Load-Sharing in Soft and Spiny Paws for a Large Climbing Robot

A novel end-effector is presented for a large climbing robot. The gripping surfaces are covered with sharp spines to achieve a high shear stress on rocky surfaces. Soft, flexure-based joints and the natural compliance of a particle-jamming pad in the palm allow the end-effector to conform to a variety of shapes without complex controls, while strong tendons and the application of vacuum to the palm create rigidity when applying loads of 250 N and greater. A differential mechanism distributes the force from a single actuator to the phalanges of the fingers, providing approximately equal tangential forces at each contact. The particle-jamming palm allows many spines to contact a rough surface, then becomes nearly rigid so that they share the load. Tests on instrumented surfaces confirm the predicted load-sharing of the fingers and performance of the palm.