快速反射镜是空间相机中常用的像移补偿装置, 而支撑结构的机械特性将直接影响快速反射镜系统的响应速度及闭环带宽。以某近地轨道空间相机中的音圈电机驱动型快速反射镜为研究对象, 设计了基于十字型柔性铰链的两轴柔性支撑结构, 该结构具有空间利用率高、中心漂移小等优点。根据悬臂梁的挠曲线近似微分方程, 建立了柔性支撑结构两轴转动刚度的数学模型, 针对快速反射镜机构的谐振频率要求, 选择了柔性铰链的主要结构参数, 并利用有限元软件MSC.Patran对机构进行了模态分析, 分析结果表明, 快速反射镜机构在两个工作方向上的谐振频率分别为18.6 Hz和18.7 Hz, 而其他非工作方向上的谐振频率均在292.2 Hz以上, 证明了柔性铰链结构参数的选择具有合理性。为了检验理论模型的准确性, 加工了快速反射镜的样机并搭建实验平台, 对机构的转动刚度和谐振频率进行了检测, 检测结果与理论分析得到的结果在允许的误差范围内具有一致性。

The fast steering mirror is a commonly used image motion compensation device in space cameras. The mechanical properties of the support structure will directly affect the response speed and closed loop bandwidth of the fast steering mirror system. A fast steering mirror driven by voice coil motor in a low earth orbit space camera was taken as the research object, and a two-axis flexible support structure based on cross-shaped flexible hinges was designed, which had the advantages of compact structure and small center drift. According to the approximate differential equation of cantilever beam deflection, the mathematical model of the rotational stiffness of the two-axis flexible support was established. The main structural parameters of the flexible hinge were selected for the resonant frequency requirements of the fast steering mirror mechanism, and a modal analysis of the mechanism was performed by using the finite element software MSC.Patran. The analysis results show that the resonant frequency of the fast steering mirror mechanism in the two working directions is 18.6 Hz and 18.7 Hz, while the resonant frequencies in other non-working directions are above 292.2 Hz, which proves that the choice of flexible hinge structural parameters is reasonable. In order to test the correctness of the theoretical model, a prototype of the fast steering mirror was processed and the experimental platform was built. The rotational stiffness and resonant frequency of the mechanism were tested. The results of the test and the theoretical analysis are consistent within the allowable error range.