Finite Element Model of Kinematic Pair Clearances of Elastic Linkage Mechanisms

Abstract

The elastic deformation of the links in robot mechanisms affects the precision of their motion and fatigue strength. Kineto-elastodynamics (KED)-the dynamics analysis of mechanisms that considers the elasticity of their links-emerged early in studies of mechanisms and has been the subject of extensive research and applications since. However, there have been no reports on the effects of kinematic pair clearances on the elastic vibration of mechanisms. This is mainly because no finite element (FE) model has been developed for describing kinematic pair clearances in KED research of elastic linkage mechanisms. In this study, an FE model was proposed for describing kinematic pair clearances. The mass matrix of the model was obtained by considering the lumped masses of the pin and bearing. The stiffness matrix of the model was obtained based on the moduli of elasticity of the pin-bearing pair. The model was applied to KED modeling and was verified through simulation and complementary experiments. The results show that the model is suitable for KED research of elastic linkage mechanisms with small kinematic pair clearances but not suitable for those with large kinematic clearances. Our FE model of kinematic pair clearances may be useful for investigating the vibration of elastic-body robot mechanisms.