Dynamic characteristics of electrohydraulic servosystems exciting with square-like pressure wave

摘要

This paper uses the square-like wave produced by square pressure wave generator to excite the electrohydraulic servosystem and simulate the aeroservoelasticity, so as to evaluate the dynamic characteristics of electrohydraulic servosystem after exciting by high frequency square-like pressure waves. Such a simple hydraulic testing system can replace the resource-consuming wind tunnel test of aeroservoelasticity. In the system, a PID-controller is employed to give electrohydraulic servovalve a command via AD/DA interface card in order to drive the actuator. In the meantime, the square-like pressure wave of the different pressures and frequencies produced by square pressure wave generator would forcefully excited the actuator. Then linear variable differential transformer is used to measure the displacement of the actuator, ultimately achieving the feedback signal and positioning of the actuator. The results show that the electrohydraulic servosystem system is unstable and uncontrollable when the external static pressure approaches the pressure of electrohydraulic servosystem. Raising the frequency of the exciting can reduce the amplitude of the actuator at positioning. However, as the frequency of exciting is at a certain particular region, the amplitude will achieve the maximum value. During this time, the positioning of the actuator which is controlled by electrohydraulic servosystem becomes unstable. Apart from developing a new testing method of the dynamic characteristics of electrohydraulic servosystem, this paper makes an in-depth dynamic analysis of electrohydraulic servosystem.