A Flexibly Grasping and Manipulating Mechanism Composed of Many Elastic Cords — Posture Control of Grasped Object

The authors have proposed a flexibly grasping and manipulating mechanism composed of two circular rings and many elastic cords between the rings. Aiming to control posture of the grasped object and to give the mechanism a remote center compliance ability, the mechanism is improved so that the relative translation between two rings can be given. A new numerical method to iteratively calculate the posture of a grasped object due to relative angular and translational displacements between the rings is established based on the equilibrium of force and moment applied by elastic cords. A prototype with a planar parallel mechanism with 2 DOF to give a pure relative translational motion between rings is built and experimentally examined. The prototype mounted on a spatial serial robot arm can grasp a cylinder and insert it into a circular hole in inclined surface by utilizing posture control and remote center compliance.