PID Parameter Optimization Design Based On Matlab And Electro-hydraulic Proportional System

Process control has become one of the most important branch of the automation technology in the production process with its development. And the PID control has become the essential part of the process control, whether the final control effect can meet requirements or not is determined by the PID parameter obtained. However, the tuning of PID controller parameters has been a perplexing problem, in generally speaking, which is completed by experienced engineering and technical personnel, resulting in laborious, time-consuming, poor effect. So it has important theoretical significance and practical value for the PID parameter optimization design.PID controller is constituted of the proportional, integral and differential, which affect on controlled process throughing the linear combination of outputs of the controller with the use of their respective advantages. In the field of industrial control, a variety of new emerging controller springing up, but PID controller is still in a dominant position with the advantages of simple structure, reliable performance, strong robustness and so on. The limitation of its control is decided because of the simple structure of PID controller, each parameter value is changed as the controlled object is different, and the requirement of control performance is higher. In order to quickly, effectively setting out the best parameter value of PID controller, this paper attempts first to establish mathematical models of the electro-hydraulic proportional control system based on pressure and position, then the simulation experiment is made using simulink, fitting the curve to search for the correlation model between parameters and the system overshoot and the convergence time, then simulation model is tested and revised which is established by simulation experiment, based on what is to design the best parameters of the system of PID controller tuning.First of all, taking the electro-hydraulic proportional control system based on pressure and position as the research object, the mathematical model of the control system is established, and the parameters of PID controller is determined by the simulation experiment. Using single factor method for the simulation experiment, first, simulation experiment is made taking shortest convergence time as control target, determined the best value of P; the P value is maintained constant, and simulation experiment is carried out with the control target of overshooting, then curve fitting of the experimental is obtained with data points by Matlab to determine the correlation model between parameters and the system overshoot and the convergence time, the correlation model is established respectively.Then, closed loop control system of the electro-hydraulic proportional control system based on pressure and position were built with taking the FESTO hydraulic test device as the platform, then the sensor and the PID controller were connected to the system. According to the steps of the simulation experiment, the correlation model established on simulation test were verified and revised, which is obtained by output the displacement and pressure variation through the oscilloscope.Through the experiment, the function relationship is got between parameters and the system overshoot and the convergence time. Finally, the optimization objective is taken as the shortest overshoot and the convergence time, the three parameters of PID controller is adjusted using the correlation of the established simulation experiment, and the best combinations of parameter value of P, I and D is adjusted only two times, the PID parameters are optimized, which makes the adjustment of process parameters is more rapid and accurate.