MIMO variable structure control of a precision stage using PMLSM drives

Due to the highly improvement of the precision engineering, a positioning stage which can perform precision motion has become one of the main issues in this area. The paper presents a single layer precision stage driven by four permanent magnet linear synchronous motors. The stage also uses air bearings to reduce the friction. A MIMO variable structure controller is designed to perform tracking control of the stage. By the inherent robustness of the variable structure controller, simulations show that the precision stage can track the trajectory precisely and can reject the disturbance introduced by thrust ripples.