Design And Application Of Control System Of Precision Double Side Polishing Machine

The precision double-sided polishing machine polishes the two surfaces of optics simultaneously,which can effectively improve machining efficiency.The key factor for the double-sided polishing machine to achieve precision machining is the precise control of the polishing disk rotating speed.At present,the control system used in double-sided polishing machine tend to be special numerical control systems(such as Siemens 840D),which integrate the PI or PID control strategy,and connect to servo motor driver through field bus.The speed control of polishing disk can be realized through only a minimal amount of code and configuration.However,the professional CNC systems cannot effectively integrate selfdeveloped advanced control strategy,so it may has some defects such as oscillation and weak anti-interference ability in applications requiring high control accuracy and robustness.In order to solve this problem,this paper carried out a research on the speed control method of the polishing disc of the double-sided polishing machine based on the linear active disturbance rejection control strategy(LADRC).The main research work includes the following contents:1)Based on the working principle of double-sided polishing machine,the overall scheme of the control system is designed.The hardware design scheme is given from three aspects of motion controller interface,network communication and electrical schematic,and the software architecture of the control system is described in detail.2)In this paper,the physical characteristics,mathematical modeling and traditional control method of the rotating motor of polishing disk are studied.Based on the theoretical research of ADRC control strategy,a LADRC controller model for the speed control of the polishing disk rotating motor is proposed.The simulation results of the traditional PID controller and LADRC controller for the polishing disc rotating speed are analyzed on MATLAB,which show that our LADRC controller can make the speed servo system of the polishing disk quickly enter the steady state without overshoot,and improve the antiinterference ability to ensure the stable operation of polishing disk.3)With a focus on the programming realization of the LADRC strategy on Siemens SIMOTION motion controller,the LADRC control function module based on the ladder diagram language is developed.The step response and disturbance suppression experiments of the polishing disk under the traditional control strategy and LADRC strategy are carried out in actual machining process.The experimental results reveal that,compared with the general numerical control system based on the traditional control strategy,the speed servo system based on LADRC controller has less adjustment time and smaller speed fluctuation in the speed servo system with strong mechanical coupling and a variety of unknown disturbances,shows significant advantages in variable speed tracking and anti-interference ability.