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This article introduce a kind of displacement sensor and the matching circuits with it. The sensor can be used to measure the displacement of cartridge insert valve in the medium of pressure with amplitude ranged from 0 Mpa to 32 Mpa.

Paper illustrates a steering system of a lifting robot vehicle which is used for assembling and disassembling the active wheel of blower mill in power station. The whole steering system is controlled by a microprocessor. The axles of the four wheels are driven hydraulically. Proportional valves, which are controlled by the output signals of microprocessor calculated from the rotation angle of steering wheel, are used to control the flow into the cylinder. The step response of the system is calculated by digital simulation and the calculated result is compared with the experimental result, They are close to each other.

Base on the experience of practical operation and the results of model test, paper points out the features of tensioner hydraulic system and two main troubles that often cause the damage of hydraulic components. The mathematical model of the system is analyzed and the pressure response is calculated with respect to the step input of torque on hydraulic actuator. This calculated result agrees with our experimental result. For overcoming the shortage of pressure impulse, the measure of “prebuilding up pressure” is suggested, which was tested in our laboratory. The test proofs that this measure can effectively prevent pressure impulse caused by starting under full load.

When the speed of actuator is quickly changed in hydraulic system, the great pressure surge and noise are generally caused. In this paper, the optimal control for the minimum pressure surge in shortest speed conversion time is approached. The optimal control is obtained by applying the Pontryagin's Maximum Principle. Experimental results and simulation calculation show that using the optimal control can reduce the pressure surge to about 5 times in comparison with that of step input.