Method and apparatus for determining the position of an underwater object in real-time

• US 20070106462A1
• Filed: 03/16/2006
• Published: 05/10/2007
• Est. Priority Date: 09/23/2004
• Status: Active Grant

• Current Assignee: Hydro-Quebec (Province of Québec)
• Original Assignee: Hydro-Quebec (Province of Québec)
• Inventors: Blain, Michel, Laliberte, Richard, Houde, Regis
• Granted Patent: US 7,257,483 B2
• Time in Patent Office: Days
• US Class Current: 701/207
• CPC Class Codes: G05D 1/10 Simultaneous control of position or course in three dimensions G05D1/12 takes precedence

Abstract

A method and apparatus is disclosed for providing a determined position in real-time of an underwater object using a plurality of sensors operating at various sampling rates and for using the determined position in real-time in order to perform inspection tasks inter alia.

Claims

1. A method for determining a position underwater in real-time of an object, said method comprising:

sampling an estimation of said position of said object at a first given frequency, with a mean position error equal to zero;

sampling an estimation of at least one of a velocity and an acceleration of said object at a second given frequency higher than said first given frequency, resulting in a position estimate with a mean error which is not equal to zero; and

combining said estimation of said position with said estimation of at least one of a velocity and an acceleration to provide said position at said is second given frequency.

2. The method as claimed in claim 1, wherein said combining comprises compensating for a delay between a first time at which said position is estimated and a second time at which said estimated position is available.

3. The method as claimed in claim 1, wherein said combining comprises associating a first weight to said estimation of said position of said object, and a second weight to said estimation of at least one of said velocity and said acceleration.

4. The method as claimed in claim 3, wherein said associating of said first weight to said estimation of said position, and said second weight to said at least one of said estimation of said velocity and said acceleration comprises using Kalman filtering.

5. The method as claimed in claim 1, wherein said estimation of said position is provided using an acoustic position sensor unit.

6. The method as claimed in claim 5, wherein said acoustic position sensor unit provides an X, Y position signal and further wherein a Bathymeter sensor unit provides a Z position signal.

7. The method as claimed in claim 1, wherein an estimation of said velocity is provided, further wherein said sampling of said estimation of said velocity comprises using a Doppler velocity sensor unit.

8. The method as claimed in claim 1, wherein an estimation of said acceleration is provided, further wherein said sampling of said estimation of said acceleration comprises using a gyroscope and accelerometer sensor unit.

9. The method as claimed in claim 1, wherein said object comprises a vehicle, further comprising using said determined position in real-time of said vehicle with an acquired data signal of an immersed structure, provided by a data acquisition unit, in order to perform an inspection of said immersed structure and to further provide a result of said inspection in a virtual environment.

10. The method as claimed in claim 9, wherein said immersed structure comprises at least one of a dam and a bridge pillar and further wherein said inspection is performed in order to inspect at least one of a crack, a rock-concrete interface and a defect.

11. The method as claimed in claim 9, wherein said immersed structure comprises an intake structure and further wherein said inspection is performed in order to inspect at least one of a trash rack, a gate and a penstock.

12. The method as claimed in claim 9, wherein said immersed structure comprises a spillway and further wherein said inspection is performed in order to inspect at least one of a gate, concrete and pier.

13. The method as claimed in claim 9, further comprising manipulating an operation arm, secured to said vehicle in order to perform a task after performing said inspection.

14. The method as claimed in claim 13, wherein said task comprises at least one of welding, grinding, cleaning and grabbing an object.

15. The method as claimed in claim 1, further comprising using said determined position in real-time of said object to perform an inspection of at least one of a stop log and a draft tube.

16. The method as claimed in claim 1, further comprising using said determined position in real-time of said object in order to perform an inspection of an hydroelectric turbine in order to detect at least one of a cavitation erosion damage and a crack.

17. The method as claimed in claim 1, further comprising using said determined position in real-time of said object in order to perform an inspection of a ship hull in order to detect at least one of a defect, a foreign object, and a security threat.

18. An apparatus for determining a position in real-time of an object underwater, said apparatus comprising

a position sensor unit having a mean error equal to zero for providing an estimated position signal of said object at a first given frequency;

at least one of an instantaneous velocity sensor unit and an acceleration sensor unit for providing at least one of a corresponding instantaneous velocity signal and a corresponding instantaneous acceleration signal at a second given frequency higher than said first given frequency; and

a position providing unit receiving and combining said estimated position signal and said at least one of said corresponding instantaneous velocity signal and said corresponding sampled instantaneous acceleration signal to provide said position signal in real-time at said second given frequency.

19. The apparatus as claimed in claim 18 wherein said position providing unit comprises a Kalman filtering unit receiving said estimated position signal and said at least one of said instantaneous velocity signal and said instantaneous acceleration signal to provide said position signal in real-time for said object.

20. The apparatus as claimed in claim 18, wherein said position sensor unit comprises an acoustic position sensor unit.

21. The apparatus as claimed in claim 19, wherein said acoustic position sensor unit provides an X, Y position signal, further wherein said apparatus further comprises a Bathymeter sensor unit providing a Z position signal.

22. The apparatus as claimed in claim 18, wherein said instantaneous velocity sensor unit comprises a Doppler velocity sensor unit.

23. The apparatus as claimed in claim 18, wherein said instantaneous velocity sensor unit comprises a gyroscope and accelerometer sensor unit.