SENSORS. HAIN An Integrated Acoustic Positioning and Inertial Navigation System

Transkript

1 SENSORS HAIN An Integrated Acoustic Positioning and Inertial Navigation System Hans Petter Jacobsen and Jan Erik Faugstadmo Session Chair Steve Browne, Thales Geo Solutions September 16-17, 2003 Houston, Texas

2 HAIN Hydroacoustic Aided Inertial Navigation HAIN Integrated acoustic positioning and inertial navigations system Jan Erik Faugstadmo Hans Petter Jacobsen AS Dynamic Positioning Conference, Houston, September arranged by 1

3 HAIN Benefits Survey: Increase accuracy Increase update rate Dynamic Positioning: Extend both SSBL and LBL operation limits Use slow acoustic update rate -> Save batteries Position update during acoustic drop-out 2

4 HAIN Acoustic positioning: Inertial positioning: Relativ high and evenly distributed noise No position drift Very low short term noise. Relativ large position drift 3

5 HAIN Inertial Navigation acc x acc y acc z Navigation calculations Velocity Position gyro x gyro y gyro z Attitude calculations Attitude (Roll, pitch, heading) The IMU measurements are relative to inertial space. Integrate accelerometers 1x gives velocity, 2x gives position Integrate gyros 1x gives attitude 4

6 HAIN INS classes INS systems are usually classified by the standard deviation of the position error growth of their free unaided performance Class Traditional application Gyro technology Gyro bias Accelerometer bias 1nmi/h Marine, air and land navigation RLG, FOG 0.01 /h 50µg >10nmi/h Tactical systems RLG, FOG 1 /h 1mg 5

7 HAIN Kalman Filter Structure Reset Compass $ ψ north, naveq - ~ ψ north, cmps ψ north Find. DVL Gyros Accelerometers IMU ~ B ω IB, gyro ~ B f IB, acc INS Navigation Equations ~ R$ (Attitude) LB naveq, L v$ EB, naveq $z naveq (Depth) (Velocity) R$ (Position) EL naveq, B v EB, DVL Decompose in L - - DGPS + HiPAP L v$ EB, DVL ~ R EL, posm Error state Kalman filter - ~ zdepthm Pressure sensor Estimates (of errors in navigation equations and colored sensor errors) 6

8 HAIN VesselPos 7

9 HAIN VesselPos Acoustic Pos. Lat/lon Acoustic Pos. & Aided Inertial Position Aided Inertial Pos. & Status APOS DP System INC 10 IMU Heading Roll&Pitch HiPAP Transceiver Td Acoustic signals 8

10 HAIN - Simulations Simulation parameters: HiPAP SSBL angle accuracy: dgps position white/coloured noise: 0.1 in x and y 0.15m/0.1m North and East 9

11 HAIN - Simulations Drop-out during vessel move IMU:1nmi/h Drop-out Accelrates Recover pos. HiPAP SSBL 1000 m Black : Correct position Blue : HiPAP Green : HAIN Vessel accelerates during a HiPAP dropout between 1240s and 1250s 10

12 HAIN - Simulations VesselPos accuracy during HiPAP dropout. 1nmi/h IMU 11

13 HAIN - Seatrials The measurements in the trials are: HiPAP positions relative to a TP on the seabead with known lat long position. The waterdepth is 200m. Known depth (The vessel is at the surface) Readings with 100 Hz from the IMU

14 HAIN - Seatrials B61. AL15.txt. 49 positions Reduces HiPAP update rate North Start East. Blue crosses: Vessel position from HiPAP updates, 1.5 to 20 second. Green crosses: Vessel positions from real time HAIN estimates every second 13

15 HAIN - Seatrials 80 B61. AL15.txt. 49 positions. 80 B61. AL15.txt. 49 positions East North Time [s] since 15:00: Time [s] since 15:00:00 The time plots show the same circles as the scatter plot on the previous slide. 14

16 HAIN - Seatrials 0.9 B61. AL15.txt. 49 positions. HAIN 1-sigma accuracy before HiPAP measurement 0.8 Horizontal 1-Sigma HAIN 1-sigma accuracy after HiPAP measurement Time [s] since 15:00:00 Blue crosses: Estimated HiPAP 1-sigma accuracy, based on Signal to Noise level, distance and geometry Green line: HAIN 1-sigma estimated accuracy. Based on these values we should expect 0.90m difference between HiPAP measurement and HAIN estimate. 15

17 HAIN - Seatrials B61. AL15.txt. 49 positions East difference for one measurement East The average of the difference in the horizontal plane is 0.64m Time [s] since 15:00:00 It is not possible to distinguish between HiPAP error and HAIN error. The average difference 0.64 m in the horizontal plane corresponds to a HiPAP angle error of 0.13º in X and Y. The difference is less than expected, which is 0.9m. 16

18 HAIN Seatrials with offshore DP vessel Vessel position during the test as logged with dgps DP used HAIN as the position reference during the test 17

19 HAIN Seatrials with offshore DP vessel Timeplot North co-ordinate HAIN green, HiPAP blue, dgps red 18

20 HAIN SubseaPos 19

21 HAIN dgps Acoustic Pos. Lat/lon SubseaPos Acoustic Pos. & Aided Inertial Position dgps HiPAP Operator Station DP System Survey Aided Inertial Pos. & Status Heading Roll&Pitch HiPAP Transceiver Td ROV HCS 10 Acoustic signals DVL IMU Depth 20

22 HAIN - Simulations Simulation parameters: HiPAP angle accuracy 0.1 in x and y dgps position white/coloured noise: DVL speed white/coloured noise: 0.15m/0.1m North and East 0.02m/s / 0.015m/s 21

23 HAIN Pipeline route survey - Depth 650m Sceen dump, real-time data HiPAP SSBL grey line, HAIN blue line 22

24 HAIN Pipeline route survey - Depth 650m HiPAP SSBL blue, HAIN real-time green, post processed red 23

25 HAIN Seabed Survey Depth 4000m Survey lines post processed 24

26 HAIN Seabed Survey Depth 4000m LBL blue, HAIN real-time green, post processed red 25

27 HAIN Seabed Survey Depth 4000m LBL blue, HAIN real-time green, post processed red 26