A 3-DOF parallel manufacturing module and its kinematic optimization

Parallel tool heads with three degrees of freedom (DOFs), namely, two orientational DOFs and one translational DOF, have become important manufacturing module in the field of machine tools so that these have drawn extensive attention from academia and industry. A decoupled 3-DOF parallel tool head without parasitic motion is proposed in this paper, and a detailed discussion of the architecture of the tool head is presented. On the basis of the tilt-and-torsion angles and the roll-pitch-yaw angles, the inverse kinematics of the tool head is analyzed and its orientational capability is investigated. To explore the potential of the proposed tool head, two cases are identified and discussed respectively. Taking motion/force transmissibility into consideration, performance indices with respect to the local transmission index are defined and the corresponding atlases are presented. Using the atlases as bases and the optimal kinematic designs of the tool head is carried out. A preferable set of optimized parameters is obtained after comparing the results of the two cases, and the optimized result is used in the development of the tool head. (C) 2011 Elsevier Ltd. All rights reserved.