An Improved Method for the Magnetometer Calibration Based on Ellipsoid Fitting

The three-axis MEMS magnetometer is widely applied to assist the inertial sensor to estimate the attitude (especially heading) in strapdown inertial navigation system. It is necessary that the system errors of the magnetometer are analyzed and compensated, just like the inertial sensor. The system errors that contain biases, scale factors, nonorthogonal angles and iron effects can be quantified by the calibration. In general, error items can be derived based on the geomagnetic field vector observation. In most magnetometer calibration algorithm, the data from the sensor is processed directly by ellipsoid fitting without any pretreatment. In order to guarantee the reliability of the data, this paper proposes a new method for testing the rationality and gross errors of the calibration data based on geometric parameters of the ellipsoid. The experimental results show that the unreasonable data is detected, so that the calibration accuracy is improved to some extent.