基于二阶滑模的PMLSM悬浮平台直接解耦控制

Direct Decoupling Control of PMLSM Levitation Platform Based on Second-order Sliding Mode

永磁直线同步电机(PMLSM)悬浮平台利用直线电机的法向力实现动子悬浮,本身具有的无摩擦,零传动等优点满足了精密加工中对于高精度和高速度的要求。但是由于水平推力和法向力之间存在非线性耦合,加之负载扰动和参数变化等不确定性因素降低了系统的伺服性能。为了保证PMLSM悬浮平台动子的定位精度,针对上述问题分别独立设计水平轴和竖直轴的二阶滑模(2SMC)控制器对其进行直接动态解耦控制。控制律采用二阶滑模的螺旋算法,将不连续控制作用于变量的高阶微分上,理论上可以削弱抖振。仿真结果表明该控制策略能够实现对水平方向和竖直方向的动态解耦,使系统对参数变化和负载扰动具有很强的鲁棒性,从而提高了定位精度。

The permanent magnet linear motor（PMLSM） levitation platform uses the normal force to make the mover suspending.It has the merits of no friction and direct-drive of the system,that coincidence the requirement of high precision and speed requirements for the modern industry.But the servo performance is affected by the nonlinear coupling between vertical thrust and normal force,load disturbance and parameter uncertainty.In order to ensure the mover positioning strictly,the second-order sliding（2SMC） controllers of the horizontal axis and vertical axis are designed to directly decoupling control.Control law was achieved by twisting algorithm of the second-order sliding mode.The discontinuous control effects on the higher differential,and eliminate the chattering phenomenon theoretically.Simulation results show that the control strategy can achieve the dynamic decoupling between horizontal direction and vertical direction,enhance the robustness performance of the system against parameter variations and load disturbances and improve the positioning precision.