A Novel Sliding Mode Motion Control for Parallel Mechanism of Virtual Axis Machine Tool

Abstract

This paper addresses the motion control of the parallel mechanism of virtual axis machine tool, which has a complex system model, the nonlinear and strong coupling characteristics and has strong external disturbances in high-speed machining. To further enhance its motion control performances, a novel adaptive dynamic sliding mode control method is proposed. The designed control system stability is proved theoretically. By building a new switching function, the second-order dynamic sliding mode control algorithm is designed to reduce the chattering of the conventional sliding mode control effectively and overcome the adverse effects of the fast changing dynamics of the actuators. By introducing the adaptive control, unknown external disturbances can be estimated online, which can improve the ability of resisting strong disturbances and the control precision of virtual axis machine tool. The simulation results for the virtual axis machine tool show that the designed control system has the good performances in tracking and resisting strong disturbances and can achieve the high precision motion control of the parallel mechanism of virtual axis machine tool.