 J3 1 J7 3 Blue J3 7 J3 8 J2 3 J2 2 N C J3 11 J3 9 N C N C N C J5 2 J2 5 J6 2 J6 6 N C J3 7 N C J5 5 J5 7 J6 1 J6 3 J7 4 Black Oxford Technical Solutions 77 Heyford Park Upper Heyford S Oxfordshire OX25 5HD www oxts co uk Copyright Oxford Technical Solutions 2002 J3 Radio Confidential Information The information in this document is confidential and must not be disclosed t
39. RT3000 Inertial and GPS Measurement System User Manual Confidently Accurately S OT Legal Notice Information furnished is believed to be accurate and reliable However Oxford Technical Solutions Limited assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use No license is granted by implication or otherwise under any patent or patent rights of Oxford Technical Solutions Limited Specifications mentioned in this publication are subject to change without notice and do not represent a commitment on the part of Oxford Technical Solutions Limited This publication supersedes and replaces all information previously supplied Oxford Technical Solutions Limited products are not authorised for use as critical components in life support devices or systems without express written approval of Oxford Technical Solutions Limited All brand names are trademarks of their respective holders Copyright Notice Copyright 2003 Oxford Technical Solutions Revision Document Revision 030728 See Revision History for detailed information Contact Details Oxford Technical Solutions Limited 77 Heyford Park Upper Heyford Oxfordshire OX25 5HD Tel 01869 238 015 Fax 01869 238 016 http www oxts co uk mailto info oxts co uk 8 Oxford Technical Solutions RT3000 User Manual Ls Table of Contents
40. Read Configuration gt Use advanced settings Primary Antenna Dual Antenna Heading o 00 deg Secondary Antenna Options Pitch o 00 deg Commit Finish Roll 10 00 deg Confidently Accurately ti EJ Oxford Technical Solutions RT3000 User Manual To make it simpler to configure the RT3000 s orientation in the vehicle RT3000Cfg asks the user to define the direction that the main connector points in the vehicle After that stand facing the main connector and enter the direction that the antenna connectors are compared to the main connector In the list there is no option for the main connector facing upwards or downwards It is necessary to use the advanced settings to configure the unit to be mounted this way To make small adjustments use the advanced settings This allows the user to zero any slip angle offsets pitch offsets or roll offsets Although it is possible to mount the RT3000 in any orientation Dual antenna systems do not perform as well when mounted with the main connector pointing upward or downward There is a singularity in the GPS Antenna Orientation estimates when the mounting pitch angle is at 90 degrees To avoid this Dual antenna systems should not be mounted with pitch close to 90 degrees Single antenna systems are not affected Specifying the Position of the Primary Antenna The RT3000 is able to measure the position of the Primary Antenna itself However th
41. ble 49 607h Heading Pitch Roll Table 50 608h Angular Rates body X Y Z Table 51 609h Angular Rates Forward Pitch Yaw Table 52 60Ah Slip Angle Track Angle Table 53 60Bh Distance Table 54 60Chto 60Fh Reserved for future use Note 1 The Status Information in NCOM is output over the CAN bus on Identifiers 500h to SFFh The offset from 500h is the same as the Channel number in the NCOM message definition The bytes 0 7 are the same in the CAN message as in the NCOM packet Table Heading Definitions The fields in the tables have the following meanings Offset bits This is the offset into the Message where the Signal starts To compute the offset in bytes divide the value by 8 Length bits This is the length of the Signal in bits To compute the length of the Signal in bytes divide the value by 8 Type This specifies either an unsigned value U or a signed value S Units This is the units for the signal Factor This it the factor that the integer unit should be multiplied by to get the Signal into the units given in the table Revision 030728 E j wit 3 EN e omit Offset This is the value of the Signal when the integer value in the CAN message is Zero It is zero for all the RT3000 signals and can usually be discarded Signals The following tables describe the signals in each of the messages Table 43 Identifier 600h Date and Time Description 0 8 U year 1 0 Year within century
42. dio modems The communications settings of the radio modem will have to match the communication settings of the GPS receiver listed below Note If the base station antenna is moved then it is necessary to re average the position or to re enter the new surveyed co ordinates Once the base station has had its position fixed the valid position light will be on even when there are no valid satellites i e at start up before it has correctly acquired the satellites and before it is transmitting valid corrections Revision 030728 Et nw EN S A C e Opi Changing the RT3000 s Configuration The default parameters that the RT3000 is shipped with will work for most applications To get the best results from your RT3000 it is necessary to change the configuration to suit the way you have installed the RT3000 in your vehicle The program RT3000C g EXE can be used to do this This section describes how to use RT3000Cfg and gives additional explanations on the meanings of some of the terms used It is only possible to change the RT3000 s configuration using Ethernet It is necessary to have the Ethernet on your computer configured correctly in order to communicate with the RT3000 and change the settings Overview In order to give the best possible performance the RT3000 needs to know the following things e The orientation that the RT3000 is mounted at in the vehicle e The position of the Primary GPS antenna compared to the RT3
43. duct Positioning Position Accuracy Velocity Accuracy Acceleration Bias Linearity Scale Factor Range Roll Pitch Heading Angular Rate Bias Scale Factor Range Track at 50km h Slip Angle at 50 km h Lateral Velocity Update Rate Calculation Latency Power Dimensions Weight Operating Temperature Vibration Shock Survival Base Station Included Internal Storage Twin Antenna Upgradeable GPS RT3002 L1 L2 Kinematic 2cm 16 open sky 0 05 km h RMS 10 mm s lo 0 01 0 1 lo 100 m s 0 03 lo 0 1 lo dynamic 0 01 s lo 0 1 lo 100 s 0 07 RMS 0 15 RMS 0 2 100 Hz 3 9 ms 9 18 V d c 15W 234 x 120 x 80 mm 22 kg 10 to 50 C 0 1 g Hz 5 500 Hz 100G 2ms sine Yes 512 MB No Yes to dual antenna RT3020 L1 Kinematic 20cm 16 open sky 0 08 km h RMS 10 mm s lo 0 01 0 1 lo 100 m s 0 04 lo 0 1 1o dynamic 0 01 s lo 0 1 lo 100 s 0 1 RMS 0 15 RMS 0 2 100 Hz 3 9 ms 9 18 V d c 15W 234 x 120 x 80 mm 2 2 kg 10 to 50 C 0 1 g Hz 5 500 Hz 100G 2ms sine Yes 512 MB No Yes RT3100 Stand Alone DGPS 1 8m CEP Stand Alone 0 4m CEP DGPS 0 1 km h RMS 10 mm s lo 0 01 0 1 lo 100 m s 0 06 lo 0 2 1c dynamic 0 01 s lo 0 1 lo 100 s 0 2 RMS 0 25 RMS 0 4 100 Hz 3 9 ms 9 18 V d c 15W 234 x 120 x 80 mm 22 kg 10 to 50 C 0 1 g Hz 5 500 H
44. e 26 2 Internal Information about GPS1 3 Position Accuracy Table 28 4 Velocity Accuracy Table 29 3 Orientation Accuracy Table 30 6 Gyro Bias Table 31 7 Accelerometer Bias Table 32 8 Gyro Scale Factor Table 33 9 Gyro Bias Accuracy 10 Accelerometer Bias Accuracy 11 Gyro Scale Factor Accuracy 12 Position estimate of the Primary GPS antenna Table 34 13 Orientation estimate of Dual Antenna systems Table 35 14 Accuracy of Position of the Primary GPS antenna Table 36 15 Accuracy of the Orientation of Dual antenna systems Table 37 16 RT3000 to Vehicle Rotation from initial setting defined by user Table 38 17 Internal Information about GPS2 18 Internal Information about Inertial Measurement Unit 19 Software version running on RT3000 Table 39 20 Age of Differential Corrections Table 40 21 Disk Space Size of current internal log file Table 41 22 Internal Information on timing of real time processing 23 System Up Time Number of consecutive GPS rejections E 24 Reserved DS Reserved 26 Reserved 2g Internal Information about Dual Antenna Ambiguity Searches 28 Internal Information about Dual Antenna Ambiguity Searches 29 Details on the initial settings 30 255 Reserved for future use I O M Note Channels with no corresponding table are not described in this manual Contact Oxford Technical Solutions if you require specific informatio
45. e RT3000 outputs are complete for all aspects of vehicle motion apart from angular acceleration There are instances when other outputs will be required or when the same output is required in a different measurement co ordinate frame For example you may wish to compute the following parameters l compute velocity at a point remote from the RT3000 measurement point 2 compute the slip angle of the vehicle 3 compute the lateral acceleration perpendicular to gravity so that vehicle roll does not affect the measurements 4 plot position on a flat metric grid Many of these outputs are computed using the RT CAN unit or using the software provided The equations are provided here to help understanding and to make it easier for engineers who need to write their own interpreters for the RT3000 output Before computing the additional outputs you should have a clear understanding of the definitions of heading pitch and roll The RT3000 uses quaternions internally to avoid the problems of singularities and to minimise numerical drift on the attitude integration Euler angles are used to output the heading pitch and roll and these have singularities at two orientations The RT3000 has rules to avoid problems when operating close to the singularities if you regenerate the rotation matrices given below then they will be correct The Euler angles output are three consecutive rotations first heading then pitch and finally roll that transform a
46. e earth s co ordinate frame North East Down Gravity is subtracted and Coriolis acceleration effects removed The accelerations are integrated to give velocity This is integrated to give position The Strapdown Navigator uses a WGS 84 model of the earth the same as GPS uses This is an elliptical model of the earth rather than a spherical one The position outputs are in degrees Latitude degrees Longitude and Altitude The Altitude is the distance from the model s earth sea level The Kalman filter used in the RT3000 is able to apply corrections to several places in the Strapdown Navigator including Position Velocity Heading Pitch Roll Angular Rate Bias and Scale factor and Acceleration Bias E Oxford Technical Solutions RT3000 User Manual Kalman Filter Kalman Filters can be used to merge several measurements of a quantity and therefore give a better overall measurement This is the case with Position and Velocity in the RT3000 the Kalman filter is used to improve the Position measurement made from two sources inertial sensors and GPS Using a model of how one measurement affects another the Kalman filter is able to estimate states where it has no direct measurement Consider a lift or elevator in a building We might make measurements of acceleration and we might know what our position is when we pass a floor these are the two measurements our system makes A Kalman filter could be used to measure velocity in this
47. e on the disk no more data will be written Note The values are output in kilobytes Revision 030728 2 S UN e omi CAN Messages and Signals The RT CAN uses identifiers 500h to 5FFh for RT3000 Status Information and 600h to 60Fh for navigation information All values from the RT3000 are encoded in Little Endian format Intel style Termination Resistor The CAN bus output does not include a termination resistor It is essential to include a 120 resistor at each end of your CAN bus Otherwise the CAN bus will not work CAN DB File A CAN DB file is available for download on the Oxford Technical Solutions web site This file contains definitions for the Status messages as well as the Measurement outputs Only the Measurement outputs are described here CAN Bus Messages Table 42 below lists all the messages that the RT3000 puts on the CAN bus and the identifiers that are used for the messages The signals in each message are listed in the tables that follow u Oxford Technical Solutions Mins RT3000 User Manual g Table 42 CAN Bus Messages Data Contents See Table 500h to SFFh Reserved for RT3000 Status Information See NCOM Status Channel 600h Date and Time Table 43 601h Latitude Longitude Table 44 602h Altitude Table 45 603h Velocity North East Down Table 46 604h Velocity Forward Lateral Table 47 605h Accelerations body X Y Z Table 48 606h Accelerations Forward Lateral Down Ta
48. ely To save a copy of the settings in a local folder check the Preserve these settings in folder check box and enter the folder name n Oxford Technical Solutions h rst RT3000 User Manual Ethernet Configuration To obtain maximum use of the RT3000 it is necessary to use the Ethernet connection The operating system at the heart of the RT3000 product allows connection to the unit via FTP The use of FTP allows the user to manage the data logged to the unit files can be uploaded for reprocessing and deleted to make space for future files Configuration files for alternative configurations require FTP to put the configuration files on to the RT3000 The RT3000 outputs its data over Ethernet using a UDP broadcast The use of a UDP broadcast allows everyone on the network to receive the data sent by the RT3000 It is advisable to use the RT3000 on its own private network This will help avoid loss of data through collisions on the network Due to processing restrictions in the unit and collisions on the network it is advisable not to use the FTP services while the unit is being used to process data The FTP server has a very low priority and will be slow while the RT3000 is running i e while the top LED is green The settings of the RT3000 s Ethernet adapter are given in Table 14 below Table 14 RT3000 Ethernet Settings Setting Value IP Address 195 0 0 x where x is the serial number Subnet Mask 2552552550
49. from RT3000 Primary Antenna Dual Antenna Secondary Antenna C Read current settings from RT3000 Options Commit Finish Confidently Accurately ee REG E Y Dev ID 030724 14am i Cancel Default Settings To use the default settings select this radio button The following pages will contain the default settings that the RT3000 was delivered with Read from a Folder It is possible to store a configuration in a folder The configuration requires several files so it is tidier to keep it in a folder by itself To read the configuration from a folder select this radio button A group box will appear and the folder can be selected Read from an NCOM File If the RT3000 has been running for some time then it will have improved the configuration parameters If the NCOM file was logged to disk then the improved parameters can be read from this NCOM file Select this radio button and choose the file in the group box that appears Read Initial Settings from RT3000 If the RT3000 is connected to the computer via Ethernet then it is possible to read the initial settings directly from the RT3000 The initial settings are the settings that the RT3000 starts up with before it makes any improvements Select this radio button and enter the correct IP address of your RT3000 Read Current Settings from RT3000 If the RT3000 has been running for some time then it will have improved the configuration parameters RT3000Cfg can p
50. ick up Revision 030728 E nw 4 S NEAN ON Nnm the improved settings from a serial COMM port that is transmitting NCOM or from the UDP Ethernet broadcasts Orientation of the RT3000 in the vehicle The RT3000 can be mounted at any angle in the vehicle The outputs can be rotated so that the measurements can be referenced to the vehicle co ordinate frame For correct initialisation it is also necessary to get the heading orientation correct If the vehicle level option is used then the pitch and roll orientations must also be correct The RT3000 gets its initial heading by assuming that the lateral velocity or slip angle is small If the definition of the vehicle s X axis forward direction is incorrect in the RT3000 then it will not initialise correctly when the vehicle drives forwards The orientation of the RT3000 in the vehicle is normally specified using three consecutive rotations that rotate the RT3000 to the vehicle s co ordinate frame The RT3000 co ordinate conventions are listed in Figure 3 above and Table 7 above Figure 6 below shows the orientation screen of RT3000C fg Figure 6 RT3000Cfg Orientation Screen RT3000 Configuration Wizard x Orientation RT3000 Specify how you have mounted the RT3000 in the vehicle Inertial and GPS Connector to Rear Measurement The RT3000 will rotate ety Antenna connectors to Right its outputs to the vehicle s co ordinate Step 2 of 8 system
51. is takes time and better results can be achieved sooner if the user measures the distance accurately Getting these measurements incorrect is one of the main reasons for poor results from the RT3000 so it is important to be careful with the measurements Figure 7 below shows the Primary Antenna screen Revision 030728 E nw 4 S NEAN Nomi Figure 7 RT3000Cfg Primary Antenna Screen RT3000 Configuration Wizard x es Primary Antenna RT3000 Specify the Primary GPS Antenna position on the vehicle Inertial Pao Ahead o000m to within o 500 m Measurement Tell the RT3000 where utii Right o 000m ta within o 500 m the Primary Antenna is 3 i located compared to the Step 3 of 8 measurement point Above 1 000 m ta within o 500 m Read Configuration Orientation k Dual Antenna Secondary Antenna Options Specify each accuracy separately Commit Finish Overall accuracy 0 500 m Confidently Accurately Hu p 7 It is necessary to tell the RT3000 the distance from the measurement point shown on diagram 14A0007x at the end of this manual to the GPS antenna measurement point This should be entered in the vehicle s co ordinate frame note that the software deliberately uses a left handed co ordinate frame here because it is conceptually easier The accuracy of the measurements should also me specified Care should be taken here because it is very easy to measure distance to
52. ision 030728 EJ nw S N e omi NCOM Packet Format The NCOM packet format is a 72 byte packet transmitted at 115 200 baud rate with 8 data bits 1 stop bit and no parity It has an optional low latency format where the output can be derived after the first 22 characters have been received 1 9ms additional latency More convenient processing of the data can be achieved after 62 characters have been received 5 3ms additional latency Full functionality requires multiple packets to be received since low data rate information is divided up and sent in 8 bytes tagged on to the end of each packet To save space many of the data packets are sent as 24 bit signed integer words 16 bit precision does not provide the range precision required for many of the quantities whereas 32 bit precision makes the packet much longer than required All words are sent in little endian format meaning little end first or LSB first which is compatible with Intel microprocessors The packet is also transmitted over Ethernet as a 72 byte UDP broadcast The port number is 17 Ethernet provides the lowest latency output from the system since the transmission speed is nearly 1000 times faster than the serial communications Table 19 Word Length Definitions Terminology Data Length Byte UByte 8 bit integer unsigned Short UShort 16 bit integer unsigned Word UWord 24 bit integer unsigned Long ULong 32 bit integer unsigned
53. istances start from zero when the RT CAN unit is powered up i Oxford Technical Solutions RT3000 User Manual v lh Mie Revision History Table 55 Revision History Revision Comments 011211 020225 020528 021021 030131 030331 030401 030407 030522 030623 030728 Draft Draft Added NCOM description Reflects the modification of the system to use RTCA corrections instead of CMR Upgrade to the specification Added information about initialisation deriving additional outputs Changed operating temperature specification to 50degC Added Lab Test procedures Specification Changes Dual Antenna now simpler other small changes Clarified antenna type supplied Added section on Operating Principles Added Status Information Computing Performance Metrics and RT300Cfg Corrections Dual antenna Multi path explanation Changed small RT3000 dimensions height increased from 63 to 68mm Added RT Base references Added CAN Inside option Advanced Slip OmniStar configuration Revision 030728 Ea J wit 3 EN e Nl i Drawing List Table 56 below lists the available drawings that describe components of the RT3000 system Many of these drawings are attached to the back of this manual Note that the x following a drawing number is the revision code for the part If you require a drawing or different revision of a drawing that is not here then contact Oxford Technical Solutions
54. itions of the LEDs are given in Table 8 below Table 8 LED Descriptions LED Position Description 1 Top Strapdown Navigator State D Top Single Antenna Position Solution Middle Dual Antenna GPS Heading Solution 3 Bottom Middle OEMA GPS Self test 4 Bottom Power Comms Strapdown Navigator LED States The Strapdown Navigator LED shows the state of the Strapdown Navigator in the system Table 9 below gives the states of this LED Table 9 Strapdown Navigator LED States Colour Description The operating system has not yet booted and the program is not yet running This occurs at un start up Red The operating system has booted and the program is running The GPS receiver has not yet Flash output a valid time position and velocity The GPS receiver has locked on to satellites and has adjusted its clock to valid time the IPPS output will now be valid The Strapdown Navigator is ready to initialise If the Red vehicle is travelling faster than 5 m s then the Strapdown Navigator will initialise and the system will become active On dual antenna systems the system will initialise once the GPS receiver has determined heading even if the vehicle is stationary or moving slowly The Strapdown Navigator has initialised and data is being output but the system is not Y Sew real time yet It takes 10 seconds for the system to become real time after startup Green The Strapdown Navigator is running and the system is real time
55. lable Only low rate information is transmitted next Table 22 NCOM Packet Definition Batch 3 Byte Quantity Notes 62 Channel The channel number determines what information is sent in Bytes 0 to 7 below 63 Byte 0 64 Byte 1 65 Byte 2 66 Byte 3 67 Byte 4 68 Byte 5 69 Byte 6 70 Byte 7 71 Checksum 3 This is the final checksum that verifies the packet See the section on Status Information for the information included in Batch 3 Revision 030728 EI j w 3 CN c Nl jm Table 23 NCOM Navigation Status Byte 21 Value Description 0 All quantities in the packet are invalid 1 Raw IMU measurements These are output at roughly 10Hz intervals before the system is initialised They are useful for checking the communication link and for verifying the operation of the accelerometers and angular rate sensors in the laboratory In this mode only the accelerations and angular rates are valid they are not calibrated or to any specification The information in the other fields is invalid 2 Initialising When GPS time becomes available the system starts the initialisation process The strapdown navigator and kalman filter are allocated but do not yet run Angular Rates and Accelerations during this time are output 1s in arrears There will be a 1s pause at the start of initialisation where no output will be made while the system fills the buffers The system has to run 1s in arrears at this time in orde
56. les Read Configuration Orientation Primary Antenna Dual Antenna Secondary Antenna Options gt Finish Confidently Accurately eee ae i i Dev ID 030724 14am lt Back ii j Cancel Enter the IP address of the RT3000 that you want to configure The IP address is usually 195 0 0 x where x is the serial number of the RT3000 The changes to the configuration do not take effect until after the RT3000 is reset or next power on To reset the RT3000 after downloading check the Reset RT3000 after downloading files check box Press Commit to save the configuration on the RT3000 Revision 030728 la N nw Ju j SAS Qa Nomi Saving a copy of the settings locally Before finishing it is possible to save a copy of the settings in a folder on your computer This can then be reloaded next time The Finish screen also lets you know if the settings have been committed successfully to the RT3000 or not Figure 13 below shows the Finish screen Figure 13 RT3000C g Finish Screen xi Liro Finish RT3000 Save configuration in a folder Inertial SDR You have not yet committed your TET changes tothe RT3000 Go back Specify the folder you Sitti to Commit to retry would like to save your configuration in Step 8 of 8 Read Configuration Orientation Primary Antenna Dual Antenna Secondary Antenna Options Iv Preserve these settings in folder Commit c DataN El Confidently Accurat
57. ltipath received is from the vehicle s roof The antennas supplied with the RT3000 are designed to minimise multipath from the vehicle s roof when the roof is made of metal For use on non metallic roofs a different type of antenna is required for example the GPS 600 supplied with the base station This type of antenna can be supplied as an option When stationary the heading from the RT3000 will show some drift the size of the drift depends on the multipath in the environment Table 13 below lists the drift you can expect when stationary with a 1m base line Table 13 Typical Heading Drift for when Stationary in different Environments Environment Typical Drift Complete Open Sky 0 3 degrees max 0 1 degrees 16 Near Trees Buildings 0 7 degrees Next to Trees Buildings 2 degrees Typical figures using a 1m base line E Oxford Technical Solutions h i rst RT3000 User Manual Setting up the Base Station For correct operation of the higher accuracy systems it is necessary to use a base station GPS receiver Refer to Table 1 above to see if the system includes a base station All of the systems can be successfully used without a base station however the specification will only be met if a base station is used The base station is a separate GPS receiver that monitors the signals from the GPS satellites Using its knowledge of position it works out the errors in each satellite s signal It also measures the carrier
58. m 300mm For example 14C0002x 100 specifies a cable length of 100cm x is the revision J6 Network 10B T Connection Cable Details Special Notes J1 Supply 16 02 Blue Supply Return 16 02 Black J2 Pin 3 Nav Data RS232 TX J2 Pin 2 Nav Data RS232 RX N C J3 Pin 3 GPS Data RS232 TX J3 Pin 2 GPS Data RS232 RX N C J4 Pin 3 DSP Data RS232 TX J4 Pin 2 DSP Data RS232 RX J5 PPS out Centre conductor 0 007010 n J2 Pin 5 RS232 Common J6 Pin 2 J6 Pin 6 N C J3 Pin 5 RS232 Common J4 Pin 5 RS232 Common J5 PPS out GND Screen N C J6 Pin 1 J6 Pin 3 EMI Ground Green Cable outers braided and connected to EMI Ground J1 13 20 Twisted see NOTE A J1 14 21 Twisted see NOTE A NOTE A J6 is a RJ45 UTP patch lead which is cut to length and terminated at J1 FEC 480 125 will make two assys Power cores 1 2 and 22 16 02 All other signals 7 02 PPS OUT connector to be screened cable whose screen is isolated from the outer EMI braid The screen connects to PPS Ground and the centre conductor connects to PPS Out Edit History Date 27 11 00 Part 14C0009A Document RT3000 User Cable Sheet 1 of 1 Connector Boot Details J1 Deutsch AS612 35SA J2 9 Way Male D type and shell J3 15 Way Male D type and shell 9 Way Female D type and shell 8 Way RJ45 10 Base T Plug
59. m A little time spent now will save you considerable time later Revision 030728 Eg nw EN S S gt e Opi RT3000 Family Variants The RT3000 product family includes several different products based on the same technology Each product has been selected to serve a different accuracy requirement or operating condition The family is split between single antenna systems and dual antenna systems Single Antenna Models It is only possible for a single antenna RT3000 product to provide accurate heading when the vehicle is accelerating When stationary or moving at constant speed in a straight line the heading will drift Single antenna variants can remain stationary for about 60 minutes before their heading output will have drifted too far for them to recover after that it will be necessary to restart the system For vehicles that are dynamic e g racing cars the heading performance of a single antenna model is the same as that of a dual antenna model The single antenna models are simpler to use since only one antenna and less configuration is required For many road vehicles the performance of the single antenna systems are sufficient The single antenna models are as follows e RT3100 Differential GPS with positioning accuracy to0 4m CEP using a suitable differential source e RT3020 L1 Kinematic GPS with positioning accuracy to 20cm RMS e RT3002 LI L2 Kinematic GPS with positioning accuracy to 2cm RMS The l
60. n integer good calibrated heading lock Revision 030728 E nw 2 S CN c omi Self Test LED The Self Test LED gives Novatel information about a failed GPS card During normal operation this LED will flash Green Power Comms LED The Power Comms LED shows the state of the internal 5V power supply and the state of the TX line of the J2 connector Table 12 below gives the states of this LED Table 12 Power Comms LED States Colour Description Off There is no power to the system or the system power supply has failed Green The 5V power supply for the system is active Orange The system is outputting data on connector J2 E Oxford Technical Solutions lh yit RT3000 User Manual Fitting the Secondary Antenna For best performance of the dual antenna systems it is necessary to fit the secondary antenna to the system The system is very sensitive to incorrect fitting and operation of the secondary antenna and these instructions should be followed carefully otherwise it is unlikely that the system will operate correctly Before fitting the secondary antenna bear the following information in mind 1 In the default configuration the primary antenna should be at the front of the vehicle s roof and the secondary antenna should be at the rear 2 The antenna separation must be correct to 3mm or better 3 t is essential to orientate the antennas the same way Always have the cable exiting from each
61. n message types on connector J3 The RT Base transmits RTCA messages RTCM RTCM 104 or CMR Trimble can also be selected or the port can be disabled The Advanced option should not be used except in specialised applications The corrections are always received at 9600 baud For WAAS enabled systems the GPS receiver can be set up to receive corrections in North America or Europe Because WAAS North America and EGNOS Europe are in test mode they can sometimes be unreliable the corrections can be disabled by selecting None For systems that do not have WAAS capability this setting has no effect and is ignored For OmniStar Enabled Systems the correct satellite should be selected for the region where you are operating The correct satellite must be selected before OmniStar can send a new license For systems that do not have OmniStar capability this setting has no effect and is ignored Figure 10 RT3000Cfg OmniStar Properties mnistar Properties x General Iv Enabled Satelite Location FrequencyMHz BaudRate _ amp AMSC West North amp merica 1551 4890 1200 AMSC Central North amp merica 1554 4970 1200 AMSC East North America 1556 6250 1200 AM Sat America 1535 1375 1200 Australia N Z 1558 5100 1200 Asia 1535 1375 1200 b Use Advanced Settings Frequency MHz 1935 1525 Baud Rate 1200 Revision 030728 E nes H 2 2 Y Nomi Se
62. n on these channels Revision 030728 e j wit 2 CN Q T mi Table 25 Status Information Channel 0 Bytes Format Definition Invalid When 0 3 Long Time in minutes since GPS began Value lt 1000 midnight 06 01 1980 4 UChar Number of GPS satellites tracked by the Primary GPS Value 255 receiver 5 UChar Position Mode of Primary GPS Value 255 6 UChar Velocity Mode of Primary GPS Value 255 7 UChar Orientation Mode of Dual Antenna Systems Value 255 Note For the definitions of Position Mode Velocity Mode and Orientation Mode see below Table 26 Definitions of Position Mode Velocity Mode and Orientation Mode 0 None The GPS is not able to make this measurement 1 Search The GPS system is solving ambiguities and searching for a valid solution 2 Doppler The GPS measurement is based on a Doppler Measurement 3 Stand Alone The GPS measurement has no additional external corrections 4 Differential The GPS measurement used code phase differential corrections 5 RTK Float The GPS measurement used L1 Carrier phase differential corrections to give a floating ambiguity solution 6 RTK Integer The GPS measurement used L1 L2 Carrier phase differential corrections to give an integer ambiguity solution 7 255 Reserved or Invalid Oxford Technical Solutions lh TS RT3000 User Manual Table 27 Status Information Channel 1 Bytes Format Definition Valid When 0 Char Bits to 7 Position X I
63. nnovation Bit 0 1 1 Char Bits 1 to 7 Position Y Innovation Bit0 1 2 Char Bits 1 to 7 Position Z Innovation Bit0 1 3 Char Bits 1 to 7 Velocity X Innovation Bit0 1 4 Char Bits 1 to 7 Velocity Y Innovation Bit0 1 5 Char Bits 1 to 7 Velocity Z Innovation Bit0 1 6 Char Bits 1 to 7 Orientation Pitch Innovation Bit0 1 7 Char Bits 1 to 7 Orientation Heading Innovation Bit0 1 Note The innovations are always expressed as a proportion of the current accuracy Units are 0 1 o Asa general rule innovations below 1 06 are good innovations above 1 06 are poor Usually it is best to filter the square of the innovations and display the square root of the filtered value Note 2 If the Orientation Pitch Innovation and or the Orientation Heading Innovation are always much higher than 1 06 then it is likely that the system or the antennas have changed orientation in the vehicle Or the environment is too poor to use the dual antenna system Table 28 Status Information Channel 3 Bytes Format Definition Valid When 0 1 Short North Position Accuracy Age 150 2 3 Short East Position Accuracy Age 150 4 5 Short Down Position Accuracy Age 150 6 UChar Age 7 Reserved Note The units of the Position Accuraccies are 1mm Table 29 Status Information Channel 4 Bytes Format Definition Valid When 0 1 Short North Velocity Accuracy Age lt 150 2 3 Short East Velocity Accuracy Age 150 4 5 Short Down Velocity Accuracy Age lt 150 6 UCha
64. nts the RT3000 products to be free of defects in materials and workmanship subject to the conditions ser forth below for a period of one year from the Date of Sale Date of Sale shall mean the date of the Oxford Technical Solutions Limited invoice issued on delivery of the product The responsibility of Oxford Technical Solutions Limited in respect of this warranty is limited solely to product replacement or product repair at an authorised location only Determination of replacement or repair will be made by Oxford Technical Solutions Limited personnel or by personnel expressly authorised by Oxford Technical Solutions Limited for this purpose In no event will Oxford Technical Solutions Limited be liable for any indirect incidental special or consequential damages whether through tort contract or otherwise This warranty is expressly in lieu of all other warranties expressed or implied including without limitation the implied warranties of merchantability or fitness for a particular purpose The foregoing states the entire liability of Oxford Technical Solutions Limited with respect to the products herein E Oxford Technical Solutions RT3000 User Manual Specification The specification of the products is listed in Table 2 Table 3 and Table 4 These specifications are listed for operation of the system under the following conditions e After a warm up period of 15 minutes continuous operation e Open sky environment free fr
65. nvironment Some Obstructions about the environment Step 6 of 8 where the RT3000 is Differential RTCA being used ern Feng was None Orientation Omnistar Disabled Primary Antenna Advanced Slip Disabled Dual Antenna CAN Disabled Secondary Antenna gt Commit Finish Confidently Accurately E f If you know that the vehicle will be level when starting to within about 5 degrees then the Level option can be used This saves about 40 seconds during the initialisation process since the RT3000 does not have to take the time to compute an initial roll and an initial pitch In high vibration environments the Not Level option may not work and so the RT3000 can only start if the vehicle is level and the Level option has been specified The Normal vibration level is adequate for most circumstances The RT3000 is very tolerant of vibration and has been used successfully in environments with more than 2g RMS using the Normal setting If the velocity innovations are very high and many GPS packets are being dropped then this setting can be changed If the system is used predominantly in open sky then the open sky setting should be used In environments with a lot of GPS multi path the other two settings can be used This will allow less accurate GPS measurements to update the system E Oxford Technical Solutions ines RT3000 User Manual g The RT3000 can be configured to use several different Differential correctio
66. o other parties or used to build the described components without the written permission of Oxford Technical Solutions o MER xS 20 30 Me ene sates w A te eden AA RRS REE SRO eee X SOSS ess toit en A S Ae Ae ettet HOP eem DS SE sce SS COSS m me me w eo XX s e e t S a ote A4 Not to scale mm me one J7 Power 10mm J5 PPS OUT J6 Network 10B T Special Notes All Cable outers braided and connected to EMI Ground apart from J7 where no braid exists J1 13 20 Twisted see NOTE A J1 14 21 Twisted see NOTE A NOTE A J6 is a RJ45 UTP patch lead which is cut to length and terminated at J1 FEC 480 125 will make two assys Date 08 11 01 Part 14C0016A Document RT3000 User Radio Cable Sheet 1 of 1 Connector Boot Details Deutsch AS612 35SA 9 Way Male D type and shell 15 Way Male D type and shell 9 Way Male D type and shell BNC Socket crimp and inline 8 Way RJ45 10 Base T Plug Hellerman 154 42 G FEC 357 649 472 748 FEC 357 649 472 748 FEC 357 649 472 748 FEC 309 679 Suggested See Note A OR Oxford Technical Solutions 77 Heyford Park J2 Nav Dat Upper Heyford A S i A S Oxfordshire QNS My OX25 5HD uaa www oxts co uk
67. o the RT3000 For quick operation of dual antenna models connect to the primary top antenna connection and do not use the secondary antenna Refer to the section on the secondary antenna for additional information on using the secondary antenna 4 Connect the GPS Cable to the GPS antenna 5 Secure the GPS antenna on the top of the vehicle where it has a clear view of the sky and is not obstructed at any angle by masts aerials or other high objects For best results before configuration of the RT3000 system try to keep the antenna roughly above the RT3000 system The RT3000 system will be delivered expecting the antenna to be 1m above the RT3000 unit with no X or Y axis displacement it will assume that these measurements are accurate to about 1m a Oxford Technical Solutions PEERS RT3000 User Manual ey 6 Use the Null Modem Cable to connect J2 of the User Cable 14C0009A to a serial port on a laptop computer Run the program ENGINUITY EXE it can be run directly from the CD 7 Apply power to the RT3000 The bottom LED will turn green to show that power has been applied Wait for the top LED to flash red this will happen when the operating system has booted and will take about 30 seconds Wait for the top LED to turn permanently red this will happen when the GPS receiver has found sufficient satellites to provide valid time position and velocity and will take between 60 seconds and 20 minutes from power on It is very ra
68. o the remote point expressed in the body co ordinate frame The operator between p and p is the cross product operator Revision 030728 a 3 gt CN e omi Computing the Slip Angle The Slip Angle or Yaw angle is the difference between the Heading and the direction of travel over the ground Figure 15 Relationship between Heading Slip Angle and COG North Heading Slip Angle COG gt Path of vehicle COG Course over Ground also known as Track or Vector In Figure 15 above the Heading angle is the angle that the vehicle is pointing compared to North The Course over Ground is the direction that the vehicle is going over the ground this angle varies depending on the position in the car and it depends on whether the car is slipping across the surface of the road or not The Course over Ground direction is also known as Track Track over Ground Vector or Vector Velocity The Slip Angle is the difference between the Heading and the Course over Ground To compute the Slip Angle it is necessary to compute the Track angle first The track angle can be computed only when speed is non zero using the four quadrant arc tan function usually called atan2 180 Track atan2 V ev uj T The Slip Angle is then Slip Heading Track EJ Oxford Technical Solutions RT3000 User Manual ey You should test the slip angle to make sure it is in the correct range 180 If not you will get large spikes in your
69. olutions 2001 TNC Connector Confidential Information The information in this document is confidential and must not be disclosed to other parties or used to build the described components without the written permission of Oxford Technical Solutions 0 10 20 30 Print Size A4 Scale 1 1 Units mm Tolerances 1 mm 3rd Angle Date 21 08 01 Part 201 990146 789 Document Magnetic GPS Antenna Sheet 1 of 1
70. om cover by trees bridges buildings or other obstructions The vehicle must have remained in open sky for at least 5 minutes for full accuracy e The vehicle must exhibit some motion behaviour Accelerations of the unit in different directions are required so that the Kalman filter can estimate the errors in the sensors Without this estimation some of the specifications degrade e The distance from the system to the GPS primary antenna must be known by the system to a precision of 5mm or better The vibration of the system relative to the vehicle cannot allow this to change by more than 5mm The system will estimate this value itself in dynamic conditions e For dual antenna systems the relative orientation of the two antennas must be known to the system to 0 05 or better The system will estimate this value itself under dynamic conditions e For single antenna systems the heading accuracy is only achieved under dynamic conditions Under benign conditions such as motorway driving the performance will degrade The performance is undefined when stationary for prolonged periods of time Optionally extended measurement ranges covering 30G acceleration and 300 s angular rate may be requested The specification using the extended measurement range sensors can be marginally worse than those listed here Revision 030728 E Y E MWS 2 A C e NM Table 2 Performance Specification for the RT3000 Single Antenna Systems Pro
71. onfidential Information The information in this document z is confidential and must not be Section through B B disclosed to other parties or used to build the described components without the written permission of Oxford Technical Solutions 0 10 20 30 Print Size A4 Scale 1 2 Half Units mm Tolerances X X 0 1 Projection 3rd Angle Material Alu Finish Painted Notes A Channel for Mounting Edit History Date 08 11 01 Part 4 N A Document Novatel Power Pak ll Sheet 1 of 1 77 Heyford Park Upper Heyford Oxfordshire OX25 5HD www oxts co uk Copyright Oxford Technical Solutions 2002 Confidential Information The information in this document is confidential and must not be disclosed to other parties or used to build the described components without the written permission of Oxford Technical Solutions its mm Projection 3rd Angle L1 Ant Blue Rim L1 L2 Ant Black Rim 5 8 11 UNC Adaptor 41mm should be left under the antenna for the cable bend radius Cable Connector shown below Date 08 11 01 Part ff GPS 600 Document Novatel GPS Antenna Sheet 1 of 1 Oxford Technical Solutions 77 Heyford Park Upper Heyford Oxfordshire OX25 5HD www ots ndirect co uk Copyright Oxford Technical S
72. ores 1 2 and 22 16 02 All other signals 7 02 PPS OUT connector to be screened cable whose screen is isolated from the outer EMI braid The screen connects to PPS Ground and the centre conductor connects to PPS Out The information in this document is confidential and must not be disclosed to other parties or used to build the described components without the written permission of Oxford Technical Solutions 0 10 20 30 Print Size A4 Not to scale J6 is a RJ45 UTP patch lead which is cut to length and terminated at J1 FEC 480 125 will make two assys Edit History 26 04 02 14C0021A Date Part Document RT3000 User Cable Sheet 1 of 1 Connector Boot Details Deutsch AS612 35SA 9 Way Male D type and shell 15 Way Male D type and shell 9 Way Male D type and shell BNC Socket crimp and inline 8 Way RJ45 10 Base T Plug Hellerman 154 42 G FEC 357 649 472 748 FEC 357 649 472 748 FEC 357 649 472 748 FEC 309 679 Suggested See Note A 14C0023A J1 Tail Lengths 300mm 300mm 300mm 2000mm 300mm Length XX is denoted in the part ordered by the final digits of the part number in centimetres For example 14C0023x 100 specifies a cable length of 100cm x is the revision Supply 9 18 Volts DC Supply Return EMI
73. ower specification systems can be upgraded to a higher specification through a GPS receiver software upgrade and use of the correct base station The Single Antenna models can also be upgraded to dual antenna unless the small box option has been specified in which case the second GPS card does not fit Dual Antenna Models With a dual antenna RT3000 product the system uses the difference in position between the two antennas to keep heading accurate even when stationary The vehicle can remain stationary or have low vehicle dynamics and still maintain accurate heading Dual antenna systems are recommended for road vehicle testing on low friction surfaces e g ice rail track vehicles aerial survey and marine use ships survey vessels GPS only dual antenna systems require open sky environments to operate because they can take several minutes to acquire heading lock Advanced processing in E Oxford Technical Solutions A RT3000 User Manual ey the RT3000 allows relock to occur after 5s of a sky obstruction in this time the RT3000 s heading will not have significantly decreased The fast relock time is made possible because the RT3000 s own heading is used resolve the ambiguities in the GPS measurements resolution of these ambiguities is what normally takes several minutes The heading software in the RT3000 enables significantly better performance and coverage compared to GPS only solutions The dual antenna models are as follow
74. phase of the signal for kinematic corrections The carrier phase observations and the satellite signal errors are sent from the base station GPS to the RT3000 via a radio modem not provided The position of the base station GPS antenna can either be determined by the base station GPS receiver or can be surveyed in by a chartered surveyor If the base station GPS receiver determines its own position through position averaging then any error in the base station receiver will also result in error at the RT3000 In order to relate the RT3000 signals to maps or other items on the world it is necessary to have a surveyor measure the position of the GPS antenna and then tell the base station GPS receiver what position to use For many applications it is not necessary to survey in the base station antenna since an absolute world reference is not required Instead a local grid can be used Using the RT Base The RT Base system is a self contained GPS Radio Modem and Battery all in an IP65 rated Peli case For instructions on how to use the RT Base see the RT Base User Guide The RT Base is supplied with a SATEL radio modem This should be connected to the Radio connector of the RT3000 User Cable supplied normally 14C0021A This cable supplies power to the Radio Modem as well as sending the differential corrections to the RT3000 Using the Novatel Power Pak For base stations supplied as a Novatel Power Pak now superseded by the RT Ba
75. r Age 7 Reserved Note The units of the Velocity Accuracies are 1mm s Revision 030728 j wit 2 CN Q V mi Table 30 Status Information Channel 5 Bytes Format Definition Valid When 0 1 Short Heading Accuracy Age 150 DEO Short Pitch Accuracy Age 150 4 5 Short Roll Accuracy Age lt 150 6 UChar Age 7 Reserved Note The units of the Orientation Accuracies are le 5 radians Table 31 Status Information Channel 6 Bytes Format Definition Valid When 0 1 Short Gyro Bias X Age 150 DES Short Gyro Bias Y Age 150 4 5 Short Gyro Bias Z Age 150 6 UChar Age 7 Reserved Note The units of the Gyro Biases are 5e 6 radians Table 32 Status Information Channel 7 Bytes Format Definition Valid When 0 1 Short Accelerometer Bias X Age 150 2 3 Short Accelerometer Bias Y Age 150 4 5 Short Accelerometer Bias Z Age 150 6 UChar Age 7 Reserved Note The units of the Accelerometer Biases are 0 1mm s Oxford Technical Solutions j TT RT3000 User Manual e S om Table 33 Status Information Channel 8 Bytes Format Definition Valid When 0 1 Short Gyro Scale Factor X Age 150 2 3 Short Gyro Scale Factor Y Age 150 4 5 Short Gyro Scale Factor Z Age 150 6 UChar Age 7 Reserved Note The units of the Gyro Scale Factors are 1ppm 0 000194 Table 34 Status Information Channel 12 Bytes Format Definition Valid When 0 1 Short Distance to Primar
76. r to synchronise the GPS data with the inertial data and perform the initialisation checks During the Initialising mode the Time Acceleration and Angular Rate fields will be valid 3 Locking The system will move to the locking mode if b The velocity exceeds 5 m s or c The dual antenna GPS locks a suitable heading solution In locking mode the system runs in arrears but catches up by 0 1s every 1s locking mode lasts 10s During locking mode the outputs are not real time 4 Locked In Locked mode the system is outputting real time data with the specified latency guaranteed All fields are valid 5 255 Reserved Status Information Batch 3 of the NCOM packet transmits the Status information on the RT3000 There is a lot of internally used information in the Status Information but some of this information is useful customers The Status Information is transmitted at a low rate Each cycle a different set of 8 bytes are transmitted The Channel field defines which set of information is included in the 8 bytes Some of the Status fields have special bits or values that denote invalid The invalid values or the validity bits are noted in the tables B Oxford Technical Solutions h Mins RT3000 User Manual g Table 24 NCOM Packet Definition Batch 3 Channel Information See 0 Full Time Number of Satellites Position Mode Velocity Mode Dual Table 25 Antenna Mode 1 Kalman Filter Innovations Tabl
77. re for the GPS to take 20 minutes to find satellites the typical lock time is less than 90 seconds though if the unit has just been shipped from another part of the world then lock time will increase 8 Accelerate gently on a forward direction The system will initialise and start to output data once the speed of the vehicle exceeds about 5 m s 10 km h The top LED will turn orange when real time data is not yet available and then turn green after 10 seconds when the outputs are real time and the latency is to specification The RT3000 is now operating Fully specification will not be achieved within the first 15 minutes of operation During this time dynamic vehicle manoeuvres will help the system achieve full specification Revision 030728 19 nw S CN e man Initialisation Process Before the RT3000 can start to output all the navigation measurements it needs to initialise itself Before it can initialise itself it needs to have all the measurements listed in Table 5 below Table 5 Quantities required for Initialisation Quantity Description Time Measured by internal GPS Position Measured by internal GPS Velocity Measured by internal GPS Heading Approximated to Course over Ground when the vehicle moves with large error Some Dual Antenna systems can initialise when stationary Roll Pitch Vehicle Level option Assumed zero with a large error Otherwise Estimated over first 40s of motion with large error
78. rectory It will need to be installed on the computer 6 Open a connection to the GPS receiver Any baud rate can be used as the software will search for the correct baud rate Open a Command Console window and an ASCII Logs window The best baud rate to use for connecting to the base station is the default 9600 7 If the base station GPS receiver is determining its own position use the POSAVE command to average the position and then store it For example to average the position for 0 1 hours 6 minutes type POSAVE 0 14 OEM3 or OEM4 receiver If the base station antenna position is known then use the FIX POSITION command to enter the exact position of the antenna For example to fix the position of the GPS antenna at 51 3455323 degrees north latitude 114 289534 degrees west longitude and 1201 123 metres above the geoid reference type POS FIX 51 3455323 114 289534 1201 1234 OEM3 FIX POSITION 51 3455323 114 289534 1201 1234 OEM4 Refer to the Novatel Millennium GPS Card Commands Description Manual for more details on these commands e Oxford Technical Solutions RT3000 User Manual 8 Once the base station has fixed its position this position can be saved to non volatile memory and used automatically next time the GPS receiver is turned on To do this type SAVECONFIGH 9 While the base station is averaging its position connect COM2 of the base station GPS to the ra
79. s e RT3102 Differential GPS with position accuracy to 0 4m using a suitable differential source e RT3022 L1 Kinematic GPS with position accuracy to 20cm RMS e RT3003 LI L2 Kinematic GPS with position accuracy to 2cm RMS The lower specification systems can be upgraded to a higher specification through a GPS receiver software upgrade and use of the correct base station Satellite Differential Corrections To improve the positioning accuracy of the standard GPS two satellite based differential correction services are available These are WAAS or EGNOS and OmniStar WAAS EGNOS is a free service mainly directed at aircraft It provides an accuracy of about 1m CEP It is currently in test mode and the corrections are not guaranteed OmniStar is a subscription service The RT3000 systems that have OmniStar capability include the necessary hardware to receive the OmniStar corrections In addition to this it is necessary to pay OmniStar a license fee to activate the corrections OmniStar provides two levels of correction These are VBS Virtual Base Station and HP High Performance For more information on OmniStar see the OmniStar web site www omnistar com Revision 030728 o 1 Mi 4 FS omi Scope of Delivery Table 1 below lists all the items that are delivered with each RT3000 model Table 1 Summary of the RT3000 System Components Description Vehicle Components 1 RT3000 System Unit v v v v v v v
80. s the other items are not subject to shock and do not need to be tested as thoroughly Accelerometer Test Procedure To check that the accelerometers are working correctly follow this procedure 1 Ifthere is a mobile vat file in your system to convert from the RT3000 co ordinate frame to the vehicle s co ordinate frame then it needs to be removed and the system needs to be restarted 2 Connect power to the system connect the system to a laptop computer and run the visual display software ENGINUTIY EXE 3 Orient the RT3000 in the following ways and check that the accelerations measurements are within the specifications shown in Table 16 below Table 16 Acceleration Measurement Specifications Orientation Acceleration Measurement Y Flat Flat Down Z Acceleration between 9 7 and 9 9m s Flat Flat Up Z Acceleration between 9 7 and 9 9m s Down Flat Flat X Acceleration between 9 7 and 9 9m s Up Flat Flat X Acceleration between 9 7 and 9 9m s Flat Down Flat Y Acceleration between 9 7 and 9 9m s Flat Up Flat Y Acceleration between 9 7 and 9 9m s This test is sufficient to ensure that the accelerometers have not been damaged Typically a damaged accelerometer will read full scale about 100m s or 100m s or will not change its value Revision 030728 D j w 2 CN e Nil jm Gyro Test Procedure To check that the gyros angular rate sensors are working correctly follow
81. se the following instructions apply You are advised to look at the Novatel Millennium GPSCard Command Descriptions Manual for more details on how the base station operates The manual includes a lot of information on base stations and covers the topic in more detail than is described here Revision 030728 a 2 S UN S omi Recently the type of base station supplied has changed The new base station receivers use an OEM4 GPS card from Novatel whereas the original ones use an OEM3 card Please follow the instructions specific to your card where marked in the text To set up a base station the following steps must be followed 1 Place the base station GPS receiver at a suitable location The receiver should be inside in a dry environment and it will require a 12V 9 36V d c power supply 2 Place the GPS antenna where it has a clear view of the whole sky It is very important for the base station GPS to have full view of the whole sky any satellite it cannot receive cannot be used by the RT3000 even if the RT3000 can see the satellite It is also important to place the GPS antenna in a low multipath environment 3 Connect the GPS antenna to the base station GPS receiver using the GPS antenna cable provided 4 Connect COMI of the base station GPS receiver to a laptop computer 5 Run Novatel s GPSoln32 OEM3 model software or GPSolution4 OEM4 This software is included on the RT3000 Software CD in the OEM3 OEM4 di
82. ted see NOTE A Power cores 1 2 and 22 16 02 All other signals 7 02 PPS OUT connector to be screened cable whose screen is isolated from the outer EMI braid The screen connects to PPS Ground and the centre conductor connects to PPS Out J6 is a RJ45 UTP patch lead which is cut to length and terminated at J1 FEC 480 125 will make two assys Edit History 02 05 02 14C0023A Date Part Document RT3000 User Cable Sheet 1 of 1 Oxford Technical Solutions 77 Heyford Park Upper Heyford Oxfordshire OX25 5HD www oxts co uk Copyright Oxford Technical Solutions 2002 The information in this document is confidential and must not be disclosed to other parties or used to build the described components without the written permission of Oxford Technical Solutions 0 10 20 30 14C0019B J4 Print Size A4 Scale 1 1 Units mm Tolerances 10 0 3rd Angle Connections Parts VS J4 1 to J1 1 J3 14 J3 15 J3 1 using blue 16 02 wire J1 2 1mm Locking Power Jack 12mm stem See Note ii GND J4 2 to J1 2 J3 7 J3 8 J2 5 using black 16 02 wire J2 9 way Female D type and shell FEC 472 785 472 748 TX J2 3 to J3 11 using 7 02 wire J3 15 way Male D type and shell FEC 463 061 472 750 J4 Cigarette Lighter Socket FEC 658
83. titude Longitude Base Latitude and Base Longitude are all expressed in degrees The Northings and Eastings are measured in metres Computing Performance Metrics There are several methods of monitoring the performance from the RT3000 For each state a Kalman filter has there is a corresponding accuracy In the RT3000 there are accuracies for all of the Kalman filter states These are available in the NCOM output format The most useful quantities that measure performance of the system are the Position accuracies the Velocity accuracies the Heading Pitch and Roll accuracy Since these ES Oxford Technical Solutions RT3000 User Manual are 9 separate measurements it is often useful to group them into fewer values that can be monitored Position Accuracy In general it is best to monitor the horizontal position accuracy This can be computed from the North Position Accuracy and the East Position Accuracy fields in the Status Information of the NCOM output Use the formula 2 2 HorizontalPositionAccuracy Eos Schon PosAocEast t POE 2 Velocity Accuracy Similar to Position Accuracy in general it is more useful to monitor the horizontal velocity accuracy This can be computed from the North Velocity Accuracy and the East Velocity Accuracy fields in the Status Information of the NCOM output Use the formulae 2 2 HorizontalVelocityAccuracy DVEISCONDAN Sj Vela te VIS 2 VelAccNorth VelAccEast VelAccDown Velocity
84. tly the format is provided here It is also possible to have a standard NMEA output from the RT3000 to mimic the output of GPS standard receivers Oxford Technical Solutions offers a service to tailor the serial output format to the customer s specifications Contact Oxford Technical Solutions for details of this service Co ordinate Frame Conventions The RT3000 uses a co ordinate frame that is popular with most navigation systems Figure 3 below shows how the axes relate to the RT3000 box ri Oxford Technical Solutions RT3000 User Manual D Oy m Figure 3 RT3000 Co ordinate Frame Definition ho To ven wn Table 7 below lists the directions that the axes should point for zero heading pitch and roll outputs when the default mounting orientation is used Table 7 Direction of Axes for zero Heading Pitch and Roll outputs Axis Direction Vehicle Axis X North Forward Y East Right Z Down Down If the axes of the RT3000 and the Vehicle Axes are not the same as those listed in Table 7 above then they can be aligned by reconfiguring the RT3000 for a different mounting orientation See section Changing the RT3000 s Configuration below Revision 030728 j w 3 CN e Nl ji LED Definitions The front panel of the RT3000 has four LEDs These give an indication of the internal state of the system They can also be used for some simple operational checks on the system The defin
85. ts are made in a deterministic amount of time The outputs from the Navigation Computer are available over Serial RS232 or as a UDP broadcast on Ethernet The Sync pin on the output of the RT3000 is normally configured as a 1PPS output directly from the GPS card It may also be configured as a 100Hz sampling output or as an event input As an event input the RT3000 is able to time when the input becomes closed circuit An internal pull up resistor keeps the voltage high and the Sync pin can be connected directly to a brake switch or a camera shutter trigger Accurate timing in the RT3000 can measure this event with lus resolution No more than one event per second should be made Differential corrections can be supplied directly to the GPS receiver to improve the positioning accuracy The differential corrections can be supplied via radio modems from a base station via cell phones from a base station or from a separate differential source such as OmniStar or US Coast Guard Strapdown Navigator The outputs of the system are derived directly from the Strapdown Navigator The role of the Strapdown Navigator is to convert the measurements from the accelerometers and angular rate sensors to position Velocity and orientation are also tracked and output by the Strapdown Navigator Figure 17 below shows a basic overview of the Strapdown Navigator Much of the detail has been left out and only the key elements are shown here Revision 030728 E
86. veral satellites have been pre programmed into the software In the future more satellites may exist or their properties may change In this case it is necessary to use the Advanced Settings to set the Satellite s Frequency and Baud Rate The Advanced Slip feature uses characteristics of land vehicle motion to improve heading and slip angle This feature must be disabled for airborne and marine systems where the lateral velocity can be significant The Advanced Slip feature applies heading correction when the land vehicle is not slipping when the car is slipping the lateral acceleration is usually large enough so that the normal heading corrections provide excellent results Figure 11 RT3000Cf g Advanced Slip Properties xi x Advanced Slip Advanced Slip y Uses non steering wheels to improve heading and Uses non steering wheels to improve heading and slip angle slip angle Rear Wheel Position Road Surface Rear Wheel Position Road Surface IV Enable Advanced Slip Select Surface Normal hed Position of Rear Wheels Surface Properties Initial Delay s fi DOO Ahead 1 200 m to within fi 200 m z Update Period s fi 500 Right n 000 to within 0200 m e d vir Slip Angle deg 0 500 Above 0 500 m to within fo 200 m z Minimum Speed m s poo Minimum D ov E DOO Specify each accuracy separately HM Overall accuracy 0 200 m Maximum Accel m s 2 000 Minimum Tum Radius m 20 000
87. y GPS Antenna in X direction Age 150 23 Short Distance to Primary GPS Antenna in Y direction Age 150 4 5 Short Distance to Primary GPS Antenna in Z direction Age 150 6 UChar Age 7 Reserved Note The units of the Distances are Imm Table 35 Status Information Channel 13 Bytes Format Definition Valid When 0 1 Short Heading Orientation of the GPS Antennas Age 150 2 3 Short Pitch Orientation of the GPS Antennas Age 150 4 5 Short Distance between the GPS Antennas Age 150 6 UChar Age 7 Reserved Note The units of the distances are 1mm The units of the Orientation Angles are 1e 4 radians Revision 030728 j wit 2 CN Q V mi Table 36 Status Information Channel 14 Bytes Format Definition Valid When 0 1 Short Accuracy of Distance to Primary GPS Antenna in X Age 150 direction DEUS Short Accuracy of Distance to Primary GPS Antenna in Y Age 150 direction 4 5 Short Accuracy of Distance to Primary GPS Antenna in Z Age lt 150 direction 6 UChar Age 7 Reserved Note The units of the Distance Accuracies are 0 1mm Table 37 Status Information Channel 15 Bytes Format Definition Valid When 0 1 Short Accuracy of Heading Orientation of the GPS Antennas Age 150 PES Short Accuracy of Pitch Orientation of the GPS Antennas Age 150 4 5 Short Accuracy of Distance between the GPS Antennas Age lt 150 6 UChar Age 7 Reserved Note The units of the distances are Imm The units of
88. z 100G 2ms sine No 512 MB No Yes Note The single antenna units may be supplied in a smaller box with a single antenna port The dimensions are 243 x 108 x 68mm and the weight is 2 1kg This box does not allow the single antenna system to be easily upgraded to dual antenna Oxford Technical Solutions EU oce RT3000 User Manual h TS 4 Qu QM Table 3 Performance Specification for the RT3000 Differential Systems Product Positioning Position Accuracy Velocity Accuracy Acceleration Bias Linearity Scale Factor Range Roll Pitch Heading Angular Rate Bias Scale Factor Range Track at 50km h Slip Angle at 50 km h Lateral Velocity Update Rate Calculation Latency Power Dimensions Weight Operating Temperature Vibration Shock Survival Base Station Included Internal Storage Twin Antenna Upgradeable GPS RT3040 OmniStar HP 10cm CEP 0 07 km h RMS 10 mm s 1o 0 0196 0 196 1o 100 m s 0 03 lo 0 1 lo dynamic 0 01 s lo 0 1 lo 100 s 0 08 RMS 0 15 RMS 0 2 100 Hz 3 9 ms 9 18 V d c 20W 234 x 120 x 80 mm 2 3 kg 10 to 50 C 0 1 g Hz 5 500 Hz 100G 2ms sine Yes 512 MB No No RT3050 OmniStar VBS 50cm CEP 0 08 km h RMS 10 mm s lo 0 01 0 1 lo 100 m s 0 04 lo 0 1 16 dynamic 0 01 s lo 0 1 lo 100 s 0 1 RMS 0 15 RMS 0 2 100 Hz 3 9 ms 9 18 V d c 20W 234 x 120 x

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