Digitala Vetenskapliga Arkivet

Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Design and Control Parameter Optimization of Soft Ankle Exoskeleton for People with Dropfoot and Excessive Inversion
KTH, School of Engineering Sciences (SCI), Engineering Mechanics. (KTH MoveAbility Lab)
2023 (English)Licentiate thesis, comprehensive summary (Other academic)Alternative title
Design och Optimering av Kontrollparametrar för Mjuk Fotledsexoskelett för Människor med Fallfot och Överdriven Inversion (Swedish)
Abstract [en]

Wearable robotics and exoskeletons have been explored for their efficacy in physical rehabilitation and for assistance in daily activities for people with motor disorders. The overall objective of this thesis is to design a powered soft exoskeleton for people with dropfoot and excessive inversion, commonly after a stroke, and to optimize the control parameters for each individual while considering different dimensions. This compilation thesis is based on two papers that focus on the design and verification of the ankle joint exoskeleton prototype, and control parameters optimization using human-in-the-loop optimization, respectively.

In the first paper, we presented the design of the powered soft ankle exoskeleton, mainly consisting of the actuation system, Bowden cables, and textile components, to assist two degrees of freedom (DoF), dorsiflexion and eversion, simultaneously.A proof-of-concept study was performed to verify the functionality of the exoskeleton in two aspects: assisting/controlling two DoFs simultaneously and compensating for the resistance during ankle plantarflexion. Our results suggested that two-DoF assistance can be delivered with the structure, and the proposed force-free controller can counteract the inherent resistance in the system.

In the second paper, a multi-objective-based human-in-the-loop optimization method was proposed, aiming at optimizing gait quality in different aspects simultaneously.In this case study, the multi-objective optimization method, Non-dominated Sorting Genetic Algorithm II, was implemented in the human-in-the-loop optimization. Four generations, comprising ten sets of control parameters in each generation, were tested on one non-disabled subject wearing the exoskeleton described in paper I. The results indicated that this novel method can identify the control laws that optimize both gait quality metrics. In the set of solutions, control laws with different focuses can be selected for different purposes or individual uses.

Abstract [sv]

Bärbara robotar och exoskelett har utforskats för deras effektivitet inom fysisk rehabilitering och som stöd i dagliga aktiviteter för personer med motoriska störningar. Det övergripande målet med denna avhandling är att designa en kraftdriven mjuk exoskelett för personer med fallfot och överdriven inversion, vanligt efter en stroke, och att optimera kontrollparametrarna för varje individ med hänsyn till olika dimensioner. Denna sammanställda avhandling bygger på två artiklar som fokuserar på design och verifiering av prototypen för fotledsexoskelett samt optimering av kontrollparametrar med mänsklig medverkan.

I den första artikeln presenterade vi designen av det kraftdrivna mjuka fotledsexoskelettet, som huvudsakligen består av aktiveringssystem, Bowden-kablar och textilkomponenter, för att assistera i två grader av frihet (DoF), dorsiflexion och eversion, samtidigt. En konceptbevisstudie genomfördes för att verifiera funktionen hos exoskelettet avseende två aspekter: assistera/styra två DoFs samtidigt och kompensera för motståndet under plantarflektion i fotleden. Våra resultat antydde att två-DoF-assistans kan levereras med strukturen och att den föreslagna kraftfria styrenheten kan motverka det inneboende motståndet i systemet.

I den andra artikeln föreslogs en mänsklig medverkande optimeringsmetod baserad på flera mål, med syfte att optimera gångkvaliteten i olika aspekter samtidigt. I denna fallstudie implementerades den flerobjektiva optimeringsmetoden Non-dominated Sorting Genetic Algorithm II i den mänskliga medverkansoptimeringen. Fyra generationer, med tio uppsättningar av kontrollparametrar i varje generation, testades på en icke-funktionshindrad försöksperson som bar det exoskelett som beskrivs i den första artikeln. Resultaten indikerade att denna nya metod kan identifiera styrregler som optimerar både gångkvalitetsmått. I uppsättningen lösningar kan styrregler med olika fokus väljas för olika ändamål eller individuella användningsområden.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2023.
Series
TRITA-SCI-FOU ; 2023:60
Keywords [en]
Assistive device, Biomechanics, Gait impairment, Movement augmentation
Keywords [sv]
Assistiv enhet, Biomekanik, Gångnedsättning, Rörelseförstärkning
National Category
Robotics Production Engineering, Human Work Science and Ergonomics
Research subject
Engineering Mechanics
Identifiers
URN: urn:nbn:se:kth:diva-339524ISBN: 978-91-8040-778-6 (print)OAI: oai:DiVA.org:kth-339524DiVA, id: diva2:1812101
Presentation
2023-12-04, D31, Lindstedtsvägen 5, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 231115

Available from: 2023-11-15 Created: 2023-11-15 Last updated: 2023-12-04Bibliographically approved
List of papers
1. Multi-Objective-Based Human-in-the-Loop Optimization for Ankle Exoskeleton: A Preliminary Experimental Study
Open this publication in new window or tab >>Multi-Objective-Based Human-in-the-Loop Optimization for Ankle Exoskeleton: A Preliminary Experimental Study
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Wearable robotic exoskeletons have been explored for their efficacy in physical rehabilitation and for assistance in daily activites in people with motor disorders. The concept of human-in-the-loop optimization has been used to identify ideal exoskeleton assistive torques based on measured individual performance metrics, for instance, metabolic cost, but few studies have attempted to optimize several performance metrics simultaneously.We have previously developed a cable-driven ankle exoskeleton that can provide assistance to the ankle in both sagittal and frontal planes, aimed for persons with dropfoot and excessive inversion. In this study, we propose a multi-objective human-in-the-loop optimization that identifies the ankle exoskeleton properties that improve gait quality, defined here as normal foot segment kinematics and step length symmetry. One able-bodied subject tested the feasibility of the proposed method. The subject wore the exoskeleton while walking on a treadmill. An extra weight was attached on the right foot to simulate the gait deviations associated with dropfoot and excessive inversion.  The Pareto front, comprising six results, was sorted, which illustrated the improvement in both foot segment kinematics and step length symmetry. Within this set of results, each represents a unique compromise or balance between the two objectives, and it was observed that enhancing step length symmetry might lead to an increase in foot segment deviation, showcasing the inherent trade-off relationship between these two aspects.These results suggest that this method can potentially be useful in determining subject-specific exoskeleton control laws that improve several measures of gait in persons with gait disability. 

National Category
Robotics Production Engineering, Human Work Science and Ergonomics
Identifiers
urn:nbn:se:kth:diva-339497 (URN)
Note

QC 20231120

Available from: 2023-11-13 Created: 2023-11-13 Last updated: 2023-11-20Bibliographically approved
2. Soft Ankle Exoskeleton to Counteract Dropfoot and Excessive Inversion
Open this publication in new window or tab >>Soft Ankle Exoskeleton to Counteract Dropfoot and Excessive Inversion
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Wearable exoskeletons are emerging technologies for providing movement assistance and rehabilitation for people with motor disorders. In this study, we focus on the specific gait pathology dropfoot, which is common after a stroke. Dropfoot makes it difficult to achieve foot clearance during swing and heel contact at early stance and often necessitates compensatory movements. We developed a soft ankle exoskeleton consisting of actuation and transmission systems to assist two degrees of freedom simultaneously, dorsiflexion and eversion. The actuation system consists of two motors worn on a waist belt. The assistive force is transmitted to the medial and lateral sides of the forefoot via Bowden cables. The coupling design enables variable assistance of dorsiflexion and inversion at the same time. As a proof-of-concept study, we evaluated the performance of the exoskeleton on five able-bodied subjects in three movement cases - assisting dorsiflexion and eversion, controlling plantarflexion, and compensating for device resistance. In the first two cases, errors between the desired and the achieved ankle joints in two DoFs were low; errors of < 1.5° were achieved in assisting dorsiflexion and/or controlling plantarflexion, and of < 1.4° in assisting ankleeversion. The proposed force-free controller in case 3 significantly compensated for the device resistance during ankle joint plantarflexion. Our findings support the feasibility of the new ankle exoskeleton design in assisting two degrees of freedom at the ankle simultaneously.

National Category
Production Engineering, Human Work Science and Ergonomics
Identifiers
urn:nbn:se:kth:diva-339495 (URN)
Note

QC 20231120

Available from: 2023-11-13 Created: 2023-11-13 Last updated: 2023-11-20Bibliographically approved

Open Access in DiVA

fulltext(2332 kB)114 downloads
File information
File name FULLTEXT05.pdfFile size 2332 kBChecksum SHA-512
f0a3fe5f67bad2340482802700fcf75591598dfd2082ca0b6193806e792b59ac7ed1ddb3e51e1b054b6048a1c8e6bff8ab1f20c2e769259c396a6935848a4550
Type fulltextMimetype application/pdf

Search in DiVA

By author/editor
Zhang, Xiaochen
By organisation
Engineering Mechanics
RoboticsProduction Engineering, Human Work Science and Ergonomics

Search outside of DiVA

GoogleGoogle Scholar
Total: 165 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 717 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf