Design of a truss-shaped deployable grasping mechanism using mobility bifurcation

This paper presents a novel truss-shaped deployable grasping manipulator (T-SDGM)consisting of a series of metamorphic mechanism modules (MMMs)with mobility bifurcation for grasping objects. A scissor-shaped mechanism is applied to design the grasping sub-mechanism in the MMM such that it has single deployment mobility. A special revolute joint couple is used in the grasping sub-mechanism for mobility bifurcation, which changes its mobility from deployment to grasping motions. A supporting mechanism is designed based on the deployment and grasping mobilities of the grasping sub-mechanism, which enhances the grasping force and stiffness. A connecting mechanism is designed to connect the MMMs to a grasping manipulator without changing its deployment and grasping mobilities, and the manipulator can be deployed synchronously. Then, the grasping force and shape adaptability for grasping objects are analyzed. Finally, a simple actuator using an elastic latex tube is designed for the T-SDGM to drive the mechanism to perform deployment and grasping motions. A physical prototype is also fabricated, and grasping tests are conducted to demonstrate the adaptability of the proposed T-SDGM to various objects with different shapes.