Real-time attitude-independent gyro calibration from three-axis magnetometer measurements

A new real-time approach for gyro bias calibration using three-axis magnetometer measurements without any attitude knowledge is derived. This approach relies on a conversion of the three-axis magnetometer measurement and its derivative into an attitude-independent formulation. The goal is to use a calibrated three-axis magnetometer to determine the gyro biases before attitude information is available, which is often the case during orbit injection. Real-time algorithms are derived based on the Unscented filter, which is more robust to initial errors than an extended Kalman filter. The new formulation is tested with realistically simulated data based on the Tropical Rainfall Measurement Mission spacecraft. Simulation results indicate that accurate gyro bias calibration is possible.