Study On Theory And Experiment Of Nonlinear Dynamics Behavior Of Electro-hydraulic Servo System

For a long time, many scholars in the field of machinery and control have beenplagued by the nonlinear factors in the servo system. With the intensification ofinternational competition, the higher performance requirements of servo system are putforward increasingly. The covering areas include the actuator of high-power equipment,the precision machining of electronic equipment, and so on. The nonlinear factors reducethe system performance in a certain degree, and hinder the further improvement of thesystem performance seriously. Therefore, in order to improve the system performancethoroughly, it is necessary to reduce or eliminate the adverse effects of nonlinear factors.To achieve this goal, it is urgent to investigate the characteristics and mechanisms ofnonlinear factors. Furthermore, the laws of them impact on system performance should berevealed profoundly.The actuator of electro-hydraulic servo system was considered as the main researchobject of this paper. The modern nonlinear vibration theory was introduced intoelectro-hydraulic servo system. Based on the principle of the nonlinear dynamics，wefocused on the influence laws of nonlinear hydraulic spring force and nonlinear friction onmovement characteristics of electro-hydraulic servo system. The modeling, bifurcationand chaos analysis were performed to the nonlinear dynamic behaviors of hydraulic springforce and friction. Moreover, the coupling effect of them was also studied. Theapplicability of the models was validated through experimental research. The purpose ofthis study was to reveal the nonlinear vibration incentives of servo system and thenonlinear dynamics nature of the actuator movement.In this paper, some conclusions are obtained through theoretical study, simulationanalysis and experimental verification. The effect of nonlinear hydraulic spring force canbe described by Duffing equation, and the effect of nonlinear friction can be described byVan Der Pol equation. Moreover, the coupling effect of them can be described byDuffing-Van Der Pol equation. The nonlinear vibration of the electro-hydraulic servosystem in the working process is due to the interaction of the "jump phenomenon" caused by soft or hard hydraulic spring property and the limit cycle oscillation caused bynonlinear friction. This research presents important theoretical guidance and practicalengineering significance to improve the operation stability of the electro-hydraulic servosystem, and prevent system from producing nonlinear vibration.