Satellite Attitude Determination and Estimation using Two Star Trackers

Abstract

This paper deals with the attitude determination and the estimation algorithm of the satellite with two star trackers. The estimation accuracy of the attitude using primary star tracker can be improved by utilizing the attitude information of the secondary (back up) star tracker. Therefore, the attitude determination algorithm using two star trackers is proposed to enhance the accuracy of the attitude estimation. The unscented Kalman filter is used to estimate the attitude of the nonlinear satellite systems, and the decentralized scheme in a federated configuration is adopted so that sensor fault can be easily detected and isolated by employing the fault detection and isolation algorithm. Using the proposed algorithm, the satellite can continuously perform its mission despite the fault occurrence of the attitude sensor. Numerical simulation is performed to verify the effectiveness of the proposed attitude determination and estimation algorithm.