A correction method of magnetic gradient tensor system to improve magnet localization accuracy

Abstract

The magnetic gradient tensor systems using vector magnetic sensors are easily affected by single sensor error and sensor array misalignment, significantly affecting target localization accuracy. To address this problem, based on the differential measurement theory of magnetic gradient tensor, a vector sensor error model was established, and the single sensor errors were corrected using the total least square (TLS) ellipsoid fitting method. Besides, a misalignment error correction model for the sensor is obtained by constructing a rotation matrix for the magnetic sensor's three-axis orthogonal coordinate system transformation, and the tensor system can be aligned by performing the TLS estimation of the rotation angle. After calibration, the experimental results show that the outputs of each sensor have high coincidence and coaxiality. The root mean square error (RMSE) of the total magnetic intensity (TMI) is reduced to within 100 nT, and the RMSE of the tensor component is reduced to within 85 nT/m. Within a range of 5 m, the magnetic target positioning error is reduced to less than 25.1 cm. This technology can improve the measurement accuracy of the magnetic gradient tensor system with high stability and reliability.