Singularity Characteristics of a Class of Spatial Redundantly actuated Cable-suspended Parallel Robots and Completely actuated ones

This paper aims to study singularity characteristics of a class of spatial redundantly actuated Cable-Suspended Parallel Robots(CSPRs) and completely actuated ones with pairwise cables. This study focuses on the CSPRs with purely three translational degrees of freedom using redundant actuators or complete actuators. One class of CSPRs is able to perform the translational movement with pairwise cables as parallelograms. There are two types of singularity to be discussed, which result from dynamic equations of CSPRs and parallelogram pairwise cables configurations. To assure three-translational dofs without the rotation of the end-effector, the matrix formed by normals of pairwise cables should maintain in full rank. In the case study, one type of CSPRs with a planar end-effector is discussed to clarify and conclude the singularity features. The results show that in some configurations of CSPR there exists singularity of completely actuated CSPR but redundantly actuated ones are able to fulfill the three-translational-dof movement.