Abstract: With the measurement of the Earth’s magnetic field, magnetic compass can provide high frequency heading information. However, it suffers from local magnetic interference. An intelligent ellipsoid calibration method based on the grey wolf is proposed to generate optimal parameters for magnetic compass to generate high performance heading information. With the analysis of the projection relationship among the navigation coordinate frame, the body frame and the local horizontal frame, the heading ellipsoid equation is constructed. Furthermore, an improved grey wolf algorithm is proposed to find optimization solution in a large solution space. With the improvement of the convergence factor and the evolutionary mechanism, the improved grey wolf algorithm can generate optimized solution for heading ellipsoid equation. The effectiveness of the proposed method has been verified by a series of vehicle and flight tests. The experimental results show that the proposed method can eliminate errors caused by sensor defects, hard-iron interference, and soft-iron interference effectively. The heading error generated by the magnetic compass is less than 0.2162 degree in real flight tests.

Key words: magnetic compass, ellipsoid parameters, grey wolf algorithm, error model