Comparison between a 4-DOF hybrid module and Tricept module focusing on inverse kinematics and stiffness

In this paper, a novel 5-Axis parallel kinematic machines (PKMs) and a 4-degree-of-freedom (DOF) hybrid module is presented and the comparison between the 4-DOF hybrid module and the Tricept focusing on inverse kinematics and stiffness is carried out. Compared to the Tricept, the Tricept-IV and the 4-DOF hybrid module are formulated by adding an active prismatic joint to the constrained passive limb or moving platform so as to enlarge the workspace/volume ratio. The unique underlying architecture demonstrates that the volume of Tricept-IV or 4-DOF hybrid module is much smaller than that of the Tricept approaching the same workspace. On basis of the analytic stiffness modeling and FEA model, the stiffness comparison between the two modules is carried out in this paper.