SoFiE: Soft Finger Exoskeleton for Intelligent Grasping

2026-05-29

AI Summary

This work proposes SoFiE, a modular soft finger exoskeleton designed to overcome the limitations of conventional rigid hand exoskeletons, which are often bulky and incompatible with natural finger kinematics. The system employs a 3D-printed compliant structure actuated by tendon-driven DC motors to provide lightweight, low-profile flexion assistance, while passive elastic elements enable extension. Innovatively integrating StretchSense resistive proprioceptive springs and MagSense magnetic tactile sensors—fused with motor encoder feedback—SoFiE achieves accurate finger pose estimation, object stiffness recognition, and grasp-type classification. Its fully wireless, co-located actuation-sensing architecture demonstrates high-fidelity finger state perception and adaptability across multiple tasks in experimental validation, offering an effective solution for soft wearable hand-assistive robotics.

Abstract

Soft wearable robotic systems have emerged as a promising solution for assisting individuals with reduced hand function. This paper presents SoFiE, a modular soft finger exoskeleton designed to assist index-finger flexion during grasping tasks. The proposed system is primarily fabricated using 3D-printed flexible materials, enabling a lightweight, low-profile, and modular design. Actuation is achieved through a tendon-driven mechanism powered by a compact DC motor, while passive extension is provided by a compliant conductive spring. This element, termed StretchSense, also functions as a proprioceptive sensor by exhibiting resistance changes under deformation. Furthermore, a novel tactile sensing approach, MagSense, is introduced, using a magnet and magnetometer pair embedded in a soft fingertip structure to estimate contact force and object compliance. The system is fully untethered and controlled by an embedded microcontroller. In addition, actuator-level sensing through motor encoder feedback enables estimation of the system state, providing a foundation for safe and adaptive control strategies. Experimental validation demonstrates the capability of the system to provide reliable pose estimation, distinguish between materials with different stiffness, and generate distinct sensor signatures across different grasping tasks. This paper details the design, fabrication, and sensing concepts of the proposed exoskeleton as a proof of concept toward modular, soft, and assistive wearable robotics.

Problem

• soft exoskeleton
• hand assistance
• grasping
• wearable robotics
• proprioceptive sensing

Innovation

• soft exoskeleton
• proprioceptive sensing
• tactile sensing
• modular wearable robotics
• untethered actuation