Autonomous vehicle power line position and load parameter estimation

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.

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.

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.