大视场星敏感器标定技术研究

Calibration Method for Wide Field of View Star Sensor

大视场星敏感器光学系统,由于畸变量较大,在轨标定过程中,直接采用最小二乘最优估计(LMS)或扩展卡尔曼滤波方法(EKF)无法精确求解其标定参数。在深入分析星敏感器测量误差因素的基础上,对考虑畸变和不考虑畸变两种情况的在轨标定结果进行了仿真对比;指出了标定焦距之前需先标定光学畸变的必要性,并介绍了4种可用于在轨校正光学畸变的方法;提出先标定主点偏差,再标定光学畸变参数,最后标定焦距的标定方法。仿真结果表明,可以采用像面旋转法求取主点偏差,利用高阶多项式方法求取光学畸变参数,畸变校正后,采用LMS和EKF标定算法估计焦距,标定精度达到了3.1μm和2.2μm。对100幅模拟星图处理后,星间角距统计偏差约为传统在轨标定方法的1/10～1/8。

It;s very difficult to calculate the calibration coefficients precisely using least mean squares（LMS） and extended Kalman filters（EKF） algorithm for wide field of view star sensor because of large optical aberration.And the error factors that affect measuring precision of star sensors are analyzed,which indicate that it is important to calibrate optical distortion before focal length calibration by comparing simulation data with and without distortion and noise.At the same time,four kinds of optical distortion methods are introduced.In order to improve calibration precision,a new method is proposed,in which main point is calibrated firstly,optical distortion parameter secondly and focal length finally.Simulation results demonstrate that the focal length calibration deviation reaches 3.1 ？？ and 2.2 ？？ using LMS and EKF algorithm after optical aberration correction.The statistical error of star angular distance is about 1/10~1/8 of the traditional on-orbit calibration method.