Complex manipulation with a simple robotic hand through contact breaking and caging

Abstract

Humans use all surfaces of the hand for contact-rich manipulation. Robot hands, in contrast, typically use only the fingertips, which can limit dexterity. In this work, we leveraged a potential energy-based whole-hand manipulation model, which does not depend on contact wrench modeling like traditional approaches, to design a robotic manipulator. Inspired by robotic caging grasps and the high levels of dexterity observed in human manipulation, a metric was developed and used in conjunction with the manipulation model to design a two-fingered dexterous hand, the Model W. This was accomplished by simulating all planar finger topologies composed of open kinematic chains of up to three serial revolute and prismatic joints, forming symmetric two-fingered hands, and evaluating their performance according to the metric. We present the best design, an unconventional robot hand capable of performing continuous object reorientation, as well as repeatedly alternating between power and pinch grasps-two contact-rich skills that have often eluded robotic hands-and we experimentally characterize the hand's manipulation capability. This hand realizes manipulation motions reminiscent of thumb-index finger manipulative movement in humans, and its topology provides the foundation for a general-purpose dexterous robot hand.