Research On Multi-motor Synchronous Control Based On Sliding Mode Control

As one of the core subsystems in the lithography machine,dual wafer stage system,adopts the control mode of macro-micro combination,to achieve the desired performance index.And the multi-motor synchronous operation of the macro platform in the X direction is the key to grab and card successfully,otherwise it can't realize stages exchanging.Therefore,in this paper,the synchronous control of the multiple-motors is studied from two aspects of synchronous control structure and synchronous control algorithm.A variety of control methods are applied to improve the synchronization performance of the system from different angles.First of all,applying the Euler-Lagrange equation,models for the dual stage macro platform system,and obtains the dynamic coupling model of the system,and then calculates the state-space expression,that is multi input and multi output system,served as the foundation for the following simulation experiment.Analyzing the disturbance factors existing in real systems,such as locating force,its approximate mathematical model is identified,that's served as the disturbance input on the simulation.Secondly,according to the actual requirements of the control system,the paper puts forward a double cross coupled control structure,the advantages of which are in case that the system exists synchronization errors,the interaction of the position controller of each subsystem together eliminates the error quickly,and when the system synchronization error is less than a certain value,will become the master-slave synchronization control structure,two subsystems are given from the same position controller,in order to ensure the synchronization effect of the system.And in Simulink,building a cross coupled control and double cross coupled control structure,then the simulation is carried out under the condition of disturbance input and no disturbance input,and the theoretical feasibility of the improved scheme is verified.Thirdly,in terms of the actual system's disturbance factors,and in order to improve the system's robust performance,put forward the whole integral sliding mode control,in which the initial state of the system is in the sliding surface,when the system enters the sliding surface,it mainly depends on the state feedback control to keep the dynamic performance of the system.Considering the constraints of the actual system's control input,and when the initial error is very large,the transient performance of the system will deteriorate because of integral Windup effect,and even cause instability of the system,so the nonlinear integral sliding mode surface was put forward.And the effectiveness of the design is verified by simulation.Finally,experiments were carried out on the dual wafer stage system,and here are the actual control effect of double cross coupled synchronous control,full integral sliding mode control and nonlinear integral sliding mode control: the whole sliding mode control algorithm is not dominant in the control precision,but the anti-interference performance is strong.And the nonlinear integral sliding mode control algorithm improves the system's transient performance on the basis of the whole sliding mode control algorithm.