OXTS Survey+ v3 User Manual Download Page 96

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Oxford Technical Solutions

Figure 41. Schematic of the strapdown navigator

People familiar with inertial navigation systems will note that “angular rates” and

“accelerations” are labelled as the inputs. In reality the DSP in the converts these

to “change in angle” and “change in velocity” to avoid problems of coning and sculling.

Summary of Contents for Survey+ v3

Page 1: ...xF User Manual Covers Survey v3 models The inertial experts Survey 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: ... repair at an authorised location only Determination of replacement or repair will be made by Oxford Technical Solutions Limited personnel or by personnel expressly authorised by Oxford Technical Solutions Limited for this purpose In no event will Oxford Technical Solutions Limited be liable for any indirect incidental special or consequential damages whether through tort contract or otherwise Thi...

Page 4: ..._____________________________________________________ 11 BeiDou ___________________________________________________________________________ 11 200 250 Hz ________________________________________________________________________ 11 Satellite differential corrections ________________________________________________________ 11 Scope of delivery__________________________________________________________...

Page 5: ...____________________________ 51 IMU orientation tab __________________________________________________________________ 51 Primary antenna tab _________________________________________________________________ 53 Secondary Antenna tab ______________________________________________________________ 55 GNSS Differential Corrections tab_______________________________________________________ 60 Interface...

Page 6: ..._____________________________ 95 Internal components_________________________________________________________________ 95 Strapdown navigator ________________________________________________________________ 95 Kalman filter_______________________________________________________________________ 97 Revision history_______________________________________________________________ 98 Drawing list________...

Page 7: ...y the inertial sensors This innovative approach gives the Survey several distinct advantages over systems that only use GNSS The Survey has a high 100 Hz 200 Hz or 250 Hz update rate and a wide bandwidth The outputs are available with low 3 5 ms latency All outputs remain available continuously during GNSS blackouts when for example the vehicle drives under a bridge The Survey recognises jumps in ...

Page 8: ...e obtained from most vehicles A laptop computer allows real time viewing of the results Self correcting Unlike conventional inertial navigation systems the Survey uses GNSS to correct all its measurements GNSS makes measurements of position velocity and for dual antenna systems heading Using these measurements the Survey is able to keep other measurements such as roll and pitch accurate Tight coup...

Page 9: ...https 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...

Page 10: ...g while completely stationary and while driving with low vehicle dynamics Single antenna systems can experience reduced heading accuracy on aircraft boats or in low speed land vehicles Dual antenna Dual antenna systems provide high accuracy heading information and almost constant heading performance under all conditions For aircraft or marine applications or road vehicle applications on low fricti...

Page 11: ...n BeiDou as well as the American constellation GPS and Russian constellation GLONASS This means an extra 34 satellites are available for the Survey to lock on to and obtain position and velocity updates from BeiDou is not compatible with the gx ix tight coupling algorithms 200 250 Hz 1 All Survey have the option of coming with a 200 250 Hz output of the inertial measurement unit IMU The IMUs used ...

Page 12: ...s that have TerraStar capability include the necessary hardware to receive corrections It is necessary to pay a licence fee to activate these corrections Capable Survey systems will use the TERRASTAR D service which can provide better than 10 cm position accuracy TerraStar is available on all continents Marine versions also exist For more information see TerraStar s website http www terrastar net ...

Page 13: ...m components Description RT500 and RT3000 Survey unit Power cable 77C0002B User cable Specify at point of ordering Aux user cable Specify at point of ordering GNSS antennas Specify at point of ordering Ethernet cable cross over USB stick with manual and software Tape measure Quick start guide The Survey product is RTK capable and requires the correct differential corrections in order to work to fu...

Page 14: ... to 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 wil...

Page 15: ... 1 Range 100 m s2 Angular rate Bias 0 01 s 1 Scale factor 0 1 1 Range 100 s Lateral velocity 0 2 1 Update rate 100 Hz 250 Hz Input voltage4 10 48 V dc Power 14 W consumption Dimensions 184 120 71 mm Mass 1 5 kg 1 Optional upgrade 2 To achieve specification relevant differential corrections from a base station NTRIP or TerraStar subscription are required The RTK accuracies are based on v2 products ...

Page 16: ...accuracy in airborne applications The 1 specification has been used for parameters where offset cannot be measured by the Survey for example position the offset of the base station cannot be found by the Survey 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 t...

Page 17: ...ve connectors fitted to both TNC antenna connectors and to use self amalgamating tape over the TNC connectors Export control classification number Export control regulations change and so the classification number of the Survey may also change The information presented here was correct when the manual was published Survey products can fall under two different export control categories depending on...

Page 18: ...he 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 Survey 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 T...

Page 19: ...efore the 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 Manua...

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: ...vehicle There are times however when installing an Survey in the default configuration is not possible for example when using the RT Strut The Survey can be mounted at any angle in the vehicle as long as the configuration is described to the Survey 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 ...

Page 22: ...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 Survey mounted securely in the vehicle If the angle of the Survey can change relative to the vehicle then the dual antenna system will not wo...

Page 23: ...power is applied the Survey requires no further input from the user to start logging and outputting data This section covers some basic information required for operation of the Survey Front panel layout Figure 3 shows the layout of the Survey front panel Table 7 lists the parts of the front panel labelled in Figure 3 Figure 3 Survey front panel layout ...

Page 24: ...n 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 Descripti...

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

Page 26: ...ed by the Survey 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: ...hen 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 Survey axes and the vehicle axes are not the same as those listed in Table 12 they can be aligned by reconfiguring the Survey for a different mounting orientation using the NAVconfig software ...

Page 28: ...gation frame definition North The north axis N is 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 poi...

Page 29: ...U is 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 ...

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: ...ointing 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...

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: ...ve configurations require FTP to put the configuration files on to the Survey The default username and password are both user The Survey 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 by default the same rate as the IMU In order to communicate via Ethernet each S...

Page 34: ...ns navigate the list to find Internet Protocol Version 4 TCP IPv4 Select it and click Properties 6 In the TCP IPv4 Properties 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 a Survey can be fou...

Page 35: ... is possible to change the IP address of Survey systems If the IP address has been changed then NAVdisplay should still be able to identify the address that the Survey is using as long as the PC has a valid IP address and this is not the same as the RT s ...

Page 36: ...ect the coupler to the hub The Survey 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 socke...

Page 37: ...ery 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 Survey or on the delivery note This IP address will differ from the Ethernet output The IP address of the computer being used to communicate with the Survey may need to be changed so it matches the subne...

Page 38: ...et data transmission Once you are on the same IP range as the Survey you can connect to the it via Wi Fi Via your PC s network settings you should be able to select the Survey as a Wi Fi network The Survey that you wish to connect to can be identified by its serial number See Fig 14 below ...

Page 39: ...RT Range User Manual Revision 190902 39 Figure 14 Connect to Wi Fi on the Survey Wi Fi settings are configured using NAVconfig and this process is explained later in this manual ...

Page 40: ...s sufficiently accurate then the Survey will solve the RTK Integer dual antenna attitude mode using the inertial heading If the antenna angle is offset from the Survey by a significant amount then the RTK Integer solution that is solved will be incorrect For a 2 m antenna separation the Survey orientation and the secondary antenna orientation should be known to within 5 For wider separations the s...

Page 41: ...the errors caused by multipath This can be from buildings trees roof bars etc Multipath is where the signal from the satellite has a direct path and one or more reflected paths Because the reflected paths are not the same length as the direct path the GNSS receiver cannot track the satellite signal as accurately The dual antenna system in the Survey works by comparing the carrier phase measurement...

Page 42: ...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 43: ... assignments The main connectors are keyed so the user cable must be correctly aligned for it to connect The system can output data on the serial port and Ethernet The standard serial output of the Survey 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 decode the output of the Survey More inform...

Page 44: ...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 45: ...er is selected in the Ethernet Output option in NAVconfig Trigger information is contained within status message 24 and 43 output over NCOM for the low rate triggers 1 Hz The fast trigger information 50 Hz can only be output over NCOM In output mode the trigger generates pulses based on distance or in synchronisation with the IMU clock rate The pulse width of the distance based signal is 1 ms wher...

Page 46: ...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 RT1003 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 should...

Page 47: ...n of the primary GNSS antenna compared to the Survey The orientation of dual antennas if applicable compared to the Survey The position of the rear wheels or non steering wheels compared to the Survey Some environment parameters The Survey can work out many of these parameters by itself but this takes time Measuring the parameters yourself and configuring the Survey reduces the time taken to achie...

Page 48: ... 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 are starting a new configuration mo...

Page 49: ...RT Range User Manual Revision 190902 49 Figure 16 NAVconfig Home section Start Read Configuration section in NAVconfig Figure 17 NAVconfig Start Read Configuration section ...

Page 50: ...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 18 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 51: ...ilor the settings available to edit in NAVconfig Hardware Setup section in NAVconfig This section contains settings related to the position and orientation of the Survey in the vehicle and the GNSS antennas as well as the profile of the vehicle in which the Survey 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 orient...

Page 52: ...s point in the vehicle Figure 5 on page 28 shows the Survey axes directions The Orientation page of the configuration wizard shown in Figure 20 also has illustrations to visualise the orientation of the Survey 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 53: ...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 Survey can calculate the position of the primary antenna itself However this takes time and better results can be achieved sooner if the user use differential corrections from a...

Page 54: ... between its measurement origin shown in Figure 5 and the GNSS antenna s measurement point This should be entered in the vehicle s co ordinate frame The Survey will try to improve the position of the primary GNSS antenna during use To use the values the Survey has estimated use the Improve configuration wizard after your warm up on the Home page of NAVconfig ...

Page 55: ...ot enabled the Survey 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 22 NAVconfig Secondary Antenna tab i...

Page 56: ... angle of the antennas The Enable static initialisation option is useful for slow moving vehicles or where it is essential to start the Survey 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 separation is smaller This can ...

Page 57: ...ey when GNSS is not available is drastically reduced Figure 23 shows the Lateral No Slip tab Figure 23 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 Figu...

Page 58: ... than 20 cm will increase the drift of the Survey 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 pos...

Page 59: ...gle offset of the Survey compared to the vehicle After the Survey is initialised and warmed up use the Improve configuration option from the NAVconfig Home section to automatically read the Survey s slip angle offset estimate This ensures a slip angle of zero is measured when driving straight on a level track See pages 84 to 89 for steps on the Improve configuration wizard ...

Page 60: ...gured to use several different differential correction message types on connector J3 Figure 26 shows the Differential corrections properties window and Table 21 gives details on the correction types available Figure 26 NAVconfig Differential corrections tab in the Hardware Setup section ...

Page 61: ... differential corrections over WiFi When Network correction transmitter is selected a Survey will broadcast differential corrections it is receiving via a radio modem from an OxTS base station using a WLAN device Other OxTS devices that are on the network as the broadcasting Survey will then be able to receive the DGPS messages and use them To do this the Network correction receiver option should ...

Page 62: ...In North America the SBAS service is known as WAAS in Europe it is known as EGNOS and in Japan it is known as MSAS Select the option that is most suitable for the territory you are in TerraStar corrections TerraStar corrections are configured on the GNSS Differential Corrections tab within the Hardware Setup section You can choose between Manual or Automatic Satellite Selection and if you choose M...

Page 63: ...g the dropdown list If a trigger has been configured as an event 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 packet...

Page 64: ...64 Oxford Technical Solutions ...

Page 65: ... the Wi Fi to connect to an existing 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 Survey will not be able to see what network it could connect to If the Access Point is enabled the Survey will not connect to an existing network Under Wireless networks in range of device you can choose which network you wish to connect the S...

Page 66: ...MEA 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 Survey can also generate NMEA messages from pulses ...

Page 67: ...ta 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 Survey is initiali...

Page 68: ...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 initialisation speed is 5 m s However some slow vehicles cannot achieve this speed For these vehicles adjust the initialisation speed to a different value In contrast some faster vehicles will achieve much higher speeds and wil...

Page 69: ...the High Very High vibration setting should be used include those where vibration mounts have been used or where the Survey 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 Survey remains stationary for long periods of time To solve this the Survey includes an option to lock the...

Page 70: ... to the garage to have some modifications Without Garage mode enabled the Survey may drift too far and may not be able to recover When Garage mode is active the Survey applies a zero velocity update and assumes that the vehicle is stationary This keeps the roll pitch and velocity within acceptable limits while the Survey has no GNSS With heading lock also enabled the Survey can also keep the headi...

Page 71: ...her than at its actual location This function displaces all of the outputs position velocity acceleration to this new location To enable output displacement click the checkbox and enter the offsets to the new location in the vehicle The offsets are measured from the Survey in the vehicle co ordinate frame Select the directions from the dropdown lists and input the distances Note that the noise in ...

Page 72: ...d 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 28 shows the wheel speed configuration window To enable the wheel speed input ensure the checkbox is checked If this option is disabled the Survey will ignore correc...

Page 73: ...Filter The Improved settings utility see page 84 for details can be used to apply a more accurate value calculated by the Survey from a calibration run If this option is used then the Survey should be allowed to recalibrate the scaling value occasionally to account for tyre wear The wheel speed corrections will not be as effective in reducing the drift of the Survey if the wheel speed is measuring...

Page 74: ...ake a very long time to apply the correction Under these circumstances it may be preferable to jump the measurement to the correct value quickly By specifying a time in the Time limit section for the correction the Survey 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 Survey will ...

Page 75: ...thm 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 Figure 30 shows both tabs in the GNSS control properties window Figure 30 NAVconfig GNSS Control tab in Advanced Tools within NAVconfig ...

Page 76: ... developed and improved As such there are some limitations to its compatibility Table 24 details the current compatibilities of gx ix mode Table 24 gx ix compatibility GNSS mode Real time Post process GPS SPS GPS DGPS GPS RTK SBAS x x GLONASS SPS GLONASS DGPS GLONASS RTK Note only RTCM V3 format differential corrections are supported in gx ix mode GNSS Recovery tab The GNSS Recovery tab controls h...

Page 77: ...system starts believing it again Global Coordinate System tab The Survey 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 31 Figure 31 NAVconfig Global Coordinate System properties window ...

Page 78: ...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 measurem...

Page 79: ...gives details on how to do this Figure 32 shows the Write Configuration page Figure 32 NAVconfig Write Configuration page Enter the IP address of the Survey 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 con...

Page 80: ... 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 Survey In order to relate the Survey 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 81: ...the system 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 Survey requires th...

Page 82: ...curately in advance The Survey was turned on as soon as possible In this case it took us 15 minutes to get all the other equipment sorted out The Survey was stationary for most of this period which is not a problem Although in this example the Survey was receiving corrections from a base station while stationary it is not necessary The base station should be working before the dynamic driving star...

Page 83: ...this point the heading accuracy is worse than the scale of the graph d in Figure 34 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 Survey is driven it is the small loop on the east side in Figure 33 not the figures of eight This small ...

Page 84: ...84 Oxford Technical Solutions Figure 34 Example warm up accuracy estimates a Forward velocity b Position accuracies c Velocity accuracies d Orientation accuracies ...

Page 85: ...e can be updated Notice how close to the specification the Survey 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 Survey Improving the configuration after a warm up Committing the configuration to the Survey After the warm up pr...

Page 86: ...ed 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 or Read settings from a folder by locating the file or folder on your PC ...

Page 87: ...sion 190902 87 RT Range User Manual Figure 36 Choose where to read configuration from Click Next to continue Confirm whether the improved data should be read from The Device or a File Click Next to continue ...

Page 88: ... Confirm if configuration should be read from device or logged file 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 89: ...xt 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 t...

Page 90: ...e 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 Survey includes the NAVsolve software which can be used to reprocess the data The NAVsolve Wizard also gives the user the ability to change the NCOM binary output format to text A full explanation of NAVs...

Page 91: ...avigation tab and ensure the x y and z accelerations values 19 to 21 are within specification when the Survey is placed on a level surface in the orientations according to Table 26 Table 26 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 ac...

Page 92: ...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 Survey is capable of correcting the error in the angular rate sensors very accurately It is no...

Page 93: ...le 28 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 ...

Page 94: ...orrect 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 i...

Page 95: ...hematic view of the components in the Survey system Figure 40 Schematic showing the internal components of the Survey The schematic shows the layout for a dual antenna system Strapdown navigator The outputs of the system are derived directly from the strapdown navigator The role of the strapdown navigator is to convert the measurements from the accelerometers and angular rate sensors to position V...

Page 96: ...wn navigator People familiar with inertial navigation systems will note that angular rates and accelerations are labelled as the inputs In reality the DSP in the Survey converts these to change in angle and change in velocity to avoid problems of coning and sculling ...

Page 97: ...es latitude degrees longitude and altitude The altitude is the distance from the model s earth sea level The Kalman filter used in the Survey 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 quan...

Page 98: ... 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 two vehicle mounting angles for advanced slip and vertical 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 this is applied slowly rather tha...

Page 99: ...ng 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 30 List of available drawings 14A0085 RT500 RT3000 system outer dimensions drawing 14C0213D RT500 RT3000 Aux user cable 77C0002B RT500 RT3000 power cable 14C0038D RT500 RT3000 primary user cable Drawing Description 14C0062B...

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