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空间望远镜在观测时会受到不确定性扰动,这些扰动的特性为幅值小,频带宽,控制难,而且望远镜平台的振动成分大部分在10 Hz以内。为了减小这些低频振动造成的干扰,对空间望远镜的大口径FSM系统进行控制器设计使其能够对低频扰动具有良好的抑制作用,选择的控制算法为在ITAE指标最优情况下的PID算法和带有积分作用的LQG算法。利用Simulink对系统搭建模型,仿真结果表明:FSM系统在PID控制器作用下的响应时间为0.4 s,在LQG控制器作用的响应时间为0.04 s,且都无稳态误差。利用OICETS卫星的振动功率谱密度数据对系统的抑制能力进行验证,在低频段0~10Hz范围内:跟踪模式时,系统在PID控制器作用下,抑制能力为14.5 d B,系统在LQG控制器作用下,抑制能力为32.5 d B;瞄准模式时,系统在PID控制器作用下,抑制能力为10.3 d B,系统在LQG控制器作用下,抑制能力为23.6 d B。经过比较,该大口径FSM系统在LQG控制器作用下的系统性能明显优于在最优PID控制器作用下。
Space telescopes are subject to uncertainties during observation. The characteristics of these disturbances are small amplitude, wide bandwidth and difficult control, and most of the vibration components of the telescope platform are within 10 Hz. In order to reduce the interference caused by these low-frequency vibrations, the controller design of the large-aperture FSM system of space telescope can suppress the low-frequency disturbance effectively. The selected control algorithm is the PID algorithm under the optimal ITAE index and LQG Algorithm with Integral Function. The simulation results show that the response time of FSM system with PID controller is 0.4 s and the response time of LQG controller is 0.04 s with no steady-state error. In the low frequency range of 0 ~ 10Hz: In tracking mode, the system under the action of PID controller, the inhibition capacity of 14.5 d B, the system in the LQG controller Under the action of the LQG controller, the suppression capacity is 32.5 dB. When aiming at the model, the system has a suppression capacity of 10.3 dB under the action of the PID controller. The system has a suppression capacity of 23.6 dB under the LQG controller. After comparison, the system performance of the large-caliber FSM system under LQG controller is obviously better than that under the optimal PID controller.