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Inertial Explorer User Guide

1. ok Cancel IMU Time Range Options Process All IMU Data If this option is enabled the software obtains the beginning and end times from the raw binary IMU file These times are in GPS seconds of the week for typical GPS time tagged applications Use GNSS start end times When selected IMU processing will start and end based on a time range set under the General tab of the GNSS processing options menu Begin Time For forward processing this time should correspond to a time in the trajectory files created during GNSS processing If it is then Inertial Explorer uses the GNSS derived position at that time to seed the inertial processing lt The time used here is mission dependent and should be chosen with care because a poor alignment results in poor attitude and coordinate information End Time Same considerations as above This time determines the point at which forward processing stops and when reverse processing begins 18 Inertial Explorer Initial Static Alignment Period The length of time assigned to static alignment depends on the method of alignment being used In all cases it is important that the values entered are in accordance with the Begin and End times specified under the General tab of the GNSS processing options menu To perform a static alignment specify the length of time that the IMU was stationary If this is unknown the Velocity Profile plot obtained from the
2. Manufacturers Sensor Orientation X Right Side Y Front Z UB Positive Pitch Rate Positive Roll Rate Positive Yaw Rate m Define the IMU manufacturers sensor system Select orientation of X AXIS in the sensor frame New Sensor Definiton Select Ke Available Orientations Inertial Explorer will rotate this system into a Y forward roll rate X right side pitch rate Z up yaw rate definition How to define the orientation of the IMU 1 Specify the X direction by selecting the direction that corresponds to the X axis of the sensor frame 2 Click Select to set that direction to the X axis 3 Specify the Y direction by selecting the direction that corresponds to the Y axis of the sensor frame 4 Click Select to set that direction to the Y axis lt Given the constraint that the frame is right handed this direction will be automatically determined by the software 5 Click Update to apply the new sensor orientation to the profile lt Ifa mistake is made at any point during the process click Clear to start over 6 Click Save to save the new profile lt It should immediately appear in the scroll down list under the IMU Profiles box of the main window 35 Chapter 2 36 Conversion Utilities Inertial Explorer 8 50 User Guide Rev 9 Chapter 3 Data and File Formats 3 1 Data Formats In theory virtually any IMU sensor can be used with Inertial Explorer The o
3. LE kk kk kk keka kak kk k kK kk KA KAK Ak K KK KA KA KA A KA KA A 13 1 2 View Menu Ja RS 13 1 50 Process Menun a hasta br Ga 14 1 5 1 Process LC loosely coupled and TC tightly coupled iii Eze 14 1 5 2 Gombine Solutions os 2 ied ste eal et ore ete ean ae 26 1 5 3 Solve BoresightidgANgles oocinmnicn ne 27 10 Settings Menu titi rafa 29 17 Output Ment iets ti a da ee dk tie ee 30 1731 Plot Results iii n e dt dd ae 30 Vis 2EXPOREWIZ di ad dt Sen 30 1 8 Tools Menu A are rear 31 1 9 Interactive WINdOWS uvaner de AS an 31 140 Processing WIN Wicca ed 31 191 Help MOU ear OS 31 TAM AN 31 1 11 2 NovAtel Waypoint Products Web Page ooococooococcccccnoooncccconononcncnonanononccnnnnnnnnnnnnnnncnnnnnnnnnncncnnnns 31 1 12 About Inertial Explorer cccccesccccccceceeceee eee a aa a a a aa a i ea a a aaa a e a aa Eea aa aa aa 32 Chapter 2 Conversion Utilities 33 2 1 Raw IMU Data Converter rrrnnnnnnnnnrnnnvnnnnnrnnnnnnrnnrnntrnn nr caaeeaaaanaecaeeeeeeeeeesegsneaaeaeeeeeeeeeeeeesnssensaneeeees 33 2 1 1 Waypoint IMU Data Conversion siei eee E E AE R E A Ra EEES 33 2 1 2 Creating Modifying a Conversion Profile Li Ek kk kk kk kk KAK kK KA 34 2 1 3 Sensor Orientation Settidgs oooocccnnnnnncccnnnnnnccccnnnnnncncnnnnnnncnncnnnnnncnonnnnnn ee ARAE A Hele Kek Ker KA 35 21 A Decoder Settings lt 44 ne yk dek Se DE up 35 Chapter 3 Data and File Formats 37 3 1 Data For
4. Must be set if sMeasType 2 velocity measurements 1 if logging velocity in meters second 2 if logging velocity in ticks second Scale factor m count or m s count Must be set if sValueType is set to 0 1 0 if logging accumulated tick count or ticks seconds If logging in meters or meters second then dScale will scale measurements into corresponding units char szAxisName DMI MAX DIM 16 double dWheelSize 40 Name of various axes DMI optional NULL terminated Size of the wheel circumference in meters Must be set if logging accumulated tick count or ticks second Inertial Explorer 8 50 User Guide Rev 9 Data and File Formats Chapter 3 long ITicksPerRevolution Number of tick counts per wheel revolution Must be set if logging accumulated tick count or ticks second char cExtra2 420 Reserved for future use bytes should be zeroed The single header which is a total of 512 bytes is followed by one of the following structure types for each DMI measurement record struct dmi_lrec_type If logging using LONG values short sSync Syne byte Set to Oxffee short sWeek GPS week number set to 1 if not known double dTime GPS time of week in seconds unsigned long Value DMI_NUM_DIM values counts DMI NUM DIM should be equal to sDim struct dmi_drec_type If logging using DOUBLE precision short sSync Sync byte Set to Oxffee short sWeek
5. WAY PH N I PRODUCTS GROUP A NovAtel Precise Positioning Product Inertial Explorer User Guide OM 20000106 Rev 9 April 2013 Inertial Explorer User Guide Publication Number OM 20000106 Revision Level 9 Revision Date April 2013 This manual reflects Inertial Explorer software version 8 50 Warranty NovAtel Inc warrants that its GNSS products are free from defects in materials and workmanship subject to the conditions set forth on our web site www novatel com products warranty and for the following time periods Software Warranty One 1 Year Computer Discs Ninety 90 Days Return instructions To return products refer to the instructions on the Returning to NovAtel tab of the warranty page www novatel com products warranty Proprietary Notice Information in this document is subject to change without notice and does not represent a commitment on the part of NovAtel Inc The software described in this document is furnished under a licence agreement or non disclosure agreement The software may be used or copied only in accordance with the terms of the agreement It is against the law to copy the software on any medium except as specifically allowed in the license or non disclosure agreement No part of this manual may be reproduced or transmitted in any form or by any means electronic or mechanical including photocopying and recording for any purpose without the express written permission of a duly authori
6. ES r Smoother Settings Smooth both directions and combine C Forward C Reverse Solution s to smooth TC Solutions both directions present Y r Time Range IV Smooth entire time range Cancel Inertial Explorer 1 5 2 Combine Solutions Refer to the GrafNav GrafNet 8 50 User Guide for information regarding these options Only points relevant exclusively to Inertial Explorer are made here Smooth Solutions Inertial Explorer is capable of combining processing directions and or performing Kalman filter smoothing on inertial trajectory This option requires that the inertial data is already processed Smoothing provides the most significant results on those data sets where GNSS outages were a problem By using this smoother the position velocity and attitude errors can be reduced when GNSS updates are not available Smoothing can also clean up position and velocity accuracies even if there are no gaps Smoother Settings RTS smoothing can be performed in just one direction or both Much like GNSS and GNSS IMU processing it is recommended that smoothing be performed in both directions Solution s to smooth This option performs RTS smoothing on the loosely coupled or tightly coupled solution Time Range This setting controls which period of time to perform the combining and or smoothing of the trajectories Epochs outside of this time range are not considered and do not appear in the outpu
7. N NovAtel SPAN Data 37 49 P V plots Variance factors 23 IMU data 30 list of Inertial Explorer plots 30 Plotting 11 Attitude 11 Processing IMU options 14 Processing Profiles GNSS IMU 18 processing window 31 Project Wizard 12 steps 12 Q quick start 9 R Remote File Adding 12 RIL File see Message Logs 43 RIM File see Trajectory File 43 rotation sensor frame to body frame 15 RTL File see Message Logs 43 RTM File see Trajectory File 43 RTS Smoother options 26 S Smoother see RTS Smoother 26 System tab 14 T Tightly coupled processing 25 time range processing range in Inertial Explorer 18 Trajectory File format and description 43 U updates coordinate 23 GPS source file 14 GPS velocity 23 zero velocity 24 User Defined Options adding commands 25 list of commands 45 50 Inertial Explorer 8 50 User Guide Rev 9
8. 1 3 3 Add Remote File When the adding the remote GNSS data file leave the antenna height at zero The vertical offset should be accounted for as part of the IMU to GNSS lever arm 1 3 4 Add IMU File When starting a new project the program needs the data collected from the IMU lt The IMU file must be in the IMR format before being added Inertial Explorer 8 50 User Guide Rev 9 Inertial Explorer 1 3 5 Load LC Solution Loosely Coupled Loads the loosely coupled solution TC Solution Tightly Coupled Loads the tightly coupled solution Camera Mount Data Loads auto stabilized camera mount information 1 3 6 Convert Raw GNSS to GPB Raw GNSS data must be converted to GPB format for processing Refer to the GrafNav GrafNet 8 50 User Guide Raw IMU Data to Waypoint Generic IMR IMU data must be converted to IMR format in order to be processed by Inertial Explorer Use this utility to perform this conversion See Convert IMU Data on page 10 for more information GPB to RINEX This converts GPB files to a RINEX file It supports the creation of Version 2 0 and 2 11 of the RINEX format For additional information refer to the GrafNav GrafNet 8 50 User Guide 1 3 7 Removing Processing Files This utility removes all the files associated with any given project Refer to the GrafNav GrafNet 8 50 User Guide for details of this utility The Inertial Explorer capabilities are discussed here Files to Remove
9. Plots the difference between the East North and Up components of velocity computed eran MN during forward and reverse processing Requires that both directions be processed and combined This plot shows the difference between the GNSS solution and the mechanized INS positions obtained from the GNSS INS IMU GPS processing This is a good analysis tool used Position to check the GNSS INS solution as well as Misclosure checking INS stability Large jumps or spikes may indicate a bad INS solution whereas separations nearing zero confirms the GPS solution Sheet 2 of 3 31 Chapter 1 Table 1 IMU Plots continued Plot Description This plot shows the difference between the IMU GPS GNSS calculated velocity and the Velocity mechanized INS velocity obtained from the Misclosure GNSS INS processing Another good analysis tool used to check INS stability This plot is the difference between the IMU IMU Heading heading and the GNSS course over ground COG difference values Effects of crabbing shows up as a direct bias in this plot Use this plot to see the raw gyroscope and Hen Data accelerometer measurements as they appear in the IMR file Sheet 3 of 3 Manufacturer files available to download from Waypoint s FTP site manufact dn1 List of base stations available for the Download utility This is usually updated monthly manufact dtm List of datums ellipsoids and transformations be
10. User Guide found on the NovAtel web site and the corresponding version of Waypoint s Inertial Explorer software Prerequisites To run Waypoint software packages your personal computer must meet or exceed this minimum configuration Operating System Windows XP Vista 7 or 8 Hard Drive Space 90 MB of available space on the hard disk Processor A Pentium or Xeon processor is required Simultaneous forward reverse processing is possible on dual CPU and Xeon systems At least 256 MB of RAM is also required Although previous experience with Windows is not necessary to use Waypoint software packages familiarity with certain actions that are customary in Windows will assist in using the program This manual has been written with the expectation that you already have a basic familiarity with Windows Conventions This manual covers the full performance capabilities of Inertial Explorer 8 50 data post processing software The following conventions are used in this manual lt This is a note box that contains important information before you use a command or log or to give additional information afterwards This manual contains shaded boxes on the outside of the pages These boxes contain procedures screen shots tables and quick references Inertial Explorer 8 50 User Guide Rev 9 7 Customer Service If the software was purchased through a vendor please contact them for support Otherwise for software updates and customer
11. Automated Alignment Recommended This option forces Inertial Explorer to scan the available data and automatically determine what type of alignment to perform This option is highly recommended The other options should only be used if automated alignment is failing Static coarse alignment only The data being used for alignment must be completely static as any motion results in an error Coarse alignment is performed for the first 30 to 120 seconds of static IMU data collection and is used as a seed value for attitude information for either fine alignment or navigation Coarse alignment uses the sensed gravity vector components to estimate roll and pitch It uses sensed Earth rotation rate to provide an initial estimate of the yaw of the IMU lt Most low accuracy sensors such as MEMS can measure gravity components but the Earth rotation rate which is roughly 15 arc seconds per second at the equator may be masked by gyro noise As a result the initial yaw estimate from the coarse alignment may be wrong For applications involving constant GNSS updates coarse alignment is often enough to start kinematic IMU navigation Inertial Explorer 8 50 User Guide Rev 9 Inertial Explorer Chapter 1 Static coarse fine alignment Use this option if the IMU is static for longer than 120 H seconds Metho TENE ST NERE SR ETT OF lt Many high precision IMU applications recommend Static coase sigment
12. GNSS processing is useful lt This field does not apply for transfer alignment or for kinematic alignment Initial Position and Velocity The two options include the following Determine from GNSS suggested This method is for collected GNSS data in addition to IMU data The starting position and velocity is read in from the GNSS trajectory specified under the Source of GNSS Updates box in LC processing and in the General tab for TC processing Use entered values IMU only This option is for performing IMU only processing If GNSS data has been processed load the position from a computed trajectory Otherwise enter it manually In either case click the Enter Position and Velocity button to access the input window Auto Kinematic Align Tolerances Min GPS Speed This parameter specifies the minimum speed that the system must be traveling before kinematic alignment is attempted It should only be lowered if the application involves very low dynamics Heading SD Tol This parameter specifies the tolerance below which the heading standard deviation must fall before the alignment routine will move onto navigation mode Lower this value if the software is not achieving a good alignment Raise this value if the software is not aligning at all IMU Time Range These options are in the shaded box Manage GNSS IMU Processing Profiles Current Profile Loaded Displays the profile that is being used To see what each profile s c
13. all copyright trade secret patent and other proprietary rights in the Software and the Software is protected by national copyright laws international treaty provisions and all other applicable national laws You must treat the Software like any other copyrighted material and the Software may only be used on one computer at a time No right is conveyed by this Agreement for the use directly indirectly by implication or otherwise by Licensee of the name of NovAtel or of any trade names or nomenclature used by NovAtel or any other words or combinations of words proprietary to NovAtel in connection with this Agreement without the prior written consent of NovAtel 3 Patent Infringement NovAtel shall not be liable to indemnify the Licensee against any loss sustained by it as the result of any claim made or action brought by any third party for infringement of any letters patent registered design or like instrument of privilege by reason of the use or application of the Software by the Licensee or any other information supplied or to be supplied to the Licensee pursuant to the terms of this Agreement NovAtel shall not be bound to take legal proceedings against any third party in respect of any infringement of letters patent registered design or like instrument of privilege which may now or at any future time be owned by it However should NovAtel elect to take such legal proceedings at NovAtel s request Licensee shall co operate reasonably with NovA
14. decimal degrees Use positive rotation clockwise from north IE uses yaw i e rotation counterclockwise from north yaw heading Standard deviation of update decimal degrees zero if unknown Distance between antennas in metres Only if ucType 2 dual antenna Pitch between two antennas in degrees Only if ucType 2 dual antenna Standard deviation of the pitch in degrees zero if unknown 34 bytes Inertial Explorer 8 50 User Guide Rev 9 Data and File Formats Chapter 3 3 3 Output Files This section discusses the different output files that are created when processing with Inertial Explorer 3 3 1 FIL RIL FTL RTL Files Message Log files echo all error and warning messages sent to the Process Window during INS processing Some example messages are below Coarse Alignment Succeeded on attempt 1 This message appears at the beginning of forward reverse processing It indicates that the coarse alignment was successful Reading GrafNav Record 1000 Scanning the GPS IMU data before processing Warning Coarse Alignment has used up all of the Align Time Will Continue Processing anyway This message indicates that the INS processor used all the coarse alignment time entered Warning GUPT Missing in GPS data gt DT 0 200 This message indicates the presence of a gap in GPS data of time DT seconds As a result the processor cannot use this time as a GPS update Warning Trace of B
15. methods 16 antenna frame 15 height 12 lever arm 10 15 22 31 Auto Start description 12 how to use 12 B BIF File data structure 44 BIR File data structure 44 Boresighting angles 27 BTF File data structure 44 BTR File data structure 44 Cc coarse alignment description 16 combining solutions forward and reverse smoothed 26 Convert GNSS Data 10 IMU Data 10 Converting creating profile for raw data conversion 34 raw IMU data to IMR 33 D data interval for GPS updates in Inertial Explorer 23 DMI Options 24 DMR File 40 E error model settings 19 Export Final Coordinates 11 export wizard 30 F FIL File see Message Logs 43 File Data Coverage Determine Alignment Method 10 Inertial Explorer 8 50 User Guide Rev 9 FIM File see Trajectory File 43 fine alignment description 17 FTL Files see Message Logs 43 FTM File see Trajectory File 43 G GNSS updates Using 23 H Heave applying 22 HMR File 42 format and description 42 l IMR File converting to 33 format and description 38 IMU Process loosely coupled setting 14 IMU file adding to Inertial Explorer 12 In Motion Kinematic Alignment description 17 L lever arm solve values 22 lever arm offset IMU to alternate sensor 30 IMU to GNSS 15 read values 15 Loosely coupled processing 14 M manufacturer files downloading latest files 32 Message Logs format and description 43 Mount tab 25
16. the gyro measurements the inverse of the accelerometer scale factor is required As well the accelerometer measurements can take two forms the first being data velocity or velocity increments and the other being acceleration Timing Settings Enter the data collection rate of the IMU sensor and specify any offset that may exist between the GNSS and the IMU time tags Byte Order This flag must be properly set DX If the proper byte order is not specified the decoding of the binary raw file will fail Time Tag Format There are two options available as the data is either acquired in the GPS time frame or the UTC time frame This must be correctly identified in order for the IMU data to be properly aligned with the GNSS data Inertial Explorer 8 50 User Guide Rev 9 Conversion Utilities Time Tag Source Specify whether the time tags represent the GPS Corrected Time or the GPS Received Time 2 1 3 Sensor Orientation Settings Define the orientation of the IMU here using the steps in the shaded box lt The orientation will always be right handed 2 1 4 Decoder Settings Specifies which library is used to perform the conversion based on the input format of the raw data file For most sensors this should be left untouched lt For SPAN the IMU decoding is handled through the GNSS decoder Inertial Explorer 8 50 User Guide Rev 9 Chapter 2 Sensor Timing Settings Sensor Orientation Decoder Settings
17. with a MEMS based system If no static data is present at the start and or end times of the Velocity Profile plot then perform a kinematic alignment instead For static alignment this plot helps to determine how much time is available for the processor to use The amount of time for the alignment can be set under the Method for Initial Alignment options accessed through Advanced System The correct time length must be assigned because any movement during the static alignment results in an error lt Fine static alignment is only practical for high accuracy IMUs and generally requires at least 10 minutes Kinematic alignment requires 4 8 seconds Process IMU Data The steps for processing IMU data are in the shaded box Inertial Explorer 8 50 User Guide Rev 9 Inertial Explorer Plotting and Quality Control Once processing is complete view the quality of the results by analyzing the IMU plots Under the Output menu choose Results to access the following IMU plots Attitude Roll and Pitch This plot shows the roll and pitch profile of the processed IMU data Attitude Azimuth Heading This plot shows the heading azimuth of the IMU and the GNSS course over ground They should be in reasonable agreement If the red line and green line are 180 different then the IMU has been mounted backwards and a rotation of 180 about the Z axis will need to be entered under the Process Tightly Coupled or Process Loosely Couple
18. zero separation is ideal Acceleration Attitude as it indicates matching solutions in the Separation forward and reverse IMU processing Spikes at the beginning and the end of the plot are common as they indicate the periods of alignment Body Frame This plot shows the components of acceleration in the vehicle body frame Body Frame Velocity This plot shows the components of velocity in the vehicle body frame DMI Scale Factor This plot presents the DMI scale factor as computed by the Kalman filter It should be loaded separately for forward and reverse processing to ensure that the same scale factor is computed in both directions Ideally the plotted line should be horizontal indicating a constant scale factor DMI Residual This plot presents the difference between the computed displacement or velocity and that reported by the DMI DMI Analysis Tool This tool allows DMI users to view the raw data measurements found in their DMR file They can use the options available here to find an appropriate scale factor that will make the DMI data fit best with the values computed from the GNSS IMU data Estimated Accelerometer Bias Accuracy This plot shows the estimated standard deviation of the accelerometer bias It is plotted in terms of the X right direction Y forward direction and Z up direction of the INS body Estimated Attitude Accuracy Sheet 1 of 3 30 Th
19. 0 User Guide Rev 9 5 5 Term and Termination This Agreement and the rights and licences hereby granted shall continue in force in perpetuity unless terminated by NovAtel or Licensee in accordance herewith In the event that the Licensee shall at any time during the term of this Agreement 1 be in breach of its obligations hereunder where such breach is irremediable or if capable of remedy is not remedied within 30 days of notice from NovAtel requiring its remedy then and in any event NovAtel may forthwith by notice in writing terminate this Agreement together with the rights and licences hereby granted by NovAtel Licensee may terminate this Agreement by providing written notice to NovAtel Upon termination for any reasons the Licensee shall promptly on NovAtel s request return to NovAtel or at the election of NovAtel destroy all copies of any documents and extracts comprising or containing the Software The Licensee shall also erase any copies of the Software residing on Licensee s computer equipment Termination shall be without prejudice to the accrued rights of either party including payments due to NovAtel This provision shall survive termination of this Agreement howsoever arising 6 Warranty NovAtel does not warrant the contents of the Software or that it will be error free The Software is furnished AS IS and without warranty as to the performance or results you may obtain by using the Software The entire risk as to the results and perf
20. 00e 002 metres s 2 Gyro Drift 2 77778e 002 2 77778e 002 2 77778e 002 deg s Spectral Densities Values square root of X Axis Y Axis Z Axis Misalignment 8 78410e 004 8 78410e 004 8 78410e 004 deg Accel Bias 3 16228e 006 3 16228e 006 3 16228e 006 metres s 2 Gyro Drift 8 78410e 010 8 78410e 010 8 78410e 010 deg s Velocity 1 00000e 003 1 00000e 003 1 00000e 003 m s Position 1 00000e 003 1 00000e 003 1 00000e 003 m Cancel 21 Chapter 1 x System States Updates Mount User Cmds Error Model Solve IMU gt GNSS Lever Am E Solve for Lever Arms Initial Std Dev bc z y 0 200 m Min Req Velocity 5 000 m s Accel and Gyro Extra States Initial Std Deviations E Accel Scale 0 ppm E Accel Orthog 0 arcsec E Gyro Scale 0 pm FlGyro Orthog 0 arcsec Gyro G Sensitivity 0 00000 deg sec m 2 Compute Heave for Marine E Apply Heave E 22 Inertial Explorer Solve IMU gt GNSS Lever Arm Lever arm accuracy is critical to post processing results as position velocity and phase updates measured at the GNSS antenna phase center need to be applied at the IMU center of navigation The position variance should be greatly increased values of 50 to 100 if processing without accurately measured lever arms or if solving for them using the Solve lever arm values as additional Kalman filter states option Solve for Lever Arms Use this opti
21. 3 1 00000e 003 m How to create a custom profile Click the Add From button to create of a new model based on a default model or click the Edit button which accesses the default models Generally the former method is recommended because it allows the default models as provided by the manufacturer to remain available for future use lt In either case disabling the Lock selection setting is required before the selection of any error model can be made Once an error model has been selected this setting should be re enabled to ensure that it is not accidentally changed 19 Chapter 1 ane Lic Name NovAtel SPAN LN200 Source Manufacturer Initial Standard Deviation Values X Axis Y Axis ZAxis Misalignment 5 00000e 001 5 00000e 001 5 00000e 000 deg Accel Bias 3 00000e 002 3 00000e 002 3 00000e 002 metres s 2 Gyro Drift 2 77778e 002 2 77778e 002 2 77778e 002 deg s Spectral Densities Values square root of X Axis Y Axis Z Axis Misalignment 8 78410e 004 8 78410e 004 8 78410e 004 deg Accel Bias 3 16228e 006 3 16228e 006 3 16228e 006 metres s 2 Gyro Drift 8 78410e 010 8 78410e 010 8 78410e 010 deg s Velocity 1 00000e 003 1 00000e 003 1 00000e 003 m s Position 1 00000e 003 1 00000e 003 1 00000e 003 m Cancel Inertial Explorer Initial Standard Deviation Values The following mathematical quantities are available Misalignment These terms pertain to the difference betwee
22. GPS week number set to 1 if not known double dTime GPS time of week in seconds double dValue DMI_NUM_DIM values double precision DMI NUM DIM should be equal to sDim Inertial Explorer 8 50 User Guide Rev 9 41 Chapter 3 3 2 3 HMR File Data and File Formats The 256 byte header contains information that is vital to processing and must be filled in The C C structure definition of the HMR header is as follows typedef struct char szTitleStr 12 unsigned char ucType double dBoreSightRotationZ SIMUHEADING O NULL terminated ASCII string Set to 1 if external or 2 if dual antenna Heading boresight rotation about Z in degrees Set to zero if unknown Use positive boresight rotation as clockwise from north TE will use the yaw definition by negating this so we have a right hand definition that fits with internal computations double dBoreSightRotationZStdDev char Extra 227 heading_hdr_type accuracy of the boresight in degrees zero if unknown Reserved bytes should be zeroed 11256 bytes The single header is then followed by the 34 byte structure type below for each heading update record typedef struct double dGpsTime short sGpsWeek double dHeading float fHeadingStdDev float fBaselineLength float fPitch float fPitchStdDev heading_rec_type 42 GPS time of week in seconds GPS week number set to 1 if unknown Heading update in
23. ILE NAME filename INS_LOWPASS 0 1 INS_PROCESS_DIR FORWARD REVERSE INS_PROCESS_MODE mode INS_TIMERANGE start end INS TYPE type INS_VERBOSE ON OFF MISALIGNMENT NOISE sd1 sd2 sd3 MISALIGNMENT SD esddev nsddev hsddev NUM STATES number POSITION MEAS VAR cov POSITION NOISE sd1 sd2 sd3 POSITION SD esdev nsdev usdev PREDICTION RATE n TIME OFFSET offset 46 If known input initial East North Up velocities m s for forward and reverse alignment INS BODYFRAME OFFSETS roll pitch yaw Constant angular offsets in degrees from the IMU axes to vehicle body frame axes INS DATAGAP TOL Num consectutive epochs missing Exit on a single data gap that is larger than this number Name of IMU binary measurement file INS GPS TIME FRAME GPS TIME FRAME RCVR TIME FRAME GPS TIME FRAME i e revr time revr clock biasjJRCVR TIME FRAME i e nominal rev time Use I for low pass filter on raw data FORWARD REVERSE direction INS processing GPS INS or INS ONLY Indicates IMU processing time range and whether to process ALL or PARTIAL LTN90 LRF 3 LN200 HG1700 JAMI IMU GENERIC IMU imr Writes extra messages to FIL and RIL files Spectral density of misalignment states in aresec s A priori Kalman standard deviations for East North Up misalignment states in arc seconds Number of Kalman filter states Variance R matrix of Kalman CUPT observation in m Spectral density of t
24. If you do not know it set this to zero and then fill it in from the interface dialog boxes Scale multiply the gyro measurements by this to get degrees sec if bDeltaTheta 0 Scale the gyros by this to get degrees if bDeltaTheta 1 If you do not know it then the data can not be processed Our default is to store the gyro data in 0 01 arcsec increments or 0 01 arcsec sec so that GYRO SCALE 360000 Scale multiply the accel measurements by this to get m s if bDeltaVelocity 0 Scale the accels by this to get m s if bDeltaVelocity 1 If you do not know it the data can not be processed Our default is to store the accel data in le 6 m s increments or le 6 m s so that ACCEL_SCALE 1000000 Defines the time tags as being in UTC or GPS seconds of the week 0 Unknown default is GPS 1 UTC 2 GPS Defines whether the GPS time tags are on the nominal top of the second or are corrected for receiver time bias 0 do not know default is corrected time I receive time on the nominal top of the epoch 2 corrected time i e corr_time rev time revr_clock_bias Inertial Explorer 8 50 User Guide Rev 9 Data and File Formats double dTimeTagBias char szimuName 32 unsigned char reserved1 4 char szProgramNamef 32 time type tCreate bool bLeverArmValid long IXoffset long lYoffset long IZoffset char Reserved 354 Chapter 3 def
25. S decoder automatically extracts the IMU data lt This manual assumes the use of the GrafNav GrafNet 8 50 User Guide You can request a copy from Customer Service or download it from our Web site at www novatel com 1 2 Getting Started with Inertial Explorer This section provides a step by step procedures on how to process data in Inertial Explorer Installation Verify that the installation was successful by ensuring that you have a Waypoint Inertial Explorer program group on your computer If this program group is not there refer to the GrafNav GrafNet 8 50 User Guide for installation instructions Inertial Explorer 8 50 User Guide Rev 9 Precise KULUL WAY PI NT A PRODUCTS GROUP Now4tel How to start Inertial Explorer 1 Verify installation 2 Click on Inertial Explorer to start the program Chapter 1 How to convert IMU data 1 Open the conversion utility via File Convert Raw IMU Data to Waypoint Generic IMR 2 Click the Browse button to locate the raw IMU data file 3 Under the JMU Profiles box select the appropriate IMU type 4 Click Convert to create the IMR file See Chapter 2 Conversion Utilities on page 33 for more information 5 Add the file to the project via File Add IMU File How to process IMU Data 1 Click the Process menu and then select Process LC Loosely Coupled or Process TC Tightly Coupled lt If you are processing in loosely coupled mode make sure t
26. Selects files to remove from the project or folder Inertial Processing LC and TC Removes all ASCII and binary files created during IMU processing including message logs and trajectories 1 4 View Menu Refer to the GrafNav GrafNet 8 50 User Guide for a description of all the features available in this menu lt In Inertial Explorer view IMU message logs and trajectory files under View Forward Solution and View Reverse Solution See Section 3 2 File Formats on page 38 for information on file formats Inertial Explorer 8 50 User Guide Rev 9 Chapter 1 How to start a new project using Auto Start con t 4 Choose the IMR file The IMU data must be concurrent with the master station base station and remote data To verify this click the Plot Coverage button to display the File Data Coverage plot lt The IMU data must be converted to the IMR format before being added to the project 5 Choose the DMR file If any DMI data is available select the Enable DMI data option This data must be collected concurrently with the rest of the data in the project Use the Plot Coverage button to find overlapping DMR data 6 Choose a Processing Profile that best suits the application and the IMU being used 7 Enter the Master Station Coordinates 8 Enter the Remote Station information 13 Chapter 1 Inertial Explorer 1 5 Process Menu r a maz az TIT Sar A QESE ES comers Refer to the GrafNav Gra
27. a and File Formats lt All odometer data must be written into Waypoint s generic format DMR before it can be used within Inertial Explorer struct dmi_hdr_type char szHar 8 short sHdrSize short sRecSize short sValueType short sMeasType short sDim short sRes short sDistanceType short sVelocityType double dScale DMIRAW 10 NULL terminated ASCII string Size of header in bytes Must be set to 512 Size of each record refer to dmi lrec type and dmi drec type 12 8 sDim if sValueType DMI VALUE DOUBLE 12 4 sDim if s ValueType DMI VALUE LONG where sDim is number of DMI sensors Number type DMI VALUE LONG DOUBLE 0 if logging data using LONG values 1 if logging data using DOUBLE precision Measurement type distance or speed 1 if logging a distance measurement 2 if logging a speed measurement Number of DMI sensors Maximum is 3 but only 1 can be used in Inertial Explorer Measurement resolution of DMI 1 if low resolution i e only makes measurements on the full wheel revolution 3 if high resolution i e makes measurements at partials of a wheel revolution or on fixed time intervals Type of distance measurement Must be set if sMeasType 1 distance measurements I if logging accumulated tick count 2 if logging distance in meters 3 if logging accumulated distance in meters Type of velocity measurement
28. ar Direction 16 char Reserved2 392 imu_hdr_type lt The RecSize variable should always be checked as the structure size and format may change in future versions Contact Waypoint Support if you have any questions The single header is then followed by the 121 byte structure type below for each processed epoch typedef struct double GpsTime short WeekNum GPS time of this record seconds of week week number unsigned char FixedFlagAndHeave 2 plh_type_double GeoPos fxyz_type LLVel fxyz_type LLAcc iatt_type LLAtt fxyz type LLAttDot fxyz type stdPos fxyz type stdVel fxyz type stdAtt char Reserved 1 imu outrec type typedef struct double phi lamda double ht plh type double typedef struct float x y z fxyz_type typedef struct signed long iRoll iPitch iYaw iatt type bit 0 Fixed solution on float solution off bits 1 14 heave 16 384 m bit 15 sign of heave geographic position of this record deg deg m local level velocity m s local level acceleration m s local level attitude deg scaled body frame rotational rate deg s position standard deviations m velocity standard deviations m s attitude standard deviations deg latitude and longitude deg ellipsoidal height m attitude deg scaled by 1 0e 6 The rotation matrix from body to local level is defined as RES Rx yaw Ry pitc
29. ariy approximately 2 minutes of coarse alignment Static coarse fine align followed by 8 to 10 minutes of fine alignment Kinematic Alignment gt Set IMU Time Range Manually Transfer alignment enter known attitude Enter Attitude e od Infial Position and Veloci Within 5 to 10 minutes GNSS updates enable the Initial Static Alignment Period Mil Fostion and Velocity Determine from GNSS suggested IMU to provide attitude information consistent with 60 00 6 ker OED the accuracy level achievable by the accelerometer 0 00 6 ising trajecin y gyro triad with or without fine alignment This _ la depends on the type of IMU and the application s N Kinemat Paes TE requirements After roll pitch and yaw are roughly estimated for coarse alignment fine alignment refines them to a better level of precision OK Cancel Kinematic alignment When neither static data or a priori attitude information are available alignment can be done using vehicle motion This requires a short period of time where the vehicle is relatively level and moving in a relatively straight line followed by some higher dynamics such as an aircraft S turn The time period can range from 4 to 40 seconds depending on the dynamics at the chosen start time Min GPS Speed 20 m s Heading SD Tol 15 0 deg This feature is useful when there is no static data While Inertial Explorer has been successful at aligning tactical grad
30. ault is 0 0 but if you have a known millisecond level bias in your GPS 3 INS time tags then enter it here Name or type of inertial unit that is being used Reserved for future use bytes should be zeroed Name of calling program skip if writing directly to this format Creation time skip if writing directly to this format 12 bytes Set to true if the sensor definition that follows is valid Lever arm is from IMU to GPS phase centre X value of lever arm in millimeters Y value of lever arm in millimeters Z value of lever arm in millimeters Reserved for future use bytes should be zeroed The single header which is a total of 512 bytes long is followed by a structure of the following type for each IMU measurement epoch typedef struct double Time long g9x 9y 9Z long ax ay az INS type GPS time frame seconds of the week delta theta or angular rate depending on flag in the header delta v or acceleration depending on flag in the header this is the binary structure type expected in GPSIMU lt The angular increments or angular rates are scaled long integers The scale factor to obtain a double precision word must be supplied in the header Similarly the accelerations or velocity increments are signed four byte words and must be scaled by a double precision variable given in the header Inertial Explorer 8 50 User Guide Rev 9 39 Chapter 3 3 2 2 DMR File Dat
31. be found on the distribution CD or the NovAtel web site 11 Chapter 1 Project Wizard Steps 1 Create and name the project 2 Add the rover data to the project lt The rover data can be in Waypoint s GPB format or in the receiver s raw format If the data is in the receiver s raw format the Wizard converts it to GPB for you If you are a NovAtel SPAN user and you add a raw data file the Wizard automatically detects the IMU model for conversion to IMR format 3 Add the base station data to project lt You can add your own local base station data in raw or GPB format or you can have the Wizard download free service data from the Internet If you plan to process with PPP you can skip the previous step and download the precise satellite clock and orbit files from the Internet How to start a new project using Auto Start 1 Enter a name for the project with File Name Check that the file path is pointing to the directory where the project files are saved lt Choosing a name of an existing project overwrites that project 2 Choose the Master Station File s This is the GNSS data file collected at the reference station lt Raw GNSS data files must first be converted to Waypoint s common format GPB Refer to the GrafNav GrafNet 8 50 User Guide for more information on converting data 3 Choose the Remote File It must contain GNSS data collected during the same time period as th
32. be entered in m s Gyro Drift These values refer to the initial uncertainty of the a priori knowledge of the sensor drift in the gyroscopes If the biases are left at zero then enter standard deviations values here that reflect this The program attempts to compute reasonable values during processing All values should be entered in degrees sec Inertial Explorer 8 50 User Guide Rev 9 Inertial Explorer Spectral Densities Values Generally speaking the lower the grade of the sensor the larger the spectral densities that should be used for processing s previously discussed the spectral densities add noise to the covariance propagation process prior to filtering Therefore the higher the densities the greater the weight that is placed on the GNSS updates during filtering The following mathematical quantities are available Misalignment A misalignment noise density in degrees becomes a covariance when multiplied by some time interval dt If the sensor triad is problematic in terms of providing an accurate attitude matrix or if initial alignment is poor then you may need to introduce large spectral density values here These spectral components add noise to the computed Kalman covariances for misalignment which in turn forces the processor to rely more heavily on the GNSS position and velocity updates As a result large errors in the direction cosine matrix are compensated for Accel Bias Accelerometer bias d
33. d can thus be useful in troubleshooting if the values in the MMR file are suspect Gyro Drift Rate This is the apparent change in angular rate over a period of time as computed by the GNSS INS Kalman filter The effects are usually random It is plotted in terms of the X right direction Y forward direction and Z up direction of the INS body Generally they should stabilize after the alignment period and agree when processed in both directions This plots shows the misclosure residual of Gyro Attitude gyroscope Kalman filter updates Large Misclosure values here could be an indication of attitude instability This plot shows the gyroscope rate of change IMU Angular of attitude in the X Y and Z axes of the IMU Rates body with the drift removed This plot is used to check the gyros Shows the status of IMU processing IMU Status Flag Specifically this plot provides indication of the type of update if any being applied at each epoch IMU GPS Lever Arm This plots presents the body frame components of the lever arm offset between the IMU and GNSS antenna If the offset was manually entered then this plot has constant horizontal lines If left to be solved by the Kalman filter this plot shows the computed values IMU Heading COG difference This plot is the difference between the IMU heading and the GNSS course over ground values Effects of crabbing shows up as a direct bias in this plot
34. d settings window Attitude Separation This plot requires that forward and reverse have both been processed It shows the difference between their attitude values Ideally they should agree IMU GNSS Position Misclosure This plot shows the difference between the GNSS only and the GNSS IMU trajectories These plots should agree DM Use the Build Custom button to add some of the these plots to a customized list Smooth Solution Select Process Smooth Solutions to smooth and combine the two directions This is strongly recommended in order to achieve the best results Export Final Coordinates The steps for exporting final coordinates are in the shaded box Inertial Explorer 8 50 User Guide Rev 9 Chapter 1 Plot Results Select Plot x Axis Y Axis List of variables CTRL click to select multiples E 8 sa E E E E E E E Most Common bes Accuracy Pes Measurement bes Separation pe Quality Control far Coordinate Values far Attitude bee IMU Pes Miscellaneous Bss All How to export final coordinates 1 Select Output Export Wizard 2 Specify the source for the solution Epochs outputs the trajectory while Features Stations exports positions only for loaded features such as camera marks 3 Select a profile For Inertial Explorer select IMU Data as the profile 4 Click Next 5 Use the processing datum for the datum screen XI If prompted for the geoid undulation file it can
35. deg I Update navigation angles on entry 53 Boresight module version 8 10 2130 53 c Copyright NovAtel Inc 2008 15 53 Settings New Load gt View gt ClearMsg Close xl 29 Chapter 1 Plot Description Accelerometer Bias Table 1 IMU Plots This is the apparent output in acceleration when there is no input acceleration present It is computed by the GNSS INS Kalman filter and the effects may be sinusoidal or random It is plotted in terms of the X right direction Y forward direction and Z up direction of the INS body Generally they should stabilize after the alignment period and agree when processed in both directions Plots the heading and GNSS COG course over ground that was computed from the GNSS INS processing Effects of crabbing is visible in this plot if the GNSS COG bears a Roll and Pitch en constant offset from INS heading The MU Heading Heading COG Difference plot shows the 9 difference between these two heading values Note that any transitions between a heading of 359 degrees and 0 degrees shows Up as a vertical line Plots the roll and pitch values from GNSS INS Attitude processing In airborne data it is common to see roll values between 30 degrees and pitch values of around 10 degrees depending on the flight pattern of the aircraft itself This plot shows the difference between the forward and reverse solutions in terms of roll pitch and heading A
36. densities that work optimally for that particular IMU For some MEMS sensors it is critical that spectral densities match the sensor noise of the system In some cases IMU processing cannot be performed at all without a properly chosen error model Inertial Explorer 8 50 User Guide Rev 9 Chapter 1 r TN ES System States Updates Mount User Cmds Error Model Solve IMU gt GNSS Lever Arm E Solve for Lever Arms Initial Std Dev v 2 y 0 200 m Min Req Velocity 5 000 m s Accel and Gyro Extra States Initial Std Deviations Accel Scale 0 ppm E Accel Orthog 0 arcsec Gyro Scale 0 E Gyro G Sensitivity 0 00000 ppm F Gyro Orthog 0 arcsec deg sec m 2 Compute Heave for Marine Apply Heave 30 0 F ot a kaz Name NovAtel SPAN LN200 Source Manufacturer Initial Standard Deviation Values X Axis Y Axis Z Axis Misalignment 5 00000e 001 5 00000e 001 5 00000e 000 deg Accel Bias 3 00000e 002 3 00000e 002 3 00000e 002 metres s 2 Gyro Drift 2 77778e 002 2 77778e 002 2 77778e 002 deg s Spectral Densities Values square root of X Axis Y Axis Z Axis Misalignment 8 78410e 004 8 78410e 004 8 78410e 004 deg Accel Bias 3 16228e 006 3 16228e 006 3 16228e 006 metres s 2 Gyro Drift 8 78410e 010 8 78410e 010 8 78410e 010 deg s Velocity 1 00000e 003 1 00000e 003 1 00000e 003 m s Position 1 00000e 003 1 00000e 00
37. e determine the composition of the variance covariance matrix used in the least squares procedure to derive the final boresighting values Choose to enter a set of constant standard deviation values to apply to all measurements or have the values derived from either the navigation SD values the photo SD values if provided or a combination of both The other setting here pertains to the outlier tolerance The value specified here determines at which point a measurement is removed from the least squares procedure Display Units These options pertain to the values displayed in the Solve Boresight Angle window and determine which units are used when writing to the Boresight Report file These options also allow the number of decimals places to which all values are displayed or written to be modified New This button clears any stored data from previous calibration runs in order to start a new one Load Use this button to load the required navigation and exterior orientation input data The navigation data can be obtained either by loading the latest set of roll pitch and heading values computed by Inertial Explorer or by an external file which contains this information for each camera event Alternatively if such information is available there is the ability to provide the module directly with the omega phi and kappa angles required to rotate the ground system into the IMU frame Obtaining the attitude angles directly from Iner
38. e reference station Continued in the shaded box on the next page 12 Inertial Explorer 1 3 File Menu Refer to the GrafNav GrafNet 8 50 User Guide for information on the features available via this menu The points relevant to Inertial Explorer are discussed in this section of the manual 1 3 1 New Project Project Wizard The Project Wizard offers you a guided step by step way of creating a project The Project Wizard steps are listed in the shaded box Auto Start Auto Start prompts for all the information required to process IMU data This option adds reference and remote stations and allows a project setting that best suits the application The steps for starting a project using Auto Start are in the shaded box 1 3 2 Add Master File s Entering the proper reference station coordinates is essential for obtaining high accuracies The values that appear are averaged from the GPB file and may have errors of 10 metres or more For many publicly available stations i e IGS CORS etc precise coordinates are pre loaded in the Favourites Manager Alternatively you can click the Compute from PPP button to have the software attempt to solve for the precise coordinates using the PPP engine Refer to the GrafNav GrafNet 8 50 User Guide for more information Proper datum selection is very important as well WGS84 coordinates are different from NAD83 coordinates by 2 m so care should be taken when using these coordinates
39. e systems using this method there is no guarantee regarding lesser grade IMUs It might even be necessary to pick a different error model in order to prevent instabilities arising in the Kalman filter Transfer alignment If roll pitch and yaw are known these values can be entered as initial integration constants to allow navigation to proceed Attitude angles can be provided by another IMU in which case the misalignment between the IMUs must be applied or they can be extracted from another trajectory such as the opposite processing direction Click Enter Attitude to enter initial attitude information manually or select Get from Trajectory to scan at a specified time from a defined IMU trajectory The first epoch appearing in the IMU trajectory file of the direction opposite that of the one being processed is used The attitude and velocities as well as their standard deviations are loaded Inertial Explorer 8 50 User Guide Rev 9 17 Chapter 1 r YY nnn System States Updates Mount User Cmds File Info IMU file iPSDataVnertial SPAN Features VRemotelspan 1imr Method for Initial Alignment Forward Alignment gt Automatic Mode Reverse Alignment gt Automatic Mode Options IMU Time Range V Process all IMU data Use GNSS start end times 604 00 Begin time 332604 00 End time 335942 00 Manage GNSS IMU Processing Profiles Current Profile Loaded SPAN Airbome LN200 Profile Manager
40. een read in After the calibration procedure is complete the final boresighting values as well as the number of iterations needed to arrive at them are displayed The following options are available via the buttons along the bottom of the Solve Boresight Angles window Compute Assuming all the required input data has been loaded click this button to begin the iterative least squares procedure The Message Window contains pertinent information regarding the success or failure of the procedure Inertial Explorer 8 50 User Guide Rev 9 Chapter 1 Solve Boresight Angles xj Show Navigation values v Angles in degrees SD Resid and BS in ArcMin Pitch Heading RollSD PitchSD HeadsD Latitude 2 IV Add results to list use for Export I View report after computation I Update navigation angles on entry y Settings Calibration name fs o B S Angles de 9 15 53 Boresight module version 8 10 2130 9 15 53 c Copyright NovAtel Inc 2008 9 15 5 Settings New Load gt View gt ClearMsg Close Values that are visible with the Show drop down menu Navigation values The roll pitch and heading values along with their associated standard deviations are displayed for each loaded camera event The coordinates of the IMU at the time of the event are also displayed These values are generally transferred from Inertial Explorer directly and correspond to the IMU values interpolated at camera event t
41. ensities when multiplied by the prediction time interval act as additive noise to the accelerometer bias states As such larger values here may help to compensate for large biases in the accelerometers Gyro Drift Gyroscope drift densities similarly act as additives to the covariances computed for the gyroscope drift states In the case of inexpensive units larger values here may be necessary Velocity Velocity spectral densities are noise densities that account for unmodeled velocity effects during each Kalman prediction Increasing this value permits more emphasis to be placed on the GNSS update data but may also lead to an increase in error growth during outages For this reason these values should be determined as part of the tuning process The default values are recommended unless dealing with a trajectory of unusually high dynamics such as a race car in which case these may need to be reduced by an order of magnitude Position Position spectral densities are noise densities that account for unmodeled position effects during each Kalman prediction Apply all of the considerations mentioned above for the velocity spectral densities Inertial Explorer 8 50 User Guide Rev 9 Chapter 1 cacon DES eem Name NovAtel SPAN LN200 Source Manufacturer Initial Standard Deviation Values X Axis Y Axis Z Axis Misalignment 5 00000e 001 5 00000e 001 5 00000e 000 deg Accel Bias 3 00000e 002 3 00000e 002 3 000
42. es of these applications include where a low quality IMU is used where it is impossible to follow recommended alignment procedures or where a vehicle moves very slowly and or does not experience many changes in heading The HMR data format is described in Section 3 2 2 DMR File on page 40 Mount If you have mounted your IMU onto a gyro stabilized platform you will need to provide Inertial Explorer with the angular rotations to compensate for the changing lever arm between the IMU and GNSS antenna User Commands Certain options available in Inertial Explorer cannot be accessed through the options menu A full list of configured options is available under this tab and may be invoked to employ special features or overwrite defaults For an explanation of all the commands available see Appendix A Summary of Commands on page 45 Inertial Explorer 8 50 User Guide Rev 9 Chapter 1 IMU Processing Settings System States Updates Mount User Cmd IMU gt Gimbal Lever Arm 0 0 0 at IMU gt X 1t side Y fwd Z up NOTE IE will output ALL Coordinates at Gimbal Centre if Filled in x 2 000 y 0 000 z 10 000 metres I Enable extemal auto stabilized camera mount input using file Import DIOWSE mount data must be in standard format and reference use Import Info m Additional Corrections o Camera boresiaht angles as solved by Inertial Explore Phi Kappa order is W P 25 Chapter 1 26
43. f standard deviation quality factor and Doppler RMS are below tolerances GPS_POSITION_UPDATES ON OFF Enable disable GPS position updates GPS_TRAJECTORY_SOURCE source Set GPS solution file O CMB 1 FWD 2 REV 3 Jexternal file GPS_VELOCITY_UPDATES ON OFF Enable disable GPS velocity updates GPS_UPDT_INT n GPS updates every n seconds FIXED FLOAT ambiguities def FLOAT std dev GPS coord def 2m Q factor 1 6 def 6 DopplerRms m s GRAFNAV FILE filenamel filename2 Name of trajectory source file for GPS updates forward and reverse GYRO BIASES xyz X Y Z gyro drifts in deg sec GYRO NOISE sd1 sd2 sd3 Spectral density of the gyro drift states in arcsec sec Inertial Explorer 8 50 User Guide Rev 9 45 Appendix A GYRO SD xsdev ysdev zsdev INITIAL ATTITUDE KNOWN att Summary of Commands A priori Kalman standard deviations for X Y Z gyro drift states in arcsec sec ATTITUDE KNOWN HEADING KNOWN ATTITUDE_UNKNOWN Refers to validity of the initial roll pitch yaw values INITIAL_ATTITUDES rowfwd pitchfwd azfwd rowrev pitchrev azrev If known input initial roll pitch azimuth degrees for forward and reverse alignment INITIAL_INS_POSITION latfwd lonfwd htfwd latrev lonrev htrev INITIAL_POSITION_SOURCE source INS position for forward and reverse processing in DMS DMS m 0 CMB FWD REV 1 manual entry of position INITIAL VELOCITIES vefwd vnfwd vhfwd verev vnrev vhrev INS F
44. fNet 8 50 User Guide for Update data GNSS Combined OK a trowse External information regarding all of the features available from this menu Only those features that are exclusive to Inertial File name C GPSData Inertial SPAN_Features C F Process INS Data Only h Heste Explorer are discussed here 9 Both Forward 5 Reverse Processing Settings 1 5 1 Process LC loosely coupled and Profile SPAN Airborne LN200 Y TC ti gh tly Cc oupl ed V Filter Profiles N aia This window provides access to most settings related to x Y z ET a IMU processing 0 141 m 1 227 m 0 592 mg stjert pre Valg gt P 8 No lever arm info in IMR fie Source File for GNSS Updates LC Processing Body gt IMU Rotation Rotate vehide frame into the IMU frame Update Data BED 0 00 E RED 0 00 den Use this option to select the GNSS file from which las en a noka Asay ane k y 1a z EGE Inertial Explorer obtains updates In most cases the combined solution is suggested However you may Processing Information Description IMU 1 User Unkn 3 Zik ua specify an alternate file by selecting External trajectory from the drop down menu and clicking the Browse External button File Name Process Tightiy Coupled Xs Displays the selected file that will be used for updates Processing Method Differential GNSS 5 Precise Point Positioning PPP Process INS Data Only Processing Direction This opt
45. h R gt roll 44 Inertial Explorer 8 50 User Guide Rev 9 Appendix A Summary of Commands ACCEL BIASES x yz Accelerometer biases in m sec ACCEL NOISE sd1 sd2 sd3 Spectral densities of the accelerometer bias states in m s ACCEL SD xyz A priori Kalman standard deviations for accelerometer bias states in m s ALIGNMENT_MODE mode O coarse fine align 1 coarse align only 2 no alignment transfer or on the fly alignment ASCII OUTPUT INTERVAL Interval ASCII IMU output to FIM RIM files Default is 1 Hz COARSE ALIGNMENT MODE mode O static coarse alignment 1 enter the az 2 transfer alignment COARSE ALIGNMENT TIME timel time2 Seconds of coarse alignment for FWD REV processing CORRELATION TIMES yro time accel time Correlation time for Gauss Markov gyroscope and accelerometer bias states in seconds DATA RATE rate Data rate for IMU 64 Hz for LTN90 50 Hz for LRF3 50 Hz for LN200 100 Hz for HG 1700 DYNAMICS MODE mode O low 1 high 2 extreme ERROR MODEL IMU Name Error model name from manufact imu or user imu GPS COVARIANCE SCALE pos vel Scale GPS Kalman co variances for positions and velocities by this amount GPS HEADING UPDATES OFF ON const StdDev ON OFF Use GPS heading updates constant offset deg standard deviation of offset angle deg GPS INS OFFSETS dx dy dz Lever arm in metres measured in body frame GPS_INS_UPDATE_TOL FLOAT FIXED sdev Q D_rms Only use GPS updates i
46. hapter 2 Conversion Utilities on page 33 for more details Because it contains vital information for reading and decoding the data the first 512 bytes of the generic IMU data format is a header which must be filled in read and interpreted In a C C structure definition the generic format header has the following fields struct imr_header_type char szHeader 8 char bisintelOrMotorola double dVersionNumber int bDeltaTheta int bDeltaVelocity double dDataRateHz double dGyroScaleFactor double dAccelScaleFactor int iUtcOrGpsTime int iRcvTimeOrCorrTime 38 SIMURAW W0 NULL terminated ASCII string 0 Intel Little Endian default I Motorola Big Endian swap bytes for IExplorer This can be set for any user who directly writes in our format with a Big Endian processor IExplorer will swap the bytes Program version number i e 8 50 Default is 1 which indicates the data to follow will be delta thetas meaning angular increments i e scale and divide by by dDataRateHz to get degrees second If the flag is set to 0 then the data will be read directly as scaled angular rates Default is 1 which indicates the data to follow will be delta v s meaning velocity increments i e scale and divide by dDataRateHz to get m s If the flag is set to 0 then the data will be read directly as scaled accelerations i e 100 0 records second
47. hat you have processed the GNSS data first 10 Select a processing settings profile based on the IMU type and application Enter the 3D lever arm offset from the IMU sensor to the GNSS antenna Add body rotation information if the IMU data was not decoded as Y Fwd X Right Z Up Click Process Inertial Explorer Convert and Process GNSS Data Refer to the GrafNav GrafNet 8 50 User Guide to process GNSS data The only exception is that the new project is created in Inertial Explorer not GrafNav PX For NovAtel SPAN be sure that the Extract inertial SPAN data option is enabled in the OEM4 decoding options so that Waypoint s generic IMR raw IMU data file is created automatically Convert IMU Data IMU data must be converted to Waypoint s generic IMR format for processing To do this follow the steps in the shaded box lt NovAtel SPAN users don t have to follow these steps because they have a one step process to convert their IMU data Determine Alignment Method DI Automated alignment forces the software to scan the data and determine the best alignment method Only set the alignment options manually if the automated method returns poor results Once the GNSS data is processed use the File Data Coverage plot in conjunction with the Velocity Profile plot to decide which alignment mode to use Perform a static coarse alignment for two minutes in both directions for optimal processing unless you are working
48. he coordinate states in m s A priori Kalman standard deviations for E N U coordinate states in metres Kalman filter predictions every n seconds Default is 0 5 Correction in seconds to GPS times in the IMU binary file Default is zero Inertial Explorer 8 50 User Guide Rev 9 Summary of Commands TOTAL ALIGNMENT TIME timel time2 VEL MEAS VAR var VELOCITY NOISE sd1 sd2 sd3 VELOCITY SD sdev1 sdev2 sdev3 WRITE BINARY OUTREC ON OFF ZUPT ALIGN INTERVAL interv ZUPT AT name start end ZUPT OPTION num ZUPT TIME time ZUPT VEL TOL tol Inertial Explorer 8 50 User Guide Rev 9 Appendix A Seconds of coarse fine alignment Note that no fine alignment is performed when total align time coarse align time Variance R matrix of Kalman ZUPT observation in m s Spectral density of the velocity states in m s A priori Kalman standard deviations for E N U velocity states in metres sec Write binary structure to disk at mechanization rate for FWD REV combination Length of time for a ZUPT during fine alignment Name start time GPS sec and end time GPS sec of ZUPT OJone epoch or 1 best fit over ZUPT_length seconds Default is 1 Minimum length of time for a ZUPT Reject a ZUPT with velocity above this tolerance in m s 47 Appendix A Summary of Commands 48 Inertial Explorer 8 50 User Guide Rev 9 A accelerometer 9 17 20 Add 12 Master File s 12 Remote File 12 Alignment
49. ication 14 Inertial Explorer 8 50 User Guide Rev 9 Inertial Explorer Advanced GNSS TC Processing This button provides access to advanced settings related to GNSS processing Refer to the GrafNav GrafNet 8 50 User Guide for information Advanced IMU TC Processing This button provides access to advanced settings related to INS data processing and lets you choose the options best suited to your application Lever Arm Offset IMU gt GNSS Antenna To perform GNSS updates accurately enter the 3 D offset in metres from IMU sensor array s navigation centre to the GNSS antenna This offset vector must be entered with respect to the body frame of the vehicle as the image in the shaded box shows You must also specify whether the Z value applies to the antenna s reference point ARP or L1 phase center To specify ARP you must select an antenna model when you add the remote GPB file to the project In this case the antenna model s offset value is applied to the Z value to raise the Z value to the L1 phase center DI Save lever arms for future access using the Favorites button Read from IMR file If the lever arm values are written to the header of the IMR file then use this option to extract them Body to IMU Rotations Rotate Vehicle Frame into IMU Frame Many typical IMU installations have the surface of the IMU directly attached to the floor of the vehicle so the sensor frame of the IMU and the body frame of
50. imes Photo E O values The omega phi and kappa values along with their associated standard deviations are displayed for each loaded camera event These values are produced externally in a photogrammetric package Matches residuals Before the computations begin choose whether or not to include the observations associated with a camera event in the least squares procedure by right clicking on the event After the least squares procedure has finished the window is updated with the final residual values at each camera event Additional information such as quality indicators and computed omega phi and kappa values are also displayed 27 Chapter 1 Boresight Settings xl Axes System Definition System EREE v T po deg Order W primary P secondary K tertiary ondt gt T j 0 deg z Grid Map Definition Datum wases pl Grid Zone 15 Change Average ground height poa r Measurement Weighting Display Units SD source Use constant values below Altitude values Degrees nDecimals 4 OmegaSD 0 0167 deg El SD residual and boresight values PhisD 0 0167 deg Arc Minutes Y nDecimals 2 KappaSD 0 0500 deg order TATYTZ MUS Sensor Outlier detection tolerance 3 0 nSD Factory Defaults Cancel Axes System Definition options System The selection made here defines the ground coordinate system to which the omega phi and kappa values are o
51. ion disables the use of GNSS data during INS JET TE E ez processing Updates will only be performed with user Processing Setinge entered coordinate updates Profile SPAN Airborne LN200 v Advanced GNSS V Filter Profiles Datum wess4 gener J lt This mode of processing is not recommended It is Lever Arm Offset IMU gt GNSS Antenna only used for special applications such as pipeline X T z Z to ARP E SENSOR A 0 141 m 0 511 m 127 m 6 SARERA cak eS pigging No lever arm info in IMR file EY Body gt IMU Rotation Rotate IMU into Vehicle Frame Process Se t tings xRot 0 00 deg yRot 0 00 deg Rot 0 00 deg Pro fi le A EE Select an appropriate profile from the drop down ocessing Information A Description TC 2 D Unknown menu prior to processing This ensures that the GNSS and IMU settings are configured in an optimal way C Use the Advanced button to make adjustments to the settings lt If pre processing was performed during GNSS data conversion a profile is automatically selected Filter Profiles Enabling this feature ensures that only the profiles specific to your IMU model are shown in the list This option scans the IMR header to determine the name of the IMU and is largely aimed at NovAtel SPAN customers Advanced LC Processing This button provides access to advanced settings related to INS data processing and lets you choose the options best suited to your appl
52. is plot shows the standard deviation computed in the GNSS INS Kalman filter in terms of roll pitch and heading Inertial Explorer 1 7 Output Menu Refer to the GrafNav GrafNet 8 50 User Guide for information regarding all of the features available from this menu Only those features exclusive to Inertial Explorer are discussed here 1 7 1 Plot Results Refer to the GrafNav GrafNet 8 50 User Guide for information regarding all of the GNSS plots available By default the software generates all plots at the GPS update interval You can raise the interval as high as the IMU data rate to get a denser plot but generation takes longer This setting is available under the X axis tab This option requires that you have generated a combined binary file for your trajectory before or after smoothing see Section 1 5 3 Solve Boresighting Angles on page 27 The combined file must be re generated after every processing run to ensure that the plot reflects the latest results Table 1 IMU Plots in the shaded box on this page and the following page contains descriptions of the IMU plots available only through Inertial Explorer 1 7 2 Export Wizard Only the Export Wizard window exclusive to Inertial Explorer is discussed here Refer to the GrafNav GrafNet 8 50 User Guide for additional information concerning this feature IMU Epoch Settings Epoch Output Interval The Kalman GPS interval indicates the interval used during GPS proce
53. matsuunun dr Huba s n kb b y ad ek dee Kin Pev kk yekek Ey b l Sava da 37 3 1 1 NovAtel s SPAN Technology cccccoococcccccnoconccccnanoncnnnonnno kaka kalak kaka kak kk Ay ww AWA A AA WAA A WAA WAW AA KA 37 Inertial Explorer 8 50 User Guide Rev 9 3 Table of Contents 312 File Formatst tarer kaiene ted bedende aina are anbe eee 38 3 2 TIMR Fe it a loa a 38 A Serena nedre 40 3 2 3 A A ed 42 3 3 Output FIES adaptere ea aan 43 33 1 FILRIL FTERTE AMS uti add da ais 43 3 3 2 FIWRIMWETM RTM Files ic irene ane hadde dren didas 43 3 3 3 BIF BIR BTF BTR Fils aula dass RS 44 Appendix A Summary of Commands 45 Index 49 4 Inertial Explorer 8 50 User Guide Rev 9 Software License BY INSTALLING COPYING OR OTHERWISE USING THE SOFTWARE PRODUCT YOU AGREE TO BE BOUND BY THE TERMS OF THIS AGREEMENT IF YOU DO NOT AGREE WITH THESE TERMS OF USE DO NOT INSTALL COPY OR USE THIS ELECTRONIC PRODUCT SOFTWARE FIRMWARE SCRIPT FILES OR OTHER ELECTRONIC PRODUCT WHETHER EMBEDDED IN THE HARDWARE ON A CD OR AVAILABLE ON THE COMPANY WEB SITE hereinafter referred to as Software 1 License NovAtel Inc NovAtel grants you a non exclusive non transferable license not a sale to use the software subject to the limitations below You agree not to use the Software for any purpose other than the due exercise of the rights and licences hereby agreed to be granted to you 2 Copyright NovAtel owns or has the right to sublicense
54. n the computed direction cosine matrix and relate the IMU body frame to the computation frame ECEF in Inertial Explorer and an error free idealized direction cosine matrix or attitude matrix These values represent the best estimate of the sensor s ability to compute roll pitch and yaw during coarse alignment assuming any is present Roll and pitch are estimated from the sensed gravity components in the horizontal axes of the accelerometer triad while yaw is estimated from the sensed Earth rate about the leveled gyro axes Typically while even MEMS sensors can make some estimation of roll and pitch the Earth rate is often masked by noise for lower grade IMUs The values entered here for x and y which represent pitch and roll are often as much as an order of magnitude smaller than that for z which represents yaw If in doubt simply enter large values in the range of thousand of arc seconds and allow the IMU Kalman filter time to eventually compute more sensible estimates of the error in the computation of the attitude matrix These values must be entered in degrees Accel Bias These values represent the initial uncertainties in the a priori knowledge of the constant bias errors in the accelerometer triad If these bias values were left at zero meaning that they are unknown then the standard deviation values entered here should reflect this uncertainty The processor then computes the biases on the fly These values should
55. nly requirement is that the data be logged in the format provided in this section which allows easy decoding with the IMU Data Conversion utility described in Section 2 1 1 Waypoint IMU Data Conversion on page 33 Table 2 Binary Structure of Raw Data presents the binary structure in which the conversion utility expects the raw IMU data to be logged 3 1 1 NovAtel s SPAN Technology With the use of NovAtel s SPAN technology note the difference in the IMU data decoding procedure Since the raw IMU data measurements are embedded into the same binary file containing the raw GNSS measurements only one step is needed to separate the data and convert it into the Waypoint Group s format Therefore the Raw IMU Data Converter utility does not need to be used Instead decode the GNSS and IMU data simultaneously via the Convert Raw GNSS data to GPB utility which can be accessed from File Convert When adding the measurement file to the Convert Files window for decoding ensure that the drop down menu under the Receiver Type box has been set to NovAtel OEM4 0EMV OEM6 Then click either the Global Options or Options button to gain access to the IMU decoding settings Inertial Explorer 8 50 User Guide Rev 9 Table 2 Binary Structure of Raw Data Size Word bytes Type Description time of the current IMU rate GpsTime 8 real measurements in GPS seconds of
56. ody Earth matrix lt 0 after update Check on Fix 1 tr C of transform matrix 0 056389 This message is purely a mathematical computation warning 3 3 2 FIM RIM FTM RTM Files These files contain the trajectory information computed by the inertial filter and are available for both tightly coupled and loosely coupled processing They are typically output at a minimum rate of 1Hz but can be higher depending on the GNSS update interval The first line of the output file always begins with OUTREC and is followed by the version number the processing engine and the type of output An example is given below SOUTREC Ver8 30 0329 GPSINSDLL Forward GpsInsOutput The format of these ASCII trajectory files is outlined within the header of the forward reverse files and are not discussed here Inertial Explorer 8 50 User Guide Rev 9 43 Chapter 3 Data and File Formats 3 3 3 BIF BIR BTF BTR Files Here is the C C structure definition of the header which is 512 bytes typedef struct char Str 16 SIMUOUT long HdrSize size of this header long IsExtended true if extended format used long RecSize size of this record see note below for later zero data interval s program name that created this file version that produced file Forward Reverse or Combined reserved for future use zero at creation of new file long Reserved1 double Interval char ProgramName 32 char VersionName 32 ch
57. on if the 3 D offset from the IMU sensor array center of navigation to the GNSS antenna phase center is not precisely known or not known at all The accuracy achieved with this option depends on the type of IMU used but is normally better than 20 cm Initial Std This value reflects the uncertainty in the entered lever arms values For the first iteration this value should be left at 5 meters In any subsequent iteration it should be lowered until the values have converged reasonably Minimum Velocity This value specifies the minimum velocity that must be reached before the solving routine will start accepting data Accel and Gyro Extra States These options add scale and or non orthogonality states to the Kalman filter for the accelerometer and gyroscope measurements Apply Heave Correction to Height For marine users who wish to apply heave compensation to the computed ellipsoidal height use this option to utilize Inertial Explorer s low pass filter The algorithm requires that a window size reflecting the period of the wave motion be entered The value computed with this option replaces the ellipsoidal height All trajectory files output files and plots where ellipsoidal heights are provided with this option will now show the new heave compensated height values Inertial Explorer 8 50 User Guide Rev 9 Inertial Explorer Updates Variance Factors Applied in GNSS Residual Testing Inertial Explorer performs residual
58. onfiguration looks like click the Profile Manager button Inertial Explorer 8 50 User Guide Rev 9 Inertial Explorer States Error Model The options available are to use one of the error models provided or use a custom model The former option entails selecting one of the models from the scrolling window each of which has a set of initial standard deviation and spectral density values associated with it These models have been optimized for the indicated application or sensor through the processing of multiple sets of applicable data Because all values have been empirically derived through a trial and error process the accuracy achievable by their use cannot be guaranteed Certain profiles have been tailored for certain conditions as opposed to specific sensors For example the Navigation High Precision model is most suitable for high end units with gyro drift rates on the order of 0 01 hr or better whereas the Tactical Medium Precision model is aimed at medium grade systems with drift rates in the range of 1 hr to 10 hr The Automotive Low Precision model allows the Kalman filter to loosen up in order to compensate for poor field conditions such as short or non existent static alignment Edit Error Model Values This is one of the most important components of processing IMU data successfully In general the less expensive the sensor package the more tuning that is required to find initial variances and spectral
59. ontaining the GPS time as well as the gyroscope and acceleration measurements of all three axes for the first thousand epochs Use this to detect any errors that may occur during the conversion such as the use of an incorrect scale factor Path Displays the path to the directory containing the input file All output files created by this utility are saved to this directory IMU Profiles Displays a scroll down list of profiles available for use during conversion Each profile contains a set of conversion parameters designed to decode measurement data files produced by the indicated sensor Choose one profile from the list or if necessary create one See Section 2 1 2 Creating Modifying a Conversion Profile on page 34 for help After all the appropriate fields have been entered click the Convert button to start converting IMU data into IMR format A message window appears to show the status of the conversion process Inertial Explorer 8 50 User Guide Rev 9 Conversion Utilities 19 Waypoint IMU Data Conversion x Input Output Files Input Binary IMU File E Browse Output Waypoint Binary File AAA ooo Output Waypoint ASCII File For viewing the data first 1000 epochs I Output ASCII Path IMU Profiles iMAR_FJl_O x_1 y_2 2_1000Hz MAR FMS 0 1 9 22 200H2 MAR FMS O x1 4 2 2 400H2 El Delete Rename New Copy Modify About Convert mul Close 33 Chapter 2 34 Senso
60. ormance of the Software is assumed by you See product enclosure if any for any additional warranty 7 Indemnification NovAtel shall be under no obligation or liability of any kind in contract tort or otherwise and whether directly or indirectly or by way of indemnity contribution or otherwise howsoever to the Licensee and the Licensee will indemnify and hold NovAtel harmless against all or any loss damage actions costs claims demands and other liabilities or any kind whatsoever direct consequential special or otherwise arising directly or indirectly out of or by reason of the use by the Licensee of the Software whether the same shall arise in consequence of any such infringement deficiency inaccuracy error or other defect therein and whether or not involving negligence on the part of any person 8 Disclaimer and Limitation of Liability a THE WARRANTIES IN THIS AGREEMENT REPLACE ALL OTHER WARRANTIES EXPRESS OR IMPLIED INCLUDING ANY WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE NovAtel DISCLAIMS AND EXCLUDES ALL OTHER WARRANTIES IN NO EVENT WILL NovAtel s LIABILITY OF ANY KIND INCLUDE ANY SPECIAL INCIDENTAL OR CONSEQUENTIAL DAMAGES INCLUDING LOST PROFITS EVEN IF NOVATEL HAS KNOWLEDGE OF THE POTENTIAL LOSS OR DAMAGE b NovAtel will not be liable for any loss or damage caused by delay in furnishing the Software or any other performance under this Agreement c NovAtel s entire liability and your exclusi
61. pdates cannot be performed at a rate higher than the GNSS data processing lt Performing updates at a rate higher than I Hz is generally not helpful unless the data was collected in an environment with high dynamics 23 Chapter 1 Advanced IMU Properties xj r Zero Velocity Updates ZUPTS r Coordinate Updates IMU Only Name Stats Endis 4 gt 4 gt Add Edi Remove Load Add Edit Remove Load OK Cancel System States Updates Mount User Cds Variance Factors Applied in GNSS Residual Testing Position 3 0 Range 2 0 Phase 10 0 Automated ZUPT Detection Tolerances Raw Measurement m s Period sec GNSS Updates V Update Interval from GPS Data deg s Velocity User Entered Zero Velocity Coordinate Updates Distance Measuring Instrument DMI Updates VIGNSS Velocity Update Y Enable DMI from file imandLine Test1 Remote SPAN_1 dmr Browse DMI Options Heading Updates Enable Hdg from File Headina Optior 24 Inertial Explorer Zero Velocity Updates ZUPTS Inertial Explorer takes advantage of periods when the IMU is static Such periods of time are referred to as 9zero velocity updates ZUPT Upon reaching the start of a ZUPT Inertial Explorer assumes the data to be static and replaces the GNSS velocity update values with zeros DI Inertial Explorer automatically detects the presence of ZUPTs b
62. r Timing Settings Sensor Orientation Decoder Settings gt Gyro Measurements Inverse Gyro Scale Factor 1 Gyro Scale Data is delta theta C Data is angular rate m Accelerometer Measurements Inverse Accelerometer Scale Factor 1000000 00000000 1 Accel Scale Data is delta velocity Data is acceleration Timing Settings Byte Order Data Rate 100 0 Hz Intel GPS IMU time tag bias offset 0 0000 s Motorola GPS Corrected Time C GPS Received Time GPS seconds of week UTC seconds of week m Time Tag Format Time Tag Source Conversion Utilities 2 1 2 Creating Modifying a Conversion Profile New Creates a customized profile to convert a unique format into Waypoint s generic IMR format This is used for custom scale factors data rates and orientations in raw data files Modify Allows changes to be made to an existing profile Delete Deletes an existing profile Rename Renames an existing profile Sensor Timing Settings Gyro Measurements Pertains to the measurements made by the gyroscopes lt The inverse value of the scale factor is required For example a scale factor of 0 0004 which can be represented fractionally by 1 2500 should be entered as 2500 The gyro measurements can take the form of delta theta where angular increments are being observed or angular rate Accelerometers Measurements Similar to the scale factor of
63. riented Normally they are referenced to a map projection which is defined in the Grid Map Definition settings Order This setting defines the order in which the omega phi and kappa angles are to be applied during the transformation from the ground system to the image or IMU system Only the omega primary phi secondary and kappa tertiary rotation order is supported Axes Use this setting to define the orientation of the image system The most commonly used system is the conventional frame where the x axis points forward the y axis points left and the z axis points upwards The frame defined here determines the composition of the R matrix Import Photo EO WPK Angles xj File name Browse File format ID omega phi kappa y View Attitude units Degrees hel emen 28 Inertial Explorer Settings This button gives access to the Boresight Settings window which is useful for configuring many parameters used in the boresight calibration Axes System Definition These options are listed in the shaded box Grid Map Definition The options made available here depend on the system definition chosen If the input angle was provided with respect to a map grid then the selection made here determines the convergence value a used to form the R matrix In addition grid users are given the opportunity to enter the average ground height in order to maximize accuracy Measurement Weighting The selections made her
64. s and DLLs associated with Inertial Explorer The date and time of the files are shown as well as a quick description of the file Click Download latest manufacturer files to connect to Waypoint s FTP site Internet connection required to download the files listed in the shaded box Most of these manufact files have an associated user file where personal information is saved These files are not modified when you download the latest manufacturer files It is important for this reason to not modify the manufact files as they are overwritten when this option is used Inertial Explorer 8 50 User Guide Rev 9 Chapter 2 2 1 Raw IMU Data Converter The JMU Data Converter utility is a Win32 application program that converts custom data formats into a generic raw IMU data format This utility is available exclusively to users of Inertial Explorer and may be accessed from File Convert Raw IMU Data to Waypoint Generic IMR 2 1 1 Waypoint IMU Data Conversion Input Output Files Refers to the names and locations of all input and output files Input Binary IMU File Click the Browse button to locate the raw IMU data file Output Waypoint Binary File By default the binary output file created is given the same filename as the input file but with an IMR extension It is saved to the directory containing the input file Output Waypoint ASCII File If the Output ASCII option is enabled the utility generates an ASCII file c
65. s being processed then the values displayed are those computed in the Kalman filter However during the IMU processing the values displayed reflect those calculated in the IMU Kalman filter using the GNSS information as updates Ideally these values should agree When they do not monitor the position and velocity misclosure 1 11 Help Menu 1 11 1 Help Topics Opens an HTML version of this manual with the GrafNav portion included This feature is a quick and easily accessible reference 1 11 2 NovAtel Waypoint Products Web Page This option opens a web browser to the Waypoint Products Group s page on the NovAtel website On this page are found details on the latest versions patches information on GNSS INS and technical reports Inertial Explorer 8 50 User Guide Rev 9 Chapter 1 Table 1 IMU Plots continued Plot Description Estimated Gyro Drift Accuracy This plot shows the estimated standard deviation of the gyro drift rate which generally decreases with time It is plotted in terms of the X right direction Y forward direction and Z up direction of the INS body Gimbal Data Values Inertial Explorer supports data processing from IMU s mounted on a gyro stabilized platform gimbal When doing so it is required to import an MMR file in order to compensate for the changing lever arm between the IMU and GPS when the gimbal is engaged This plot shows the decoded rotations within the MMR file an
66. service contact NovAtel s Waypoint Products Group using the following methods Call U S amp Canada 1 800 NovAtel 1 800 668 2835 China 0086 21 54452990 8011 Europe 44 1993 848 736 SE Asia and Australia 61 400 883 601 Email support novatel com Web www novatel com Write NovAtel Inc Customer Service Department 1120 68 Avenue NE Calgary AB Canada T2E 8S5 8 Inertial Explorer 8 50 User Guide Rev 9 Chapter 1 Inertial Explorer 1 1 Overview of Inertial Explorer Waypoint Products Group s Inertial Explorer post processing software suite integrates rate data from six degrees of freedom IMU sensor arrays with GNSS information processed with an integrated GNSS post processor same as GrafNav s Inertial Explorer utilizes strapdown accelerometer Av and angular rate A0 information to produce high rate coordinate and attitude information from a wide variety of IMUs Inertial Explorer implements either a loose coupling LC of the GNSS and inertial data or tightly coupled TC processing that uses GNSS data to limit error during periods where satellite tracking is limited or variable even if only 2 or 3 satellites are visible It is important to time tag the inertial measurements to the GNSS time frame during the data collection process Proper synchronization is vital Otherwise the IMU data will not process In NovAtel s SPAN system IMU data is automatically synchronized and Inertial Explorer s GNS
67. ssing while the IMU integration interval displays the interval at which the IMU data was processed These values can only be changed prior to processing The Output data interval defines the interval to export solutions The output interval can be set as high as 1000 Hz regardless of what interval the data was processed at lt The time range for which to obtain outputs can also be limited here Lever Arm Offset Allows for the coordinates of the IMU calculated via the IMU Kalman filter to be transferred to an alternate sensor s location Note the orientation of the frame in which these coordinates must be entered You are also free to save your offset for future use via the Favorites button Inertial Explorer 8 50 User Guide Rev 9 Inertial Explorer 1 8 Tools Menu Refer to the GrafNav GrafNet 8 50 User Guide for information regarding all of the options available via this menu 1 9 Interactive Windows Refer to the GrafNav GrafNet 8 50 User Guide for information regarding the Map Window and the features available within it 1 10 Processing Window Table 1 IMU Plots on page 30 contains a list of the additional parameters available for viewing in Inertial Explorer during processing Display these values via the View button in the Processing Window The values in the GrafNav GrafNet 8 50 User Guide differ in the manner in which they are computed depending on the mode of processing being performed If the GNSS i
68. t files Inertial Explorer 8 50 User Guide Rev 9 Inertial Explorer 1 5 3 Solve Boresighting Angles Show This drop down menu is linked to the window below it and gives viewing access to the values listed in the shaded box Settings The following features are available Calibration name Enter a name to distinguish calibration runs from one another Inertial Explorer keeps a history of calibration runs so a unique identifier is helpful when trying to recover previous results This is useful for using multiple systems and or tracking stability over time Boresight Angles Upon successful completion of the calibration procedure the final values for the computed boresight angles are displayed here Add results to list When this option is enabled the last values computed by the program are stored so that they are easily accessible by the Export Wizard View report after computation Enabling this option forces the software to launch the boresighting report upon successful completion of a calibration The contents of the report are discussed later on Update navigation angles on entry When this option is enabled Inertial Explorer loads the latest navigation values for the camera events into the boresighting module Message Window This window provides valuable insight on the status of the current calibration Whenever input data is being loaded read the messages to ensure the expected number of camera events have b
69. tart end times Begin time 332604 00 End time 335942 00 Manage GNSS IMU Processing Profiles Current Profile Loaded SPAN Airbome LN200 ok Cancel r mon WT Met Static coarse alignment only Static coarse fine align 5 Kinematic Alignment gt Set IMU Time Range Manually Transfer alignment enter known attitude Enter Attitude Initial Position and Velocity 0 Determine from GNSS suggested Use entered values IMU only Initial Static Alignment Period 60 00 s 0 00 6 using trajectory Auto Kinematic Align Tolerances Min GPS Speed 20 m s Heading SD Tol 15 0 deg ok Cancel 16 Inertial Explorer Advanced This button provides access to advanced settings related to INS data processing and lets you choose the options best suited to your application System File Info The following fields are displayed IMU file Displays the path to the binary IMU measurement file that was added to the project If incorrect go to File Add IMU File to locate the proper raw data file Method for Initial Alignment Initial alignment whether processing forward or reverse determines the initial roll pitch and yaw of the IMU Alignment settings should be set with care to ensure that the best possible alignment is formed The following options are available and are largely dependent on the length of static data present
70. tel in all legal actions concerning this license of the Software under this Agreement taken against any third party by NovAtel to protect its rights in the Software NovAtel shall bear all reasonable costs and expenses incurred by Licensee in the course of co operating with NovAtel in such legal action 4 Restrictions You may not a use the software on more than one computer simultaneously b distribute transfer rent lease lend sell or sublicense all or any portion of the Software without the written permission of NovAtel c alter break or modify the hardware protection key dongle thus disabling the software copy protection d modify or prepare derivative works of the Software e use the Software in connection with computer based services business or publicly display visual output of the Software implement DLLs and libraries in a manner that permits automated internet based post processing contact NovAtel for special pricing g transmit the Software over a network by telephone or electronically using any means except when downloading a purchased upgrade from the NovAtel web site or h reverse engineer decompile or disassemble the Software NovAtel retains the right to track Software usage for detection of product usage outside of the license terms You agree to keep confidential and use your best efforts to prevent and protect the contents of the Software from unauthorized disclosure or use Inertial Explorer 8 5
71. testing using a standard least squares approach on position phase and range updates Phase updates applied where there is a minimum of two satellites are only available in tightly coupled processing GNSS position updates and ZUPTs which are detected from raw IMU measurements can be applied in either loosely or tightly coupled processing Updates are accepted only if the computed residual is within the set tolerance The IMU processing profiles contain pre defined position variances for NovAtel SPAN models These have been tested to help ensure good results on typical surveys provided that the lever arm has been accurately measured Automated ZUPT Detection Tolerances These settings control the software s ability to detect periods of zero velocity Raw Measurement The raw gyro measurement threshold This value may need to be raised for lower grade sensors i e MEMS to accommodate the noisier measurements Velocity The GPS velocity threshold Potential ZUPTs are rejected if the GNSS derived velocity exceeds this value Period Length of time span over which measurements are averaged GNSS Updates These options are listed in the shaded box Zero Velocity Coordinate Updates This option is only available for performing IMU processing without the aid of GNSS data Otherwise this functionality must be carried out automatically via GNSS updates throughout the mission GrafNav uses Doppler information to compute GNSS deri
72. the vehicle are more or less aligned In these installations the roll pitch and yaw of the vehicle are directly sensed by the IMU Some IMUs are installed in a tilted position with respect to the body frame of the vehicle If the tilt between the IMU frame and body frame is known Inertial Explorer compensates so that the attitude information produced is with respect to vehicle body frame not the IMU sensor frame The order of rotations employed is R then R followed by R in decimal degree units Inertial Explorer 8 50 User Guide Rev 9 Chapter 1 GPS Desa Left Direction of Travel Figure 1 Body Frame Definition for Lever Arm Offset The IMU is the local origin of the system and the measurements are defined as the following X The measured lateral distance in the vehicle body frame from the IMU to the GNSS antenna Y The measured distance along the longitudinal axis of the vehicle from the IMU to the GNSS antenna Z The measured height change from the IMU to the GNSS antenna lt All measurements are from the navigation center of the IMU to the GNSS antenna phase center 15 Chapter 1 ez System States Updates Mount User Cmds File Info IMU file iPSData Inertial SPAN_Features Remote span_1 imr Method for Initial Alignment Forward Alignment gt Automatic Mode Reverse Alignment gt Automatic Mode Options IMU Time Range Y Process all IMU data E Use GNSS s
73. the week scaled X body axis gyro Gyrox 4 long measurement as an angular increment or angular rate scaled Y body axis gyro GyroY 4 long measurement as an angular increment or angular rate scaled Z body axis gyro GyroZ 4 long measurement as an angular increment or angular rate scaled X body axis accelerometer measurement AccelX s long as a velocity increment or acceleration scaled Y body axis accelerometer measurement AccelY 4 long as a velocity increment or acceleration scaled Z body axis accelerometer measurement AccelZ s long as a velocity increment or acceleration if Novate OEMA OEMV OEM6 Options LL NN NE eza General SPAN IMU SA eI EEE I Extract inertial SPAN data if available I Re compute position and clock offset I Verbose messaging mode SPAN Model Automatic ll I Create separate file for each MARKNTIME record I Show receiver status event wamings I Create trajectory files fsp for supported records Distance Measurement Unit DMI GLONASS PRN offset 37 I Set wheel size L2C phase conection 0 25 cycles 1 96 Sene Kirman Mer T Set tick counts per wheel revolution Auto C Kinematic C Static Eo Factory Defaults gt i Cancel XX AG11 AGS58 AG17 AG62 37 Chapter 3 3 2 File Formats 3 2 1 IMR File Data and File Formats Waypoint converts all custom IMU raw binary formats into a generic format IMR which is read from Inertial Explorer following the decoding process in JMU Data Converter See C
74. tial Explorer is by far the most common usage Inertial Explorer 8 50 User Guide Rev 9 Inertial Explorer The exterior orientation parameters for each photo must be supplied by an external file This file should contain the omega phi and kappa angles required to rotate the ground system into the image system View This button gives access to the post calibration report The report contains relevant boresight calibration information as well as a list of all the input data provided for each camera event The bottom of the report displays the boresight values and residuals from the final iteration lt This report can be viewed through either NotePad or the internal Inertial Explorer ASCII viewer This button also gives you access to the calibration history For each calibration run the final boresighting results are saved assuming the Add results to list option is enabled Clear Msg This button clears the Message Window of any messages currently displayed 1 6 Settings Menu Refer to the GrafNav GrafNet 8 50 User Guide for information regarding all of the features available from this menu Inertial Explorer 8 50 User Guide Rev 9 Solve Boresight Angles Chapter 1 Show Navigation values X Angles in degrees SD Resid and BS in ArcMin Pitch Heading RollSD PitchSD HeadsD Latitude 2 r Settings Caan rane BS IV Add results to list use for Export I View report after computation B 5 Angles
75. tween datums Refer to the GrafNav GrafNet 8 50 User Guide for details manufact fvt List of Favourites and the groups they are contained in manufact grd List that contains available grids such as UTM US State Plane Gauss Kruger etc Refer to the GrafNav GrafNet 8 50 User Guide for more details manufact svi A file that associates a PRN number with a satellite type Block II Block IIA etc for purposes of determining the center of mass of the satellite Used by PPP manufact cim Provides a set of default conversion parameters for various IMU raw data formats This file is accessed during the conversion from raw data to IMR format See Chapter 2 Conversion Utilities on page 33 for details manufact imu Contains the error profile parameters for various types of IMUs The values associated with each model have been empirically derived by the Waypoint Products Group staff based solely on the data sets they have encountered manufact dcb List of the differential code biases in nanoseconds between the P1 and C A code for each satellite Used by PPP 32 Inertial Explorer 1 12 About Inertial Explorer This window displays information about the software version build dates copyright information hardware lock key information and DLL information Access the hardware key utility from this window by clicking Key Util Upgrade This tool is useful for upgrades The Dependent Files window displays a list of executable
76. ve remedies for our liability of any kind including liability for negligence for the Software covered by this Agreement and all other performance or non performance by NovAtel under or related to this Agreement are to the remedies specified by this Agreement 9 Governing Law This Agreement is governed by the laws of the Province of Alberta Canada Each of the parties hereto irrevocably attorns to the jurisdiction of the courts of the Province of Alberta 10 Customer Support For Software UPDATES and UPGRADES and regular customer support see Customer Service on page 8 6 Inertial Explorer 8 50 User Guide Rev 9 Foreword Congratulations on purchasing Waypoint Products Group s Inertial Explorer Inertial Explorer is a Windows based suite of programs that provide GNSS Global Navigation Satellite System and inertial data post processing This manual will help you install and navigate your software Scope This manual contains information on the installation and operation of Inertial Explorer It allows you to effectively navigate and post process GNSS IMU Inertial Measurement Unit and wheel sensor data It is beyond the scope of this manual to provide details on service or repair see the Customer Service on page 8 for customer support How to use this manual This manual is based on the menus in the interface of Inertial Explorer It is intended to be used in conjunction with the most recent revision of the GrafNav GrafNet
77. ved velocities XI Doppler accuracies vary significantly depending on the receiver View the LI Doppler Residual RMS values from Output Plot Results The standard deviation of the Doppler measurements used by the GNSS Kalman filter can be controlled via Settings Individual Measurements Inertial Explorer 8 50 User Guide Rev 9 Chapter 1 r E States Updates Mount User Cms Variance Factors Applied in GNSS Residual Testing Position 3 0 Range 2 0 Phase 10 0 Automated ZUPT Detection Tolerances deg s Velocity Raw Measurement m s Period sec GNSS Updates 7 Update Interval from GPS Data User Entered Zero Velocity Coordinate Updates Add Updates Distance Measuring Instrument DMI Updates VIGNSS Velocity Update Y Enable DMI from file DMI Options Heading Updates Enable Hdg from File Browse imandLine Test 1 Remote SPAN_1 dmr Browse ito __ GNSS Updates Options Update Interval from GPS data This option forces the processor to use every computed epoch outputted during GNSS processing It sets the update interval equal to that used for GNSS processing Clear this option if you wish to manually specify the rate at which the software will perform GNSS updates Note that the updates cannot be applied at a higher rate than the GNSS data interval Enter GNSS update interval s This value specifies the rate that Inertial Explorer performs GNSS updates U
78. velocity vector If tick counts are recorded Inertial Explorer converts them into velocity vectors If velocity vectors have been recorded then the software uses them as such Detect ZUPTs from DMI sensor A DMI can often be used to determine periods of zero velocity which can help improve accuracies The performance of this feature is dependent on the type Inertial Explorer 8 50 User Guide Rev 9 Inertial Explorer of DMI being used so it is suggested to process data with and without this option to determine its usefulness Measurement standard deviations The standard deviation associated with the DMI measurements depends on the DMI being used As such this value may need to be determined empirically Wheel circumference The default value is 1 96m Change this value if it is not correct Small errors are compensated for by the computed scale factor during processing It is also possible to allow the software to determine this value based on the header in the DMR file assuming such information is available Heading Updates External heading updates are obtained by first processing the relative vector between two antennas mounted on the same vehicle as the IMU For best results knowledge of the accuracy of the heading update as well as the constant offset between the IMU and the two GNSS antenna must be known Heading Updates from File Certain applications benefit greatly from the use of external heading updates Exampl
79. y analyzing the GNSS IMU and if available DMI data This is true for both loosely and tightly coupled processing As such the manual entry of ZUPTs is generally not necessary except in cases of poor data quality Consult the JMU Status Flag plot after processing to determine the periods where a ZUPT was detected If a known ZUPT was missed manually enter it here Coordinate Updates IMU Only Without the presence of GNSS data the positions being computed from the inertial data are likely to drift drastically over time This option bounds these errors by allowing the processor to correct its trajectory at any given time where the position is known This requires that the IMU has traveled over a previously surveyed point and that you know the exact time at which this occurred Since it is unlikely that the IMU was physically placed upon this point the lever arm offset should also be entered Distance Measuring Instrument DMI To integrate the data from distance measurement instruments DMI select the Enable DMI from file option Enable DMI from file Use the Browse button to locate the DMR file containing the measurements from the DMI After a valid file has been selected the software scans it to detect how many sensors were used Use the Info button to view information concerning the selected file DMI Options The following settings pertain to the added DMR file lt A typical DMI will either output a tick count or a
80. zed representative of NovAtel Inc The information contained within this manual is believed to be true and correct at the time of publication NovAtel Waypoint Inertial Explorer OEM6 OEMV OEM4 GrafNav GrafNet and SPAN are registered trademarks of NovAtel Inc All other product or brand names are trademarks of their respective holders 2 Inertial Explorer 8 50 User Guide Rev 9 Table of Contents Software License 5 Foreword 7 SCOPE e O EE E E A 7 H w t sethis man alsrss oia it ka TE weya KEN Ek HA k eke Eae a ean 7 Prerequisites usant feen aid neu da sed ne dnd alee 7 CONVENTIONS 4 10d AAA trender needed 7 Gustomer Service avuanuakelusanm ate eens nada death vated ene ee 8 Chapter 1 Inertial Explorer 9 1 1 Overview of Inertial Explorer ccccecceeceeceecceeeeeeeeeee Ek kk kak kak kak KAK A KAKA KK KAKA kK KA KK K KK KAK KA KA KAK KA 9 1 2 Getting Started with Inertial Explorer ELu EEE EEE kk kk kk kk kk kek KA KA KAK KAK rk KA KAK AR 9 13 File N D yx n bnee gt _eooemm mm ee 12 kat NOW PrO SCT 3o4 an a ra HAWA Kel kan reken Ran256 ee R y A idad 12 1 3 2 Add Master FIle S A c Ac a n ra K RE Qula a id Va a ak va Kuwa d ka ka ra de kaya waa xu aa S da Ku e dl 12 1 3 3 Add RemoteF l uante 12 1 3 4 Add IMU Filed un eee daa ed 12 13 35 LOA gt WAW sects hver 13 13 6 COnVeM ined es Aa A ee nee ee de de rene ee a hl 13 1 3 7 Removing Processing Files

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