Calibration of tri-axial magnetometer in magnetic compass using vector observations

In this paper, we propose a novel calibration scheme for a tri-axial magnetometer used in a magnetic compass. We first demonstrate that the most commonly used calibration method for tri-axial magnetometer, which is based on ellipsoid fitting, is unable to determine the inter-triad misalignment in a multi-sensor system. Then we discuss an improved calibration scheme that utilizes the invariance of the dot product of two constant vectors to overcome the weakness of the ellipsoid fitting method. Simulation and experiment results show that the proposed scheme is more accurate and stable compared with the conventional method.