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IXSEA S.A.S.

PHINS, an all-in-one sensor for DP applications

DP conference, HoustonSeptember 28-30, 2004

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INTRODUCTION

Positioning sensor is one of the key elements of DP systemsDGPS is a great positioning system but it may be subject to some interruptions in service:

Scintillation effectsSignal maskingMultipath

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INTRODUCTION

Continuity, integrity and availability are the characteristics needed for the positioning reference system.Complementing DGPS with additional sensors is a solution:

PHINS, an inertial navigation systemGAPS a compact, portable calibration free acoustic position system

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PHINS, a Fiber Gyro Navigation System

Small, lightProvides :

PositionRoll, PitchHeadingHeave, AltitudeRate of turn

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PHINS

Inertialcomputations

Attitude, positions, speeds

Other sensors(DGPS, DVL, USBL,

etc.)

Estimated biases

Navigation errors

Sensor compensation

Estimatedsensor errorsGyroscopes

Accelerometers

Kalman filter

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PHINS

GPS data

DVL data

USBL data

OptimalPositiondata

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PHINS

RTK GPS

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PHINS

GPS data

DVL data

USBL data

OptimalPositiondata

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PHINS TEST RESULTS

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PHINS

GPS data

DVL data

USBL data

OptimalPositiondata

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PHINS test resultsPosition drift in pure inertial mode (no GPS aiding, no DVL aiding)

0

5

10

15

20

25

0 50 100 150 200 250 300

time (s) since beginning of pure inertial mode

posi

tion

drift

(m)

Trial 1Trial 2Trial 3Trial 4Trial 5Trial 6Trial 7Trial 8Trial 9Trial 10

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PHINS

PHINS

DPControl system

DGPS likeinterface

DGPS 1

DGPS 2

DVL

USBL

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PHINS

Detects and rejects any DGPS position jumpAble to maintain 2 meter accuracy for one hour with DVL aidingCan use USBL data and no GPS at all for eliminating common mode errorsProvides data at high rate (up to 100 Hz)

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GAPS

USBL :Contains :

3D acoustic antennaBroadband signal processingFOG based navigation systemKalman filter

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GAPS

Single, minimally sized housing Free of calibration Improved accuracy and higher acoustic position update rate Short time update of subsea positions during acoustic drop-out Complete acoustic coverage with tracking close to surface Robust to GPS outage Cost savings and outstanding value-for-money for hardware and performance

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GAPS

Operates in the 19-30 KHz frequency range4000 meters rangeAccuracy : 0.2 % of slant range

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GAPS TESTS RESULTS

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GAPS TEST RESULTS

GAPS : Transponder Position Error

-10

-8

-6

-4

-2

0

2

4

6

8

10

-10 -8 -6 -4 -2 0 2 4 6 8 10

East Error (m)

Nor

th E

rror

(m)

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GAPS USE

The beacon is mooredWhile DGPS is available, GAPS computes automatically beacon positionWhen DGPS no more available, GAPS computes vessel position using beacon position and acoustimeasurements.

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CONCLUSION

PHINS and GAPS are alternative sensors that would allow enhancing

IntegrityAvailabilityRedundancy

of DP positioning reference systems