Pro-note 2013-01 POS MV Installation Essentials
Contents
1. Pro Note No 2013 01 Date 20 Jul 2013 Title POS MV Installation Essentials V1 4 Executive Summary The POS MV GNSS Aided Initial Navigation System and the post processing software POSPac MMS are a very advanced suite of tools whose capabilities are well known However common setup errors can easily negate the expected gains in accuracy This Pro Note attempts to highlight the essential and sometimes overlooked considerations in installing and using a POS system This Po Note is not meant to replace the POS MV V5 Installation and Operation Guide but to supplement it References e POS MV V5 Installation and Operation Guide Rev 3 e HYPACK 2012 User Manual e QINSY Knowledge Base e PDS2000 User manual e CARIS HIPS amp SIPS 7 1 Users Guide Observations 1 IMU Placement There are two competing schools of thought as to IMU placement The first states that the IMU should be as close as possible to the Sensor Sonar LIDAR position whereas the other states that the IMU should be placed as close as possible to the vessel Centre of Rotation CoR The POS MV manual states e Ideally install the IMU at a location for which you require roll pitch heading and heave measurements Usually this implies mounting the IMU close to or even on the MosaicHydro Ltd 2013 Page 1 of 16 Pro Note No 2013 01 Date 20 Jul 2013 multibeam transducer The chosen location must provide rigid support so that th2. Sensor 2 Frame w rt Ref Fra X deg 0 Y deg 0 gt Z deg po MosaicHydro Ltd 2013 Page 10 of 16 Pro Note No 2013 01 Show Vessel View Sensor View ble Ei m A am Z Rotation _ gt Horizont shito 4 r _o Zoom 44 af gt 100 Enter aa Move Ref Coord Sys Show Short menu lt r xta m v Vessel a S 3 doo Y 2m Lock 2 rt of Rotation m Beno Unlock 11141 Primary GPS Secondary GPS i Aux 1 GPS 7 View Vessel Aux 2 GPS Default fio Length m Sensor 1 Sensor 2 Top down ig Width m Lever Arm Cen of Rat Profle fF Heihi Show Detailed Menu MosaicHydro Ltd 2013 Date 20 Jul 2013 Sensor View Show Vessel View Z Rotation L gt Horizont Shit 0 4 oe Zoom 44 gt 100 Enter 2 fag Move Ref Coord Sys Show Short menu IKI B gt XE m M Vessel aI moo 2m n iest Z neti of Rotation 4 gt Z 0m g Mires M Primary GPS Secondary GPS View Vessel Aux 1 GPS Aux 2 GPS Default fi 0 Length m Sensor 1 Sensor 2 Top down Profile fs Width m fa Height m ma Lever Arm IMU Lever Ple cw m Lel E Rot
3. P ene Show Detailed Menu i Page 11 of 16 Pro Note No 2013 01 Date 20 Jul 2013 Example 1 Results In this example the position Lat Lon produced by the POS is at the IMU Target Recording Software set up no changes to be made to MV POS View 1 Designate Software Vessel CoG POS Vessel CoR 2 Physical IMU Target Location e 1 0m forward of CoG e 1 94m starboard of CoG e 0 532m above CoG 3 Physical Sonar Location e 1 0m forward of CoG e 1 94m starboard of CoG e 1 032m below CoG 4 IMU location relative to Vessel CoR in Recording Software e Positioning System location in HYPACK HIPS is 1 94 1 0 0 532 e Positioning System location in QINSy PDS2000 is 1 94 1 0 0 532 5 Sonar location relative to Vessel CoR in Recording Software 6 IMU to Vessel Centre of Rotation lever arm has been entered in MV POSView and IMU Sonar lateral positions are coincident therefore e Heave Sensor Location Sonar Location e HYSWEEP HIPS Attitude Heave amp Sonar Locations are 1 94 1 0 1 5 e QINSy PDS2000 Attitude Heave amp Sonar Locations are 1 94 1 0 1 5 MosaicHydro Ltd 2013 Page 12 of 16 Pro Note No 2013 01 Date 20 Jul 2013 Example 2 Hull Mount on 15m Dedicated Survey Vessel e The IMU Target is the user designated Reference Point e The Vessel Lever Arm CoG is coincident with the Vessel Centre of Rotation e IMU is mounted forward port and above the Vessel CoG
4. Lever Arms amp Mounting Angles Sensor Mounting Tags AutoStart Ref to Aux 1 GPS Lever X m fo Y m deg NU r 1 Frame w r t Ref Sensor 2 Frame w rt Ref Fra X deg fo Y deg 0 Z deg otis MosaicHydro Ltd 2013 Page 15 of 16 vi z Wesson aie Pro Note No 2013 01 Date 20 Jul 2013 Installation Wizard xj Installation Wizard xj Sensor View Show Vessel View Sensor View Show Vessel View Primary Antenna f qs hes sag Lees gt a 3 i VCog lt gt VCor 0 gt Bi m el m Primary Sensor 1 Antenna ZRotation J _ gt Horizont shito 4 r _of Z Rotation T gt Horizont shito 4 r of Zoom e7 a gt 100 Enter 87 Zoom 87 a gt 100 Enter 87 ak Move Ref Coord Sys Show Short menu Move Ref Coord Sys Show Short menu iJ u az X 1 m Aux 1 GPS F 4 rly Om Lock af gt Om C Lock Aux 2 GPS om Unlock Unlock Sensor 1 j gt 200m af gt Z 0m 7 Views Sensor 2 Lever Arm IMU Lever Arm Vessel v Lever Arm Cen of Rot Default fr 5 Length m Lever Arm Primary GPS View Vessel Lever Arm Vessel Lever Arm Cen of Rot Default fis Length m Lever Arm Primary GPS Lever Arm Se
5. when designating Lever Arms and Mounting Angles understanding the definition of each is fundamental to properly installing a POS e Reference Point A user defined point from which the distance to the IMU and Primary GPS antenna can easily be measured Once the measurements are made the Reference Point must then be tied to the Vessel Lever Arm both in lateral offsets and angular rotation e Vessel Lever Arm The point at which POS and POSPac MMS calculates all positions i e Latitude Longitude and Height If there is an angular misalignment between the Reference IMU frame and the Vessel Frame then the angles should be entered in the 1 M U Frame w r t Ref Frame section of the MV POSView Lever Arms and Mounting Dialogue e Centre of Rotation The point in the vessel where all pitch roll and yaw movements are zero More specifically the point in the vessel where the least amount of movement occurs From Point 2 above remember that failure to identify the Centre of Rotation in MV POSView will lead to motion errors cannot be corrected in post processing for sonars that use real time motion input from the POS for motion compensation stabilization real time beam steering i e Kongsberg without HIPS KM DLL R2Sonic Reson and Teledyne ODOM Typical users can simplify their setup by making the Reference Point and Vessel Lever Arm the same point however if this point is not coincident with the Vessel Centre of Rotation th
6. and there is an angular misalignment that has been determined via total station e Sonar is aft starboard and below Vessel CoG e POS GNSS Antennae are mounted on the top of the cabin and in line with the vessel longitudinal axis e Primary GPS Antenna Offsets o Antenna is 0 15m aft of IMU Target Reference Point o Antenna is in line with longitudinal axis of Vessel 0 45m to starboard of IMU o Antenna is 2 24m above IMU e IMU Offsets IMU is 1 3 m forward of CoG o IMU is 0 45m port of CoG o IMU is 0 23m above CoG o The IMU Lever Arm has a 2 degree counter clockwise rotation from the Vessel Z Axis e Sonar Offsets o Sonar is 2 1m aft of IMU Target Reference Point o Sonar 1 0m starboard of IMU o Sonar is 2 53m below IMU MosaicHydro Ltd 2013 Page 13 of 16 Pro Note No 2013 01 Date 20 Jul 2013 MV POSView Installation Lever Arms and Mounting Dialogues Lever Arms amp Mounting Angles x Lever Arms amp Mounting Angles Sensor Mounting Tags AutoStart IMU Frame w r t Ref Fram Target to Sensing Cent Resulting Lever X deg fo X m 0 008 X m 0 000 Y deg Yim 0 034 Y m fo 000 Zt 130 Z m Jo 000 ef to Vessel Lever Ref to Centre of Rotation Lever X m X m f 3 Yim a pas Zim foz Y m los Z m 224 MosaicHydro Ltd 2013 Page 14 of 16 Pro Note No 2013 01 Date 20 Jul 2013 Lever Arms amp Mounting Angles
7. bjects are created enabled PDS2000 Group 102 Sensor 1 Position Velocity Attitude Heave amp Dynamics Group 104 Performance Metrics for 50Hz MosaicHydro Ltd 2013 Page 6 of 16 Pro Note No 2013 01 Date 20 Jul 2013 QINSy Specific Hints If you are planning on using QINSy Processing Manager to post process your data vice CARIS HIPS e When Sensor1 is the MBES then QINSy s heave filter removes roll pitch trend from data to get heave at CoG and in the process means that delayed heave can t be applied Therefore for vessel s other than an all on pole setup where the remainder of the vessels offsets are not relevant if possible configure the POS to provide SENSOR1 as CoG CoR QINSy REF to QINSy which has the following advantages o Delayed heave can be quickly applied to Object track in QINSy processing without having to use the ShiftZ per QPD procedure o POSPac SBET valid at CoG CoR can also be applied quickly in processing to the object track o Dual head set up and delayed heave application is not hampered by the fact that TrueHeave is not provided on Sensor 2 8 POS Position Where is it POS MV and POSPac MMS calculate position at the centre of the Vessel Lever Arm What does this mean o If the Reference Point and Vessel Lever Arm are coincident then the POS position is calculated at the Reference Point o If the Reference Point and Vessel Lever Ar
8. ces such as a 3D imaging laser or photogrammetric system Measurements to the Primary GNSS antenna must be to the Phase Centre of the antenna not just the bottom of the antenna Failure to account for the vertical Z offset from the bottom of the antenna to the phase centre 8 43cm for a Trimble 382AP GNSS Antenna will affect the MosaicHydro Ltd 2013 Page 2 of 16 Pro Note No 2013 01 Date 20 Jul 2013 POS MV position Refer to the POS MV Manual Drawings section to verify the location of your antenna phase centre GAMS Calibration Routine and GAMS Vector From Peter Stewart Applanix Choosing whether you accept the results of the GAMS calibration routine in real time or via POSPac or the values calculated via total station derived dimensional control depends on 1 The uncertainty associated with the dimensional control survey both in offsets and misalignment angles 2 The uncertainty in the GAMS calibration process aiding and vessel size dependent see below any calibration or validation of lever arms or GAMS vector is dependent on the quality of the GNSS aiding at the time The better the aiding RTK in real time or even better PPK in POSPac the better the calibration results There is also a dependence on the dynamics of the vessel The figure 8 s we call for are there to induce acceleration the greater the acceleration the more reliable the calibration Obviously a smaller more agile vessel has
9. condary GPS i Lever Arm Aux 1 GPS Topdom i Mee Lever Arm Aux 2 GPS Lever Arm Sensor 1 X u C Show Detailed Menu Lever Arm Secondary GPS 7 Lever Arm Aux 1 GPS 4 seau Lever Arm Aux 2 GPS See eet Lever Arm Sensor 1 ha Profle E Him e a a Show Detailed Menu Results In this example setup the position Lat Lon produced by the POS is at Vessel CoG Recording Software Implications e Positioning System location in HYPACK HIPS QINSy PDS2000 is 0 0 0 e IMU to Vessel Centre of Rotation lever arm and Sensor 1 offsets have been entered in MV POSView therefore o Heave Sensor Location Sonar Location o HYSWEEP HIPS Attitude Heave amp Sonar Locations are 1 2 0 55 2 76 o QINSy PDS2000 Attitude Heave amp Sonar Locations are 1 2 0 55 2 76 MosaicHydro Ltd 2013 Page 16 of 16
10. e IMU does not move relative to the GNSS antennas see GNSS System on page 2 4 e It is not necessary to install the IMU at the vessel s centre of rotation There is no degradation of POS MV performance if the IMU is mounted away from the vessel s centre of rotation although this offset should be measured and applied during configuration of the system see the POS MV Configuration topic starting on page 4 7 Regardless of where the IMU is placed all installation offset lever arm measurements must be referenced to the Vessel Centre of Rotation and entered in MV POSView Failure to tell MV POSView where the IMU and Primary antenna is relative to the Vessel CoR will result in motion errors Specifically for an IMU forward or aft of the CoR pitch will be confused with heave and for a vessel where the IMU is either port or starboard of the CoR roll will be confused with heave These motion errors cannot be corrected in post processing for sonars that use real time motion input from the POS for motion compensation stabilization real time beam steering i e Kongsberg without HIPS KM DLL R2Sonic Reson and Teledyne ODOM Accuracy of Lever Arm Measurements From the POS MV manual When using DGPS lever arms should be measured to 0 05m When using RTK or POSPac MMS IAPPK lever arms should be measured to 0 005m When using RTK or POSPac MMS solutions lever arms must be measured by total station or other high resolution devi
11. en that offset MUST be entered in MV POSView Lever Arms and Mounting Dialogue MosaicHydro Ltd 2013 Page 5 of 16 Pro Note No 2013 01 7 Message Groups Real time Networking Date 20 Jul 2013 MV POSView gt Logging gt Ethernet Realtime controls which messages are being sent from the POS MV to the data collection software and at what rate Group 1 should NEVER be used for multibeam LIDAR surveys as the message only contains Vessel Position Attitude amp Dynamics but is missing Velocity and Heave Use Messages 102 amp 104 for Sensor 1 and or 103 amp 105 for Sensor 2 Program Messages Required Output Rate Notes HYPACK HYSWEEP Group 3 Primary GNSS status Group 7 PPS Time Recovery and Status Group 10 General Status and FDIR Group 20 IIN Solution Status Group 102 Sensor 1 Position Velocity Attitude Heave amp Dynamics Group 111 Heave amp True Heave Data 25Hz QINSy Group 3 Primary GNSS status Group 10 General Status and FDIR Group 11 Secondary GNSS status Group 20 IIN Solution Status Group 102 Sensor 1 Position Velocity Attitude Heave amp Dynamics Group 104 Performance Metrics for Sensor 1 Position Velocity and Attitude Group 111 Heave amp True Heave Data Group 112 NMEA Strings 50 Hz QINSy divides the POS MV into 5 sub components with each component existing in the Database as a separate object Ensure all o
12. he IMU s longitudinal axis e Vessel Centre of Rotation VCoR is inboard and forward of the IMU Target e Primary GPS Antenna Offsets o Antenna is 0 819m forward of IMU o Antenna is in line with longitudinal axis of IMU o Antenna is 1 118m above IMU e IMU Offsets o IMU is 1m aft of VCoR o IMU is 1 94m starboard starboard of VCoR o IMU is 0 532m above VCoR MosaicHydro Ltd 2013 Page 9 of 16 Weseticn Ale Pro Note No 2013 01 Date 20 Jul 2013 MV POSView Installation Lever Arms and Mounting Dialogues Lever Arms amp Mounting Angles x Lever Arms amp Mounting Angles Sensor Mounting Tags AutoStart mRef to IMU Te Frame w rt Ref Fral Target to Sensing esulting Lever X m X deg jo X m 0 008 X m fo 000 Y m D Yim T 0 031 Ym o 000 Z m fo Lo 130 Zim fo 000 Ref to Primary GPS Lever Ar to Centre of Rotation Lever X m 0 819 X m 1 0 Y m fo Y m 1 94 Z m jns Z ff foss2 Reference Point and Vessel Centre of Rotation Vessel Lever Arm are Required to correctly Coincident compute heave at IMU Lever Arms amp Mounting Angles x Lever Arms amp Mounting Angles Sensor Mounting Tags AutoStart ef to Aux 1 GPS Lever Arm p Ref to Aux 2 GPS Lever Arm X m p X m fo Ymp Y m pooo Z m jo Z m jo Sensor 1 Frame w rt Ref Frame a X Y and Z are 0 as IMU is directly above the Sensor sonar i e no remote heave
13. m are NOT coincident then the POS position is calculated at the centre of the Vessel Lever Arm How does populating the Ref to Centre of Rotation Lever Arm fields affect the calculated POS position o It doesn t Populating these fields ensures that heave measurements for an IMU not at the Centre of Rotation are correctly calculated MosaicHydro Ltd 2013 Page 7 of 16 ae Pro Note No 2013 01 Date 20 Jul 2013 How does populating the Ref to Sensor 1 or 2 Lever Arm fields affect the calculated POS position o It doesn t Populating these fields ensures that remote heave calculations for the Sensor s are correctly calculated o N B If the Sensor Lever Arm fields are populated then the offsets of the heave sensor as entered in the recording software HYSWEEP QINSy PDS2000 should match the sensor s MosaicHydro Ltd 2013 Page 8 of 16 Pro Note No 2013 01 Date 20 Jul 2013 9 MV POSView Installation Offset Setup Example Example 1 Pole Mount on 9m Vessel of Opportunity e The IMU Target is the user designated Reference Point e The Vessel Lever Arm CoG is designated as coincident with the IMU Lever Arm and there are no measured angular offsets between the two Coordinate systems e IMU and Sonar are ona pole mount on the starboard side of the vessel e Sonar is 1 5m directly below the IMU on the pole e POS GNSS Antennae are mounted on the top of the pole and aligned with t
14. n accuracy of 0 02 then you must measure the mounting angles to an accuracy of 0 02 e Not measuring the mounting angles to the required accuracy will cause a constant offset in all the images from the multibeam sonar Additionally some multibeam sonar may calculate the beam forming parameters incorrectly IMU vs Vessel axes rotation angles must be measured by total station or other high resolution devices such as a 3D imaging laser or photogrammetric system to an accuracy of 0 02 4 Lever Arms Coordinate System The POS MV uses a right hand Cartesian co ordinate system meaning that X to Bow Y to Starboard and Z Down which is not the same as most survey software Converting POS X Y Z to other Survey Software Axis POS MV HYPACK QINSy PDS2000 HIPS Forward Aft Xpos Yuypack Xpos Yainsy Xpos Ypps2x Xpos Yuies Xpos Port Starboard Ypos Xhypack Y pos Xainsy pos X pps2x Y pos Xuips Y pos Up Down Zpos Zuvpack Zpos Zainsy 1 Zpos Z pps2x 1 Zpos Zuips Zpos 5 POS Motion Signs MosaicHydro Ltd 2013 Page 4 of 16 Pro Note No 2013 01 Date 20 Jul 2013 Motion HYPACK QINSy PDS2000 Roll Positive Heeling to Automatically Starboard 6 Automatically Selected by HYSWEEP ae Selected by PDS2000 Pitch Positive Bow Up Driver Driver Heave Positive Downwards 6 Point Definitions Applanix uses three different points
15. the advantage here For larger platforms specifying or performing a dimensional control survey to the millimetric level will mean that you can directly input the various lever arms as well as the GAMS vector At that point the lever arm and GAMS calibration processes whether in real time or in POSPac become validation tools instead If significant deltas are observed wrt the dimensional control survey this would be your cue to revisit the dimcon and check your sums Otherwise my recommendation would be to accept the dimcon results on the assumption that these have been validated for blunders and provide the millimetric precision you had asked for IMU Mount Rotation Angles Any misalignment between the IMU axes and the vessel axes must be measure and entered in MV POSView These angular offsets cannot be measured by a multibeam patch test which MosaicHydro Ltd 2013 Page 3 of 16 Pro Note No 2013 01 Date 20 Jul 2013 measures the angular offsets from the multibeam sonar relative to the IMU Failure to do so will result in systematic misalignment errors For example An IMU installed with a 1 misalignment about the yaw axis will result in a 0 1 roll error for 5 of roll The POS MV manual states e Measure the mounting angles to the same degree of accuracy that you require of POS MV For example if you require POS MV to deliver roll measurements for multibeam sonar compensation stabilization to a
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