Research On Digital Hydraulic Agc System Based On The Control Of Highspeed On-off Valve

In recent years, with the increasing attention of country for numerical control generation and intelligent manufacturing, the electro-hydraulic digital control technology has been rapid development and widely application. The high-speed on-off valve as an important component in the numerical control system, its application field is becoming more and more widely. This article presents the idea of making high-speed on-off valve instead of servo valve to be used in hydraulic AGC system of rolling mill, and realizes its digital control.The article researches the problem of flow control imprecise for high-speed on-off valves deeply. At first the article analyzes the valve core's movement characteristic and flow control characteristic of high-speed on-off valves. And then conducts the linear transformation of duty ratio formula and establishes the PWM control model based on linear transformation of duty ratio. At last carry out the simulation and experimental research for the control model. Through the simulation and experimental research, we can know that the PWM control model based on linear transformation of duty ratio can solve the problem of flow control imprecise of high-speed on-off valves. And then realizes the precise position control of the hydraulic cylinder.The article establishes digital hydraulic AGC system in rolling mill of laboratory based on characteristics of the hydraulic AGC system and the high-speed on-off valve. And then mathematical modeling and simulation analysis are carried out for position closed loop of the hydraulic AGC system. In order to realize the purpose of quickly and accurately position control of the hydraulic cylinder controlled by high-speed on-off valve, the article research position control methods of the digital hydraulic AGC system according to the idea of combining the traditional PID controller and the fuzzy adaptive PID controller with the PWM control based on linear transformation of duty ratio respectively. And then the position control characteristics and dynamic characteristics of the hydraulic AGC system are analyzed and compared with above two control methods.Through the analysis and comparison, we can know following conclusions, above two control methods can realize the purpose of quickly and accurately position control of the hydraulic cylinder; The system based on fuzzy adaptive PID controller has better dynamic performance and faster response contrasting with the system based on traditional PID controller.In a word, above control model and position control methods can provide a new research idea for the digital control of hydraulic AGC.