Soft Exosuit Tension Control for Natural Joint Assistance

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Solution Overview

Problem

Rigid exoskeletons cause significant impedance and kinematic restrictions, misalignment with human joints, and add considerable inertia, leading to increased metabolic power and potential injury due to their rigid frameworks and misaligned pin-joints.

Innovation Solution

A soft exosuit using flexible connection elements and actuators to apply assistive forces at beneficial moments, reducing mechanical impedance and allowing natural joint motion, with optional rigid elements for support.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If rigid exoskeletons with linkages and pin-joints are used, then structural support and stability are provided, but considerable inertia and mechanical impedance are added to limb movement

Engineering Contradiction:
Improvestructural stabilityVSAvoidmechanical impedance
Core Design Contradiction:
Stability of the object's compositionVSForce

Solution Approach 1:

The patent replaces rigid exoskeleton linkages with flexible connection elements including straps, webbing, cables, and functional textiles. These flexible elements maintain structural support while eliminating the high mechanical impedance and inertia of rigid components, allowing natural limb movement without resistance.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The patent substitutes the rigid mechanical linkage system with a soft textile-based system. Instead of rigid pins and linkages that create friction and impedance, the invention uses flexible textiles that conform to body movement, dramatically reducing mechanical resistance while maintaining structural integrity.

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

2Stability of the object's composition

If rigid exoskeletons with pin-joints are used, then joint support is provided, but misalignment with human joint axes causes pain and injury

Engineering Contradiction:
Improvejoint supportVSAvoidjoint misalignment injury
Core Design Contradiction:
Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The flexible textile connection elements can dynamically adapt to the complex three-dimensional paths of human joint movement. Unlike rigid pin-joints that require precise alignment, the soft textiles conform to natural joint excursions, eliminating misalignment forces that cause pain and injury while maintaining joint support.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The patent employs dynamic, flexible connection elements that can change their configuration in real-time to match natural joint movement paths. This dynamic adaptability allows the exoskeleton to follow the intricate three-dimensional trajectories of human joints without requiring precise pre-alignment, preventing injury during full range of motion.

Inventive Principle:
Principle #15Dynamics

3Force

If rigid exoskeleton linkages are used, then movement assistance is provided, but considerable restriction to natural limb motion occurs

Engineering Contradiction:
Improvemovement assistanceVSAvoidmotion freedom
Core Design Contradiction:
ForceVSEase of operation

Solution Approach 1:

The flexible textile connection elements provide movement assistance through tension and elasticity while allowing complete freedom of natural limb motion. The textiles can stretch and conform to body movement, providing support forces without restricting the user's ability to move through full range of motion in any direction.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The patent changes the physical parameters of the connection elements from rigid to flexible, allowing the material properties to adapt to natural limb movement. The flexible textiles can change their tension, angle, and configuration dynamically during movement, providing assistance forces while maintaining complete motion freedom unlike rigid linkages.

Inventive Principle:
Principle #35Parameter changes

4Adaptability or versatility

If redundant passive degrees of freedom are added to exoskeletons, then wearer motion compatibility is improved, but system weight increases

Engineering Contradiction:
Improvemotion compatibilityVSAvoidsystem weight
Core Design Contradiction:
Adaptability or versatilityVSWeight of moving object

Solution Approach 1:

The patent uses flexible textile connection elements that inherently provide motion compatibility through their ability to stretch, bend, and conform to body movement. This flexibility replaces the need for redundant passive degrees of freedom found in rigid exoskeletons, achieving motion adaptability without the additional weight of complex mechanical joints and linkages.

Inventive Principle:
Principle #30Flexible shells and thin films

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The soft exosuit reduces metabolic cost and joint loading, enhances mobility, and minimizes injury risk by providing assistive forces that align with natural joint movements, while maintaining comfort and flexibility.

Implementation Method 1

a wearable soft exosuit includes a first anchor element configured for positioning at or near a first body part of a person wearing the wearable soft exosuit and a second anchor element configured for positioning at or near a second body part... a plurality of connection elements extending between the first anchor element and the second anchor element

Methodology Applied
Scientific EffectTension: Tension

Implementation Method 2

at least one actuator and at least one controller configured to actuate the at least one actuator at a predetermined time during movement of the at least one joint to generate a beneficial moment about the at least one joint

Methodology Applied
Scientific EffectElectromagnetic conversion: Electromagnetic Induction

Data Source

PatentEP3791834B1Soft exosuit for assistance with human motion
Publication Date: 2026.03.04 PRESIDENT & FELLOWS OF HARVARD COLLEGE
  • EP3791834B1 patent drawingFigure 1
  • EP3791834B1 patent drawingFigure 2A~2D
  • EP3791834B1 patent drawingFigure 3A~3C

AI summary

In at least one aspect, there is provided a system for generating force about one or more joints including a soft exosuit having a plurality of anchor elements and at least one connection element disposed between the plurality of anchor elements. The system also includes at least one sensor to determine a force the at least one connection element or at least one of the plurality of anchor elements and to output signals relating to the force, at least one actuator configured to change a tension in the soft exosuit and at least one controller configured to receive the signals output from the at least one sensor and actuate the at least one actuator responsive to the received signals.