基于模型预测控制的大口径快摆镜随动系统

Large aperture fast steering mirror servo system based on model predictive control

为了满足地基大口径望远镜精密稳像系统的需求,对大口径快摆镜(FSM)的控制方法进行了研究。为了解决三促动器FSM的运动解耦为系统辨识带来的困难,通过解析法和系统辨识法相结合建立了FSM的传递函数模型。依据该模型,设计了PID控制器与模型预测控制器(MPC),采用仿真和实验两种方式比较了两种控制器的效果。仿真结果表明,在受到阶跃扰动后,MPC控制器的恢复速度是PID控制器的45倍。在50 Hz正弦信号下,由于FSM的大惯量特点,PID控制器有严重的时滞,而MPC控制器能以1.224×10^-6″的误差稳定跟随。在噪声抑制方面,对实时加入10%幅值噪声的随机信号,MPC控制器的噪声抑制效果是PID控制器的13.3倍。实验结果表明,MPC控制器能以0.430″的误差稳定跟随50 Hz正弦信号,其跟踪精度是PID控制器的3.212倍,采用MPC控制器的快摆镜能满足快摆镜高带宽和高精度的需求。

In order to meet the requirement of precision image stabilization system for ground-based large aperture telescopes, the control method of large aperture fast steering mirror(FSM) was studied.For the sake of solving the difficulty of system identification caused by motion decoupling of three actuator driven FSM, the transfer function model of FSM was established by combining analytical method and system identification method. According to the model, the PID controller and the model predictive controller(MPC) were designed, and the performance of the two controllers were compared by simulation and experiment. The simulation results show that the recovery speed of the MPC controller was 45 times faster than that of the PID controller after step disturbance. Under 50 Hz sinusoidal signals, due to the large inertia of FSM, the PID controller had a serious time delay, while the MPC controller could track steadily with an error of 1.224 ×10^-6″. In terms of noise suppression, under the random signal with 10% amplitude noise added in real time, the noise suppression performance of the MPC controller was 13.3 times better than that of the PID controller. The experimental results show that50 Hz sinusoidal signal could be tracked stably by the MPC controller with an error of 0.430″. The tracking accuracy of the MPC controller was 3.212 times higher than that of the PID controller. The results show that the fast steering mirror with MPC controller could satisfy the requirements of high bandwidth and high precision of the fast steering mirror.