Gain-scheduled EKF for Nano-satellite Attitude Determination System

Extended Kalman filter (EKF) has been widely used for attitude determination in various satellite missions. However, it 1 requires an extensive computational power which is not suitable for nano-satellite application. This paper proposes a gain-scheduled 2 EKF (GSEKF) to reduce the computational requirement in nano-satellite attitude determination process. The proposed GSEKF 3 eliminates the online recursive Kalman gain computation by analytically determines the Kalman gain based on the sensor parameters, 4 such as the gyroscope noise variance, the quaternion variance, the observation matrix and the satellite rotational speed. Two GSEKF 5 Kalman gains for two satellite operating modes are presented: the sun pointing and nadir pointing modes. The simulation and 6 experimental results show that the proposed method has comparable attitude estimation accuracy to the conventional EKF. In addition, 7 the proposed GSEKF reduces 86.29% and 89.45% of the computation load compared to the multiplicative EKF and Murrell’s version. 8