Extended Kalman Filter-Based Gyroscope-Aided Magnetometer Calibration for Consumer Electronic Devices

Magnetometers are low-cost sensors that are widely used for orientation sensing in consumer electronic devices. The sensor is affected by non-idealities that can be greatly compensated by proper calibration and determining parameters, such as bias, non-orthogonality, gain, and hard/soft iron. This paper presents a magnetometer calibration method, with the aid of a gyroscope. The algorithm is designed on a principle that the variation of magnetometer output should be aligned with device rotation, which can be sensed by the gyroscope. Based on this notion, an extended Kalman filter is established to estimate calibration parameters. The method evaluation is achieved by first running numerous simulations, followed by a series of experiments on real devices. The result shows that the proposed method can achieve within ten degrees of accuracy, with less than 5 s of convergence. Compared with least square ellipsoid fitting, our proposed method delivers five times better accuracy and avoids over fitting on ill-distributed calibration data sets. This advantage is especially useful for autonomous dynamic calibration in consumer electronic devices.