Experimental Attitude Estimation Using Real-time Magnetometer Calibrated Data

Magnetometer is one of the main sensors in Attitude Determination and Control Subsystem (ADCS) of Low Earth Orbit (LEO) satellites and since it is operable in all times during an orbital period, it can be utilized in almost all functional modes like detumbling, nadir pointing and orbit transfer. Consequently, the accuracy of magnetometer data and its calibration have vital roles in mission success. In this paper, regarding to the importance of real-time approaches in practical applications, an Extended Kalman Filter (EKF) is used for magnetometer calibration. Then, in order to study the role of magnetometer calibration in attitude estimation (AE) results, calibrated data is employed in the structure of a Multiplicative Quaternion EKF (MQEKF). Finally, a Hardware in the Loop (HIL) test bed which is equipped with a three axis Helmholtz coil and a three degree of freedom platform is utilized to measure the performance of developed algorithms experimentally. In the calibration process, magnetometer parameters are estimated and used in AE filter. The results show that the attitude error decreases gradually and the final accuracy increases.