Hydraulic serve system is wide used in the industry machine due to its high ratio of power and volume, move placidity, high speed of dynamic response. The position precision and moving stability of hydraulic cylinder controlled by servo valve system is important to the whole system. The flow and the pressure of the load are the key to establishing the mathematics’ model for the drive mechanism. Therefore research for control strategy of servo system has the very important meaning.After consulting numerous related literatures and reference materials at home and abroad, the outline and current trend of domestic and oversea cylinders controlled by the servo valve is summarized in this paper. And show the variable kinds of the compensation measures and their deficiency. Based on these, the research of direction of this thesis is determined.In according with the research actuality of the cylinders controlled by the servo valves system, this paper discussed the flow and the pressure of the load and upon this established the models of the asymmetry mechanism including symmetry valve and asymmetry valve. This paper also established the transfer function of oiitput displacement, load pressure and working pressure. The asymmetry performance comparisons were made between the two situations and gave a plain introduction of its compensations according to the asymmetry performance and pressure jump.In view of the asymmetry performance and pressure jump of the asymmetry mechanism, PID, speed and acceleration feedback is adapted to get the export precision and stability of the working pressure, diminish the asymmetry performance of the displacement in two directions. This paper does some simulation and experimental research according to these control measures. The results proved that these measures could perfectly compensate the asymmetry characteristic, cut down the disturbance of the system and improve the export preference. In order to diminish the interfere of disturb, the unchangeable structure principle is adapted to solve this problem.According to the principle of the compensation and the asymmetry characteristic of the asymmetry cylinder, order an asymmetry servo valve matched with the cylinder. And finally do plenty experiment on the motion system prototype and comparison the two systems.
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