复合滑模控制在精密PMLSM激光切割运动平台的应用

针对永磁直线同步电机激光切割运动平台的位置伺服控制低抖振、高精度、强鲁棒的要求,在传统双幂次滑模趋近律的基础上,提出一种变边界层的双幂次滑模趋近律带滑模扰动观测器的复合趋近律滑摸控制方法。变边界层方法是对控制系统的控制精度要求和降低抖振的权衡,而所提出的方法又继承了传统双幂次滑模趋近律方法的有限时间收敛特性。为了降低控制系统设计的保守性,设计了一种基于超螺旋算法的滑模扰动观测器对系统的未知扰动进行估计,并在此算法中添加一个幂指数,通过仿真实验证明了提高幂指数的数值可加快未知扰动的估计值的收敛速度。结合Lyapunov稳定性理论,证明了闭环系统的稳定性。最后,搭建了用于激光切割的永磁直线同步电机平移试验台对所提出的控制器进行测试。实验结果表明:本文所提出的控制器的位置跟踪误差不超过1μm,且误差波动较小,能够满足伺服控制系统的要求。

Application of composite sliding mode control on motion platform of PMLSM precision laser cutting

A composite sliding mode control method, which was based on the traditional double power sliding mode reaching law method, was adopted for the requirements of low chattering, high-performance and strong robustness on the motion platform of permanent magnet linear synchronous motor precision laser cutting. A variable boundary layer of double power reaching law with sliding mode disturbance observer has been proposed in this paper. The method of variable boundary layer is a trade-off between control precision and chattering reduction, and it inherits the finite time convergence properties of the double power sliding mode reaching law. In order to reduce the conservatism of the system design, a sliding mode disturbance observer based on super-twisting algorithm was used to estimate the unknown disturbance on the system. A power exponent was added in this algorithm and the simulation experiments verified that increasing the value of the power exponent can accelerate the convergence rate of the unknown disturbance estimations. The stability of the closed-loop system was proved by the Lyapunov stability theory. Finally, a laser cutting translation test stage based on PMLSM was built. The experimental results showed that the proposed control method could satisfy the requirements of the system.