对地观测平台恒星敏感器离焦成像折中设计分析

从对地观测平台角秒量级姿态确定需求出发,在构建星敏感器惯性系成像模型的基础上指出,恒星在成像面上的定位误差是星敏感器姿态确定误差的主要来源。同时,结合理想光学系统离焦模型,分析了星敏感器主要性能指标间的量化关系,并给出了成像面定位误差最低限。仿真结果表明,从优化系统性能考虑,成像模糊区直径为2~3个像元的配置是利用星敏感器焦平面的“轻微离焦”来实现亚像元定位的最佳方案,定位误差可达0.2个像元,能够满足星敏感器惯性姿态确定精度4″~5″的要求。理论分析和数值仿真结果可为后续星敏感器指标的提出及仪器设计提供技术参考。

Tradeoff Design Analysis for Defocused Imaging of Star Sensor on Space-to-Earth Platform

For the sake of the requirement for attitude determination at arc second order in spacetoearth platform, the imaging model of star sensor in inertial frame is constructed. It is pointed out that the main error for attitude determination of star sensor is the positional error of star in focal plane. Meanwhile, based on the defocused model of ideal optical system, the quantitative relationships among the main indexes of star sensor are analyzed and the minimum projection position error is also given. It is shown from the simulation results that, the blur area's diameter between 2～3 pixels is the best performance scheme using the slightdefocusing of star sensor's focal plane array and the positional error is only 0.2 pixel, which meets the requirement of star sensor about 4～5 arc second in inertial frame. The analyzed and simulated results can be references for the following indexes determination and designing of star sensor.