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针对CCD星敏感器光学系统存在焦距不准确、CCD平面倾斜和旋转及光学镜头畸变等误差因素,在理想针孔模型的基础上,用几何方法建立了星敏感器模型。利用地面实验数据,以最小二乘法解算该数学模型,求出焦距、CCD平面倾斜和旋转因子及畸变因子等待标定参数。将标定出的参数代回数学模型,便可由星象点测量坐标直接计算并修正入射光方向矢量,从而对光学系统的误差进行了补偿。计算结果表明:星对角距统计偏差由标定前41″降到了17″,提高了计算精度。
Aiming at the error factors of CCD star sensor optical system, such as inaccuracy of focal length, tilt and rotation of CCD plane and distortion of optical lens, the star sensor model was established by geometric method based on the ideal pinhole model. Using the experimental data from the ground, the mathematical model was solved by the least square method, and the parameters of waiting for the focal length, CCD plane inclination, rotation factor and distortion factor were obtained. By substituting the calibrated parameters back into the mathematical model, the direction vector of the incident light can be directly calculated and corrected by the coordinates of the astronomical point, so that the error of the optical system is compensated. The calculation results show that the statistical deviation of the satellite diagonal distance is reduced from 41 “to 17” before calibration, which improves the calculation precision.