Research Of Control Strategy Based On The Electro-hydraulic Proportional Position Control System

During the recent years, with the development of engineering machinery and metallurgical machinery, the hydraulic position control system of high precision becomes more and more urgent. The basic requirement of the hydraulic position control system is that the system can reach a given displacement quickly and accurately, which asks high precision, short time, small overshoot, high reliability and strong anti-interference capability. With the development of the electro-hydraulic proportional control technique, the electro-hydraulic proportional valve gradually replaced the servo valve because of its low cost and good anti-contamination capacity. The electro-hydraulic proportional valve can control the flow and direction by computer, so the electro-hydraulic proportional valve can be widely used in many areas especially in industrial area.According to the subject, we design the experimental platform for the study of electro-hydraulic proportional position control system in order to research the control strategy and performance of the control system. The implementation of the system can adopt the signal rod hydraulic cylinder, and then accord to the features of experimental platform we design the high performance controller to make research on the arbitrary point positioning and continuous trajectory tracking. During the study, research working includes two respects:the theoretical research and experimental demonstration.Firstly, analysis the structure and working principle of the position control system, and design the electro-hydraulic proportional position control system control software system, build the system hardware platform, then analysis the system model, establish the mathematical model of each component of the system. This mathematical model indicates that this system is a high order nonlinear system. Simplified the mathematical model, we can get the transfer function of system.Secondly, According to the control theory, after analysis the characteristics of nonlinearity and time-varied, we design the fuzzy self-tuning PID controller based on the fuzzy PID control strategy, and make simulink/Matlab simulation with the conventional PID control. In view of the convenient graphic programming language, we write the control software of system by adopting mixing Labview and Matlab programming. Then, make simulation on the step signal, square wave signal and sine signal response. By comparing the control curve of PID control and fuzzy PID control, we know that the fuzzy PID control has better advantages.Thirdly, establish the system experimental platform and software control interface, including electro-hydraulic control section, the microcomputer control part of hardware and software design. We write the Labview programming and build the man-machine control interface. After testing the main laboratory equipment, we make experiments on the electro-hydraulic proportional position control system and get the equipment dates, analysis this dates and compared with the simulation results, at last, we obtain the conclusions.Finally, the work of this study is summarized. For the shortages and disadvantages still existing in the study, some suggestions and expectations are put forward for further research.