Comparative analysis of a new 3 x PPRS parallel kinematic mechanism

Parallel Kinematic Mechanisms (PKMs) are well suited for high-accuracy applications. However, constraints such as end-effector rotation (i.e., platform tilt angle) and configuration-dependent stiffness often limit their usage. A new six degree-of-freedom (dof) PKM architecture based on a 3 x PPRS topology that addresses these concerns is presented in this paper - specifically, the proposed PKM can achieve high (end-effector) tilt angles with enhanced stiffness. The mechanism is also compared with similar three known 6-dof architectures, through which it is shown that the proposed PKM indeed exhibits higher stiffness relative to these three reference PKMs. The static stiffness is derived using matrix structural analysis, and the dynamic stiffness is obtained via finite-element analysis. A prototype of the proposed PKM that was designed and built is presented. (C) 2013 Elsevier Ltd. All rights reserved.