Singularity Analysis and Dimensional Synthesis of a 2R1T 3-UPU Parallel Mechanism Based on Performance Atlas

Abstract

In this paper, a symmetric 3-UPU (U and P represent universal and prismatic joints, individually) parallel mechanism and its variant mechanism under different geometric and assembly conditions are analyzed. Both have two rotational and one translational (2R1T) DOFs and do not involve any parasitic motion. First, the kinematic performance of the mechanisms is discussed based on the motion/force transmission index and constraint index. Then, the singularity of the mechanism is analyzed systematically based on the local performance atlases, performance curves, and the screw theory. Finally, the global design indices are determined in accordance with the local performance indices in consideration of the motion/force transmissibility and constrainability to achieve the dimensional optimization of the 2R1T 3-UPU parallel mechanism.