Extended-Bandwidth Spacecraft Attitude Jitter Detection Based on Adaptive Sequential Kalman Algorithm

In-orbit micro-angular vibration has been recognized as a key contributor to the satellite-borne optical communication system. Magnetohydrodynamic (MHD) angular rate sensor with extremely low noise and high frequency is the most suitable instrument for micro-angular vibration measurement. However, it exhibits poor near-DC sensitivity due to the influence of viscous force and electromagnetic force. Kalman algorithm has been verified to be an effective method to extend the sensor bandwidth by fusing with other sensors. However, traditional Kalman algorithm cannot deal with the unpredicted dynamics of the system due to its invariable parameters over time. In this work, an adaptive sequential Kalman algorithm is proposed. The high-dimensional measurement updates are reduced to multiple low-dimensional measurement updates. The covariance matrix of the measurement noise is set to be adaptively updated and computed in segments. And the process noise covariance matrix is derived via weighted coefficient analysis by minimizing the mean square error. The computing time of the proposed method is proved to be a 38.39% reduction compared to the traditional Kalman method. The proposed method is realized in real-time to experimentally verify the frequency response and noise characteristics of the composite sensor. Results show that the bandwidth can achieve 0.1Hz-700Hz with a maximum amplitude fluctuation of 1.34 dB. The equivalent noise angular rate is 0.1523°/s RMS. Allan variance analysis indicates that the bias instability and angle random walk of the composite sensor are both better than the other methods.