Research On Methods Of Satellite Attitude Determination Based On Measurement System With Star-Sensor/Gyroscope

Satellite attitude determination is the premise and base to control the satellite. For the sake of the requirement of satellites' high precision and reliability, the satellite attitude measurement system with star-sensors and gyroscopes has become the prevalent pattern. The attitude determination system with this typical scheme pattern is studied systematically in this dissertation, at the same time, the algorithms of satellite attitude determination and the factors which affect the precision of attitude determination are studied and analyzed using the theory of optimization and differential equation, the technique of extended Kalman filtering and linear regression, and the numerical calculation method in the dissertation. Then novel feasible algorithms are proposed based on studying classical attitude determination algorithms. The new algorithms are simple but efficient, the computing cost is low but the attitude determination performs well. The main work is as follows:1. Satellite Modeling: Firstly, a variety of reference coordinates and the conversion between them, attitude representation methods are generalized and analyzed systematically. Then the attitude dynamic model are developed employing Quaternion and Euler-Angles representation.2. Satellite attitude determination method: classical satellite attitude determination algorithms are researched in this part, including reference vector algorithm, rate measurement algorithm and state estimation algorithm. Simultaneously merits and disadvantages of these algorithms are analyzed here.3. Satellite attitude determination precision: based on star-sensor and gyros pattern which is typical in satellite attitude determination system, extended Kalman filtering is employed to analyze the effect brought by star-sensor measurement error, sampling frequency, geometry relation between reference vectors and satellite orbit precision.4. Novel satellite attitude determination algorithms: based on the star-sensor and gyros pattern attitude determination system, two novel attitude determination algorithms are proposed: semi-determinate algorithm and model-error compensation method, which supply new thought for attitude determination. The algorithms take measures to estimate gyroscope's excursion, which reduce the effect to the attitude determination caused by the gyroscope's excursion. In the process, it is unnecessary to model the excursion and estimate the unknown quantity in the model. So the new algorithms are computed simply and carried out easily. The simulation experiments demonstrate that the two novel algorithms perform well in satellite attitude determination, their attitude determination precise are approximately the same as employing EKF, but the calculating time they used is only one-third of EKF's.