An in-field magnetometer calibration method for IMUs

An in-field magnetometer calibration method for IMUs
Sarvenaz Salehi Mourkani, Navid Mostofi, Gabriele Bleser
Proceedings of IROS Workshop on Cognitive Assistive Systems: Closing the Action-Perception Loop IROS Workshop on Cognitive Assistive Systems: Closing the Action-Perception Loop (CAS-12), October 7, Vila Moura, Portugal

Abstract:

Magnetometers are one of the most common aiding sensors used in Inertial Measurement Units (IMU) to provide motion tracking, the latter being an important task in Cognitive Assistive (CA) systems. The basis for accurate motion tracking is a well calibrated sensor. Therefore, this paper presents an easy-to-use method for in-field magnetometer calibration and alignment with inertial sensors in an IMU. In the first step of the calibration procedure bias, scale factors and non-orthogonality parameters are estimated based on magnitude information and data collected under motion. In the second step misalignment parameters are obtained from inclination using gravity measured by accelerometers under static conditions. In each step the initial estimation of parameters based on linear least squares followed by a nonlinear optimization leads to reliable results for all the calibration parameters. Different performance aspects of the method are evaluated in several tests using real data.