Introducing V-Soft Pro: a Modular Platform for a Transhumeral Prosthesis with Controllable Stiffness

2025-12-04

AI Summary

Current upper-limb prostheses lack the controllable compliance characteristic of biological arms, hindering adaptability to diverse tasks, impact absorption, and efficient energy transmission. To address this, we propose a variable-stiffness prosthetic system for trans-humeral amputees, featuring a modular mechanical architecture that integrates passive elastic elements with variable-stiffness actuators. The system supports residual-limb–specific customization and multimodal biosignal control—primarily surface electromyography (sEMG)—enabling real-time joint stiffness modulation. This facilitates task-adaptive impedance regulation, dynamic shock buffering, and more natural, human-like motion. A fully functional prototype was developed and experimentally validated, demonstrating superior interaction safety and robust performance across complex, unstructured scenarios. Our approach establishes a new paradigm for enhancing both biomimetic fidelity and functional utility in upper-limb prosthetics.

Technology Category

• Intelligent Robots: Manipulation
• Cognitive Modeling & Cognitive Systems: Adaptive Behavior
• Humans and AI: Interaction Techniques and Devices

Application Category

• User Modeling, Personalization and Recommendation: User modeling and simulation for interactive and conversational systems
• Responsible Web: Machine-in-the-loop, human agency and autonomy
• Systems and Infrastructure for Web, Mobile and WoT: Experiences and lessons learnt from Web-based algorithms and system deployments

Abstract

Current upper limb prostheses aim to enhance user independence in daily activities by incorporating basic motor functions. However, they fall short of replicating the natural movement and interaction capabilities of the human arm. In contrast, human limbs leverage intrinsic compliance and actively modulate joint stiffness, enabling adaptive responses to varying tasks, impact absorption, and efficient energy transfer during dynamic actions. Inspired by this adaptability, we developed a transhumeral prosthesis with Variable Stiffness Actuators (VSAs) to replicate the controllable compliance found in biological joints. The proposed prosthesis features a modular design, allowing customization for different residual limb shapes and accommodating a range of independent control signals derived from users' biological cues. Integrated elastic elements passively support more natural movements, facilitate safe interactions with the environment, and adapt to diverse task requirements. This paper presents a comprehensive overview of the platform and its functionalities, highlighting its potential applications in the field of prosthetics.

Problem

• Develops a transhumeral prosthesis with controllable stiffness to mimic biological joint compliance
• Addresses limitations of current prostheses in replicating natural arm movement and interaction
• Creates a modular platform adaptable to different residual limbs and user control signals

Innovation

• Variable Stiffness Actuators replicate biological joint compliance
• Modular design allows customization for different residual limbs
• Integrated elastic elements enable natural movement and safe interaction