Singularity analysis of the planar 3-RRR parallel manipulator considering the motion/force transmissibility

Abstract

Singularity is an inherent characteristic of a closed-chain manipulator. This paper presents an approach to singularity analysis of the planar 3-RRR parallel manipulator. On the basis of screw theory, the motion/force transmission analysis of the manipulator is first achieved. The singularity is classified into three types: constraint singularity, input transmission singularity, and output transmission singularity, in which the last two ones can be investigated by two indices correspondingly. By using the proposed method, not only can all types of possible singularity configurations and their singular loci be identified, but their physical meanings are also explained in terms of their motion/force transmission performances, which make 3-RRR parallel manipulator more comprehensible. © Springer-Verlag Berlin Heidelberg 2012.