Design and Kinematic Analysis of a Flexible-Link Parallel Mechanism With a Spatially Quasi-Translational End Effector

Abstract

Intrinsic passive compliance of flexible-link parallel mechanisms makes them suitable for situations where compliant manipulation is necessary. In this work, through using elastic rods as limbs, a flexible-link parallel mechanism whose end effector can move translationally with a large workspace is proposed. The middle plate and end effector are connected to the base via two groups of three elastic rods, which are arranged in a cylindrically symmetric way with a phase difference of 60 deg. Concurrently, the middle plate is coupled with the elastic rods connected to the end effector via sliding connection. Besides, a rotating set of coplanar wheels is introduced to provide smooth coupling for the prototype. Three actuation modules are used to drive the end effector, while another three to compensate toward its configuration deviations caused by deformation compatibility. Then, based on principal axes decomposition of compliance matrix, kinetostatics models for inverse and forward kinematics are established. The numerical analysis reveals that the end effector can make quasi 3-degrees-of-freedom (DOF) translation in a large space with extremely small twist. Finally, workspace experiments at four typical slices and pose accuracy evaluation along continuous trajectories are carried out, and the results demonstrate that our design and theoretical model are correct.