RIM Hand : A Robotic Hand with an Accurate Carpometacarpal Joint and Nitinol-Supported Skeletal Structure

2026-01-20

AI Summary

This study addresses the limitations of existing anthropomorphic robotic hands in accurately modeling the metacarpal–carpal joint and achieving compliant palm deformation, which hinder natural hand-like motion and stable grasping. To overcome these challenges, this work proposes a highly biomimetic soft robotic hand that fully replicates the anatomical structure from the metacarpals to the carpal bones for the first time. The design integrates superelastic Nitinol alloy wires as skeletal supports, tendon-driven actuation, and a soft silicone skin. This novel architecture enables up to 28% palm deformation, more than doubles load-bearing capacity, and triples contact area compared to conventional rigid-palm designs. The resulting hand demonstrates significant advances in dexterity, compliance, and anthropomorphism, closely emulating the functional versatility of the human hand.

Technology Category

• Intelligent Robots: Manipulation
• Humans and AI: Interaction Techniques and Devices
• Computer Vision: Biometrics, Face, Gesture & Pose

Application Category

• Responsible Web: Machine-in-the-loop, human agency and autonomy
• Economics, Online Markets and Human Computation: Incentives in network design for Web infrastructures and ecosystems
• Graph Algorithms and Modeling for the Web: Efficient manipulation of static and dynamic Web-related graphs

Abstract

This paper presents the flexible RIM Hand, a biomimetic robotic hand that precisely replicates the carpometacarpal (CMC) joints and employs superelastic Nitinol wires throughout its skeletal framework. By modeling the full carpal-to-metacarpal anatomy, the design enables realistic palm deformation through tendon-driven fingers while enhancing joint restoration and supports skeletal structure with Nitinol-based dorsal extensors. A flexible silicone skin further increases contact friction and contact area, enabling stable grasps for diverse objects. Experiments show that the palm can deform up to 28%, matching human hand flexibility, while achieving more than twice the payload capacity and three times the contact area compared to a rigid palm design. The RIM Hand thus offers improved dexterity, compliance, and anthropomorphism, making it promising for prosthetic and service-robot applications.

Problem

• carpometacarpal joint
• robotic hand
• palm deformation
• anthropomorphism
• dexterity

Innovation

• carpometacarpal joint
• Nitinol
• biomimetic robotic hand
• tendon-driven actuation
• flexible palm deformation