三视场红外地球敏感器导航算法数值分析及实验研究

红外地球敏感器广泛运用空间飞行器,尤其是在地球轨道附近。目前最新的静态地球敏感器使用焦平面探测器来覆盖整个地球红外辐射圆。若面向飞行在70km-100km处的临近空间飞行器,他们就需要有很大的视场(>120°)且相对分辨率很低。本文针对临近空间飞行器的天文导航运用,采用线阵CCD作为探测器,设计了一个三视场红外地球敏感器。他们按照二维角度均匀分布以确保每个光学头能够均匀的指向地球红外辐射圆上。每个CCD覆盖20°以便能够精确地分辨地球辐射和空间的边界点。综合考虑地球辐射模型和地球扁率等因素,利用地球敏感器观测的向量可以获得地心矢量和飞行高度。以70-100km飞行高度为示例,建立相应的数学模型,同时提出了相应的姿态和高度确定算法并进行了仿真。综上述分析,研制了一套三视场地球敏感器原理样机并进行相关测试。仿真和实验结果表明：高度测量精度优于200m,姿态测量精度优于0.002°。

Numerical Analysis and Experimental Study of Triple-FOV Infrared Earth Sensor for Navigation

Infrared earth sensors are widely used in spacecraft, especially around earth orbit. Nowadays the state-of-art static earth sensor employs a planar infrared detector to cover the whole earth infrared irradiation circle. As a result, they need to have a very large field of view (FOV) (>120°) and relatively low accuracy for near space vehicle at 70km~100km. This paper proposed a triple-FOV (field of view) infrared earth sensor for near space vehicle navigation, using three separate line CCDs as detector. They are uniformed distributed with 2-dimension angle in space to guarantee each optical head uniformly pointing to three spots of earth infrared irradiation circle. Each CCD only covers 20° FOV to accurately realize the boundary point determination between earth irradiation and space. Through the observation vector and taking the model of atmosphere irradiation, and the earth shape into account at the same time, the earth horizon, geocentric vector, and altitude could be simultaneously acquired in the near space vehicle coordinate system. Taking 70~ 100km flight altitude as an example, the mathematic model is set up and an algorithm is proposed and simulated to obtain the attitude and altitude. Upon this analysis, a prototype of earth sensor has been built and tested. The test results show that the altitude measurement accuracy is better than 200 m, and the altitude measurement accuracy is better than 0.002°.