Compensation of Geomagnetic Vector Measurement System With Differential Magnetic Field Method

The accurate measurement of a geomagnetic field is a key technology in many applications, such as magnetic anomaly detection, underwater geomagnetic navigation, and motion tracking. However, the magnetic interference fields, such as ferromagnetic parts and other electric equipments, will seriously influence the measurement accuracy of geomagnetic vector measurement system, and thus should be compensated. In this paper, a new compensation method using differential magnetic field is proposed. As a first step, a permanent magnet with different relative positions is used to change the ambient magnetic field to construct the error model equations about unknown quantities, and the soft-iron error parameters can be estimated by solving equations with nonlinear least square method. Then, the hard-iron error parameters can be estimated by changing the fixation direction of the three-axis magnetometer. Finally, the estimated error parameters are used for compensating the magnetic interference field. In order to verify effectiveness of the proposed method, simulation and experiment are performed, and the results demonstrate that the proposed method estimates error parameters accurately and improves the measurement accuracy of geomagnetic vector measurement system greatly.