Abstract: For the satellites equipped with multiple star sensors, there will be many problems such as too many filtering constant gain matrices and complex system when using conventional CGKF (constant gain Kalman filtering) method to determine the attitude. In order to simplify the filtering system and unify the constant gain matrix, a satellite attitude determination method based on virtual star sensor is proposed in this paper. Firstly, with small calculation amount, an algorithm of time lag compensation and relative reference calibration of star sensor is presented, which is suitable for onorbit realtime calculation of onboard computer. The output data of star sensor is unified to the current star time and the measuring reference of star sensor is unified. Secondly, the output data of virtual star sensor(the installation matrix is a unit matrix) is constructed based on the output data of single star sensor/dual star sensors, and a unified constant gain matrix is designed to determine the attitude. The simulation results show that the attitude determination accuracy of the proposed method is equivalent to that of the conventional CGKF method, therefore the effectiveness of the proposed method is verified. The proposed method unifies the constant gain matrix, saves a lot of onboard computer resources, and has important engineering application value.

Key words: virtual star sensor, Kalman filter, constant gain, attitude determination, unified reference