Performance analysis of parallel mechanism architectures for CNC machining applications

In this paper we propose a set of criteria to evaluate the performance of various parallel mechanism architectures for CNC machining applications. In the robotics literature mathematical formulations of qualities like manipulability, stiffness, and workspace volume have been proposed to evaluate the performance of general-purpose robots. Here we propose a set of performance measures that specifically address features of the machining process. We define precise notions of machine tool workspace, joint and link stiffness, and position and orientation manipulability. The performance of various existing 6 d.o.f. architectures are evaluated with these measures. The analytical methodology presented here, in combination with a graphics-based CAD software environment, can serve as a useful tool in the design of high-performance parallel mechanism machine tools.