Optimal design of a parallel mechanism with three rotational degrees of freedom

This paper presents the concept design of a pose-adjustment system applied in the large fuselage or wing assembly of aircraft manufacturing which including a 3-degree-of-freedom rotational parallel mechanism (3-DoFs RPM), pogo columns and three tracks. The optimal design of the 3-DoFs RPM with its topology a 3-PUS&S mechanism is detailed, which is designed as a rigid yet compact module that can act as a pose-adjustment mechanism moving along three long tracks for large aircraft structural component assembly, a middle fuselage for example. Inverse kinematics of the 3-DoFs RPM with the exponential product method is achieved to lay the foundation for its kinematic synthesis. Next, with the commercial mathematical software, one can get the reachable workspace and define the prescribed workspace, respectively. Then, dimensional synthesis of the 3-DoFs RPM is executed to achieve a relatively good kinematic performance within its workspace. With the commercial CAE software, stiffness analysis is carried out for performance evaluation of the 3-DoFs RPM virtual prototype. (C) 2012 Elsevier Ltd. All rights reserved.