Star spot centroid extraction method in high dynamic condition based on difference hash algorithm

In high dynamic conditions, star spot exhibits a tailing phenomenon, which makes it impossible to accurately extract the star centroid. Adjusting the exposure time can shorten the tail length but it will reduce the energy received by the detector, which also makes it difficult to extract the star target. Aiming at the above two problems, this paper proposes a star spot centroid extraction method under high dynamic conditions based on different hash algorithm. The method is divided into three steps. Firstly, establish a mathematical model of dynamic star spots. Then using difference hash algorithm and Hamming distance to realize coarse positioning of star targets in star tracking window. Finally, adopt threshold segmentation and connected domain method to extract star spot centroid in the coarse location area. The experimental results show that the proposed method can adapt to various exposure time, making the star sensor realize the stable tracking at the angular velocity of 3°/s. When the exposure time is 50ms and the angular velocity is 3°/s, the angular distance error is 13 arcseconds, the average extraction rate is 96%, which is 29.6% and 29.7% better than the traditional method.