A Variable-Structure Robot Hand That Uses the Environment to Achieve General Purpose Grasps

Abstract

Modern robotic grippers are either specialized and simple, complex and general purpose, or soft and compliant hands. The first provide high reliability but are limited in the range of objects they grasp. Compliant or soft grippers can grasp wide ranges of objects, but are not yet reliable enough for real-world applications. This letter presents a novel variable-structure general purpose robotic hand. The planar-acting hand has a minimalistic structure that can adapt itself against the environment to fit a wide range of objects. The single motor, multi-finger hand utilizes a novel principle of re-arranging its structure prior to grasping. This is achieved by pressing the hand against the environment and performing a series of adjustment moves, to best suit the hand for the object to be grasped. The design and method of operation of the hand is explained. Then, a technique for determining the set of adjustments needed to re-arrange the hand according to the desired grasp is sketched. Real-world experiments are performed with the hand, showing its ability to re-arrange itself and grasp previously unseen objects. Source code for the simulations and experiments is supplemented to the paper, as well as a video clip of the variable-structure hand in action.