Research On High Update Rate Attitude Measurement Algorithm Of Star Sensor Based On Rolling Shutter Exposure Star Point Correction

The star sensor is a key device for spacecraft attitude measurement.With the swift development of space technology such as high-resolution ground imaging and highprecision mapping,the problem of the low attitude update rate(5-20Hz)of traditional star sensors has become an important bottleneck restricting the further development of China’s aerospace field,especially the progress of space remote sensing technology.Rolling shutter exposure has the characteristics of fast imaging speed and containing the pose information of moving objects at asynchronous moments,which has the potential to improve the attitude update rate.But rolling shutter asynchronous exposure has the problems of star point distortion and imaging position shift.Therefore,in response to the urgent need for a star sensor with a high update rate,a star sensor’s high update rate attitude measurement algorithm based on star point correction of rolling shutter exposure is proposed.The main work is as follows:First,aiming at the problem that the positioning error increases and the attitude accuracy decreases due to the distortion and position offset of star points imaged by star sensor in rolling shutter exposure mode,a centroid correction method of the star sensor star point based on time domain constraints is proposed.By combining the application of Kalman filter to obtain the optimal position and velocity estimation,the star points of asynchronous exposure moments are corrected to the same moment,which effectively solves the problems of star point distortion and imaging position offset,and finally improves the positioning accuracy and attitude accuracy of the imaging star points.Subsequently,to solve the problem of low attitude update rate of star sensor,a high update rate attitude measurement algorithm based on rolling shutter exposure is proposed.Accurately control the exposure time of different star points in a single frame star map by rolling shutter,based on the C-quest attitude calculation algorithm,combined with the star point correction method,the motion attitude recursive estimation and the star point corrected information are combined to achieve multiple updates of the attitude of a single frame star map,thereby improving Attitude update rate.The proposed method can select the attitude update times according to the position and number of star points in the image,and increase the attitude update rate of the star sensor by 1-15 times,up to 150 Hz.In summary,based on the above proposed method,this paper completes the numerical simulation experiment of the system and systematically analyses the performance of the proposed method in terms of accuracy,motion state and update rate,etc.Finally,a real-life turntable experiment is applied to verify the effectiveness of the experimental method,which provides an effective solution to break through the technical barrier of low attitude update rate of traditional star sensor.