光电二极管的地球反照光校正及卫星姿态估计

As a small and low-cost sun sensor, the photodiode, combined with the earth sensor, can determinate full three-axis satellite attitude. However, the photodiode is sensitive to the surrounding light sources, such as the earth, which limits its application. The mathematical model of the earth's albedo is complicated. To solve this problem, a simplified measurement model of the photodiode, describing the effects of the earth's albedo as the dynamic bias and deviation as the mixed-Gaussian noise, is established first. Then parameters in the model are online estimated and updated with windowing and random weighting strategies. To improve the accuracy of the parameter estimation and robustness of the algorithm, the multi-scale factors are used to estimate the influence of albedo on each photodiode, and the Huber function is introduced to prevent the outliers. The experimental results show that the high-precision satellite attitude estimation can be achieved by the new measurement model and the unscented Kalman filter (UKF) algorithm, and the three-axis attitude accuracy can arrive at 0.2°-0.3°.