Magnetometer Calibration Scheme for Quadrotors with On-Board Magnetic Field of Multiple DC Motors

This paper presents a 3D calibration approach of magnetometer with a new fitting error function. Unlike some iterative and numerical approaches, the method has closed form solution with great simplicity and therefore can be easily implemented by microcontroller-based on-board pilots of miniature unmanned aerial vehicles (UAV) with a potential of in-flight calibration. The experimental validation on a quadrotor in our laboratory shows its efficiency profoundly owing to its close analytical solutions. The approach was further applied to evaluate the impact of the on-board magnetic field generated by the permanent-magnets of DC motors of the quadrotor at different thrust levels, and the result shows that the relation between UAV's thrust command and motors-induced magnetic bias can be simply fitted by a linear function, which can be used for precise heading calculation during flight.