M2 gripper: Extending the dexterity of a simple, Underactuated gripper

Abstract

In the development of robotic hands, researchers have sought to increase inherent functionality without incurring greater complexity and cost. In this paper, we extend the manipulation capabilities of a simple gripper through a novel, underactuated design that produces several distinctive modes of operation. The proposed asymmetric hand design, the Multi-Modal (M2) Gripper, consists of a modular thumb with varying degrees of passive compliance and a dexterous, tendon-driven forefinger that can produce either underactuated or fully-actuated behaviors. With only two actuators and basic open-loop control, the hand is able to adaptively grasp objects of varying geometries, pinch-grasp smaller items, and perform some degree of in-hand manipulation via rolling and controlled sliding. We also detail the properties of this hand morphology that make it well-suited for future work in medical applications, haptic exploration, and studies on controlled stick-slip manipulation tasks.