望远镜主镜气压力驱动器设计

Pneumatic Force Actuator for Telescope Primary Mirror Support

为了获取优异的光学图像质量,大口径天文望远镜通常采用主动支撑结构以校正主镜面形误差。对望远镜主镜支撑系统所需的气压驱动器进行了研究。基于气动原理设计了一种采用滚动膜片结构的气压力驱动器,其中滚动膜片结构用于消除摩擦力的影响,滚珠式力解耦器用于消除侧向力、弯矩的影响。进一步设计了针对气压驱动器带死区的比例-积分-微分(PID)控制算法,以实现对气压驱动器的闭环控制。实验结果表明:气压力驱动器可精确提供主镜控制所需的支撑力,在望远镜高角变化速度达到2°/s时,输出支撑力范围为0～1000N,驱动器支撑力误差仅为满量程的±0.4%。设计的气压驱动器可实现主动支撑力的快速精确输出,能满足天文望远镜主镜主动支撑需求。

In order to obtain fine optical imaging quality,large astronomical telescopes commonly utilize active support system to correct surface deflection of the primary mirror.A device of pneumatic force actuator for telescope primary mirror support is designed and tested.Based on the principle of pneumatic systems,a type of pneumatic force actuator with a rolling diaphragm element is designed for primary mirror active support.In the actuator,a force decoupler with ball bearing is adopted to eliminate lateral force and flexural torque.In addition,a proportional-integral-differential（PID） control algorithm with dead zone is designed for the actuator.When the telescope′s elevation angle changes with the speed of 2°/s,the support force output can vary from 0 to 1000 N and the error is only ±0.4% of the full range.The experimental results show that the pneumatic force actuator designed is with good performance in static and dynamic force output.