Adaptive Dynamic Sliding Mode Motion Control for the Parallel Mechanism of Virtual Axis Machine Tool

To further enhance the control performance of the virtual axis machine tool with a complex system model which can not be accurately established and with the nonlinear,strong coupling characteristics,a novel adaptive dynamic sliding mode control method is proposed for the motion control of the parallel mechanism of the virtual axis machine tool.A second-order dynamic sliding mode control is designed by building a new dynamic switching function to solve the problem of the reduced control quality and even the system instability of the conventional sliding mode control system based on the equivalent control design,due to the neglect of the fast changing dynamics of the actuators,and to avoid the chattering of the sliding mode.The adaptive control of estimating online the external interference of the virtual axis machine tool is adopted to overcome the dependence of the sliding mode control performance on the prior estimate of the unknown interference,and enhance the ability of the high-speed processing virtual axis machine tool to resist the strong interference.Simulation and experiment results show that the proposed adaptive dynamic sliding mode control method can be an effective solution to the control of the nonlinear,time-varying,coupling virtual axis machine tool with the strong disturbance in high-speed machining.It can ensure the control system a strong robustness and a good dynamic,steady quality.