Abstract: Aiming at the problems that it was difficult to establish the vibration model of the complex space mechanisms, a simple modeling method of the vibration model of the parallel pointing mechanisms was proposed based on the number axis method, and the feasibility of the method was proved by the ANSYS modal analysis. In order to study the dynamic influences of the clearances of the kinematic pair on the modal characteristics of the mechanisms, considering the residual stiffness of the kinematic pairs, an improved method for establishing the nonlinear equivalent stiffness coefficient of the kinematic pairs with clearances was proposed. The improved nonlinear equivalent stiffness coefficient was embedded in the mechanism vibration model, and a nonlinear vibration model was established considering the clearances of the time-varying kinematic pairs. The ADAMS was used to simulate the dynamics of the mechanisms considering the clearances. According to the simulation data, the nonlinear modal characteristics of the mechanisms affected by the time-varying clearances were analyzed. The research results may provide a theoretical basis for the dynamic performance optimization, vibration suppression and fault diagnosis of the parallel pointing mechanisms.

Key words: vibration system modeling, residual stiffness, clearance of kinematic pair, nonlinear modal

摘要： 针对复杂空间机构的振动模型难以建立的问题，基于数轴法提出一种简便的并联指向机构振动模型建模方法，利用ANSYS模态分析证明了该方法的可行性。为了研究运动副间隙对机构模态特性的动态影响规律，考虑运动副残余刚度，提出了含间隙运动副的改进非线性等效刚度系数建立方法。将改进的非线性等效刚度系数嵌入机构振动模型，建立了考虑时变运动副间隙的非线性振动模型。利用ADAMS对考虑间隙的机构动力学进行仿真分析，根据仿真得到的间隙数据对受时变间隙影响的机构非线性模态特性进行分析。研究结果可以为并联指向机构的动态性能优化、振动抑制和故障诊断提供理论依据。

关键词: 振动系统建模, 残余刚度, 运动副间隙, 非线性模态