Design and Analysis of a Redundantly Actuated Spherical Mechanism with Application to Needle Insertion

Abstract

A redundantly actuated parallel haptic device having 3-DOF spherical motion and 1-DOF needle insertion is proposed. The mechanism consists of one translational motion for prismatic joint on the platform and four serial sub-chains that are connected in parallel to the platform. Particularly, all joint axes of the mechanism are placed to have a common intersection point securing that all joint motion spaces of mechanism are confined within the 3-DOF spherical motion spaces. The position and kinematic analysis of the mechanism are performed. Also, its kinematic characteristics are investigated through simulation in aspects of singularity and two kinematic design indices. The kinematic performances of the proposed haptic module involving one redundant actuator are shown to be improved by comparison of the nonredundant module. The developed mechanism can be employed as a haptic device for a needle insertion problem, which emulates 3 DOF rotational motions and one DOF force reflection. Experiment has been conducted successfully by interfacing the haptic device to a virtual space for needle insertion.