空间相机调焦机构的设计与分析

设计了一种用于空间相机的调焦机构，该机构采用步进电机带动的精密步进谐波传动。波发生器由椭圆凸轮与套在其上的柔性轴承组成，输出端连接滚珠丝杠将旋转运动转化为直线运动，带动调焦镜沿直线导轨往复运动，其中输出刚轮与绝对式编码器相连，检测调焦移动位移。该机构具有传动比大、精度高、结构紧凑、效率高、运转平稳等特点。针对该机构在空间相机的实际应用，推导出了调焦机构位移与焦面移动的位置关系，并对该调焦机构进行了误差分析，用闭环控制的方式对其精度进行了检测。试验数据表明，该调焦机构传动比为1：70，重复定位精度为2μm，满足空间相机使用要求。

Design and analysis for focusing mechanism of space camera

A kind of focusing structure of space camera is presented, which adopts a kind of precision harmonic gear drive. The wave generator in the device is combined with an elliptic cam and a flexible bearing and its output shaft connected ball screws translates the rotational motion to the linear motion and drives the focusing mirror repeated moving along a linear guide. The output rigid wheel is connected with an absolute encoder to detect the displacement of focusing movements. It has the characteristics of big transmission ratio, high precision, compact structure, high efficiency, smooth running etc. According to the practical application of this harmonic gear drive in the space camera, the location relationship between the displacement of focusing structure and the focal plane movement is derived, and the system error is analyzed. Then, the system accuracy is tested with an open-loop control method. Experimental results show that transmission ratio of the instrument is 1∶ 70, and the repeated positional accuracy is 2 μm, which meets the requirements of practical applications.