Research On High Precision Laboratory Calibration Method And Error Coupling Of Star Tracker

As a high-precision attitude measurement equipment,star tracker has been widely used in aerospace,deep space exploration,navigation measurement,weapon guidance and other high-tech fields.How to improve the attitude measurement accuracy of star tracker to meet the future higher civil and military needs has become a hot issue in this research area.The attitude measurement accuracy of star tracker mainly depends on the calibration accuracy of its internal parameters.In view of the shortcomings of the existing laboratory calibration methods,this paper focuses on the improvement of the calibration accuracy of internal parameters of the laboratory calibration methods of star tracker.The main work is as follows:1.The basic methods of star tracker calibration are analyzed.In this paper,the mathematical models of existing calibration methods that rely on attitude information is derived in detail,and the error evaluation indexes of star tracker calibration results are given.2.A calibration method of star tracker based on three-axis rotation model is proposed,the coupling effect of each parameter is analyzed.The shortcomings of the calibration method of two-axis rotation model are analyzed,that is,the calibration stability of the principle point is not good,the fluctuation range is large,the calibration error of some parameters in the model is large,and the error of star centriod reprojection is large.In view of the shortcomings of the calibration method,the two-axis rotation model is improved to three-axis rotation model.The simulation results show that the calibration results of three-axis rotation model are better than that of two-axis rotation model.The coupling effect of the parameters in the calibration model is analyzed in detail,and the matrix condition number is proposed to determine the performance of the two calibration models.3.Based on the collimating light source and the precision rotary table,the calibration experiment system is built,and the verification experiment of the calibration method of the star tracker is completed.Using two calibration methods,four groups of calibration experiments are carried out in the laboratory.The experimental results show that: the calibration accuracy of the principle point of the three-axis rotation model is significantly better than that of the two-axis rotation model;the calibration stability of the focal length of the three-axis rotation model is better than that of the two-axis rotation model;the reprojection error of the star centriod of the three-axis rotation model is better than that of the two-axis rotation model;the principle point and the Euler angle parameters are coupled with each other.The experimental results are consistent with the simulation results.