Research On PID Controller Parameter Tuning Based On Casting Machine Hydraulic Servo Control System

Hydraulic servo control system is an automatic control system based on the hydraulic transmission and automatic control theories. It is famous for its excellent dynamic performance, has been widely used in industrial practice.In the actual application of the hydraulic servo system, PID control is widely used to improve system control performance. Since is produced, PID controller has been the most widely used in the process of industrial production and has been also the most sophisticated controller. All kinds of new type of controller are constantly emerging in the field of control. With the advantages of simple structure, easy implementation and strong robustness, PID controller is in a dominant position. One of the core problems is parameter tuning and implementation in the design and application of PID controller. Generally it need experienced engineers and technicians to complete and is both time-consuming and inefficient. Because the actual control systems vary widely and such as lag, nonlinear factors exist. So it is very difficult to tune PID parameters.In recent years, more and more people have paid attention to the PID controller parameter tuning. Meanwhile, at home and abroad appears a lot of complete parameter tuning theories. Ziegler-Nichols tuning method is simple and practical, is the basic PID parameter tuning method. Combing fuzzy decision theory and PID control is the basic idea of Fuzzy PID control that can play the advantages of the two. Its response is superior to the traditional PID control, and it has good robustness. Especially for the nonlinear and time-varying controlled object, it can obtain satisfactory control effect. Both particle swarm optimization(PSO) and genetic algorithm(GA) are optimization algorithm. They are trying to simulate the adaptability of individual species on the basis of the natural characteristics and have adopted certain transformation rules by searching space to solve problems in order to obtain a satisfactory performance of the PID controller.This paper is studied based on casting machine hydraulic servo system. First, it establishes the mathematical model of servo valve controlled asymmetrical cylinder system in the application of automatic control principles of the frequency analysis method. Secondly, using MATLAB/Simulink software for its simulation experiments, put PID control into the hydraulic control system and carry on simulation correction. Meanwhile, put the following four methods, for example Z-N、PID tuning based on the fuzzy adaptive、PID tuning based on the genetic algorithm、PID tuning based on particle swarm optimization algorithm, into the hydraulic control system and then start to tune respectively the parameters of PID controller. Finally by comparing the simulation results, PID control results based on the genetic algorithm tuning are superior to other methods and also meet the requirements of roll casting experiments.