Research On Attitude Accuracy Evaluation Technology Of Star Tracker

Because of the advantages of strong autonomy,high precision and strong anti-electromagnetic interference capability,star trackers are widely used in fields such as aircraft,ships,and aerospace.As the sensor with the highest attitude measurement accuracy,its attitude accuracy evaluation has always been one of the difficult problems.In this paper,an attitude accuracy evaluation system is built for the star tracker,and the static and dynamic attitude accuracy evaluation of the star tracker is studied.The concrete contents are as follows:(1)A method for evaluating the attitude accuracy of a star tracker is proposed.During the process of static attitude evaluation,the high-precision angular motion information of the turntable and installation angle information are used to construct the static attitude reference datum;during the process of the dynamic attitude evaluation,the high-precision relative attitude measurement information of the inertial measurement unit and installation angle information are used to construct the dynamic attitude reference datum,and the corresponding attitude accuracy evaluation system has been built.The influence of installation angle calibration error,turntable error,laser gyro noise and laser gyro bias stability in the system are deeply studied.(2)The coordinate relationship between different combinations(turntable,IMU,star tracker)in the evaluation of star tracker attitude accuracy is deeply studied,and proposes turntable/IMU calibration method which is based on equivalent rotation vector observation and IMU/star tracker calibration method which is based on the prediction deviation of the observed star point centroid observation.And the effectiveness of the calibration methods is verified by simulation.(3)Conducting experiments to verify the static and dynamic attitude accuracy evaluation methods using the attitude accuracy evaluation system.After calibrating the coordinate relationship between each combination,static and dynamic accuracy evaluation experiments were carried out for the star tracker.The attitude accuracy of star tracker in single position and different positions are evaluated,and the statistical results of the accuracy in different positions are(1.23,1.54,3.02)″,and the dynamic accuracy evaluation results are obtained when the angular velocity of the star tracker around different rotation axes increases.The experimental results show that the attitude accuracy evaluation methods of the star tracker proposed in this paper can be applied to the static and dynamic attitude accuracy evaluation of the star tracker.