Research And Application Of Iterative Learning In Linear Servo System

Linear servo system serves as the core part of the motion table control system for semiconductor testing equipment.To attain accurate tracking of the motion trajectory of the semiconductor detection equipment’s motion table,while minimizing stability time of the motion table axis and finally enhancing the semiconductor detection equipment’s yield,it is imperative to investigate and meet the needs of developing a linear servo system.In this paper,we studied on the motion table of semiconductor detection equipment.We improved the filter type iterative learning control algorithm to reduce the motion stability time of the motion table,and designed a fast and stable control algorithm for the linear servo system by implementing the piecewise PID control approach.Study aims was to enhance the control performance and stability of the system.Works following below:Firstly,we analyze the mobile plinth of the semiconductor inspection tool and determine its mechanical vibrational frequency.In addition,we obtain the amplitude-frequency and phase-frequency characteristics of the system by applying white noise.Further,fit the mathematical model of the controlled apparatus with utmost precision.Lastly,proceed to both motion table interference analysis and pragmatic measurement.Secondly,we proposed a method to calibrate the initial phase angle of linear motor,and simulated and tested it on an actual motor.Furthermore,the firmware for motion control of the linear servo system has been designed.This firmware is primarily utilized for governing the motion control of every axis within semiconductor testing equipment.Thirdly,we selected piecewise PID and filter type iterative learning control approach strategies to enhance the efficiency of axial motion stability.The servo control system’s software and hardware platform has been established,and the efficacy of the piecewise PID and filter iterative learning control strategy has been tested and validated on the motion platform of semiconductor detection equipment.Experimental assembly reveals the implementation of piecewise PID control yields remarkable reductions in stability time during X and Y axis rough motion;these values were found to decrease from 260 ms to 82ms(a reduction of 31.5%)and from 142 ms to84ms(a reduction of 59.1%)respectively.Moreover,the integration of both iterative learning control algorithm and piecewise PID control further elevates the stability of the system.Specifically,the iterative learning control algorithm has been shown to improve the stability time of Y-axis rough motion from 80 ms to 59.8ms(a reduction of 74.75%)and Y-axis fretting from 125 ms to 77.6ms(a reduction of 62.08%).The improved trajectory tracking performance of the moving table in the semiconductor testing equipment is expected to boost the yield of this equipment tremendously.