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Direct Drive Volume Control (DDVC) electro-hydraulic servo system which is named valveless electro-hydraulic servo system, has the advantages of flexibility of motor control and high power of hydraulic servo system. In contrast to traditional electro-hydraulic servo system, it has stronger anti-pollution, higher efficiency, smaller integration, more convenient and economical operation. It has been widely used in many areas. But the weakness of dynamic performance restricts its further application. Therefore, it is great significant to study of the DDVC electro-hydraulic servo system to enhance the performance of the system.Magnetic Resistance displacement sensor, which is based on the magneto-resistance effect, has strong abilities to anti-earthquake, resistance of high-temperature and low-temperature, low-wear, long-life, low demand of the work environment, thus it is the ideal detection component for the electro-hydraulic servo linear displacement system. Especially, it has a very strong applicability in the mining machinery, engineering machinery and mechanical operation environment.In this paper, the fuel tank of the straightly electro-hydraulic servo-drive with the MR displacement sensor is researched. Firstly, analysis the internal working mechanisms of the MR displacement sensor, structure principles, and the circuit of the sensor signal processing. Secondly, study the role of the magnetic tag-foot rod.At the same time, analysis the principle of the pump-cylinder hydraulic power structure. the establish the AC servo motor mathematical model, set up the direct drive electro-hydraulic servo-system model, discuss the parameters impaction to the system performance, and do the computer simulation study. Then, complete the process of PID controller on the test bed.In addition, build the asymmetrical-cylinder closed-loop test-bed; take some measures to reduce the adverse effects of the external factors. Lots of experiment verify the correctness of the mathematical model.
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