www.fugro.com THSiS INS A review of the application of INS within Fugro
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www.fugro.com
THSiS INS
A review of the application of INS within Fugro
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THSiS INS
Outline
History – quick review of INS
Fugro Uses – Where and how we use INS
Fugro Developments – Off the shelf v In house developments
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History
INS has been around for a while….
Western Geophysical W-INS, late 1970’s (We invariably needed SHORAN)Shelltech/Itech land seismic use of INS for control (helicopter based Zupt’s) Mid/late 1970’sExxon/Honeywell’s DP reference systems – Riser and INS –1979British Oceanics/Intersub INS for manned submersible construction positioning (“used in place of unreliable acoustic systems”) – early 1980’s
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What is it
IMU block diagram
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What is it
Inertial Measurement Unit (IMU)What is it ?3 sensors measuring rotation around X, Y & Z axis3 accelerometers measuring acceleration along the X, Y and Z axisTime
Software takes raw rate and raw acceleration into a moreuseful product.AHRS Attitude Heading Reference SystemINS Inertial Navigation System
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What is it
Conceptually an INS uses dead reckoning navigation
It adds results from current epoch to the sum of the previous
With no aiding there will be a growth in error
10 minutes 15 minutes
5 metres
20 metres
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What is it
Many Aiding Observations can be usedDGPSDoppler Velocity (Acoustic and Radar)AltimetersDepth sensorsRange/Range
But why use a positioning system to aid ?
If I know where I am why do I need to be told ?
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What is it
Conventional Positioning Sensors are characterised by Short Term NoiseLong Term StabilityLoss of AvailabilityE.g. USBL
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What is it
Integrate INS with aiding or positioning system to –
Remove Short Term NoisePreserve Long Term StabilityImprove Availability
ScenariosDeep water untethered and or unmanned vehiclesAirborneReduced availability of positioning –
Environmental Effects
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Fugro Uses
AUV and UUV positioning
HP DGPS /HiPAPLinkQuest Acoustic ModemIXSEA IMU 90RDI DVLDigiquartz DepthTritech Altimeter
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Hugin AUV Main Components
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Recent AUV Positioning Verification
• Water Depth 1300m• Box in around as-supplied wellhead
position • 4 Lines – 4 Picks - mid swathe of
EM2000
Multibeam Survey
Easting Northing
M1_01 (090°) 619641.5 9376430.8
M1_04 (180°) 619639.1 9376431.0
M1_02 (270°) 619640.0 9376432.4
M1_03 (000°) 619641.8 9376432.0
Average 619640.6 9376431.6
Median 619640.8 9376431.5
ΔE/ΔN from as-supplied 0.1 -0.2
Absolute separation 0.2
SD 1.3 0.8
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Fugro Uses
Deep Water ROV Positioning
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Fugro Uses
• Sensors– Motion sensor, DVL– Position aiding: HP GPS HiPAP USBL– Finetrack L200 Post Processed
Pipe in trench
6m x 3m Matt
Pipeline Support
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Fugro Uses
Surface Navigation Under Cover
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Fugro Uses
• Sensors– Motion sensor, DVL– Position aiding: RTK
GPS (dual system)• Environment
– Signal masking, outliers in GPS positions
– GPS MOVIE
– INS MOVIE
Bad GPS position
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Fugro Uses
Airborne Surveys
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Fugro Uses
Reduced Navigation
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To Develop ?
Various INS/IMU units on the market
Numerous aiding positioning systems
Some integrated systems available but manufacturer specific
HAIN good example
Fugro along with other contractors use this in Hugin 3000 AUV
Mother ship must have HiPAP
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Finetrack
• Fugro developed family of filters for different hardware combinations
• Hardware Independent• Developed in house and in conjunction with other partners• FINETRACK
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Finetrack
L series Loosely CoupledAid System Position/VelocityINS Position/Velocity Enter into Kalman
T series Tightly CoupledAid System raw observationsINS rate & accelerationsEnter into Kalman
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Finetrack
T100 integrates Honeywell IMU, Sonardyne LBL and DopplerL100 primarily Doppler aided USBL or LBL with IMU as high precision MRUL300/400 Take manufacturers integrated IMU/Doppler solution and bring in to global co-ordinates by integrating LBL, USBL, Depth and or DGPS ( L300 Kearfott T16/ RDI DVL)
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Where Next ?
MEMS (micro-electro-mechanical systems )
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Summary
INS after a long gestation is here to stay
Can be used in numerous applications
Off the Shelf availability, if tie to one manufacturer is OK
INS in Action
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