Joint Space and Workspace Analysis of a 2-DOF Spherical Parallel Mechanism

This paper deals with the joint space and workspace analysis of a two degree of freedom spherical parallel mechanism designed to be used to handle an endoscope. This mechanism is composed of the three legs (2USP-U) to connect the base to a moving platform. As the manipulator can get up to six solutions to the direct kinematic problem (DKP) in four aspects, non-singular assembly modes changing trajectories may exist. The aim of the paper is to check whether a regular workspace centred on home pose can be defined in such a way that no such trajectory exists in this workspace.