利用星角距不变性标定星敏感器内部参数

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2.2×10-5rad。

Star Tracker Ground Calibration Based on the Invariant of Interstar Angles

A calibration approach based on the invariant of interstar angles has been put forward for star trackers. Compared with common approach, the sine of interstar angle is adopted to construct the observation equation instead of its cosine as which provides greater sensitivity for the small angle closed to 0°. In the calibration procedure, two step approaches and their iterative optimization are proposed to estimate the star tracker camera parameters even with nonlinear camera distortions. Furthermore, in order to improve the calibration performance, the exactly apparent position of star at the observing time is reduced. The experimental results indicate that the sine method is more robust; and the deviation of the measured interstar angle is 2.2×10-5 rad after calibrated.