Analysis of the internal torque and bending moment acting on the legs of the 3-UPU translational parallel manipulator

The 3-UPU Translational parallel manipulator, where U and P are for universal and prismatic pair respectively, is a very well known manipulator. Many studies have been reported in the literature on singularities, workspace and joint clearance influence on the platform accuracy of this manipulator. Since the stiffness is one of the most important characteristics of parallel manipulator which is related to the torsion and the flexion of the legs, much work has still to be done on the variation of these torsion and flexion in the workspace of the manipulator. This paper investigates a distribution of the torsion and the flexion of the legs in the workspace in order to find the best trajectory location of the manipulator which characterized by the highest stiffness.