Design of star tracking algorithm for star sensor assisted by gyroscope

In a large maneuvering scene, the location estimation error and the replenishment frequency of stars occur. To solve these problems, a star tracking algorithm assisted by gyroscope is proposed in this work. In a large maneuvering scene where the angular acceleration of the carrier changes dramatically, the angular velocity information measured by gyroscope is invested to keep track of the identified stars. Thus, the center-star-points of two-consecutive frames are easily obtained. The motion model of star points is established, and the position of the star points are tracked and predicted by Kalman filter. The positions of stars inside and outside the star map can be predicted in advance. The cache star database proposed in this paper can realize fast star replenishment in a large maneuvering scene. Experiments confirm that the error of star tracking is less than 2-pixels. Furthermore, the cache database reduces time of star replenishment. Both results prove that the proposed algorithm is effective, and conduces to improve the dynamic performance and update rate of star sensors.

This article proposes a star tracking algorithm assisted by gyroscopes in large maneuvering scenarios. By utilizing the difference in sampling frequencies between gyroscopes and star sensors, the intermediate position of star points is calculated between two star maps using angular velocity measurements to obtain more star position information. Kalman filtering is used to predict star position, avoiding motion model mismatch caused by sudden changes in angular acceleration and reducing star tracking error. Propose a scheme to cache the star database, reducing the frequency of accessing the star database to supplement star points in large maneuvering scenarios, and improving the overall algorithm’s timeliness. Simulation experiments have shown that the maximum tracking error of the algorithm in this paper can be guaranteed to be within 2 pixels, whether in general large maneuvering scenarios or in cases of sudden changes in angular acceleration. The cached star library scheme can reduce the overall process time by more than 30%, proving the feasibility and effectiveness of the algorithm in this paper.