激光切割永磁直线伺服系统的反演滑模控制

Back-Stepping Sliding Mode Control of Laser Cutting Permanent Magnet Linear Servo Control System

针对用于激光切割的永磁直线伺服系统,采用反演滑模控制策略对系统进行分块处理,为提高系统精度,增强系统的鲁棒性和降低抖振,分别对位置环和电流环独立设计滑模控制器。考虑运动伺服系统在低速时存在的摩擦和扰动,在位置控制器的设计中,采用非线性双观测器方法对不可测Lu Gre模型的摩擦状态及参数进行估计,提出自适应指数趋近律滑模控制方法对摩擦力和扰动进行前馈补偿。电流控制器采用无抖振终端滑模控制方法设计。利用Lyapunvo函数证明了所设计的方法具有全局有限时间收敛特性并能够保证系统全局稳定。最后,在激光切割永磁直线伺服实验台上,应用三闭环PID方法和该文所提方法对位置和速度跟踪性能进行对比实验,实验结果表明,该文所提方法可有效提高激光切割直线伺服系统的控制性能。

In this paper, a back-stepping sliding mode control strategy is adopted for laser cutting servo control system driven by permanent magnet linear synchronous motors（PMLSM）, where it is used to break the control system into subsystems for improved control. In order to improve precision, strengthen robustness and decrease chattering in the control system, the position and current loops are independently designed by using sliding mode control methods. In the position loop, the friction and disturbance of the low-speed- motion servo system are considered, a dual observer is designed to estimate the unmeasured state and parameters of LuGre friction model, and an adaptive exponential reaching law sliding controller is proposed for friction and disturbance feedforward compensation. In current loop, the chattering-free terminal sliding mode controller is designed. The global stability and global finite time convergence performance has been proved by Lyapunvo function. Finally, in order to observe the servo tracking performance of position and velocity, the three-close-loop PID control method and the proposed method have been comparatively tested on the laser cutting permanent-magnet-linear servo bench. The experimental results show that the proposed control method can effectively improve the control performance of the laser cutting servo system.