Singularity Analysis of A New Spatial Three-DOF Parallel Mechanism

This paper presents a new spatial 3-DOF parallel manipulator with two degrees of rotational freedom and one degree of translational freedom, consists of a base plate, a movable platform, and four connecting legs. Each leg is a closed-loop subchain and symmetrical six-bar spherical metamorphic mechanism. The concept of generalized kinematic pair and screw theory are used to investigate the terminal constraints of its connecting legs, containing closed-loop subchain. Considering the geometric characteristics of the manipulator, the singularity criterion of the manipulator is derived based on the dependency of the screw system, and the existing conditions of the singular configuration are determined.