Kinematic Analysis of a Novel Three Degree-of-Freedom Planar Parallel Manipulator

In this paper, a novel unsymmetrical five–four bar Planar Parallel Manipulator (PPM) with three Degree-of-Freedoms (DOFs) is proposed, the new manipulator is composed of a double-layer five-bar part with a four-bar part located in between. Targeting for the application of Chinese dish cooking machine, the detailed kinematics analysis for the new PPM is developed. Different from traditional three-DOF PPM, the manipulator has only four assembly modes. In orientation workspace analysis, the workspace map is shown to be an annular zone. The two-point velocity method is used in dexterity analysis to solve the inhomogeneous problem, and the five–four bar PPM exhibits good dexterity. By analysis of both Inverse Kinematics Singularity (IKS) and Direct Kinematics Singularity (DKS), the distributions of the singular curves in workspace are obtained, the DKS analysis also reveals the similarity between the DKS and the direct displacement analysis: the related analysis can be decomposed into a four-bar part and a five-bar part respectively. All the analysis presented in the paper can facilitate the dimensional synthesis and trajectory planning for the manipulator.