轨道姿态误差对TDI-CCD相机行周期及偏流角的影响分析

Effect Analysis of Orbital and Attitude Parameter Error on TDI-CCD's Line-shift Frequency and Veer Angle

与其他文献的几何方法不同,本文从运动学角度出发,选定合适的参考系后,按照一系列不同坐标系的坐标转换,完成星下点运动速度矢量在敏感器坐标系的推导,把姿态、轨道、安装偏差作为相关参数,经过一系列坐标变换,表征在最终的偏流角公式及行转移频率动态公式中;在通常的对地稳定指向模式下,姿态参数和安装偏差很小,仅保留一阶小量.根据矢量表达,解析地给出行转移频率及偏流角与轨道,姿态的关系,从而方便分析误差的影响,并以几个典型的低轨为实例作了说明.

Unlike other references which usually concentrate on geometric methods, kinetic approach is adopted to analyze the motion of space-born TDI-CCD camera＇s target, for a convenient analysis of kinetics, a series of coordinates is chosen. The velocity vector of the nadir is expressed in the sensor coordinate after some transformations which are functions of orbital and attitude parameters, For a nadir-pointing satellite, the first-order approximation of attitude parameters in the velocity vector is obtained with the tiny alignment error. From the relations between target＇s motion and orbital and attitude parameters, it takes little effort to derivate equations of line-shift frequency and veer angle with respect to orbit and attitude parameters, these explicit formulas of line-shift frequency and veer angle facilitate the procedure of analytical decision of error budget, especially in the primary design phase of a space mission. This application is illustrated by some typical LEO mission examples following the analysis.