A New Approach to Determine the Centroid of Star Spot for Star Tracker Based on MEMS-Gyro

Abstract

Along with the development of MEMS technology, the precision of MEMS-Gyro is increasing and the range of application of MEMS-Gyro is expanding. The accuracy of centroid determination of the spot directly relates to the precision of star tracker, but, when the exposure time is shorter or the satellite is in an unstable state, the noise of detector limits the accuracy greatly in the traditional approach of centroid determination. In view of these issues, this paper presents an approach which is based on high-precision MEMS-Gyro to determine the centroid of spot. This approach references EKF to estimate the position of centroid optimally. So, when the SNR is reduced because of shorter exposure and unstable state, this approach can help to increase the accuracy of centroid determination by introducing MEMS-Gyro. Further, it improves the precision and dynamic performance of the star tracker. In the end of this article, the feasibility of the approach is verified by the numerical simulation.