Autocalibration of an electronic compass for augmented reality

Electronic compass is often used to provide the absolute heading reference for tracking the user´s head and hands in virtual reality (VR) and augmented reality (AR), especially for outdoor AR applications. However, compass is vulnerable to environment magnetism disturbance. Existing compass calibration methods require complex steps and true heading reference which is often impossible to be obtained in outdoor AR applications, and is useful only when compass is in horizontal plane. An autocalibration method without the need of heading reference and redundant sensors is proposed in this paper. First the compass error model based on physical principle is presented, then the algorithm to calculate the compensation coefficients with a set of sample measurements of the sensors in the compass is described. Because the influence of the environmental disturbance has been effectively compensated, the calibrated compass can provided accurate heading even when it is under large tilt attitude.