基于卷帘曝光成像模式的高动态高更新率星敏感器技术研究

Star tracker with high accuracy,zero drift and long life, is the key device to improve the performance for the spacecraft.Based on frame image mode for the traditional star tracker, only one attitude update can be aquired by one frame of star image.As a result,it leads to the low attitude update rate and poor dynamic performance, and has been the major bottleneck for the technology. Based on the rolling shutter mode,a new work priciple that multiple time attitude update could be completed by one frame of star image, was proposed in this project. By precision timing control, the uniform distribution of exposuring start moment in different star spots would be formed, which make up for movement information missing in the integration time of star spots. Based on this，a new attitude determination method which fused with attitude recursive and single star spot measurement information, was proposed. And using this method, one new attitude update could be completed every extracting one navigation star,which break trough the algorithm constraint based on multiple navigation star vectors in one frame.As a result,the attitude update rate will be increased by an order of magnitude, up to 100Hz level. According to this,the continous predict extraction alorithm of star spot trace will be studied to meet the high dynamic application requirements. The result of this project is expected to get rid of the status of low update rate and poor dynamic, and will lay the foundation for satellite application of high resolution and rapid response.

星敏感器具有姿态测量精度高、零漂移、寿命长等特点，是航天器性能提升的关键性器件。传统星敏感器以帧模式为基础，一帧图像只能获得一次姿态更新，导致更新率低、动态性能差，已经成为星敏感器发展中的主要技术壁垒。本项目基于卷帘曝光原理提出了一种在单帧图像中实现多次姿态更新的研究思路，通过对单帧星图中不同星点曝光时刻的精确控制，实现不同星像点的曝光时刻均匀分布，弥补帧模式下星点成像时间内运动信息缺失的不足；并基于此提出了姿态递推和单星点测量信息相融合的方法，实现每提取一颗星，完成一次姿态更新，打破传统星敏感器姿态确定以帧图像多矢量为基础的算法约束，将姿态更新率提高一个量级，达100Hz水平；基于此开展连续高动态的星点预测提取算法研究，实现星敏感器在高动态环境中的应用。项目的研究成果将有望摆脱星敏感器姿态更新率低、动态性能差的现状，为卫星的高分辨率成像、快速响应等应用奠定基础。

星敏感器是实现航天器高精度姿态测量的关键设备。随着高分辨率遥感卫星、高精度测绘、空间攻防等的发展需求，对星敏感器的精度、动态等性能提出了越来越高的要求，急需研究高更新率星敏感器技术，突破高动态下高分辨率遥感卫星技术瓶颈。传统的星敏感器姿态测量以帧模式为基础，采用全局曝光模式，一幅星图中的所有星点同时曝光，因此一帧星图只能获得一次姿态更新，导致更新率低，已经成为星敏感器发展的主要技术壁垒。本项目针对卫星等航天器在轨高精度、高动态、高更新率姿态测量难题，基于卷帘曝光成像模式提出一种在单帧星图中实现多次姿态更新的新技术，通过对单帧星图中不同星点依次曝光成像，实现不同星像点的曝光时刻均匀分布，弥补帧模式下星点成像时间内运动信息缺失的不足。在此基础上提出了基于相关滤波和数学形态学的运动星图预处理技术、运动星图复原技术、高动态星点跟踪技术、高精度实时星点提取技术和单星点递推姿态估计方法，实现高动态情况下每提取一颗星，完成一次高精度姿态更新，打破了传统的以帧频为时间单位的姿态测量方式，姿态更新率提高了1个数量级。研制了高精度、高动态、高更新率星敏感器样机，动态性能达到了5°/s水平，姿态更新率大于100Hz。此创新成果在NS卫星上进行了在轨的验证，其是目前在轨精度最高、动态性能最好、更新率最高的纳型星敏感器。