快速反射镜的复合快速非奇异终端滑模控制

Composite fast nonsingular terminal sliding mode control of fast steering mirror

为进一步提升激光通信精跟踪系统的控制性能,本文对音圈电机驱动的快速反射镜(Fast Steering Mirror,FSM)控制方法进行了研究。针对FSM中存在的强轴间耦合与外部扰动问题,提出了融合前馈解耦补偿与固定时间扩张状态观测器的复合快速非奇异终端滑模控制策略。首先,采用系统辨识方法建立FSM的双输入双输出耦合传递函数矩阵模型,并设计前馈解耦补偿器补偿耦合分量,以实现X轴和Y轴之间的运动解耦。其次,针对解耦后的各单轴模型,设计固定时间扩张状态观测器,同时实现对角速度和外部干扰的固定时间估计。随后,构建快速非奇异终端滑模面,并在控制律设计中采用指数幂函数取代符号函数,以提高系统收敛速度并抑制控制抖振,基于Lyapunov方法验证所提控制系统的稳定性,并证明跟踪误差在有限时间内收敛。最后,通过对比实验验证了提出的复合控制策略的有效性。实验结果表明,FSM在100 Hz强扰动存在的情况下,跟踪60 Hz和120 Hz圆形轨迹,其轨迹跟踪误差的平均绝对值分别为0.0036°和0.0131°,系统能够保持良好的跟踪性能,说明所提复合控制策略是有效的,满足激光通信FSM对于高精度和强抗扰等要求。

This paper aims to improve the control performance of the precision tracking system for laser com-munication by studying the control method of Fast Steering Mirrors(FSM)driven by a voice coil motor.FSM often face the problems of strong cross-coupling characteristics and external disturbances.To over-come these challenges,we propose a composite fast nonsingular terminal sliding mode control strategy integ-rating feedforward decoupling compensation and fixed-time extended state observer.First,the FSM’s coup-ling transfer function matrix model with double inputs and double outputs is established by using the system identification method,and the feedforward decoupling compensator is designed to compensate for the coup-ling components and achieve motion decoupling between the X-axis and Y-axis.Second,the fixed-time ex-tended state observer is designed for each decoupled single-axis model to achieve a fixed-time estimation of angular velocity and external disturbances simultaneously.Then,the fast nonsingular terminal sliding mode surface is constructed,and the exponential power function is adopted to replace the sign function in control law design,so as to improve the system’s convergence speed and suppress the chattering of the sliding mode.The proposed control system’s stability and the tracking error finite-time convergence are proved based on the Lyapunov stability analysis method.Finally,the effectiveness of the proposed composite control strategy is verified by comparative experiments.The experimental results show that under the 100 Hz strong disturb-ances,for the FSM tracking 60 Hz and 120 Hz circular trajectories,the average absolute values of its traject-ory tracking error are 0.0036°and 0.0131°,respectively,indicating that the system can maintain good track-ing performance.The proposed composite control strategy is validated as effectively meeting the FSM’s high-precision and strong anti-disturbance requirements for laser communication.