Research Of Electro-hydraulic Position System Based On High Speed On-off Valve Pilot Control

Electro-hydraulic position control system is one of the most important parts of the auto-control field, and it gets widespread application in the industry. With the development and the widespread application in more area, control precision and response speed of the electro-hydraulic position control system are required higher and higher. So, the digital hydraulic component appears. It can be controlled by computer directly and is delegated by high speed on-off valve. The thesis has a detailed analysis to the work principle of the high speed on-off valve. Firstly, the physical characteristics of the electromagnetism part are studied by the method of magnetism route analysis and the mathematical model is established. Based on this, the opening and closing response curves of the high speed on-off valve is gained by simulation. Due to the shortage of its small flux, the thesis puts forward the design scheme of the electro-hydraulic position control system which is using the high speed on-off valve as the pilot valve and the hydraulic control valve as the magnified level. Then, the structure and the work principle are illuminated in detail. After analyzing the physical characteristic of each component, the mathematics model of the whole system and each sub-loop are established, therefore, the performance capacity and the reliability have been proved.Because the electro-hydraulic position control system is a complex system which is integrated with mechanism, electricity, and hydraulics. It possesses the characteristics such as nonlinear, time-varying, great dynamics and great power. The traditional classical control theory has some difficulty to ensure the control effect of the electro-hydraulic position control system. Therefore, the fuzzy PID control strategy which is combined the fuzzy control theory and the traditional PID control theory is applied to the electro-hydraulic position control system. The high performance fuzzy PID controller which use the single-chip as the main controller and the high speed on-off valve driving circuit which is based on PWM control mode are designed. The simulation result indicates that the new type electro-hydraulic position control system using the fuzzy PID controller has many characteristics such as high response and strong adaptive capacity.This thesis has the magnitude significance to the design, manufacture and control of the electro-hydraulic position control system.