Research On Motion Control System Of Precision Aerostatic Bearing Stage

The precision aerostatic bearing stage is the core component of precision machining equipment.It has a wide range of applications.With the development of linear motors and DSP controllers,the high-precision precision positioning stage with large stroke has a breakthrough development.The precise control of the aerostatic bearing stage is an important part of the research of precision aerostatic bearing stage.This paper takes the precision aerostatic bearing stage as the research object and studies how to improve the motion performance of the stage,The main contents of this paper are as follows:(1)Model analysis of the stage,including dynamic model analysis and motion control algorithm analysis.The working principle of linear motor and dynamics analysis are used to establish the X-axis transfer function model and the Y-axis gantry structure state space model,then from the perspective of control algorithm proposes a composite PID control for single motor drive and a position loop cross-coupled full coordination control for bilateral drive.(2)Control algorithm research and simulation,The composite PID control for single motor drive and the parallel control based on position loop cross coupling for bilateral drive are proposed.Simulink is used for simulation experiments.The simulation is compared with PID control algorithm and PIDVAFF control algorithm.It is concluded that PIDVAFF control has good effect on improving the dynamic characteristics of servo motion.Then traditional synchronization control method and traditional synchronization control method with cross-coupling control are compared.It proves that cross-coupling control has better control effect in reducing synchronization error.(3)Tuning parameter of the stage and experimental verification.Firstly,taking the Polaris system as the core build CNC system of the stage.The single motor control adopts the default control algorithm PID-VAFF control in Polaris controller,the synchronous control of the bilateral motor adopts full coordination control based on the crosscoupling of position loop.The synchronous control algorithm is written into the control system through the servo operation unit SPU inside the amplifier,comparing the synchronization error with and without the cross-coupling control,verify that the cross coupling control can effectively reduce the synchronization error.After continuous parameter optimization,the tracking error of the X axis is controlled at ±0.7μm,and the tracking error of the Y axis is controlled at ±1μm.The measurement and positioning accuracy compensation is performed by the laser interferometer,so that the positioning accuracy of the stage X-axis is 0.914 μm within 100 mm stroke,and the Y-axis positioning accuracy is 1.2 μm.