Compensation of Magnetic Data for Autonomous Underwater Vehicle Mapping Surveys

A method to produce compensated magnetic underwater survey data comprising:

• providing at least one magnetometer mounted on a subsea vehicle;
• maneuvering the subsea vehicle at a first altitude above the seafloor and a first heading, and at a second altitude above the seafloor at a heading 180 degrees from the first heading;
• receiving, by a microprocessor, a first set of raw output from the magnetometer;
• receiving, by a microprocessor, subsea vehicle state data and subsea vehicle performance data concurrently with the receiving of the first set of raw magnetic data;
• processing, by a microprocessor, the subsea vehicle state data, the subsea vehicle performance data, and the first set of raw magnetic data to produce magnetic compensation coefficients;
• performing a subsea mapping and receiving a second set of raw magnetic data output from the magnetometer while performing the subsea mapping;
• and
• applying, by a microprocessor, the magnetic compensation coefficients to the second set of raw magnetic data to produce compensated magnetic survey data which does not reference the Earth's geodetic frame of reference;
• wherein the subsea vehicle performance data comprises variable thruster motor currents;
• wherein the subsea vehicle state data comprises depth and altitude above the seafloor.

A system to produce compensated magnetic underwater survey data comprising:

• at least one magnetometer configured to mount to a subsea vehicle;
• a non-transitory computer readable medium;
• a processor in communication with the non-transitory computer readable medium, the processor operable to:
• receive a first set of raw output from the magnetometer;
• receive subsea vehicle state data and subsea vehicle performance data concurrently with the receiving of the first set of raw magnetic data;
• processing the subsea vehicle state data, the subsea vehicle performance data, and the first set of raw magnetic data to produce magnetic compensation coefficients;
• receiving a second set of raw magnetic data output from the magnetometer while performing the subsea mapping;
• applying the magnetic compensation coefficients to the second set of raw magnetic data to produce compensated magnetic survey data;
• wherein the first set of state data is collected while the subsea vehicle maneuvers at a first altitude above the seafloor and a first heading;
• wherein the second set of raw magnetic data is collected while the subsea vehicle is performing a subsea mapping.