Dynamic Analysis of a 3-RRR Parallel Robot With Joint Clearances Using Natural Coordinates

A general computational methodology for modeling and analysis of planar rigid multibody systems with multi clearance joints is presented. The contact points are important for contact detection, natural coordinate system is implemented to describe the rigid links in order to reduce the amount of calculation. The Lankarani-Nikravesh continuous contact-impact model is used to evaluate the contact force, in which energy dissipation in the form of hysteresis damping is considered. The improved Coulomb’s friction force model is used to describe the friction phenomenon between the joint components. Numerical results for 3-RRR mechanism with revolute clearance joints are presented and discussed. This methodology is further compared with the widely used reference coordinate system, the numerical simulation results show that the presented method is an effective and new method to predict the dynamic characteristics of planar mechanical systems with clearance joints.