A Bionic Knee Exoskeleton Design with Variable Stiffness via Rope-Based Artificial Muscle Actuation

This paper presents a novel design for a bionic knee exoskeleton equipped with a variable stiffness actuator based on rope-driven artificial muscles. To meet the varying stiffness requirements of the knee joint across different gait modes, the actuator dynamically switches between multiple rope bund...

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Main Authors: Shikai Jin, Bin Liu, Zhuo Wang
Format: Article
Language:English
Published: MDPI AG 2025-07-01
Series:Biomimetics
Subjects:
Online Access:https://www.mdpi.com/2313-7673/10/7/424
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author Shikai Jin
Bin Liu
Zhuo Wang
author_facet Shikai Jin
Bin Liu
Zhuo Wang
author_sort Shikai Jin
collection DOAJ
description This paper presents a novel design for a bionic knee exoskeleton equipped with a variable stiffness actuator based on rope-driven artificial muscles. To meet the varying stiffness requirements of the knee joint across different gait modes, the actuator dynamically switches between multiple rope bundle configurations, thereby enabling effective stiffness modulation. A mathematical model of the knee exoskeleton is developed, and the mechanical properties of the selected flexible aramid fiber ropes under tensile loading are analyzed through both theoretical and experimental approaches. Furthermore, a control framework for the exoskeleton system is proposed. Wearable experiments are conducted to evaluate the effectiveness of the variable stiffness actuation in improving compliance and comfort across various gait patterns. Electromyography (EMG) results further demonstrate that the exoskeleton provides a compensatory effect on the rectus femoris muscle.
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publisher MDPI AG
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series Biomimetics
spelling doaj-art-92b9e1147b394c0da0dcffe38352d0eb2025-08-20T03:07:54ZengMDPI AGBiomimetics2313-76732025-07-0110742410.3390/biomimetics10070424A Bionic Knee Exoskeleton Design with Variable Stiffness via Rope-Based Artificial Muscle ActuationShikai Jin0Bin Liu1Zhuo Wang2School of Mechanical Engineering, Northwestern Polytechnical University, Xi’an 710072, ChinaSchool of Mechanical Engineering, Northwestern Polytechnical University, Xi’an 710072, ChinaSchool of Mechanical Engineering, Northwestern Polytechnical University, Xi’an 710072, ChinaThis paper presents a novel design for a bionic knee exoskeleton equipped with a variable stiffness actuator based on rope-driven artificial muscles. To meet the varying stiffness requirements of the knee joint across different gait modes, the actuator dynamically switches between multiple rope bundle configurations, thereby enabling effective stiffness modulation. A mathematical model of the knee exoskeleton is developed, and the mechanical properties of the selected flexible aramid fiber ropes under tensile loading are analyzed through both theoretical and experimental approaches. Furthermore, a control framework for the exoskeleton system is proposed. Wearable experiments are conducted to evaluate the effectiveness of the variable stiffness actuation in improving compliance and comfort across various gait patterns. Electromyography (EMG) results further demonstrate that the exoskeleton provides a compensatory effect on the rectus femoris muscle.https://www.mdpi.com/2313-7673/10/7/424knee exoskeletonartificial muscleelastic actuatorvariable stiffness mechanism
spellingShingle Shikai Jin
Bin Liu
Zhuo Wang
A Bionic Knee Exoskeleton Design with Variable Stiffness via Rope-Based Artificial Muscle Actuation
Biomimetics
knee exoskeleton
artificial muscle
elastic actuator
variable stiffness mechanism
title A Bionic Knee Exoskeleton Design with Variable Stiffness via Rope-Based Artificial Muscle Actuation
title_full A Bionic Knee Exoskeleton Design with Variable Stiffness via Rope-Based Artificial Muscle Actuation
title_fullStr A Bionic Knee Exoskeleton Design with Variable Stiffness via Rope-Based Artificial Muscle Actuation
title_full_unstemmed A Bionic Knee Exoskeleton Design with Variable Stiffness via Rope-Based Artificial Muscle Actuation
title_short A Bionic Knee Exoskeleton Design with Variable Stiffness via Rope-Based Artificial Muscle Actuation
title_sort bionic knee exoskeleton design with variable stiffness via rope based artificial muscle actuation
topic knee exoskeleton
artificial muscle
elastic actuator
variable stiffness mechanism
url https://www.mdpi.com/2313-7673/10/7/424
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