Distal Hyperextension Is Handy: High Range of Motion in Cluttered Environments

Abstract

As robots branch out from the manufacturing sector into the home, there is a pressing need for new technology that can operate in cluttered and unstructured human environments. Loading and unloading a dishwasher serves as a difficult representative challenge for in-home robots, and a new robotic end-effector has been developed for this type of task. The actuation of the fingers is integrated with a bending degree of freedom that is nearly coincident with the proximal joints of the fingers, an arrangement that greatly increases the kinematic workspace in constrained environments. In addition, the distal joints of the fingers are capable of hyperextension (bending backwards), allowing them to pinch a wider range of surface curvatures and angles securely. A third feature of the hand is a palm that combines a granular jamming substrate with suction cups to adhere to wet and slippery objects of varying curvatures. Integration of these features into a single prototype allows the hand to grasp and manipulate dirty dishes reliably and with low gripping forces, as demonstrated in object acquisition and manipulation with less than 10 N of applied force.