SYSTEM AND PROCESS FOR THE PRECISE POSITIONING OF SUBSEA UNITS

• US 20090287414A1
• Filed: 05/14/2007
• Published: 11/19/2009
• Est. Priority Date: 05/14/2007
• Status: Abandoned Application

• Current Assignee: Zupt LLC
• Original Assignee: Zupt LLC
• Inventors: Vickery, Keith
• Application Number:
  US11/748,279
• Publication Number:
  US 20090287414A1
• Time in Patent Office: Days
• US Class Current: 701/220
• CPC Class Codes: G01C 21/165 combined with non-inertial navigation instruments
• CPC Class Codes: G01S 15/60 wherein the transmitter and receiver are mounted on the moving object, e.g. for determining ground speed, drift angle, ground track
• CPC Class Codes: G01S 15/86 Combinations of sonar systems with lidar systems; Combinations of sonar systems with systems not using wave reflection
• CPC Class Codes: G01S 15/874 Combination of several spaced transponders or reflectors of known location for determining the position of a receiver G01S15/872 takes precedence
• CPC Class Codes: G01S 5/30 Determining absolute distances from a plurality of spaced points of known location

Abstract

A system for precise positioning of subsea units has a remotely operated vehicle, an inertial measurement unit positioned on the vehicle so as to produce a signal relative to a position of the subsea unit, a doppler velocity log coupled to the vehicle in producing a signal relative to the position of the subsea unit, a baseline measurement device coupled to the vehicle and producing a signal relative to the position of the subsea unit, a Kalman filter cooperative with the signals from the inertial measurement unit and the doppler velocity log and the baseline measurement device, and a processor cooperative with the Kalman filter for producing an output indicative of the positioning of the subsea unit. A doppler velocity log includes a plurality of beams which are individually connected to the Kalman Filter.

Claims

1. A system for precise positioning of subsea units comprising:

a remotely operated vehicle;

an inertial measurement unit positioned on said remotely operated vehicle, said inertial measurement unit producing a signal relative to a position of the subsea unit;

a doppler velocity log coupled to said remotely operated vehicle, said doppler velocity log producing a signal relative to the position of the subsea unit;

a baseline measurement device coupled to said remotely operated vehicle, said baseline measurement device producing a signal relative to the position of the subsea unit;

a Kalman filtering means cooperative with the signals from said inertial measurement unit and said doppler velocity log and said baseline measurement device; and

a processing means cooperative with said Kalman filtering means for producing an output indicative of the position of the subsea unit.

2. The system of claim 1, said doppler velocity log having a plurality of beams, said Kalman filtering means coupled individually to said plurality of beams.

3. The system of claim 1, said baseline measurement device comprising:

a transmitter affixed to said remotely operated vehicle;

a receiver affixed to said remotely operated vehicle; and

a transponder means positioned on a subsea surface, said transponder means interactive with said transmitter and said receiver for producing the signal relative to the position of the subsea unit.

4. The system of claim 3, said receiver time tagging a signal as passed by said transmitter immediately as the signal is transmitted by said transmitter.

5. The system of claim 1, said doppler velocity log being tightly coupled to said Kalman filtering means.

6. The system of claim 1, further comprising:

a pressure transducer means connected to said remotely operated vehicle and cooperative with said Kalman filtering means for producing a signal relative to a depth of said remotely operated vehicle.

7. The system of claim 1, said processing means for recording data from said Kalman filtering means in relation to time.

8. The system of claim 1, said processing means comprising:

a UART interposed between said inertial measurement unit and said doppler velocity log and said baseline measurement device; and

a time-tagging means coupled to said UART for time tagging data immediately upon receipt by said UART.

9. The system of claim 1, said remotely operated vehicle selected from the group consisting of a towfish, a cable-connected remotely operated vehicle, and a non-cable connected remotely operated vehicle.

10. The system of claim 3, said transponder means comprising:

a pair of transponders positioned on the subsea surface, each of said pair of transponders placed in a desired position relative to a path of travel of said remotely operated vehicle.

11. The system of claim 1, further comprising:

a clock means cooperative with said processing means for assigning a time relative to the signals as received from said Kalman filtering means.

12. The system of claim 1, said Kalman filtering means for compensating for deviations occurring between the signals received from said inertial measurement unit and said doppler velocity log and said baseline measurement device.

13. A process for determining a precise position of a subsea unit comprising:

producing a first signal from an inertial measurement unit relative to the position of the subsea unit;

producing a second signal from a doppler velocity log relative to the position of the subsea unit;

producing a third signal from a baseline measurement device relative to the position of the subsea unit;

Kalman filtering said first signal and said second signal and said third signal so as to compensate for any deviations between said signals so as to produce a measurement signal; and

processing the measurement signal so as to produce an output indicative of the precise position of the subsea unit.

14. The process of claim 13, further comprising:

emitting a plurality of beams from said doppler velocity log, said second signal being transmitted from each of said plurality of beams.

15. The process of claim 13, further comprising:

placing at least a pair of transponders on a subsea surface;

transmitting an acoustic signal from the subsea unit to the transponder; and

receiving the acoustic signals by the subsea unit.

16. The process of claim 15, further comprising:

time tagging the acoustic signal immediately upon transmitting by the subsea unit.

17. The process of claim 16, further comprising:

positioning a receiver in proximity to a transmitter on the subsea unit, said receiver time tagging the acoustic signal upon an initiation of transmission by the transmitter.

18. The process of claim 15, further comprising:

moving the subsea unit relative to the transponders during the step of transmitting and receiving.

19. The process of claim 13, further comprising:

producing a fourth signal from a pressure transducer relative to a depth of the subsea unit; and

Kalman filtering said fourth signal so as to compensate for any deviations between said fourth signal and said first, second and third signals.

20. The process of claim 13, further comprising:

time tagging the measurement signal immediately prior to said step of processing.