Design And Research Of Vacuum Coating Control System

This paper summarizes the vacuum coating technology and the coating monitoring equipment at home and abroad.Compared with the foreign vacuum coating equipment,the domestic equipment needs to be improved in automation,film thickness control accuracy and equipment reliability.Based on analysis of key factors and technical difficulties affecting the film quality,a new design scheme of automatic vacuum coating monitoring system is proposed.The function principle,software and hardware selection,development environment construction,control algorithm improvement and monitoring interface design of the monitoring system are described.The design and implementation of monitoring interface and control algorithm improvement are introduced in detail.Through the development and design of the vacuum coating monitoring system,it can detect the deviation of evaporation rate and film thickness in the process of coating in real time,and provide users with real-time data of evaporation rate,real-time film thickness and control power,so that users can analyze the real-time data,so that users can quickly find the best control process.In short,it can improve the efficiency and quality of products in vacuum process and reduce the dependence of empirical parameters.The main contents of this research are as follows:(1)Running Linux system on the hardware platform with i.mx6 as the core,using software QT to design the monitoring system interface,which consists of three parts: function key control module,parameter information display module and control process parameter setting module.At the same time,the monitoring system defines10 programmable process membrane systems,in which all the necessary preconditions processing,deposition and subsequent condition processing variables for accurate deposition of materials are defined;including a material parameter library,in which each material is completely defined with four parameters: material name,chemical formula,density and Z-factor,which can be added or deleted by usersthemselves In addition,modify the material settings.(2)In view of the nonlinear,time-varying and time-delay characteristics of the temperature change of the evaporation source in the vacuum coating system,an improved control algorithm based on Smith prediction and variable universe fuzzy adaptive PID is proposed on the basis of the fuzzy adaptive PID algorithm.Based on the improved differential evolution algorithm,the transfer function of the vacuum coating temperature control system is identified,and the variable universe fuzzy adaptive PID algorithm and proportional control are combined to form the subsection control model.Finally,Matlab is used to verify the simulation results.The results show that compared with Smith predictive control and fuzzy adaptive PID control algorithm,the improved algorithm has the characteristics of short adjustment time,almost zero overshoot and no steady-state error.It has a better adaptive ability for the resistance heating vacuum coating temperature control system.(3)The self-tuning PID control algorithm can realize the real-time tuning of PID parameters to a certain extent by identifying the system model parameters based on the input and output data of the real-time acquisition controlled object.By using the excellent data processing ability of RBF and combining it with self-tuning PID control,the parameters can be adjusted online.This method is applied to the real-time control of the temperature of the evaporation source of the vacuum coating,so as to improve the control speed and accuracy of the temperature control system of the vacuum coating...