An Approach for Computing the Transmission Index of Full Mobility Planar Multiloop Mechanisms

An approach for the force/motion transmissibility analysis of full mobility planar multiloop mechanisms (PMLM) is proposed in this paper by drawing on the duality of twist space and wrench space. By making a comparison study, it is concluded that the velocity model of a full mobility planar multiloop mechanism can be expressed in the same form as that of a full mobility planar parallel mechanism (PPM). Thereby, a set of dimensionally homogeneous transmission indices is proposed, which can be employed for precisely representing the closeness to different types of singularities as well as for dimensional optimization. A 3-RRR parallel mechanism and a full mobility planar multiloop mechanism for face-shovel excavation are taken as examples to demonstrate the validity and effectiveness of the proposed approach.