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OXTS RT3000 User Manual

Gnss-aided inertial measurement systems
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GNSS-aided
inertial
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User Manual
Covers RT3000 v3 and
RT500 v1 models
The inertial experts.

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Summary of Contents for OXTS RT3000

  • Page 1 GNSS-aided inertial measurement systems User Manual Covers RT3000 v3 and RT500 v1 models The inertial experts.

  • Page 2: Legal Notices

    Document Revision: 190902 (See Revision History for detailed information). Contact Details Tel: +44 (0) 1869 814 253 Oxford Technical Solutions Limited Fax: +44 (0) 1869 251 764 Park Farm Business Centre Middleton Stoney Web: http://www.oxts.com Oxfordshire Email: support@oxts.com OX25 4AL United Kingdom Oxford Technical Solutions...
  • Page 3 Any use of misuse of the RT in a manner not intended may impar the protection provided. Please contact OxTS if you believe any service of repair is required on your RT. Revision: 190902...

  • Page 4: Table Of Contents

    BeiDou ___________________________________________________________________________ 12 250 Hz ___________________________________________________________________________ 12 Satellite differential corrections ________________________________________________________ 12 Scope of delivery ______________________________________________________________ 13 RT500 and RT3000 system components __________________________________________________ 13 Specification _________________________________________________________________ 14 Common specifications ______________________________________________________________ 16 Notes on specifications ______________________________________________________________ 16 Heading accuracy ___________________________________________________________________ 16...
  • Page 5 RT User Manual Hardware installation__________________________________________________________ 21 RT orientation and alignment __________________________________________________________ 21 Antenna placement and orientation _____________________________________________________ 21 Operation ___________________________________________________________________ 23 Front panel layout __________________________________________________________________ 23 Co-ordinate frame conventions_________________________________________________________ 26 Ethernet configuration _______________________________________________________________ 33 Wi-Fi configuration __________________________________________________________________ 36 Dual antenna systems _______________________________________________________________ 38 Inputs and outputs ____________________________________________________________ 41 Digital inputs and outputs_____________________________________________________________ 42 Configuring the RT ____________________________________________________________ 45...
  • Page 6 Accelerometer test procedure__________________________________________________________ 98 Gyro test procedure _________________________________________________________________ 98 Testing the internal GNSS and other circuitry _____________________________________________ 100 Using the orientation measurements ____________________________________________ 101 Operating principles __________________________________________________________ 102 Internal components ________________________________________________________________ 102 Strapdown navigator _______________________________________________________________ 103 Kalman filter ______________________________________________________________________ 104 CAN messages and signals _____________________________________________________ 106 Termination resistor ________________________________________________________________ 106 CAN-DBC file _____________________________________________________________________ 106...

  • Page 7: Introduction

    This functionality used to be available from the RT-Range S Hunter accessory but now runs on board the RT3000 v3 as an optional feature. If you are configuring an RT-Range S Hunter for ADAS testing then you will need to refer to the RT-Range user manual –...
  • Page 8 An RT system processes data in real time. The real-time results 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.

  • Page 9: Easy Operation

    The RT500 (v1) and RT3000 (v3) products have identical output capabilities. The serial port, Ethernet, Wi-Fi and CAN bus are the same on RT500 and RT3000 devices including the data formats. Each device comes with two user cables which house the connections needed for data transfer from the RT to other devices e.g.

  • Page 10: Related Documents

    Related documents This manual covers the installation and operation of RT systems, but it is beyond its scope to provide details on service or repair. Contact OxTS support or your local representative for customer service related inquiries. Additional manuals provide further information on some of the software and communication types mentioned in this manual.

  • Page 11: Rt Product Family

    Can be GLONASS and BeiDou enabled. The RT3000 L1 only mode is single antenna only and does not provide RTK position accuracy. The RT3000 with RTK support is dual antenna. 100 Hz and 250 Hz versions are available.

  • Page 12: Glonass

    The heading software in the RT enables significantly better performance and coverage compared to GNSS-only solutions. GLONASS GLONASS capability adds the ability to utilise the Russian satellite constellation GLONASS as well as the American constellation GPS. This means an extra 24 satellites are available for the RT to lock on to and obtain position and velocity updates from.

  • Page 13: Scope Of Delivery

    Wi-Fi antenna, software, a calibration certificate, a tape measure, and a quick start guide. RT500 and RT3000 system components Table 2 lists all items that are delivered with each standard RT500 and RT3000 model. Table 2. Summary of RT500 and RT3000 system components...

  • Page 14: Specification

    Specification Specifications for RT products can be found in Table 3 and Table 4. These specifications are listed for operation of the system under the following conditions: • After a warm-up period of 15 minutes’ continuous operation. • Open-sky environment, free from cover by trees, bridges, buildings or other obstructions.
  • Page 15 RT User Manual Table 3. RT500 and RT3000 specifications Parameter RT500 v1 RT3000 v3 RT3000 v3 (Dual L1 only (Dual antenna) (single antenna) antenna) Positioning GPS L1 GPS L1 GPS L1, L2 GLONASS GLONASS GLONASS L1, BeiDou L1, L2 BeiDou L1 Position accuracy 2.0 m CEP SPS...

  • Page 16: Common Specifications

    RT compared to the vehicle gives an offset the RT cannot measure. The accuracy of the product will depend on the operating mode of the GNSS. For example, an RT3000 operating without differential corrections enabled will have the specifications of the RT3000 L1 only. Heading accuracy The heading accuracy that can be achieved by the dual antenna system in the RTs in Table 5 is 0.2°...

  • Page 17: Environmental Protection

    Environmental protection The RT500 and RT3000 products are 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.

  • Page 18: Conformance Notices

    (1575 MHz) or L2 1228 MHz. The RT conforms to the requirements for CE. Regulator testing standards RT500 and RT3000 products o 47 CFR 15.109:2010 class A (radiated emissions). o EN 61000-4 criterion A according to standard EN 301 489-1:2008 (-2:2009 electrostatic discharge), (-3:2006+A2:2010 radiated immunity), (-4:2012 electrical fast transients), (-5:2006 voltage surge) and (-6:2009 conducted radio frequency immunity).

  • Page 19: Software Installation

    C:\Program Files (x86)\OxTS on 64 bit operating systems or C:\Program Files\OxTS on 32 bit operating systems. The first time some OxTS applications are run, a firewall warning message similar to that shown in Figure 1 may be triggered. This is because the program is attempting to listen for, and communicate with, OxTS devices on the network.
  • Page 20 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. Oxford Technical Solutions...

  • Page 21: Hardware Installation

    In most circumstances the RT should be mounted directly to the chassis of the vehicle. If the vehicle experiences high shocks, then vibration mounts may be required. The RT is compatible with the RT-Strut product from OxTS to provide a quick and secure vehicle mounting solution.
  • Page 22 then different antennas must be used. It is recommended to mount the antennas at least 30 cm from any edge where possible. For dual antenna systems, the secondary antenna should be mounted in the same orientation as the primary antenna, as shown in Figure 2. The antenna baseline should also be aligned with one of the vehicle axes where possible, either inline or perpendicular to the vehicle’s forward axis.

  • Page 23: Operation

    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.
  • Page 24 Table 7. RT3000 v3 RT500 v1 front panel descriptions Label no. Description Power LED Status LED GNSS LED User cable main connector Second user cable connector Primary GNSS antenna connector Secondary GNSS antenna connector WI-Fi antenna connector LED definitions The LEDs on the connector panel provide information about the current system state, but it is not possible for the LEDs to communicate everything the product is capable of measuring.
  • Page 25 RT User Manual Table 8. GNSS LED states Table 9. Status LED states Table 10. Power (PWR) states Revision: 190902...

  • Page 26: Co-Ordinate Frame Conventions

    Co-ordinate frame conventions Measurements made by the INS are available in a number of different reference frames for use in different applications. IMU frame The IMU reference frame used by the RT (shown in Figure 4), is popular with navigation systems –...
  • Page 27 RT User Manual Figure 4. IMU co-ordinate frame and measurement origin Table 11 lists the directions that the axes should point for zero heading, pitch and roll outputs when the default mounting orientation is used. Table 11. Direction of axes for zero heading, pitch and roll outputs Axis Direction Vehicle axis...
  • Page 28 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.
  • Page 29 The OxTS horizontal frame (sometimes called the level frame) is attached to the vehicle but does not rotate with the roll and pitch of the vehicle. It rotates by the heading of the vehicle. The definition of the OxTS Horizontal frame is listed in Table 14 and shown in Figure 7.
  • Page 30 Figure 7. OxTS horizontal frame definition The OxTS horizontal frame is attached to the vehicle. The longitudinal and lateral axes remain parallel to a horizontal plane. The longitudinal axis is also parallel to the vehicle’s heading when viewed from above.
  • Page 31 This is the vertical direction of the vehicle, pointing 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.
  • Page 32 Figure 9. Vehicle frame definition The OxTS vehicle frame is attached to the vehicle and rotates with it in all three axes. The X-axis remains parallel to the vehicle’s heading, while the Y-axis points to the right and is perpendicular to the vehicle’s...

  • Page 33: Ethernet Configuration

    To configure the RT for unrestricted data transmission it is necessary to use the Ethernet connection. The RT 500 and RT3000 v3 also support Wi-Fi data transmission and the setup of WiFi is covered later in this manual. The operating system at the heart of the RT products allows connection to the unit via FTP.
  • Page 34 1. Open the ‘Control Panel’ from the Start menu. 2. In category view, select ‘Network and Internet’ and then ‘Network and Sharing Centre’. 3. Select ‘Change adapter settings’ in the side panel. 4. Right-click the Ethernet option and select ‘Properties’. 5.
  • Page 35 RT User Manual Connection details for Ethernet configuration The RJ-45 connector on the 14C0038x user 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.

  • Page 36: Wi-Fi Configuration

    Wi-Fi configuration The RT can be configured via a Wi-Fi connection using the Wi-Fi access point inside the RT itself. Like Ethernet, the use of FTP via a Wi-Fi connection allows the user to manage the data logged to the unit; files can be downloaded for reprocessing and deleted to make space for future files.
  • Page 37 RT User Manual 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. Revision: 190902...

  • Page 38: Dual Antenna Systems

    Dual antenna systems It is often useful to have an understanding of how the RT uses the measurements from the dual antenna system. This can lead to improvements in the results obtained. To use the measurements properly the RT needs to know the angle of the GNSS antennas compared to the angle of the RT.
  • Page 39 RT User Manual In the unlikely event that the RTK Integer solution is incorrect at the start then the Kalman filter can update the secondary antenna orientation incorrectly. If this happens then things start to go wrong. The Kalman filter becomes more convinced that it is correct, so it resolves faster, but it always solves incorrectly.
  • Page 40 Table 19. Typical heading error for when stationary in different environments Typical error (3σ) Environment 0.6° (0.2° 1σ) Complete open-sky 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: Inputs And Outputs

    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 in the NCOM description manual.

  • Page 42: Digital Inputs And Outputs

    Digital inputs and outputs Table 20 describes each of the signals on the digital I/O connector J5 of the 14C0038X user cable. A more detailed explanation of each signal can be found below. Table 20. Digital I/O signals 1PPS output The 1PPS (J5-1) output is a pulse generated by the GNSS receiver.
  • Page 43 RT User Manual Trigger 1 and 2 Trigger 1 (J5-2) and Trigger 2 (J5-4) can be used to generate events within the RT for purposes of identifying external events, or to output a time/distance-based signal for the purpose of driving external events. Both Triggers are independently configurable in the Options page of NAVconfig.
  • Page 44 Wheel speed input The wheel speed 1A input (J5-3) accepts TTL pulses from an encoder on a single wheel. An encoder from a gearbox should not be used, and simulated TTL pulses (e.g. converted from the CAN bus) should not be used either. The timing of the wheel speed input pulses is critical and nothing should cause any delay to them.

  • Page 45: Configuring The Rt

    RT User Manual Configuring the RT To obtain the best results from your RT it will be necessary to configure the RT to suit the installation and application before using it. The program NAVconfig can be used to do this. This section describes how to use NAVconfig and gives additional explanations on the meanings of some of the terms used.

  • Page 46: Working Through Navconfig

    Working through NAVconfig NAVconfig is split into seven sections. Each section contains several tabs with settings that can be applied to the device. The sections are: Home, Ready Configuration, Hardware Setup, Interfaces, Environment, Advanced Tools and Write Configuration. When a device is connected via WiFi or Ethernet, the product name (including serial number) will be displayed at the top of the application.

  • Page 47: Start/Read Configuration Section In Navconfig

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

  • Page 48: Read Configuration Section

    This section becomes available when you choose “New configuration” or “Modify configuration” from the Home section. It is important to ensure the correct Product type and version is selected. The settings available in NAVconfig vary depending on the product type and version chosen. The product model and generation (version) can be found on the label on your product.

  • Page 49: Hardware Setup Section In Navconfig

    RT User Manual ‘Read settings from a raw data (RD) file:’ The RT writes the configuration it is using to the internally stored RD file. This option extracts the configuration used and loads it into the configuration wizard. Specify an RD file by clicking the ‘Browse’… button. Read initial settings from device: If the RT is connected to the computer via Ethernet or WiFi it is possible to read the initial settings directly from the RT.
  • Page 50 Figure 18. An RT device mounted on our RT-Strut Use the Y axis points and the Z axis points box to specify which way 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.

  • Page 51: Primary Antenna Tab

    RT User Manual Figure 19. NAVconfig IMU orientation tab in the Hardware Setup section For correct initialisation, it is necessary to get the heading orientation correct. The RT gets its initial heading by assuming the vehicle is travelling forwards in a straight line.
  • Page 52 Figure 20. NAVconfig Primary Antenna tab It is necessary to tell the RT the distance between its measurement 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”...

  • Page 53: Secondary Antenna Tab

    RT User Manual Secondary Antenna tab If your system has two antennas, click the ‘Secondary GNSS antenna’ checkbox on the Secondary Antenna page (Figure 22) to allow the configuration to be entered. If it is not enabled, the RT will ignore the secondary antenna and will not use it to compute a heading solution.
  • Page 54 Getting the angle wrong by more than 3° can lead the RT to lock on to the wrong heading solution. The performance will degrade or be erratic if this happens. If the angle between the antennas cannot be estimated within a 3° tolerance then contact OxTS support for techniques for identifying the angle of the antennas.
  • Page 55 RT User Manual The Lateral No-slip feature applies heading correction when the land vehicle is not slipping. When the vehicle is slipping the lateral acceleration is usually large enough that the normal heading corrections provide excellent results. When combined with a wheel speed input the drift of the RT when GNSS is not available is drastically reduced.
  • Page 56 Figure 23. Measurement point for Lateral No-slip Measuring from the RT, measure the distances to the non-steered axle position in each axis in the vehicle co-ordinate frame. Select the direction from the dropdown lists and enter the distances. The measurements are made to an accuracy of 10 cm. Selecting an accuracy better than 10 cm does not improve results.
  • Page 57 RT User Manual Figure 24. NAVconfig Lateral No-slip tab in the hardware Setup section When using No-Slip features, 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.

  • Page 58: Gnss Differential Corrections Tab

    GNSS Differential Corrections tab An RT can be configured 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 Oxford Technical Solutions...
  • Page 59 RTCMv3 corrections and sends an NMEA GGA message out from J3 back to the NTRIP server. The RT3000 v3 and RT500 house an internal NTRIP client. Select ‘Use Internal Client’ to configure the settings of the NTRIP client inside the RT.
  • Page 60 Figure 26. NTRIP Internal Client When the ‘Use internal Client’ option is selected, several additional settings are provided and need to be configured. The Host address needs to be entered to receive corrections. This is the domain name or IP address of the caster or service that will be used.
  • Page 61 Network correction transmitter is selected, an RT will broadcast differential corrections it is receiving via a radio modem from an OxTS base station, using its RT- XLAN. Other RT devices that are on the network as the broadcasting RT, will then be able to receive the DGPS messages and use them.

  • Page 62: Interfaces Section In Navconfig

    Interfaces section in NAVconfig This section contains options for configuring the interfaces of the RT. Some of these settings are feature code controlled so may not be visible to all users on all devices. Ethernet tab The Ethernet settings include configuring the Ethernet data output rate, packet type and Triggers for the RT.
  • Page 63 Network details and router details will become available to edit. The Network name (SSID) will be by default OxTS INS (SN) This can be changed to another name but cannot contain any of the following characters: [<], [>], [&], ['] and ["].
  • Page 64 CAN Output tab RT systems can be configured to send and receive data via a CAN bus. This allows RT data to be sent to external logging devices, and signals from a test vehicle’s CAN bus to be logged alongside navigation data inside an RT. By default, CAN communication is disabled.
  • Page 65 RT User Manual Disabling or reducing the frequency of navigation or status messages will remove the warning and ensure reliable operation of the CAN bus. Increasing the baud also works, but the baud rate must be common to all devices on the bus. When using an RT-ANA, the default baud rate is 1 MBaud.
  • Page 66 Each message can be enabled/disabled by clicking in the appropriate cell and selecting from the dropdown menu. The message Identifier is also changed by clicking in the cell. The identifier number should be defined in either hexadecimal or decimal format. Decimal values can be entered as normal.
  • Page 67 RT User Manual CAN FD (CAN with Flexible Data-Rate) is an extension to the original CAN bus protocol specified in ISO 11898-1. CAN FD was created to accommodate increases in bandwidth requirements within automotive networks. The CAN FD protocol has brought the software closer to “real time”...
  • Page 68 CAN Acquisition tab The CAN Acquisition tab is where incoming CAN signals are defined. These signals can be viewed in real time along with the RT’s native data using NAVdisplay, or later using NAVgraph. Channels are added to the acquisition list by clicking on the ‘Load DBC file’ button and selecting a valid CAN DBC file.
  • Page 69 Select a Packet type and Baud rate. By default, data on the serial port is output using 8- N-1, although odd/even parity and two stop bits are available by using Advanced commands. Please contact support@oxts.com for details on this. If the NMEA packet type is selected, the NMEA tab will appear in the properties window.
  • Page 70 Table 22. Serial outputs Note that it is easy to overload the serial port if there are too many events. The software computes the number of characters that will be output each second and displays this at the bottom of the window. A serial port data overflow warning message will appear if the data rate is too high for the selected baud rate;...
  • Page 71 RT User Manual Analogue tab The Analogue option is used for configuring the RT-ANA companion product. There are 16 channels in the RT-ANA, numbered from 0 to 15. The Measurement, Range, and Min and Max values for all 16 channels can be configured. Click on a specific cell to change the settings.
  • Page 72 GNSS environment Select a predefined value from the dropdown list. If the system is used predominantly in open-sky, then the Open skies setting should be used. In environments with a lot of GNSS multipath then Some obstructions or Frequent obstructions can be used depending on the environment. This will allow less accurate GNSS measurements to update the system and it also places more reliance on the inertial sensors compared to the GNSS.
  • Page 73 RT User Manual Table 23. NAVconfig heading lock options Heading lock Description Normal This option assumes the heading of the vehicle does not change by more than 2° while the vehicle is stationary. The heading accuracy recovers quickly when the vehicle moves.
  • Page 74 Figure 31. NAVconfig Surface tilt properties in the Environment section within NAVconfig. Enter the heading (compared to true north) of the uphill direction and the gradient of the surface. The RT does not change the roll and pitch outputs because of these settings. Instead there are additional outputs, surface roll, surface pitch and surface heading that are output and the transformation is applied to these outputs.

  • Page 75: Advanced Tools Section

    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.
  • Page 76 Figure 33. NAVconfig Acceleration Filters tab in the Advanced Tools section Wheel Speed Input The RT can be factory configured to include a wheel speed input. This reduces the drift in outputs when GNSS is not available. It is essential to use the Lateral and Vertical No-slip slip features at the same time as wheel speed corrections.
  • Page 77 RT User Manual Figure 34. NAVconfig Wheel Speed Input tab in the Advanced Tools section The distances from the measurement point on the RT to the measurement point of the wheel speed encoder in the vehicle coordinate frame should be input. The directions can be selected from the dropdown lists.
  • Page 78 Enter the pulses per metre of the wheel speed. A value that is accurate to 10% is sufficient unless you know the figure more accurately. The RT will improve this scaling factor itself when GNSS is available. The Improve Configuration utility can be used to apply a more accurate value calculated by the RT from a calibration run.
  • Page 79 RT User Manual Figure 35. NAVconfig output smoothing properties window The smoothing of the position, velocity and orientation corrections can be controlled independently. Enter the maximum correction that can be applied every second. For example, if 0.1 m is entered for the position smoothing then the RT will only correct a position error by a maximum rate of 0.1 m/s.
  • Page 80 In the Advanced Tools section within NAVconfig, you can select the number of Slip Points 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.
  • Page 81 RT User Manual GNSS control tab The GNSS control tab contains advanced options that control how the GNSS information is managed in the RT. The GNSS Algorithm tab 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.
  • Page 82 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.
  • Page 83 2 Hz 10 Hz This means for example, that if you wish an RT3000 to start believing both position and velocity GNSS measurements after 30 s, the device it should be configured to start believing measurements after 60 position updates and 300 velocity updates.
  • Page 84 Global Coordinate System tab The 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 Oxford Technical Solutions...
  • Page 85 Using the Commands tab you can enter device-specific commands that apply specific features or perform actions onto the RT. The OxTS technical support team often use these and can provide you with a list of useful commands if you request them at support@oxts.com.

  • Page 86: The Write Configuration Section Of Navconfig

    The Write Configuration section of NAVconfig Changes to the RT settings must be sent using Ethernet or Wi-Fi. It is necessary to configure your computer’s LAN and WLAN settings, so it is on the same network as the Figure 39 shows the Write Configuration page. Figure 39.

  • Page 87: Setting Up The Base Station

    RT User Manual Setting up the base station For correct operation of the higher accuracy systems it is necessary to use a base station GNSS receiver. 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 GNSS receiver that monitors signals from the GNSS satellites.

  • Page 88: Initialisation Process

    Initialisation process Before the RT can start to output all the navigation measurements, it needs to initialise itself. In order to initialise, the RT needs all the measurements listed in Table 26. Table 26. Quantities required for initialisation Quantity Description Time Measured by internal GNSS.

  • Page 89: Warm-Up Period

    RT User Manual Warm-up period During the first 15 minutes of operation the system will not conform to specification. During this period the Kalman Filter runs a more relaxed model for the sensors. By running a more relaxed model the system is able to: •...
  • Page 90 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 amount of driving is sufficient for the Kalman filter to gain confidence in the antenna position and to improve the alignment of the two GNSS antennas compared to the inertial sensors.
  • Page 91 RT User Manual Figure 41. Example warm-up accuracy estimates (a) Forward velocity. (b) Position accuracies. (c) Velocity accuracies. (d) Orientation accuracies. Revision: 190902...

  • Page 92: Improving The Configuration After A Warm-Up

    You can see the RT is nearly at specification after just this small amount of driving. However, experience tells us the Kalman filter will continue to make some improvements (not obvious) during the first few figures of eight. The main part of the motion occurs after 1100 s when the car was driven in a figure of eight for 6 minutes.
  • Page 93 RT User Manual Figure 42. NAVconfig Home section Read configuration section in NAVconfig improved configuration 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’...
  • Page 94 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. Oxford Technical Solutions...
  • Page 95 RT User Manual 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. Revision: 190902...
  • Page 96 Figure 45. NAVconfig Improve configuration Select Settings Select the settings that you wish to improve in the configuration from the options available. By clicking the down arrows, you can expand the settings and view the values that have been improved after the warm-up. It is recommended that you review these before clicking ‘Next’ to continue.

  • Page 97: Post-Processing Data

    The NAVsolve Wizard also gives the user the ability to change the NCOM binary output format to text. A full explanation of NAVsolve is given in the “NAVsolve manual”, which can be downloaded from the OxTS support website. Revision: 190902...

  • Page 98: Laboratory Testing

    Laboratory testing There are several checks that can be performed in the laboratory to ensure the system is working correctly. The most fragile items in the system are the accelerometers, the other items are not subject to shock and do not need to be tested as thoroughly. Accelerometer test procedure To check the accelerometers are working correctly, follow this procedure.
  • Page 99 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.

  • Page 100: Testing The Internal Gnss And Other Circuitry

    Testing the internal GNSS and other circuitry To check all the internal circuits in the RT are working correctly and 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 (NAVdisplay).

  • Page 101: Using The Orientation Measurements

    RT User Manual Using the orientation measurements This section has been provided to clarify the definitions of heading, pitch and roll that are output by the RT. The RT uses quaternions internally to avoid the problems of singularities and to minimise numerical drift on the attitude integration.

  • Page 102: Operating Principles

    Operating principles This short section gives some background information on the components in the RT 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”...

  • Page 103: Strapdown Navigator

    Serial RS232, UDP broadcast on Ethernet or CAN bus. On RT3000 products differential corrections can be supplied directly to the GNSS receiver to improve the positioning accuracy. 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.

  • Page 104: Kalman Filter

    Some other rotations are also missed in the diagram. The RT 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.
  • Page 105 RT User Manual The same principles are used in the RT. Position and velocity are compensated directly, but other measurements like accelerometer bias, have no direct measurements. The Kalman filter tunes these so the GNSS measurements and the inertial measurements match each other as closely as possible.

  • Page 106: Can Messages And Signals

    CAN messages and signals In the default configuration the CAN bus uses identifiers 500h to 5FFh for RT status information; 600h to 60Fh for navigation information; 610h to 613h for RT-ANA messages and 620h to 623h for the additional slip points. Using the configuration software it is possible to change the default message identifiers.
  • Page 107 OxTS horizontal frame IMU acceleration Table 37 1543 (607h) HeadingPitchRoll OxTS orientation Table 38 1544 (608h) RateVehicle OxTS output frame IMU angular rate Table 39 1545 (609h) RateLevel OxTS horizontal frame IMU angular rate Table 40 1546 (60Ah) TrackSlipCurvature Track, slip and curvature...
  • Page 108 1577 (629h) ApproxLatitudeLongitude Approximate latitude and longitude Table 56 1578 (62Ah) ApproxAltitude Approximate altitude Table 57 1579 (62Bh) ApproxVelocity Approximate OxTS NED frame velocity Table 58 1580 (62Ch) Reserved 1581 (62Dh) FallingTrigger Trigger 1 falling edge Table 59 1582 (62Eh) RisingTrigger...

  • Page 109: Table Heading Definitions

    RT User Manual The status information in NCOM is output over the CAN bus on Identifiers 500h to 5FFh. The offset from 500h is the same as the Channel number in the NCOM message definition. The bytes 0 to 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.

  • Page 110: Signals

    Signals The following tables describe the signals in each of the messages. Table 31. Identifier 600h (1536), DateTime Description Signal name Year within century (e.g. ‘16’ during year Year TimeYear 2016) Century (e.g. ‘20’ Year TimeCentury during 2016) Month Month TimeMonth TimeDay Hundredths of...
  • Page 112 Table 34. Identifier 603h (1539), Velocity Description Signal name OxTS NED frame 0.01 VelNorth north velocity OxTS NED frame east 0.01 VelEast velocity OxTS NED frame 0.01 vertical (down) VelDown velocity 0.01 Horizontal speed Speed2D The horizontal speed is the vector addition of north and east velocities. For forward speed (which can go negative) see message 604h.
  • Page 113 RT User Manual Table 37. Identifier 606h (1542), AccelLevel Description Signal name OxTS horizontal frame 0.01 longitudinal (forward) AccelForward IMU acceleration OxTS horizontal frame 0.01 lateral (right) IMU AccelLateral acceleration OxTS horizontal frame 0.01 vertical (down) IMU AccelDown acceleration 0.01...
  • Page 114 Table 40. Identifier 609h (1545), RateLevel Description Signal name OxTS horizontal frame °/s 0.01 longitudinal (forward) AngRateForward IMU angular rate OxTS horizontal frame °/s 0.01 lateral (right) IMU AngRateLateral angular rate OxTS horizontal frame °/s 0.01 vertical (down) IMU AngRateDown angular rate See message 608h for roll angular rate.
  • Page 115 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 Description Signal name °/s² OxTS output frame longitudinal (forward) AngAccelX IMU angular acceleration °/s² OxTS output frame...
  • Page 116 Table 46. Identifier 60Fh (1551), AngAccelLevel Description Signal name °/s² OxTS horizontal frame longitudinal (forward) AngAccelForward IMU angular acceleration °/s² OxTS horizontal frame lateral (right) IMU AngAccelLateral angular acceleration °/s OxTS horizontal frame vertical (down) IMU AngAccelDown angular acceleration Table 47. Identifier 620h (1568), TrackSlipCurvaturePoint1...
  • Page 117 RT User Manual Table 49. Identifier 622h (1570), TrackSlipCurvaturePoint3 Description Signal name ° 0.01 Measurement point 3 AngleTrackPoint3 track angle 0.01 Measurement point 3 AngleSlipPoint3 slip angle 0.0001 Measurement point 3 CurvaturePoint3 curvature Note that the slip angle of point 3 will be close to 180° when driving backwards. Table 50.
  • Page 118 Table 52. Identifier 625h (1573), TrackSlipCurvaturePoint5 Description Signal name ° 0.01 Measurement point 5 AngleTrackPoint5 track angle 0.01 Measurement point 5 AngleSlipPoint5 slip angle 0.0001 Measurement point 5 CurvaturePoint5 curvature Note that the slip angle of point 5 will be close to 180° when driving backwards. Table 53.
  • Page 119 GNSS measurement of altitude (at the GNSS antenna location). After initialisation it will contain the same altitude as message 602h. Table 58. Identifier 62Bh (1579), ApproxVelocity Description Signal name Approximate OxTS 0.01 NED frame north ApproxVelNorth velocity 0.01...
  • Page 120 NED frame east velocity Approximate OxTS 0.01 NED frame vertical ApproxVelDown (down) velocity Approximate 0.01 ApproxSpeed2D horizontal speed Before initialisation the approximate velocity message will have the GNSS measurement of velocity (at the GNSS antenna location). After initialisation it will contain the same altitude as message 603h.
  • Page 121 RT User Manual Table 61. Identifier 62Fh (1583), PosLocalNE Description Signal name 0.0001 Northing PosLocalNorth 0.0001 Easting PosLocalEast Table 62. Identifier 630h (1584), MilliTime Description Signal name Milliseconds since the MilliTime start of GPS time Seconds since the start 0.001 MilliTimeSeconds of GPS time GPS UTC offset...
  • Page 122 (forward) velocity ISO 8855 vehicle 0.01 IsoVsLateralVelocity system lateral (left) velocity ISO 8855 vehicle 0.01 IsoVsVerticalVelocity system vertical (up) velocity Table 65. Identifier 635h (1589), IsoVsAcceleration Description Signal name ISO 8855 vehicle system longitudinal m/s² 0.01 IsoVsLongitudinalAcceleration (forward) acceleration ISO 8855 vehicle m/s²...
  • Page 123 RT User Manual Table 67. Identifier 637h (1591), IsoVsAgularAcceleration Description Signal name ISO 8855 vehicle system roll °/s² (longitudinal angular) IsoVsRollAcceleration acceleration ISO 8855 vehicle system °/s² pitch (lateral angular) IsoVsPitchAcceleration acceleration ISO 8855 vehicle system °/s² yaw (vertical angular) IsoVsYawAcceleration acceleration Table 68.
  • Page 124 acceleration ISO 8855 intermediate m/s² 0.01 system lateral IsoIsLateralAcceleration (left) acceleration ISO 8855 intermediate m/s² 0.01 system vertical IsoIsVerticalAcceleration (up) acceleration Table 70. Identifier 63Ah (1594), IsoIsAngularVelocity Description Signal name ISO 8855 intermediate °/s 0.01 system roll IsoIsRollVelocity (longitudinal angular) velocity ISO 8855 intermediate °/s...
  • Page 125 RT User Manual system pitch (lateral angular) acceleration ISO 8855 intermediate system yaw °/s² IsoIsYawAcceleration (vertical angular) acceleration Table 72. Identifier 63Ch (1596), IsoEfsVelocity Description Signal name ISO 8855 earth- 0.01 fixed system IsoEfsEastVelocity east velocity ISO 8855 earth- 0.01 fixed system north velocity ISO 8855 earth-...

  • Page 126: Revision History

    160105 New CAN definitions added, new frames of reference. 160413 Added RT2500 GLONASS options. Added radio cable modem drawing. 190902 RT500 and RT3000 manual re-written to support new generation products and switch to new version of NAVconfig. Oxford Technical Solutions...

  • Page 127: Drawing List

    Oxford Technical Solutions. Table 75. List of available drawings Drawing Description 14A0085 RT500, RT3000 system outer dimensions drawing 14C0038 RT500, RT3000 primary user cable 14C0213 RT500, RT3000 Aux user cable...
  • Page 128 32.5 M4 Thread 9mm Deep 14A0085 REV: DRAWING NO: SHEET 1 OF 1 THIRD ANGLE PROJECTION NOT TO SCALE TITLE: RT3000/500 Drawing sbedford DRAWN BY 13/08/2019 DATE M6 Thread MATERIAL Oxford Technical Solutions 77 Heyford Park 14mm Deep WEIGHT 1.5kg...
  • Page 132 Oxford Technical Solutions 77 Heyford Park Upper Heyford Oxfordshire OX25 5HD www.oxts.com © Copyright Oxford Technical Solutions, 2019 Confidential Information Pin Definitions The information in this document is confidential and must not be published or disclosed either wholly J1-1 (Brown) Positive 12V Power suppl y (9–18V d.c.) or in part to other parties or used to J1-2 (White) Positive 12V Power/Charge r supply (11–18V d.c.)

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