Composite Control And Error Compensation Of Macro-micro Vertical Motion Stage

In the field of microelectronics manufacturing,vertical motion stage has a wide range of applications.With the development of precision technologies such as white light interference scanning,the vertical motion stages also are required with large motion stroke and high precision positioning.However,traditional single drive platforms have difficulty to meet the requirements of large stroke and high precision at the same time.This paper aims at the highprecision positioning of the macro-micro vertical motion stage,and studies the macro-micro control algorithm,the macro-micro collaborative control strategy and the error compensation.We proposed a super-twisting control algorithm with boundary layer for macro motion stage by permanent magnet linear synchronous motor and designed the macro-micro composite positioning strategy.Meanwhile,the displacement conversion error of vertical platform is compensated through position compensation table and online compensation.The control system of the experimental stage is built based on the Power PMAC controller,and the micro motion performance test and macro-micro composite positioning experiment are carried out.The main research contents of this paper are as follows:(1)Based on in-depth investigation of the domestic and foreign research status of precision motion stage,this paper analyzes the needs and key technologies of vertical motion stage,and clarifies the work contents and technical solutions of this paper.(2)The dynamic model of linear motor macro motion system is established,and the model parameters are identified by using the chirp signal sweep method.At the same time,the dynamic analysis of the micro motion system is carried out,and the electromechanical coupling model is established,which lays the foundation for the precise control of macromicro system.(3)For the linear motor macro motion stage,a second-order sliding mode controller based on the super-twisting algorithm with boundary layer is designed to improve the antiinterference performance of the system.The boundary layer method is used to further weaken the chattering effect of sliding mode control,and the effectiveness of the proposed method is verified through simulation and experiment.Meanwhile,a double closed-loop control structure based on PID control is built for piezoelectric micro motion stage.And according to the requirements of the vertical motion stage,the collaborative control strategy of macro-micro composite positioning and composite stepping is designed to realize the high precision positioning and nano displacement stepping.(4)Aiming at the displacement conversion error of the wedge structure,an online error compensation method is proposed through the position compensation table.The displacement feedback of the vertical axis stage is added to the servo control loop of the horizontal axis linear motor system to correct the command displacement of the horizontal axis.And the validity of the error compensation method is verified through experiments.(5)Based on power PMAC,the control system of macro-micro vertical motion stage is built and the proposed method and strategy are developed and implemented.Micro motion performance test and macro-micro composite large stroke positioning experiment are carried out to verify the performance of the vertical stage and the effectiveness of the proposed method in this paper.