Instability and self-oscillations in electro-hydraulic servo drive

One of important problems of closed-loop hydraulic systems is ability of self-oscillations. Linear simulation shows unlimited growth of amplitude, but self-oscillations appear in a real hydraulic drive because of wastages, limits of endurance and oscillation energy. Main purpose of the research is to make a numerical simulation to correspond main parameters of self-oscillations of electro-hydraulic servo drive with characteristics of drive. Results of numerical simulation could be improved with transition to nondimensional variables. In this case several nondimensional complexes present whole hydraulic system instead of many variables and parameters in case of dimensional model. Main result is stability and amplitude of self-oscillations of electro-hydraulic servo drive depends of nondimensional variable Sh, if hydraulic time constant is more than mechanical time constant, then less oscillation energy applies to drive. Simulation model in this research is quite far from real electro-hydraulic servo drive, so improvement of simulation is purpose for the future researches.