Compensation Method for the Carrier Magnetic Interference of Underwater Magnetic Vector Measurement System

This article proposed a new compensation method for an underwater magnetic vector measurement system that innovatively uses the geomagnetic total field as a benchmark. Moreover, this method does not require the use of heading angle data in the calculation of the compensation parameters, which avoids errors caused by insufficient accuracy of underwater heading angle. The implementation of these features relies on the new objective function constructed according to the characteristics of the spatial projection of the magnetic vector field on the horizontal plane of the geographical coordinate. The core matrix of the geomagnetic vector ellipsoid model is used as a constraint to determine the range of the functional solutions. The Levenberg–Marquardt algorithm is used to find the optimal solution to the new objective function. Three experiments were carried out to verify the proposed method. In the simulation experiment, the deviation between the calculated value and the preset value is less than 0.01%. In a field experiment, the standard deviation (SD) value of ${x}$ , ${y}$ , and ${z}$ magnetic components and the root-mean-square error (RMSE) of the magnetic total field after compensation are reduced from 1527.38, 1397.35, 1529.16, and 574.94 nT to 9.86 nT (0.65%), 9.99 nT (0.72%), 5.63 nT (0.38%), and 2.14 nT (0.37%). The proposed method is finally verified by the marine experiment. The SD values of ${x}$ , ${y}$ , and ${z}$ magnetic components and the RMSE of the magnetic total field after compensation are reduced from 575.02, 830.60, 620.95, and 1702.35 nT to 17.43 nT (1.11%), 14.14 nT (1.70%), 25.17 nT (4.10%), and 7.18 nT (0.42%), respectively.