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0~1000 N，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.