中文摘要：

根据非线性动力学原理，建立电液伺服系统的非线性动力学模型，探索非线性弹簧力和非线性摩擦力等非线性因素对伺服系统运动特征的影响规律。通过理论研究，指出非线性弹簧力和非线性摩擦力的耦合作用特征可以用Duffing—VanDerPol方程描述。通过数值试验分析，发现系统外加激振力、阻尼系数和弹簧力非线性项系数的大小影响系统的运动状态，当三者参数变化时系统可能做极限环型振荡、倍周期运动和混沌运动。

英文摘要：

Based on the principle of nonlinear dynamics, system （EHSS） is established. Then, the influence laws （NF） on motion characteristics of EHSS are explored. the nonlinear dynamical model of electro-hydraulic servo of nonlinear spring force （NSF） and nonlinear friction Through the theoretical study, it is found that the coupling effect of NSF and NF can be described by the Duffing-Van Der Pol equation. Furthermore, by means of numerical experimental analysis, some novel phenomena are found. The motion state of EHSS is affect by some parameters, such as exciting force, damping coefficient and the nonlinear term coefficient of NSF. As the parameters change, EHSS may do limit cycle oscillation, multi-periodic motion or chaotic motion.