Research on calibration method of magnetic gradient tensor tracking system based on magnet

Abstract

In the magnetic gradient tensor tracking system there are errors among single triaxial magnetometer and misalignment errors of coordinate systems of triaxial magnetometers. In the conventional calibration methods the homogeneous magnetic environment should be known beforehand, but the homogeneous magnetic environment is not easy to be built. Thus, a calibration method in the nonhomogeneous field is proposed in this paper. Firstly, we measure the nonhomogeneous environmental field using the magnetic gradient tensor system and then put a magnet at the known position. We record the increased magnetic field value of each sensor, and establish the nonlinearity equations about error parameters for single sensor and magnetic moment of magnet. Through changing the magnet position, we can obtain the adequate nonlinearity equations. By solving the nonlinearity equations, the error parameters can be got. According to the component values of magnetic moment of magnet in the coordinate systems of different triaxial sensors, we can get the attitude rotation angles relative to the reference coordinate system. By simulation experiment, it is proved that the calibration method can decrease the error very well in magnetic gradient tensor tracking system.