重力对星载傅里叶光谱仪动镜系统的影响

Influence of gravitation on moving mirror system in Fourier transform spectrometer

分析了太空失重对星载傅里叶光谱仪动镜系统的影响。针对动镜系统受重力影响的两个关键因素,提出了解决措施,并设计了实验室验证方法。考虑空间和地面重力环境的不同,分析了动镜未被驱动时重力对初始定位的影响和动镜被驱动后重力对运动机构回复力矩的影响。设计了精密初始机械限位使动镜从固定起始点开始运动控制,并且采用闭环PID控制与在轨可调整期望运动规律相结合的控制方法来校正动镜机构等效扭转刚度的变化。最后,提出了将整个动镜机构倒置的方式进行地面验证,并设计了动镜正、负位移不对称性偏差以及匀速区速度波动的性能测量方法。实验结果表明,正置和倒置时动镜正、负位移的不对称性偏差可以控制在6μm以内,其匀速区的速度波动均方根值分别为1.4%和1.1%。实验显示提出的解决方法简单可靠,性能指标满足傅里叶光谱仪的要求,为动镜系统的空间应用提供了技术途径。

The effect of space weightlessness on the moving mirror system in a Fourier transform spectrometer（FTS） was analyzed. Aiming at two critical factors of gravitation influence on the moving mirror system, solution schemes were put forward, and a validation method in the laboratory was designed. By taking different ground and space environments into account, the influences of gravitation on the moving mirror initial position without a driver and the restoring moment of moving mirror frame with the driver were analyzed. The initial accurate mechanical limit that allows moving mirror motion on a fixed starting point was designed. Then, a control strategy in combination with closed loop PID control and adjustable expected motion law was used to reduce the influence of restoring moment of moving mirror frame. Finally, the moving mirror mechanism of FTS was placed in up-down mode for ground validation. To obtain the bias of positive displacement and negative displacement of the moving mirror and the speed vibration in the uniform area, a test system was established. Experiments show that the bias of positive displacement and negative displacement for the moving mirror motion is less than 6 μm, and the speed vibration（RMS values） tested on upright and up-down frames are respectively 1.4% and 1. 1%. The design satisfies the performance of FTS in simpleness and reliability, and provides a application technology for moving mirror systems in space.