SoftHand Model-W: A 3D-Printed, Anthropomorphic, Underactuated Robot Hand with Integrated Wrist and Carpal Tunnel

2026-04-01

AI Summary

This work proposes a 3D-printed, anthropomorphic underactuated robotic hand integrated with a two-degree-of-freedom tendon-driven wrist, addressing the limited dexterity and efficiency of conventional underactuated hands that lack active wrist mobility and thus rely heavily on compensatory arm motions. For the first time within the SoftHand framework, active wrist articulation is combined with a human-inspired carpal tunnel tendon routing mechanism. An antagonistic design and distally located motors reduce end-effector inertia while enabling coordinated, adaptive motion between fingers and wrist. Experimental results demonstrate that, compared to its wristless counterpart, the proposed hand significantly reduces task completion time and arm compensation in cube stacking and disk rotation tasks, and successfully accomplishes previously infeasible pick-and-place operations, thereby enhancing both manipulative dexterity and human–robot compatibility.

Abstract

This paper presents the SoftHand Model-W: a 3D-printed, underactuated, anthropomorphic robot hand based on the Pisa/IIT SoftHand, with an integrated antagonistic tendon mechanism and 2 degree-of-freedom tendon-driven wrist. These four degrees-of-acuation provide active flexion and extension to the five fingers, and active flexion/extension and radial/ulnar deviation of the palm through the wrist, while preserving the synergistic and self-adaptive features of such SoftHands. A carpal tunnel-inspired tendon routing allows remote motor placement in the forearm, reducing distal inertia and maintaining a compact form factor. The SoftHand-W is mounted on a 6-axis robot arm and tested with two reorientation tasks requiring coordination between the hand and arm's pose: cube stacking and in-plane disc rotation. Results comparing task time, arm joint travel, and configuration changes with and without wrist actuation show that adding the wrist reduces compensatory and reconfiguration movements of the arm for a quicker task-completion time. Moreover, the wrist enables pick-and-place operations that would be impossible otherwise. Overall, the SoftHand Model-W demonstrates how proximal degrees of freedom are key to achieving versatile, human-like manipulation in real world robotic applications, with a compact design enabling deployment in research and assistive settings.

Problem

• underactuated robot hand
• anthropomorphic design
• wrist integration
• tendon-driven mechanism
• human-like manipulation

Innovation

• underactuated hand
• tendon-driven wrist
• carpal tunnel routing
• synergistic manipulation
• proximal degrees of freedom