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OXTS RT Series User Manual Download Page 82

82

Oxford Technical Solutions

The

GNSS Control

tab gives a choice of two algorithms for computing the GNSS

measurements. The default option is to use the algorithm provided by the GNSS receiver.
Using this algorithm, the RT will accept position and velocity from the GNSS and use it
to update the Kalman filter.

The gx/ix™ raw data processing algorithm uses the raw data from the GNSS and custom
algorithms to compute position and velocity tailored to the needs of the Kalman filter.  It
also  improves  performance  in  poor  GNSS  environments  using  single  satellite  aiding
technology  and  tightly  coupled  GNSS  and  inertial  measurements.  Gx/ix™  mode  is
recommended to achieve the highest accuracy in environments where RTK lock may be
difficult to maintain. There is also a third option to use a mix of the two algorithms in
order to gain the benefit from each mode in real time.

Note: gx/ix™ processing is a new technology and is still being developed and improved.
As such there are some limitations to its compatibility. Table 24 details the current
compatibilities of gx/ix™ mode.

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Summary of Contents for RT Series

Page 1: ...xF User Manual Covers RT3000 v3 and RT500 v1 models The inertial experts RT GNSS aided inertial measurement systems ...

Page 2: ...d names are trademarks of their respective holders The software is provided by the contributors as is and any express or implied warranties including but not limited to the implied warranties of merchantability and fitness for a particular purpose are disclaimed In no event shall the contributors be liable for any direct indirect incidental special exemplary or consequential damages including but ...

Page 3: ...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...

Page 4: ...___________________________________________________ 11 Dual antenna ______________________________________________________________________ 11 GLONASS_________________________________________________________________________ 12 BeiDou ___________________________________________________________________________ 12 250 Hz ___________________________________________________________________________ 12 Sa...

Page 5: ...__________________ 47 Read Configuration section ___________________________________________________________ 48 Hardware Setup section in NAVconfig ___________________________________________________ 49 IMU orientation tab __________________________________________________________________ 49 Primary antenna tab _________________________________________________________________ 51 Secondary Antenna ...

Page 6: ..._______________________________ 103 Kalman filter______________________________________________________________________ 104 CAN messages and signals _____________________________________________________ 106 Termination resistor ________________________________________________________________ 106 CAN DBC file _____________________________________________________________________ 106 CAN bus messages...

Page 7: ...n you will need to refer to the RT Range user manual available to download at support oxts com To obtain high precision measurements the RT 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 com...

Page 8: ...are output via an RS232 serial port over 10 100 Base T Ethernet using a UDP broadcast and on CAN bus Outputs are time stamped and refer to GPS time a 1PPS timing sync can be used to give accurate timing synchronisation between systems The inertial measurements are synchronised to the GPS clock ...

Page 9: ...ll its measurements GNSS makes measurements of position velocity and for dual antenna systems heading Using these measurements the RT is able to keep other measurements such as roll and pitch accurate Tight coupling of the GNSS and inertial measurements means the raw GNSS data can also be used There is no drift from the RT in any of the measurements while GNSS is present Interchangeable The RT500 ...

Page 10: ...support oxts com hc en us articles 115002433285 NAVdisplay Online manual NAVgraph Manual For plotting and exporting captured data https support oxts com hc en us articles 115002433465 NAVgraph Online manual NCOM Manual For decoding and using the NCOM format www oxts com Downloads Support NCOM Manual and Code Drivers ncomman pdf NCOM C Code Drivers A collection of C functions that can be used to de...

Page 11: ... section on page 16 Single antenna An advanced algorithm in the RT software means most road vehicle customers are able to use a single antenna system The Heading lock and Advanced slip features allow RT devices to maintain an accurate heading while stationary and while driving with low vehicle dynamics Single antenna systems can experience reduced heading accuracy on aircraft boats or in low speed...

Page 12: ... well as the American constellation GPS and Russian constellation GLONASS This means an extra 34 satellites are available for the RT to lock on to and obtain position and velocity updates from 250 Hz 1 All products including the RT1003 have the option of coming with a 250 Hz version of the inertial measurement unit IMU Satellite differential corrections To improve the positioning accuracy of stand...

Page 13: ...ystem components Description RT500 and RT3000 RT500 or RT3000 unit Power cable 77C0002B 14P0038 user cable Aux user cable Ethernet cable cross over USB stick with manual and software Tape measure Calibration certificate Quick start guide The RT3000 product that is RTK capable requires the correct differential corrections in order to work to full specification Differential corrections can be suppli...

Page 14: ...the primary GNSS antenna must be known by the system to a precision of five millimetres or better The vibration of the system relative to the vehicle cannot allow this to change by more than five millimetres The system will estimate this value itself in dynamic conditions For dual antenna systems the system must know the relative orientation of the two antennas to 0 05 or better The system will es...

Page 15: ...0 01 1 0 01 Scale factor 0 1 1 0 1 1 0 1 1 Range 100 m s2 100 m s2 100 m s2 Angular rate Bias 0 01 s 1 0 01 s 1 0 01 s 1 Scale factor 0 1 1 0 1 1 0 1 1 Range 100 s 100 s 100 s Track at 50 km h 0 15 1 0 15 1 0 07 1 Slip angle at 50 km h 0 25 1 0 2 1 0 15 1 Lateral velocity 0 5 1 0 4 1 0 2 1 Update rate 100 Hz 250 Hz 100 Hz 250 Hz 100 Hz 250 Hz Input voltage4 10 48 V dc 10 48 V dc 10 48 V dc Power 1...

Page 16: ...T for example position the offset of the base station cannot be found by the RT alone The RMS specification was used where the offset is known for example velocity For angles and measurements derived from the angles the 1 specification is used because the mounting of the RT compared to the vehicle gives an offset the RT cannot measure The accuracy of the product will depend on the operating mode o...

Page 17: ...C connectors Export control classification number Export control regulations change and so the classification number of the RT may also change The information presented here was correct when the manual was published RT products can fall under two different export control categories depending on the type of accelerometer fitted internally The type of accelerometer does not affect the specification ...

Page 18: ...user is encouraged to try to correct the interference by one or more of the following o Re orient or relocate the receiving antenna o Increase the separation between the equipment and the receiver The RT incorporates a GNSS receiver No GNSS receiver will be able to track satellites in the presence of strong RF radiations within 70 MHz of either the L1 GPS frequency 1575 MHz or L2 1228 MHz The RT c...

Page 19: ... data is reprocessed It can export NCOM XCOM and CSV file formats NAVgraph Used to graph NCOM XCOM and RCOM files created in post process It can display graphs cursor tables and map plots and data can be exported in CSV or KML Google Earth format NAVbase Used to configure and manage RT Base S and GPS Base base stations which can be used to achieve RTK integer level position accuracy Manuals This f...

Page 20: ...xford Technical Solutions Figure 1 Windows Firewall warning message Ensure both Private and Public networks are selected to ensure the software can continue functioning when moving from one type to another ...

Page 21: ...lt configuration is not possible for example when using the RT Strut The RT can be mounted at any angle in the vehicle as long as the configuration is described to the RT using NAVconfig This allows the outputs to be rotated based on the settings entered to transform the measurements to the vehicle frame For ease of use it is best to try and mount the RT so its axes are aligned with the vehicle ax...

Page 22: ...rom the windscreen will degrade the performance of the system Multipath affects dual antenna systems on stationary vehicles more than moving vehicles and it can lead to heading errors of more than 0 5 RMS if the antennas are mounted poorly It is critical to have the RT mounted securely in the vehicle If the angle of the RT can change relative to the vehicle then the dual antenna system will not wo...

Page 23: ...from the user to start logging and outputting data This section covers some basic information required for operation of the RT Front panel layout Figure 3 shows the layout of the RT500 and RT3000 front panel Table 7 lists the parts of the front panel labelled in Figure 3 For single antenna models the secondary antenna connector is not connected internally Figure 3 RT500 RT3000 front panel layout ...

Page 24: ...mation about the current system state but it is not possible for the LEDs to communicate everything the product is capable of measuring Instead they provide a snapshot of the current status and are useful for at a glance checks without the need for a portable PC The tables below describe the behaviour of each LED Status LED 6 Primary GNSS antenna connector 4 User cable main connector Label no Desc...

Page 25: ...RT User Manual Revision 190902 25 Table 8 GNSS LED states Table 9 Status LED states Table 10 Power PWR states ...

Page 26: ...e used by the RT shown in Figure 4 is popular with navigation systems where the positive X axis points forwards the positive Y axis points right and the positive Z axis points down When making measurements required in the configuration files measurements should be made between the point of interest and the measurement origin shown in Figure 4 The axes and measurement origin point are the same for ...

Page 27: ...when the default mounting orientation is used Table 11 Direction of axes for zero heading pitch and roll outputs Axis Direction Vehicle axis X North Forward Y East Right Z Down Down Once installed if the RT axes and the vehicle axes are not the same as those listed in Table 12 they can be aligned by reconfiguring the RT for a different mounting orientation using the NAVconfig software ...

Page 28: ...s perpendicular to the gravity vector and in the direction ofthe North Pole along the earth s surface Down The down axis D is along the gravity vector Figure 5 OxTS NED navigation frame definition The OxTS navigation frame is attached to the vehicle but does not rotate with it The down axis is always aligned to the gravity vector and north always points north The east axis E is perpendicular to gr...

Page 29: ...s co axial with the gravity vector and positive in the up direction Figure 6 ISO 8855 ENU earth fixed system The ISO earth fixed system is attached to the vehicle but does not rotate with it The north and east axes are perpendicular to the gravity vector and north always points north OxTS horizontal frame The OxTS horizontal frame sometimes called the level frame is attached to the vehicle but doe...

Page 30: ...allel to a horizontal plane The longitudinal axis is also parallel to the vehicle s heading when viewed from above ISO 8855 intermediate system The ISO 8855 intermediate system is attached to the vehicle but the X and Y axis both remain parallel to the ground plane The X axis is also aligned with the vertical projection of the vehicle heading The definition of the ISO 8855 intermediate system is l...

Page 31: ...ing up OxTS vehicle frame The OxTS vehicle frame is attached to the body of the vehicle It is related to the INS through the rotations in the Orientation page of NAVconfig It can be changed while the INS is running using the Quick Config tool of NAVdisplay The definitions of the vehicle frame are listed in Table 16 and shown in Figure 9 Table 16 Vehicle frame definition Axis Description X This is ...

Page 32: ...icle system The ISO 8855 vehicle system is attached to the body of the vehicle At rest the X axis points forwards horizontally and is parallel to the vehicle s longitudinal axis The Y axis is perpendicular to the longitudinal axis and points left The Z axis is orthogonal to the X and Y axes Definitions are listed in Table 17 and shown in Figure 10 Table 17 ISO 8855 vehicle system Axis Description ...

Page 33: ...n files for alternative configurations require FTP to put the configuration files on to the RT The default username and password are both user The RT 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 RT The data rate of the UDP broadcast is 100 Hz or 250 Hz In order to communicate via Ethernet each RT is c...

Page 34: ...window Figure 11 select Use the following IP address and enter the IP address and subnet mask to use 7 Click OK when finished Figure 11 Configuring the computer s IP address for Ethernet data transmission Once the computer is configured the IP address of an RT can be found by running NAVdisplay software this will display the IP address of any RT connected Note that it is possible to change the IP ...

Page 35: ...onnect the coupler to the hub The RT can 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 18 Note that this is not the normal configuration sold and it may be necessary to modify an existing coupler to suit Table 18 In line coupler connections Socket 1 Straight socket 2 Crossed socket...

Page 36: ...i to each device connected to its access point as a UDP unicast message In order to communicate via Wi Fi each RT is configured with a static IP address that is shown on the delivery note If the delivery note is unavailable the default IP address normally takes the form 195 0 0 sn where sn is the last two digits of the RT s serial number The serial number can be found on the front panel of the RT ...

Page 37: ...RT User Manual Revision 190902 37 Figure 13 Connect to the Wi Fi module in the RT Wi Fi settings are configured using NAVconfig and this process is explained later in this manual ...

Page 38: ...T will solve the RTK Integer problem using the inertial heading There is no need for the RT to solve the RTK Integer problem by searching If the antenna angle is offset from the RT by a lot then the RTK Integer solution that is solved will be incorrect For a 2 m antenna separation the RT orientation and the secondary antenna orientation should be known to within 5 For wider separations the seconda...

Page 39: ...n 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 GNSS receiver cannot track the satellite signal as accurately The dual antenna system in the RT works by comparing the carrier phase measurements at the two antennas This tells the syste...

Page 40: ...fferent environments Environment Typical error 3σ Complete open sky 0 6 0 2 1σ Near trees buildings 1 Next to trees buildings 2 Typical figures using a 1 m base line For accuracy specification of 0 1 RMS a 2 m separation is required Using a 2 m base line can halve the figures shown here ...

Page 41: ... so the user cable must be correctly aligned for it to connect The system can output data on the serial port over Ethernet and over CAN bus The standard serial output of the RT is a proprietary binary format referred to as NCOM OxTS offers C and C code that will interpret the packet This can be used freely in users programs to interpret the output of the RT More information about NCOM can be found...

Page 42: ...s a pulse generated by the GNSS receiver The output is active even when the GNSS receiver has no valid position measurement The falling edge of the pulse is the exact transition from one second to the next in GPS time The pulse is low for 1 ms then high for 999 ms and repeats every second The output is a low voltage CMOS output with 0 8 V or less representing a low and 2 4 V or more representing a...

Page 43: ...l has a duty cycle of approximately 50 Output signal characteristics 0 V and 5 V output low 0 8 V high 2 4 V Camera mode is a software condition that is automatically entered when the PPM distance output is configured as less than 1 PPM It exists in order to generate time stamped INS measurements synchronised with distance based output triggers The output is called camera mode as it s often used t...

Page 44: ...m the quadrature sensor to wheel speed 1A and the other to wheel speed 1B input J5 5 The odometer input should be configured as per a normal wheel speed sensor the RT will automatically detect the use of the quadrature sensor The wheel speed input requires less than 0 8 V for a low pulse and more than 2 4 V for a high pulse Limited protection is provided on this port however the input voltage shou...

Page 45: ...sition of the primary GNSS antenna compared to the RT The orientation of dual antennas if applicable compared to the RT The position of the rear wheels or non steering wheels compared to the RT Some environment parameters The RT can work out many of these parameters by itself but this takes time Measuring the parameters yourself and configuring the RT reduces the time taken to achieve full specifi...

Page 46: ...onnected to a device or editing a configuration file from an RD file then it is possible to view information related to the device in NAVconfig Click the i icon in the bottom left of the window to see a list of features related to your device NAVconfig Home section in NAVconfig NAVconfig is a universal tool that is used to configure many different devices The first step is to choose whether you ar...

Page 47: ...RT User Manual Revision 190902 47 Figure 15 NAVconfig Home section Start Read Configuration section in NAVconfig Figure 16 NAVconfig Start Read Configuration section ...

Page 48: ...d generation version can be found on the label on your product Read Configuration section The Read Configuration choice tells NAVconfig where to read the initial configuration from see Figure 18 Figure 17 NAVconfig Read Configuration section Read settings from a folder It is possible to store a configuration in a folder The configuration comprises several files so it is tidier to keep it in a fold...

Page 49: ...r the settings available to edit in NAVconfig Hardware Setup section in NAVconfig This section contains settings related to the position and orientation of the RT in the vehicle and the GNSS antennas as well as the profile of the vehicle in which the RT is being installed position of axles It is broken up into tabs and it is recommended that you work through each tab in order IMU orientation tab T...

Page 50: ... the RT s axes point in the vehicle Figure 4 shows the RT axes directions The IMU orientation tab of the configuration wizard also has illustrations to visualise the orientation of the RT in a vehicle based on the settings input The advanced settings will change to show the three rotations associated with orientation input even when unavailable ...

Page 51: ...ed then the pitch and roll orientations must also be correct To make small adjustments select the Specify exact angles checkbox to enable the rotations for editing This allows any slip angle pitch or roll offsets to be zeroed Primary antenna tab The RT can calculate the position of the primary antenna itself However this takes time and better results can be achieved sooner if the user measures the...

Page 52: ...ment origin shown in Figure 4 and the GNSS antenna s measurement point This should be entered in the vehicle s co ordinate frame The RT will try to improve the position of the primary GNSS antenna during use To use the values the RT has estimated use the Improve configuration wizard after your warm up on the Orientation utility page ...

Page 53: ...t enabled the RT will ignore the secondary antenna and will not use it to compute a heading solution Enter the antenna separation and select to position of the secondary antenna relative to the primary antenna from the dropdown list The illustrations will change according to the settings you choose to help visualise the configuration of the antennas Figure 21 NAVconfig Secondary Antenna tab in the...

Page 54: ... for techniques for identifying the angle of the antennas The Enable static initialisation option is useful for slow moving vehicles or where it is essential to start the RT running before moving for example in autonomous vehicles Static initialisation is 99 reliable in open sky but the reliability decreases in environments with high multipath Static initialisation is also faster when the antenna ...

Page 55: ...not available is drastically reduced Figure 22 shows the Lateral No Slip tab Figure 22 NAVconfig Lateral No slip tab in the Hardware setup section For the Lateral settings the system needs to know the position of the non steered axle rear wheels on a front wheel steering vehicle and vice versa A position at road height mid way between the rear wheels should be used as shown in Figure 22 Vehicles w...

Page 56: ...se than 20 cm will increase the drift of the RT Use the Accuracies tab in the Advanced Tools section to specify measurement accuracies individually The Lateral No slip feature also requires some knowledge of the road surface Select one of the predefined options from the dropdown list Normal or Low friction ice For the Vertical No Slip the system needs to know the position of the front axle A posit...

Page 57: ...s the RT can estimate the slip angle offset of the RT compared to the vehicle After the RT is initialised and warmed up use the Improve configuration option from the NAVconfig Home section to automatically read the RT s slip angle offset estimate This ensures a slip angle of zero is measured when driving straight on a level track ...

Page 58: ...red to use several different differential correction message types on connector J3 Figure 25 shows the Differential corrections properties window and Table 21 gives details on the correction types available Figure 25 NAVconfig Differential corrections tab in the Hardware Setup section ...

Page 59: ...io modem The most common baud rates used for differential corrections are 4800 baud and 9600 baud The RT Base S and GPS Base use 9600 baud The values in the Data bits Parity and Stop bit fields should be set to match the incoming signal NTRIP When selected the Enable NTRIP corrections checkbox box configures the RT for RTCMv3 corrections and sends an NMEA GGA message out from J3 back to the NTRIP ...

Page 60: ...changed or corrections will not be received by the unit The Mounting point can be selected from the list available This list will automatically populate unless the service provider requires authentication when collecting the information If the NTRIP service is protected by a login the list of mounting points will have to be accessed manually and the mounting point typed into the field The User nam...

Page 61: ... the RT that is connected to the NTRIP server should be configured with Network correction transmitter selected Other RTs should be configured with Network correction receiver selected and the IP address of the system that is configured as the transmitter should be selected in the box Regardless of whether DGPS corrections are received via NTRIP or a local base station only RTCMv3 corrections are ...

Page 62: ... input click the Output on falling edge of trigger or Output on rising edge of trigger checkboxes to choose when the extra data packet is generated If a trigger has been configured as an output trigger click the Output on camera trigger to generate extra data packets based on the output trigger settings configured earlier These packets are interpolated to the time when the event occurred and may b...

Page 63: ...xisting WLAN you will need to have the Wi Fi already enabled and have the Access Point disabled If the Wi Fi is not enabled the RT will not be able to see what network it could connect to If the Access Point is enabled the RT will not connect to an existing network Under Wireless networks in range of device you can choose which network you wish to connect the RT to and drag the network to the box ...

Page 64: ...nabled by selecting the Enable CAN interface checkbox see Figure 28 The default version is CAN 2 0 CAN FD is also available Figure 27 NAVconfig CAN output configuration tab You can select individual messages or enable all messages by choosing them from the table displayed Depending on the baud rate selected the suggested maximum CAN messages per second will change A warning message will appear if ...

Page 65: ... message binary format is described from Table 31 onwards The status message binary format is the same as the NCOM status message binary format as described in the NCOM Description manual Those status messages that do not have signals listed against them are not described at the signal level in the DBC file The binary format of these messages is quite complex and as such the DBC file it not suffic...

Page 66: ...ally If the data rate is set to 100 Hz a status message will be sent every 10 ms Some messages are transmitted more frequently than others because they appear in the list more than once At a data rate of 100 Hz each message in the Status tab will be transmitted on the CAN bus once per second The Prefix and Suffix boxes can be used to quickly add alpha numeric strings to the beginning and end of al...

Page 67: ...hrough the minimisation of delays between an instruction and transfer of data latency and higher bandwidth Enable CAN FD by selecting it from the CAN version dropdown Figure 29 displays the options available when configuring the RT for CAN FD output Figure 29 CAN FD output configuration Choose a Nominal bit rate from the dropdown list If you want to adjust the Flexible data rate select the checkbo...

Page 68: ...t by clicking on the Load DBC file button and selecting a valid CAN DBC file The top 12 messages in the list acquisition list are logged at the INS update speed of 100 Hz or 250 Hz This is not adjustable The Message name Signal name and Units can be edited in the CAN Signal Properties window Figure 30 This is opened by double clicking any signal Changes made using NAVconfig are independent of the ...

Page 69: ...he NMEA messages to output on the serial port are selected by choosing the data rate for each message type from the dropdown lists and clicking the checkbox for when to generate the message NMEA messages can also be generated in response to event input triggers Check the falling or rising edge checkbox to compute the message when the event occurs The RT can also generate NMEA messages from pulses ...

Page 70: ...rate of the selected NMEA sentences or increase the baud rate Selecting Allow extended length messages enables the full GGA and RMC messages to be output which are longer than the NMEA specification allows Please see the NMEA 0183 Description manual for more details Selecting Output approximate values before initialisation forces output of the raw GNSS measurements before the RT is initialised Cur...

Page 71: ...le options and pre defined values on one screen Initialisation Static initialisation is disabled by default If static initialisation has not been enabled the RT will need to be initialised by driving forwards in a straight line to initialise the heading to the track angle The initialisation speed is the speed at which the vehicle must travel to activate the initialisation The default initialisatio...

Page 72: ...etting can be changed Typical situations where the High vibration setting should be used include those where vibration mounts have been used or where the RT and the antenna are mounted on different sprung parts of the vehicle e g the cab chassis of a truck Heading lock The heading of single antenna systems can drift when the RT remains stationary for long periods of time To solve this the RT inclu...

Page 73: ...city within acceptable limits while the RT has no GNSS With heading lock also enabled the RT can also keep the heading accurate while stationary When using this option try to keep the vehicle s movement inside the garage to a minimum and exit the garage through the same door the car entered Surface tilt The surface tilt settings are used to compute the roll pitch and heading compared to a flat inc...

Page 74: ...ut and the transformation is applied to these outputs Note that for surfaces with a small gradient the surface heading is almost the same as heading Enable local coordinates The RT can output the displacement from an origin in a local co ordinate grid To use this option a zero location or origin must be chosen the latitude longitude and altitude for the origin must be entered into the RT If an RT ...

Page 75: ...e linear acceleration and the angular acceleration before they are output These filters affect the outputs on the CAN bus On the NCOM output the non filtered values are output together with the filter characteristics and the NCOM decoders provided by OxTS will implement the chosen filter The linear acceleration and the angular acceleration can be configured separately Due to vibration the accelera...

Page 76: ...e time as wheel speed corrections As with the Lateral No slip feature the wheel speed input can only be used on land vehicles aircraft and marine vehicles cannot use this option The wheel speed must not be used on a steered wheel it must be used on a wheel that is measuring the forward direction of the vehicle Figure 34 shows the wheel speed configuration window To enable the wheel speed input ens...

Page 77: ...istance should be measured half way between the two wheels The illustrations in the image will change depending on the settings you choose to help visualise the position of the RT in relation the wheel speed sensor Measurements by default are made to an accuracy of 10 cm Using higher precision for the measurement does not improve the results Using an accuracy figure worse than 20 cm will increase ...

Page 78: ... of the wheel is required for accurate navigation If a post differential encoder must be used then the accuracy cannot be guaranteed For best results a front wheel drive vehicle should be used with the wheel speed on a rear wheel The wheel speed pulses from driven wheels are less accurate Output smoothing tab When the Kalman filter in the RT determines that there is some error to correct this erro...

Page 79: ...e quickly By specifying a time in the Time limit section for the correction the RT will jump the measurement if it will take too long to correct Care should be taken not to make the smoothing too small If these parameters are inappropriate then the RT will not be able to make suitable corrections to the outputs and it will not work correctly Note this function is designed to improve the data in re...

Page 80: ...oints from the Slip Points tab Select the number of Slip Points you wish to set up and enter the distances and directions from the RT to the Slip Point If you have Output displacement enabled then the measurements are still from the RT and not from the output displacement point Figure 36 NAVconfig Slip Points tab ...

Page 81: ...ab can be used to select the algorithm used for merging the GNSS and the inertial data in the Kalman filter The Recovery tab can be used to decide how to begin using GNSS measurements if they have been rejected or ignored for a period of time Figure 38 shows both tabs in the GNSS control properties window Figure 37 NAVconfig GNSS Control tab in Advanced Tools within NAVconfig ...

Page 82: ...city tailored to the needs of the Kalman filter It also improves performance in poor GNSS environments using single satellite aiding technology and tightly coupled GNSS and inertial measurements Gx ix mode is recommended to achieve the highest accuracy in environments where RTK lock may be difficult to maintain There is also a third option to use a mix of the two algorithms in order to gain the be...

Page 83: ... Both the velocity and the position can be controlled separately In the default state the RT will reject up to 20 GNSS measurements before it forces the GNSS to be accepted However in high multipath environments and when wheel speed is used it may be desirable to reject more GNSS measurements Select the Start believing measurements after option and enter the number of GNSS measurements to reject b...

Page 84: ...e RT can output position relative to different coordinate frames You can change the coordinate frame settings in the Global Coordinate System tab within Advanced Tools in NAVconfig shown in Figure 39 Figure 38 NAVconfig Global Coordinate System properties window ...

Page 85: ...oid files The UGF file must be saved in C Users username Documents OXTS Shared Custom geoid files Once the file is downloaded and saved in this location it can be selected from the dropdown box A constant offset to the specified altitude reference can be applied by checking the Set offset box typing in a value into the cell Accuracies tab The NAVconfig software uses default accuracies for the meas...

Page 86: ...ws the Write Configuration page Figure 39 NAVconfig Write Configuration page Enter the IP address of the RT you want to configure or select it from the dropdown list The dropdown box will list all systems currently connected to the computer s network so ensure to select the correct system if there are multiple listed Choose whether to commit the configuration changes immediately to the unit or sav...

Page 87: ...r can be surveyed in by a chartered surveyor If the base station GNSS receiver determines its own position through position averaging then any error in the base station receiver will also result in error at the RT In order to relate the RT signals to maps or other items on the world it is necessary to have a surveyor measure the position of the GNSS antenna and then tell the base station GNSS rece...

Page 88: ...tem exceeds the value set as the initialisation speed default of 5 m s unless static initialisation has been selected If the system is mounted level in the vehicle then the Vehicle Level option will enable the system to start immediately Otherwise the system takes about 40 s to find approximate values for roll and pitch For the initialisation process to work correctly the RT requires the user to t...

Page 89: ...n were measured accurately in advance The RT was turned on as soon as possible In this case it took us 15 minutes to get all the other equipment sorted out The RT was stationary for most of this period which is not a problem Although in this example the RT was receiving corrections from a base station while stationary it is not necessary The base station should be working before the dynamic drivin...

Page 90: ...point the heading accuracy is worse than the scale of the graph d in Figure 41 the heading is not accurate and the dual antenna system cannot measure the angle of the GNSS antennas compared to the inertial sensors so the dual antenna cannot provide accurate information Just after 500 s the RT3000 is driven it is the small loop on the east side in Figure 40 not the figures of eight This small amoun...

Page 91: ...Revision 190902 91 RT User Manual Figure 41 Example warm up accuracy estimates a Forward velocity b Position accuracies c Velocity accuracies d Orientation accuracies ...

Page 92: ...ssible can be updated Notice how close to the specification the RT is even without the figure of eight manoeuvres A proper warm up is recommended in order to achieve the highest level of accuracy However the effect is small and only significant when you need the full performance of the RT Improving the configuration after a warm up Committing the configuration to the RT After the warm up process h...

Page 93: ...ation wizard If you are connected to a device via Wi Fi or Ethernet then select Read settings from a device and choose the device from the available list If the file has been logged to the PC already then you can choose Read settings from a data RD file or Read settings from a folder by locating the file or folder on your PC ...

Page 94: ...94 Oxford Technical Solutions Figure 43 NAVconfig Read Configuration Click Next to continue Confirm whether the improved data should be read from The Device or a File Click Next to continue ...

Page 95: ...ual Figure 44 NAVconfig Improve configuration data source The Select Settings screen will appear From the list displayed select the settings that you wish to view These will be determined according to what is enabled on your device ...

Page 96: ...Next to continue The final stage of the improved settings wizard is to write the configuration to the device and apply the improved settings with new accuracies You can choose whether to commit the improved settings to the device after a rest or power cycle recommended or to apply them immediately which does not get saved into the configuration file on the device For the improved settings to apply...

Page 97: ... is it can be reprocessed with different configuration settings For example if the configuration was configured incorrectly when running in real time then the configuration can be changed and the data can be reprocessed post mission The software suite provided with the RT includes the NAVsolve software which can be used to reprocess the data The NAVsolve Wizard also gives the user the ability to c...

Page 98: ...tion tab and ensure the x y and z accelerations values 19 to 21 are within specification when the RT is placed on a level surface in the orientations according to Table 31 Table 27 Acceleration measurement specifications Orientation Acceleration measurement x y z Flat Flat Down z acceleration between 9 7 and 9 9 m s2 Flat Flat Up z acceleration between 9 7 and 9 9 m s2 Down Flat Flat x acceleratio...

Page 99: ...e rotation others are small Zero Zero ve The z axis should indicate positive 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 OxTS Note that the RT is capable of correcting the error in the angular rate sensors very accurately It is not ne...

Page 100: ...Status field checks IMU packets 100 per second or 250 per second depending on product model GPS packets Between 2 and 20 per second depending on system GPS2 packets1 Between 2 and 20 per second depending on system 1 The GPS2 related fields will only increase for dual antenna systems These checks will ensure the signals from the GNSS and from the inertial sensors are being correctly received at the...

Page 101: ...ect The Euler angles output are three consecutive rotations first heading then pitch and finally roll that transform a 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 V n is vector V measured in the navigation co ordinate frame and V b is t...

Page 102: ...d antenna are not fitted on single antenna systems The accelerations and angular rates are measured in the inertial measurement unit The accelerometers are all mounted at 90 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 40 MHz floating point DSP controls the ADC and through adv...

Page 103: ...uracy The differential corrections can be supplied via radio modem from a base station via cell phone from a base station or from a separate differential source such as TerraStar or US Coastguard 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 ...

Page 104: ...titude degrees longitude and altitude The altitude is the distance from the model s earth sea level The Kalman filter used in the RT 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 Kalman filter Kalman filters can be used to merge several measurements of a quantity and ...

Page 105: ...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 GNSS antenna position x y z GNSS antennas orientation heading pitch and vehicle mounting angle for advanced slip The errors are applied smoothly to the states For example if the Kalman filter wants to correct a position error of five centimetres in the north direction then th...

Page 106: ...ut rate you do not get each status message at the specified rate All values from the RT 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 DBC file NAVconfig can output a CAN DBC file that contains all the measure...

Page 107: ...al Position in local co ordinates Table 43 1549 60Dh VelYawLocal Velocity and yaw angle in local co ordinates Table 44 1550 60Eh AngAccelVehicle OxTS output frame IMU angular acceleration Table 45 1551 60Fh AngAccelLevel OxTS horizontal frame IMU angular acceleration Table 46 1552 1555 620h 613h Reserved for RT ANA signals 1568 620h TrackSlipCurvaturePoint1 Measurement point 1 track slip and curva...

Page 108: ...h IsoOrientation ISO 8855 orientation Table 63 1588 634h IsoVsVelocity ISO 8855 vehicle system velocity Table 64 1589 635h IsoVsAcceleration ISO 8855 vehicle system acceleration Table 65 1590 636h IsoVsAngularVelocity ISO 8855 vehicle system angular velocity Table 66 1591 637h IsoVsAngularAcceleration ISO 8855 vehicle system angular acceleration Table 67 1592 638h IsoIsVElocity ISO 8855 intermedia...

Page 109: ...o 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 is the factor that the integer unit should be multiplied by to get the ...

Page 110: ...e Currently this is 16 s different from UTC Table 32 Identifier 601h 1537 LatitudeLongitude 0 32 S 1e 7 0 Latitude PosLat Table 33 Identifier 602h 1538 Altitude 0 32 S m 0 001 0 Altitude Altitude By default the altitude is output relative to mean sea level not WGS 84 The datum can be changed using NAVconfig Description Signal name Year 100 Century e g 20 during 2016 TimeCentury 56 Hour 0 Hours Tim...

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Page 112: ...xTS horizontal frame longitudinal forward velocity VelForward The forward velocity can go negative when driving backwards Table 36 Identifier 605h 1541 AccelVehicle 0 16 S m s2 0 01 0 OxTS output frame longitudinal forward AccelX IMU acceleration 16 16 S m s2 0 01 0 OxTS output frame lateral right IMU AccelY acceleration 32 16 S m s2 0 01 0 OxTS output frame vertical down IMU AccelZ acceleration D...

Page 113: ...the range of the pitch angle is 90 and the range of the roll angle is 180 Table 39 Identifier 608h 1544 RateVehicle 0 16 S s 0 01 0 OxTS output frame longitudinal forward AngRateX IMU angular rate 16 16 S s 0 01 0 OxTS output frame lateral right IMU AngRateY angular rate 32 16 S s 0 01 0 OxTS output frame vertical down IMU AngRateZ angular rate Description Signal name 16 16 m s2 0 01 OxTS horizont...

Page 114: ...Ah 1546 TrackSlipCurvature 0 16 U 0 01 0 Track angle AngleTrack 32 16 S 1 m 0 0001 0 Curvature Curvature Note that the slip angle will be close to 180 when driving backwards Table 42 Identifier 60Bh 1547 Distance 0 32 U m 0 001 0 Horizontal distance DistanceWithHold with hold 32 32 U m 0 001 0 Horizontal distance Distance without hold Note Distance with hold will not increase when the RT measures ...

Page 115: ... Yaw angle AngleLocalYaw Note The convention used for the local co ordinates uses a right handed set with the z axis up Table 45 Identifier 60Eh 1550 AngAccelVehicle 0 16 S s 0 1 0 OxTS output frame longitudinal forward IMU angular acceleration AngAccelX 32 16 S s 0 1 0 OxTS output frame vertical down IMU angular acceleration AngAccelZ Description Signal name 32 32 0 0001 Distance from origin alon...

Page 116: ...ackSlipCurvaturePoint1 0 16 U 0 01 0 Measurement point 1 track angle AngleTrackPoint1 32 16 S 1 m 0 0001 0 Measurement point 1 curvature Note that the slip angle of point 1 will be close to 180 when driving backwards Table 48 Identifier 621h 1569 TrackSlipCurvaturePoint2 CurvaturePoint1 0 16 U 0 01 0 Measurement point 2 AngleTrackPoint2 track angle 16 16 S 0 01 0 Measurement point 2 AngleSlipPoint...

Page 117: ...ote that the slip angle of point 4 will be close to 180 when driving backwards Table 51 Identifier 624h 1572 HeadingPitchRollFromSurf CurvaturePoint4 0 16 U 0 01 0 Heading relative to the AngleHeadingFromSurf road surface 16 16 S 0 01 0 Pitch relative to the AnglePitchFromSurf road surface 32 16 S 0 01 0 Roll relative to the AngleRollFromSurf road surface Note the range of heading is 0 to 360 the ...

Page 118: ...6 32 16 S 1 m 0 0001 0 Measurement point 6 curvature Note that the slip angle of point 6 will be close to 180 when driving backwards Table 54 Identifier 627h 1575 TrackSlipCurvaturePoint7 CurvaturePoint6 0 16 U 0 01 0 Measurement point 7 AngleTrackPoint7 track angle 16 16 S 0 01 0 Measurement point 7 AngleSlipPoint7 slip angle 32 16 S 1 m 0 0001 0 Measurement point 7 CurvaturePoint7 curvature Note...

Page 119: ...s message 601h Table 57 Identifier 62Ah 1578 ApproxAltitude 0 32 S m 0 001 0 Approximate altitude ApproxPosAlt By default the altitude is output relative to mean sea level not WGS 84 See altitude in the NCOM description for information on how to change this Before initialisation the approximate altitude message will have the GNSS measurement of altitude at the GNSS antenna location After initialis...

Page 120: ...2Eh 1582 RisingTrigger TTL signal level 0 NED frame east velocity Description Signal name Trigger count increments with each new trigger TriggerCountFalling 32 32 0 001 Distance with hold since last trigger TriggerDistanceFalling Description Signal name Offset bits Length bits Type Units Factor Offset 32 16 S m s 0 01 0 NED frame vertical ApproxVelDown down velocity 48 16 U m s 0 01 0 Approximate ...

Page 121: ...blem MilliTimeSeconds can be stored as a 32 bit double precision value however limitations in the double precision format mean there may be an error of up to 5 ms and the resulting decimal numbers may contain rounding errors Where possible MilliTime should be used otherwise use MilliTimeSeconds with care Table 63 Identifier 633h 1587 IsoOrientation 0 16 S 0 01 0 ISO 8855 yaw angle IsoYawAngle 32 1...

Page 122: ...tudinal forward acceleration IsoVsLongitudinalAcceleration 32 16 S m s 0 01 0 ISO 8855 vehicle system vertical up acceleration IsoVsVerticalAcceleration Table 66 Identifier 636h 1590 IsoVsAgularVelocity 0 16 S s 0 01 0 ISO 8855 vehicle system roll longitudinal angular velocity IsoVsRollVelocity 32 16 S s 0 01 0 ISO 8855 vehicle system yaw vertical angular velocity IsoVsYawVelocity Description Sign...

Page 123: ...1 0 ISO 8855 intermediate system longitudinal forward velocity IsoIsLongitudinalVelocity 32 16 S m s 0 01 0 ISO 8855 intermediate system vertical up velocity IsoIsVerticalVelocity Table 69 Identifier 639h 1593 IsoIsAcceleration 0 16 S m s 0 01 0 ISO 8855 intermediate system longitudinal forward IsoIsLongitudinalAcceleration Description Signal name IsoVsPitchAcceleration ISO 8855 vehicle system 0 p...

Page 124: ... 63Ah 1594 IsoIsAngularVelocity 0 16 S s 0 01 0 ISO 8855 intermediate system roll longitudinal angular velocity IsoIsRollVelocity 32 16 S s 0 01 0 ISO 8855 intermediate system yaw vertical angular velocity IsoIsYawVelocity Table 71 Identifier 63Bh 1595 IsoIsAngularAcceleration 0 16 S s 0 1 0 ISO 8855 intermediate system roll longitudinal angular acceleration IsoIsRollAcceleration Description Signa...

Page 125: ...ical up velocity IsoEfsVerticalVelocity Table 73 Identifier 63Dh 1597 IsoEfsAcceleration Type Units Factor Offset Description Signal name 0 16 S m s 0 01 0 ISO 8855 earth fixed system east acceleration IsoEfsEastAcceleration 32 16 S m s 0 01 0 ISO 8855 earth fixed system vertical up acceleration IsoEfsVerticalAcceleration system pitch lateral angular acceleration Description Signal name 16 16 m s ...

Page 126: ...ots to NAVconfig Removed obsolete products Updated RT s input 080121 Heading Lock changes Surface Attitude CAN IDs Surface tilt added to RT Config Specification changes for 1 Clarified positioning modes and accuracies 080804 100125 Added MGCOM1 protocol Clarifications to rotation order and dual antenna section 100624 Added RT2004 product 110505 Added the recommended fuse information added GNSS ant...

Page 127: ...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 Table 75 List of available drawings 14A0085 RT500 RT3000 system outer dimensions drawing 14C0213 RT500 RT3000 Aux user cable 77C0002B RT500 RT3000 power cable 14C0038 RT500 RT3000 primary user cable Drawing Descripti...

Page 128: ...4 0 8 112 120 120 57 32 5 71 1 5kg Oxford Technical Solutions 77 Heyford Park Upper Heyford Oxfordshire OX25 5HD www oxts co uk TITLE NOT TO SCALE WEIGHT DRAWN BY A3 MATERIAL DRAWING NO DATE 13 08 2019 sbedford REV SHEET 1 OF 1 14A0085 RT3000 500 Drawing A THIRD ANGLE PROJECTION ...

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Page 132: ... Heat Shrink 6 4mm J1 3 Blue J2 2 RS399 934 Clear Heat Shrink 6 4mm J1 4 Black J2 2 Alternative Part RS 266 0250 Car Cigarette Lighter Plug 8A fused Fuse Littelfuse Part Number 0214005 5A Torpedo Type Fuse 25 x 6mm 36V J2 Pin 2 Pin 1 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 ...

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