Design of parallel hybrid-loop manipulators with kinematotropic property and deployability

General applications of spatial overconstrained linkages are limited by their special output motions without pure rotations or translations. To promote more widespread industrial applications and to develop the potential capabilities of such linkages, this paper presents novel parallel hybrid-loop manipulators and a novel design method based on the constrained motion properties of related spatial overconstrained linkages and general parallel mechanisms. The conventional topological connecting relationships between subchains and platforms are categorized into ten basic forms, among which a novel parallel hybrid-loop form of topological arrangement is presented for the design of parallel hybrid-loop manipulators. In the presented examples of structural design, the Bennett linkage, the threefold-symmetric Bricard linkage and two linkages that will be derived, i.e., the twofold-symmetric 8-bar and the threefold-symmetric 12-bar spatial single-loop linkages are adopted as the basis for the synthesis of the structures of parallel hybrid-loop manipulators with kinematotropic property and deployability based on variable constraint analysis and the structural properties of these linkages. Other similar parallel hybrid-loop manipulators can also be developed based on the presented design method. Possible applications of parallel hybrid-loop manipulators are also highlighted.