Kinematically Redundant Hybrid Robots With Simple Singularity Conditions and Analytical Inverse Kinematic Solutions

The rotational workspace of a parallel manipulator is mainly limited by type II singularities. In this letter, we present an approach to synthesize three-legged planar $3+n$ and spatial $6+n$ degree-of-freedom kinematically redundant hybrid robots with very simple—or vanishing—type II singularity conditions. Here, $n$ denotes the number of redundancies. Moreover, the inverse kinematic problem of the proposed architectures can be solved analytically. Because of these advantages, such redundant robots are well suited for applications in physical human–robot interaction, where large rotational workspaces are typically needed.