A geomagnetic vector evolutionary compensation method using Woodbury equation

High-accuracy geomagnetic vector measurements inevitably suffer from the magnetic interference derived from ferromagnetic materials and electric equipment. Traditionally, to eliminate the influence of magnetic interference, a compensation process can be implemented to estimate the interference parameters that contain hard-iron and soft-iron parameters. The traditional compensation method did not consider the situation where the interference parameters would vary over time due to the change in magnetic properties. To overcome this problem, we proposed an evolutionary compensation method based on the Woodbury equation. Using this approach, the interference parameters can be iteratively updated during the measurement process by combining the previous information and the latest measurement data. Both simulation and experimentation were undertaken to evaluate the effectiveness of our proposed approach. The results demonstrate that the proposed method is successful in minimizing the impact of magnetic interference variations. The experiment shows that the RMS errors of geomagnetic filed total intensity and three components can be decreased from 4042.57 nT, 1425.84 nT, 5342.40 nT, and 2921.34 nT to 170.57 nT, 58.39 nT, 207.99 nT and 137.75 nT respectively by traditional method, while with evolutionary method the errors can be reduced to 47.37 nT, 16.19 nT, 57.61 nT and 38.38 nT respectively.