Magnetic compass based on MEMS is a device that can display the course of ships and the heading of aircraft, and it is widely used because of its fast measurement and low cost.
Due to the characteristics of Earth’s magnetic field and the environmental effects on magnetic compasses, determination of heading based on Earth’s magnetic field measurement still exposes several problems to overcome. Thus, lots of efforts have been made to improve the accuracy of digital magnetic compasses in different external conditions, which resulted in the development of many calibration methods.
Preceding research papers described that the locus from the sensing axes of magnetic compass is an ellipse or ellipsoid due to the influence of magnetic interference on the magnetic compass.
Ri Yong Rim, a researcher at the Faculty of Naval Architecture and Ocean Engineering, proposed a method for compensating the accidental error and improving the accuracy of MEMS magnetic compass by using robust ellipse fitting.
In order to evaluate the effectiveness of the objective function, he performed ellipse approximations by the measured values under artificial random noise. As a result, he identified the trend and shortcomings of the new objective function, and further improved the objective function to overcome the shortcomings.
Then, he obtained compensation coefficients and compensation errors by the algebraic ellipse approximation and by the improved ellipse approximation, calculated the heading, and compared it with the actual heading. The result demonstrated that the improved ellipse approximation model had good noise suppression performance and adaptability.
You can find more information in his paper “Research on Improving Heading Accuracy of MEMS Magnetic Compass Based on Robust Ellipse and Spheroid Fitting” in “Proceedings of KUTIC-2025”.