Kinematics and Orientation Workspace of a 3-DOF Parallel Robotic Wrist Actuated by Spherical Four-Bar Linkages

Abstract

This paper presents a three-degree-of-freedom fully parallel robotic wrist and its preliminary kinematics. This mechanism actuated by spherical four-bar linkages originates from a spherical parallel manipulator with co-axial inputs. The inequalities to determine the orientation workspace is derived and numerically illustrated, which shows that the manipulator can have large rotation angles, particularly, the twist angle of the end-effector. A 3D-printed prototype is built to validate the conceptual design.