Autonomous vehicle power line position and load parameter estimation

• US 9,285,222 B2
• Filed: 04/27/2015
• Issued: 03/15/2016
• Est. Priority Date: 06/21/2010
• Status: Active Grant

• Current Assignee: Optimal Ranging Inc
• Original Assignee: Optimal Ranging Inc
• Inventors: Waite, James W., Gudmundsson, Thorkell, Gargov, Dimitar
• Primary Examiner(s): Beaulieu, Yonel
• Assistant Examiner(s): KLEINMAN, LAIL A
• Application Number:
  US14/697,423
• Publication Number:
  US 20150226559A1
• Time in Patent Office: 323 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: B64U 2201/10 autonomous, i.e. by navigating independently from ground or air stations, e.g. by using inertial navigation systems [INS]
• CPC Class Codes: G01B 7/00 Measuring arrangements characterised by the use of electric or magnetic techniques
• CPC Class Codes: G01C 21/005 with correlation of navigation data from several sources, e.g. map or contour matching G01C21/30 takes precedence
• CPC Class Codes: G01C 21/20 Instruments for performing navigational calculations G01C21/24, G01C21/26 take precedence
• CPC Class Codes: G05D 1/10 Simultaneous control of position or course in three dimensions G05D1/12 takes precedence
• CPC Class Codes: G05D 1/101 specially adapted for aircraft

Abstract

A system and method for providing autonomous navigation for an Autonomous Vehicle such as an Unmanned Air Vehicle (UAV) or an Autonomous Underwater Vehicle (AUV) in the vicinity of power lines or other signal carrying lines or underwater cable is presented. Autonomous navigation is achieved by measuring the magnitude and phase of the electromagnetic field at an unknown location within a space under excitation by a set of power cables of the power line with one or more orthogonal electromagnetic sensors formed on the AV; and estimating parameters related to a position and orientation of the AV, and load parameters of each cable based on the residual error between the measured set of complex electromagnetic field values corresponding to a combined model of the set of power cables.

Claims

1. A method for providing autonomous navigation for an automated underwater vehicle (AUV) in the vicinity of an underwater transmission cable, comprising:

measuring a set of complex magnetic field values of a magnetic field emitted by the underwater cable using one or more magnetic field sensors mounted on the AUV as the AUV is traversing the magnetic field at a position and an orientation relative to the underwater cable;

modeling, by a processor, a set of expected complex magnetic field values of the magnetic field when the AUV is at the position and the orientation relative to the underwater cable based on a first model of the underwater cable;

estimating a position and an orientation of the AUV relative to the cable, and magnitude and phase of current flowing in each conductor of the underwater cable, based on a residual error between the measured set of complex magnetic field values and the set of expected complex magnetic field values corresponding to the first model of the cable;

estimating a phase offset of the current flowing in each of the conductors of the underwater cable relative to a local or grid timebase; and

navigating the AUV using the parameters related to the position and the orientation of the AUV relative to each of the conductors of the underwater cable.

2. The method of claim 1, further comprising:

estimating grid synchronized load parameters of each of the conductors of the underwater cable, wherein the load parameters for each conductor includes amplitude and phase of voltage applied current to each of the conductors, and a phase offset between the current flowing in each of the conductors and the voltage measured on each of the conductors.

3. The method of claim 2, further comprising:

validating the position and the orientation of the AUV relative to each of the conductors, the magnitude and the phase of the current flowing in each of the conductors, positions of the conductors, and the local or grid synchronized load parameters, and the phase offset of the current flowing in each of the conductors relative to the local or grid timebase, using the residual error between the measured set of complex voltages and currents and the set of expected complex voltages and currents corresponding to a combined model.

8. The method of claim 1, wherein the set of complex magnetic field values include magnitude and phase of the magnetic field.

9. The method of claim 1, wherein any of the one or more magnetic field sensors includes a 3-axis sensor being mounted along three substantially orthogonal directions on the AUV.

10. The method of claim 1, wherein the parameters related to the position and orientation of the AUV relative to each of the conductors include at least one of a horizontal offset, a vertical offset, a yaw angle of the AUV relative to each of the conductors of the submarine cable, and a pitch angle of the AUV relative to each of the conductors.

11. The method of claim 1, wherein the first model relates the current flowing in each of the conductors to the emitted magnetic field.

12. The method of claim 1, wherein the position and the orientation of the AUV relative to each of the conductors used for modeling the expected complex magnetic field values are calculated by applying a numerical optimization method to a plurality of measurements by the magnetic field sensors.

13. The method of claim 1, wherein a Kalman filter is used to estimate the parameters related to the position and orientation of the AUV relative to each of the conductors.

14. The method of claim 1, wherein one or more Kalman filters are used to estimate the parameters related to the position and the orientation of the AUV relative to each of the conductors, and the magnitude and phase of the current flowing in each of the conductors.

15. The method of claim 1, wherein a Kalman filter is used to estimate the clock bias and drift between the local processor clock and a locally stable signal phase reference.

16. The method of claim 15, wherein a single combined Kalman filter estimates the clock parameters.

17. The method of claim 14, wherein a single combined Kalman filter estimates the parameters.

4. A method for estimating a location of an Autonomous Underwater Vehicle (AUV) in the vicinity of a submarine cable and local or grid synchronized load parameters of each conductor of the submarine cable as the AUV traverses a magnetic field emitted by the cable, the method comprising:

measuring a set of complex magnetic field values of the magnetic field using one or more magnetic field sensors mounted on the AUV at a position and an orientation of the AUV relative to each of the conductors of the submarine cable;

modeling, by a processor, a set of expected complex magnetic field values of each of the conductors of the submarine cable when the AUV is at the position and the orientation relative to each of the conductors based on a first model of the set of conductors of the submarine cable;

jointly estimating parameters related to a 3-d position of each of the conductors relative to the AUV, complex electric current in each of the conductors, the grid synchronized load parameters, and phase offset of current flowing in each of the conductors relative to a grid timebase, based on a residual error between the measured set of complex magnetic field values and the set of expected complex magnetic field values; and

navigating the AUV using the parameters related to the 3-d position and the orientation of the AUV relative to each of the conductors of the submarine cable.

5. The method of claim 4, wherein embedded 3-d features of the conductors are detected when there is reduced correspondence between a 2-d model and 3-d field measurements, the embedded 3-d features including towers, intersections, or direction changes.

18. The method of claim 4, wherein the parameters related to 3-d position of the AUV relative to each of the conductors include at least one of a horizontal offset, a vertical offset, a yaw angle of the AUV relative to each of the conductors, and a pitch angle of the AUV relative to each of the conductors.

6. A navigation system for an Autonomous Underwater Vehicle (AUV), comprising:

a plurality of magnetic field sensors configured to measure a set of complex magnetic field values of a magnetic field emitted by conductors of an underwater cable, the plurality of magnetic field sensors being mounted along three substantially orthogonal directions on the AUV;

circuitry coupled to receive signals from the plurality of the plurality of magnetic field sensors, and to provide quadrature signals indicating the set of measured complex magnetic field values;

a position and orientation autopilot for indicating position and orientation over ground of the AUV relative to one or more submarine cables as it traverses the magnetic field emitted by the cables; and

a processor coupled to receive the set of measured complex magnetic field values, and to calculate parameter values related to the position of each of the conductors of the submarine cable, phase offset of current flowing in each of the conductors relative to a local or grid defined timebase, and magnitude and phase of electric current flowing in each of the conductors of the submarine cable;

wherein the processor includes software for performing the following;

modeling a set of expected complex magnetic field values of each of the conductors when the AUV is at the position and orientation relative to each of the conductors based on a first model of the submarine cable;

jointly estimating parameters related to the position of the AUV relative to each of the conductors and the magnitude and phase of the electric current in each of the conductors, based on a residual error between the measured set of complex magnetic field values and the set of expected complex magnetic field values corresponding to the first model of the cable; and

navigating the AUV using the parameters related to the position and the orientation of the AUV relative to each of the cables.

7. The navigation system of claim 6, wherein the processor is further configured to estimate the grid synchronized load parameters of each of the conductors, and

wherein the load parameters of each of the conductors includes amplitude and phase of voltage applied to each of the conductors, and a phase offset between the current flowing in each of the conductors and the voltage applied to each of the conductors.

19. The navigation system of claim 6, wherein the parameters related to the position of the AUV relative to each of the conductors include at least one of a horizontal offset, a vertical offset, a yaw angle of the AUV relative to each of the conductors, a pitch angle of the AUV relative to each of the conductors, and the common twist angle of the binder enclosing the conductors with respect to the AUV.

20. A method for providing autonomous navigation for an automated underwater vehicle (AUV) in the vicinity of an underwater cable, comprising:

measuring a set of complex magnetic field values of a magnetic field emitted by the underwater cable using one or more magnetic field sensors mounted on the AUV as the AUV is traversing the magnetic field at a position and an orientation relative to the underwater cable;

locally estimating the time varying phase drift of the AUV local oscillator from the grid reference phase, partitioning these local clock deviations from phase deviations due to the local magnetic fields, and reversing the effect of the local oscillator drift;

modeling, by a processor, a set of expected complex magnetic field values of the magnetic field when the AUV is at the position and the orientation relative to the underwater cable based on a first model of the underwater cable;

estimating a position and an orientation of the AUV relative to the cable, and magnitude and phase of current flowing in each conductor of the underwater cable, based on a residual error between the measured set of complex magnetic field values and the set of expected complex magnetic field values corresponding to the first model of the cable; and

navigating the AUV using the parameters related to the position and the orientation of the AUV relative to each of the conductors of the underwater cable.

21. The method of claim 20, wherein the underwater cable is composed of multiple conductors.

22. The method of claim 21, wherein the twist of the underwater cable relative to the center is a model parameter.