Active Exoskeleton Shoulder Rotation for Brachial Plexus Rehabilitation

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Solution Overview

Problem

Current treatments for brachial plexus injuries, such as those from motor vehicle accidents or difficult births, often result in reduced shoulder and arm mobility due to muscle weakness and joint stiffness, with existing rehabilitation methods providing limited support for controlled movement and strength augmentation.

Innovation Solution

A wearable exoskeleton system with a driven actuator that enables controlled rotation of the shoulder joint, utilizing a harness with a first pivot bearing and a driven actuator, which can be electric, pneumatic, or hydraulic, to assist in shoulder rotation and abduction/adduction, with optional electromyographic or manual control and vibrotactile feedback for enhanced muscle stimulation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a passive pivot bearing is used for shoulder support, then the device structure is simple, but the range of motion and controlled movement capability are limited

Engineering Contradiction:
Improvedevice structureVSAvoidrange of motion
Core Design Contradiction:
Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent replaces the passive mechanical pivot bearing with an active exoskeleton system that incorporates a driven actuator (motor), control unit, and sensor system. This substitution enables controlled rotation of the shoulder joint around the longitudinal axis of the humerus, transforming the system from simple mechanical support to an active rehabilitation device that can provide guided movement and assist recovery.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Productivity

If active rehabilitation exercises are performed daily, then muscle strength and range of motion improve, but the risk of joint stiffness and muscle atrophy increases without proper support

Engineering Contradiction:
Improverehabilitation effectivenessVSAvoidjoint stiffness
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent incorporates sensors that detect the position and movement of the arm, providing feedback to the control unit. This feedback mechanism enables the system to monitor rehabilitation progress, adjust assistance accordingly, and prevent excessive strain that could cause joint stiffness. The controlled actuator movement can be synchronized with patient exercises to enhance rehabilitation effectiveness while minimizing harmful effects.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The exoskeleton system acts as an intermediary between the patient and the rehabilitation exercises. The driven actuator provides controlled assistance during movement, reducing the burden on damaged muscles and joints while still enabling range of motion exercises. This intermediary support allows patients to perform rehabilitation more effectively without the risk of exacerbating joint stiffness or muscle atrophy.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Ease of operation

If patients perform reaching and grasping tasks independently, then daily life skills are maintained, but the inability to move the arm reduces functional capability

Engineering Contradiction:
Improvedaily life independenceVSAvoidfunctional capability
Core Design Contradiction:
Ease of operationVSAdaptability or versatility

Solution Approach 1:

The patent employs a counterbalancing mechanism where the driven actuator generates forces to counteract gravitational and inertial forces acting on the arm during movement. This anti-weight function reduces the effort required by the patient to initiate and control arm movements, making daily tasks such as reaching and grasping more feasible. The controlled assistance can be adjusted to provide just enough support to enable functional movements without creating dependency.

Inventive Principle:
Principle #8Anti-weight (Counterweight)

Data Source

PatentEP3797933A1Arrangement for a controlled movement of an arm of human
Publication Date: 2021.03.31 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV
  • EP3797933A1 patent drawingFigure 1
  • EP3797933A1 patent drawingFigure 2
  • EP3797933A1 patent drawingFigure 3

AI summary

The invention concerns an arrangement for a controlled movement of an arm of a human having at least one driven actuator operatively engageable with the arm to enable a rotation about an axis of a joint of the arm. The invention is characterized in that the driven actuator is designed and arranged to interact with an attachment which is fixable to an upper arm portion of the arm such that the attachment, when fixed at the upper arm portion, rotates around a longitudinal axis of the humerus.