快速反射镜的系统辨识与回路成形H∞鲁棒控制

System identification and loop shaping H∞robust control of voice coil actuator fast steering mirror

音圈式快速反射镜(Voice Coil Actuator-Fast Steering Mirror,VCA-FSM)是星间激光通信中的重要伺服机构,其基于音圈电机进行驱动,FSM内部的柔性支撑结构以及轴间相对运动使系统存在复杂耦合特性,降低了系统的控制性能。对于该问题,本文提出了一种基于模型辨识的双轴回路成形H∞解耦控制方法。首先,基于激励与响应数据求解系统脉冲响应序列,构造Hankel矩阵进行系统辨识;其次,考虑系统的耦合特性,基于标称模型进行双轴回路成形H∞鲁棒控制器的设计;最后,基于VCA-FSM伺服控制实验平台,开展方波与正弦扫频实验。实验结果表明:相较于LQG与LQR控制,本文所提出的双轴回路成形H∞鲁棒控制使系统X,Y轴跟踪闭环带宽分别最大提升了54.3 Hz和54.8 Hz,显著降低了系统的耦合特性。本文所提出的控制方法充分提高了VCA-FSM伺服系统的性能,实现了双轴VCA-FSM的高性能解耦控制。

The Voice Coil Actuator-Fast Steering Mirror(VCA-FSM)driven by Voice Coil Actuator is an important servo mechanism in inter-satellite laser communications.The flexible support structure inside the FSM and the relative motion between the axes cause complex coupling properties in the system and reduce the control performance of the system.For this problem,a two-axis loop shaping H∞decoupling control method based on model identification was proposed in this paper.Firstly,the system impulse response sequence was solved based on the excitation and response data,and the system Hankel matrix was constructed for system identification;subsequently,considering the coupling characteristics of the system,a two-axis loop shaping H∞robust controller was designed based on the nominal model;finally,s tep r esponse and sine sweep experiments were carried out based on the VCA-FSM servo control experimental platform.Experimental results show that compared with LQG and LQR control,the two-axis loop shaping H∞robust control proposed in this paper increases the X-and Y-axis tracking closed-loop bandwidth of the system by 54.3 Hz and 54.8 Hz respectively,significantly reduces the coupling characteristics of the system.The control method proposed in this paper fully improves the performance of the VCA-FSM servo system and realizes the high-performance decoupled control of the two-axis VCA-FSM.