| With the coming of the post-Moore era,the development of semiconductor products has shown the characteristics of miniaturization,lightness and thinness,as well as high density,which puts forward higher performance requirements for semiconductor packaging equipment.The X-Y motion platform is a typical core moving component in semiconductor packaging.In order to effectively adapt to the changing trend of semiconductor products,it is necessary to realize the high-precision positioning of the X-Y motion platform under conditions of highspeed and high-acceleration.However,the high-speed and high-acceleration motion characteristics will inevitably arouse residual vibration in the positioning stage,making it impossible to achieve the required positioning accuracy in a short time,and seriously affecting the fast and precise positioning performance of the motion platform.In addition,in the industry,some controller parameters are difficult to optimize under the guidance of theory,and often tuned by the way of manual trial and error,which is time-consuming and labor-intensive in a mass production situation.This article focuses on the precise positioning of the high-speed and high-precision XY motion platform and the rapid tuning of the controller parameters.To begin with,the motion planning of the point motion is studied,and the superiority of the highorder motion planning is analyzed from the perspective of the frequency spectrum,which can reduce residual vibration in the positioning stage from the source.Then,a compound control strategy combining three closed-loop PID and velocity-acceleration feedforward are proposed with a PID controller design method based on root locus and stability margin orientation,so that the system can move at high-speed and high-acceleration conditions to achieve fast and precise positioning motion.Finally,a fuzzy intelligent tuning method is proposed,which is used to automatically optimize the speed and acceleration feedforward parameters to realize the fast and intelligent tuning of the feedforward parameters.The main research contents of this article are as follows:(1)Do deep research on the current domestic and foreign research status of the X-Y motion platform for semiconductor packaging,clarify its difficulties and key points when realizing fast and precise positioning motion,and put forward the technical solutions and research ideas of this article at last.(2)Build a high-speed and high-precision X-Y experimental platform,use the VS compilation environment to develop an API-based PC software,and write bottom control algorithm based on DSP,which provides software and hardware conditions for the normal movement of the platform and related algorithm verification.At the same time,based on the dynamic analysis,the mathematical model of the single motion axis of the X-Y platform is established.Besides,the motion axis is systematically identified by the sine frequency sweep method,and its openloop transfer function is obtained,which lays the foundation for the subsequent compound controller designing.(3)In view of the problem of large residual vibration in the positioning stage,the motion planning of point motion is studied to search the type of motion planning suitable for highspeed,high-acceleration and precise positioning.Through experiments,the response of the system under several common motion planning curves is compared.And then the fast Fourier transform method is used to analyze the difference of the curve following effects of various curve orders.The research results show that the increase in the order of motion planning can effectively reduce the residual vibration in the positioning stage.Considering that if the order is too high,it will bring a huge amount of extra calculation and lead to poor real-time performance,the third-order to fifth-order S-curve motion planning is more suitable for precise positioning movement under high-speed and high-acceleration conditions.(4)Aiming at the problems of long stabilization time and poor positioning accuracy caused by residual vibration and noise in the positioning stage of the XY platform under high-speed and high-acceleration conditions,a compound control strategy combining three-closed-loop PID and velocity-acceleration feedforward and a design method of PID controller based on root locus and steady-state margin orientation are proposed,and a series of verification experiment of precise positioning of XY platform are also conducted.In order to enable the system to achieve precise positioning and high anti-disturbance capabilities,a three closed-loop PID feedback control of "current loop + speed loop + position loop" is designed and constructed,and the PID controller is theoretically designed based on the method of root locus and steadystate margin orientation.At the same time,the speed-acceleration feedforward control is added to form a compound control method,which further improves the rapid response capability of the system and indirectly reduces the positioning stabilization time.Combining the research results of point motion planning and fuzzy tuning of feedforward parameters,a precise positioning experiment is carried out on the experimental platform.Experimental results show that under the conditions of acceleration 4g,speed 0.4m/s,and movement distance 12 mm,the position error of XY motion platform while doing point movement can be adjusted to 10?m within 5ms,and the steady error is ±2?m,which satisfies the high-speed and high-acceleration precision positioning requirements of general semiconductor packaging,and has verified the effectiveness of the proposed control scheme.(5)Aiming at the problem of time-consuming and labor-consuming manual trial and error method for compound controller parameter tuning in mass production,a feedforward parameter intelligent tuning algorithm based on fuzzy control is proposed and verification experiments are carried out.Firstly,explore the influence law of speed feedforward and acceleration feedforward with the various indicators to system response through experiments.Then,formulate a fuzzy rule table of feedforward parameters combining with the dynamic characteristics of the system.Finally,develop the fuzzy tuning algorithm into a simple and easy-to-use PC software using MFC and carry out a series of verification experiments.The experimental results show that given PID parameters,the proposed fuzzy tuning algorithm can search the relatively optimal velocity feedforward and acceleration feedforward parameters within 34 s,which is much less than the manual trial and error method,verifying the effectiveness of the fuzzy intelligent tuning algorithm for feedforward parameters. |
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