利用星角距不变性标定星敏感器内部参数

摘要

A calibration approach based on the invariant of interstar angles was put forward for star trackers.Compared with common approaches,the sine of interstar angle which provides greater sensitivity for the angle changes closed to 0°was adopted to construct the observation equation instead of its cosine.In the calibration procedure,the two-step approach was proposed to estimate the principal point,focal length,and distortion parameters.The iterative optimization was also proposed to get the optimal estimations.In order to improve the accuracy of calibration, the apparent position of star at the observing time was modified.The experimental results indicate that the sine method is more accurate;and the deviation root-mean-square of the measured interstar angle is 2.2 ×10 -5 rad after calibrated.%提出了一种恒星角距不变的星敏感器内部参数的地面标定方法。较常见的星角距的标定方法不同的是，该方法利用对在0°附近的角度变化较敏感的恒星角距的正弦值建立观测方程；采用两步法分别估计焦距、主点和高阶畸变系数，并采用迭代优化的方法，获得最优估计值。为了确保标定精度，对观测时刻的导航星进行了视位置的修正。实验结果表明，采用星角距的正弦值建立观测方程，估计精度较高，采用考虑高阶畸变的改进正弦法标定后的星角距误差的均方根值为2．2×10－5 rad。