星敏感器参数标定及误差补偿

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。

Parameter calibration and error compensation of star sensor

A star sensor model is established by geometrical method on the basis of an ideal pinhole model in consideration of the error factors such as inaccurate focal length of the optical system of star sensor,plane tilt and rotating of CCD,and optical lens distortion etc.Based on the ground experimental data,the mathematical model is solved by least square method,the calibration parameters such as focal length,plane tilt and rotating factors of CCD and distortion factors etc can be obtained.The incident ray vector can be directly calculated and corrected from the measured star coordinates through substituting the calibration parameters into the mathematical model,thus the errors of the optical system can be compensated.The calculation results show that the statistical error of interstellar angular distance is reduced from 41" before calibration to 17",the calculation accuracy is improved.