ResearcResearch Of Electro-hydraulic Proportional Position Control System

In the development process of modern metalwork equipments and engineeringmachines,more and more urgent require for the technology of the hydraulic positivecontrol.In recent years,with the development of the proportional control technique,theelectro-hydraulic proportional valve gradually replaced the servo valve because of itslow cost and good anti-contamination capacity.Based on characters of system and control strategy,the control syetem performancehas been designed that can be used for researching of electro-hydraulic proportionalposition control.The performance uses proportional valve and the matching proportionalamplifier to drive the hydraulic cylinder motion.Using USB-6008 data acquisition cardproduced by Amearican company NI,and using LabView8.5 programming on computeras the human computer interface.According to the electro-hydraulic proportional controlcharacters,the mathematic models on the different parts of system is established,themodel shows that the system is high order and nonlinear.For the system's requirements, the PID control algorithm and fuzzy controlalgorithm are mainly researched and the corresponding computer program iscompiled.In the experiment, according to the results of the experiment, the experimentalparameters are adjusted in real time to obtain the best control effect.Experimental result shows that the fuzzy control has basically eliminated theasymmetry of the hydraulic cylinder motion by the method of compensation of deadzone and the effect of fuzzy control control is better than PID in fast,accuracy andstability.Fuzzy control system error in the±1mm,the control precision is higher than99.1%.PID control system error in the±1.5mm,the control precision is about 98.3%.In rapidity,it needs 7 to 9 seconds to reach the steady of the system when usedPIDcontrol,but if used fuzzy control it only needs 3 to 4 seconds.In the wholeexperiment,fuzzy control isn't shocked.It reflects that has the advantage of robust,especially suitable for the system of nonlinear, time-varying and pure delay.