The translating Î -joint: Design and applications

It is first recalled that a Π-joint is a parallelogram four-bar linkage whose coupler link undergoes pure translation w.r.t. its fixed link; moreover, all the points of the coupler link describe circles with identical radii, the length of the other two links. Innovative and sophisticated joints have a crucial role in simplifying the architecture of manipulators for specific tasks, like fast pick-and-place operations. A novel joint is introduced in this paper, dubbed the translating Π-joint, the series array of a prismatic and a Π-joint, the plane of latter being normal to the direction of the former. A realization of the translating Π-joint is the RHRRHR kinematic chain, R and H standing for revolute and screw joint, respectively. Furthermore, four implementations are disclosed here, each with unique features. In addition, the applications of this joint are studied, including two novel architectures for Schönflies-motion generators. The authors report the detailed design and fabrication of two prototypes based on the above-mentioned implementations. The experimental results are used to conduct a comparison between two designs, which reveal their advantages and drawbacks.