Task-oriented type synthesis of the lower-mobility parallel mechanisms with a common platform

Abstract

A systematic procedure for the task-oriented type synthesis of parallel mechanisms (PMs) with a common platform is proposed in this study. The method is composed of two stages. In the first stage, constraint wrenches that are compatible to specific task-oriented output motions of the PM is distributed to several limbs. In the second stage, the geometric conditions and admissible joint structures of PM limbs are identified by employing the concept of reciprocal screw. Then desired symmetric or asymmetric PMs are constructed with the proper combinations of those admissible limbs. Lastly, the suggested synthesis method is verified by identifying various forms of lowermobility PMs, such as planar 1T-type PMs, spatial 2T-type PMs and spatial 1T2R-type PMs.