A multiple-mode mechanism composed of four antiparallelogram units and four revolute joints

This paper deals with the design and analysis of a multiple-mode subunit that can be used to construct reconfigurable/polyhedron deployable mechanisms. A new multiple-mode mechanism, which possesses five motion modes and can switch between these modes at different transition configurations, is designed for the first time by using four R (revolute) joints to connect four antiparallelogram units. First, the construction of the multiple-mode mechanism composed of four antiparallelogram units and four R joints is presented, the mechanism is simplified as a spatial single-loop 8R mechanism with variable link lengths. Second, the DOF (degree of freedom) and kinematic paths of two plane-symmetric modes are calculated through the screw theory and the closure equations, and then the configurations of plane-symmetric Mode I and Mode II are presented, after which the bifurcations of Mode I and Mode II are analyzed. Third, three plane-motion modes derived from three singular configurations of Mode I and Mode II are given, the transition between the five modes of mechanism is identified. Finally, a prototype of the multiple-mode mechanism is designed and fabricated to verify the feasibility of the construction method and the analysis of the modes.