A calibration method of magnetic field sensor for body motion measurement using Extended Kalman filer

This paper proposes a calibration method of magnetic field sensor using the Extended Kalman filer. The magnetic field sensor output includes the magnetic disturbance. Therefore, the magnetic field sensor must be calibrated to compensate the static magnetic disturbance in the experimental environment. The direction angle calculated by the magnetic field sensor output includes the error by the effect of magnetic disturbance. The proposed method can estimates the calibration parameters (sensitivity and bias) of magnetic field sensor by using the gyro sensor output without the special calibration devices. Therefore, this method can be used to calibrate the magnetic field sensor in the experimental environment. We conducted the experiment, and the calibration parameters were estimated by using the calibration method. Furthermore, we conducted the measurement experiment of 3D posture using the experimental setup installing the rotary encoders, and we calculated the 3D posture by the sensor fusion using inertial and magnetic field sensors. The improvement of precision was identified by the results, and the effectiveness of this method was indicated.