Human-in-the-Loop Adaptive Control of an Ankle Exoskeleton for Gait Symmetry under Asymmetric Loading

Asymmetric weight-bearing frequently disrupts gait symmetry and increases muscular effort. This paper presents the development of a lightweight ankle exoskeleton and a human-in-the-loop (HIL) adaptive control strategy to mitigate these effects. The exoskeleton employs a modular design with remote ac...

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Published in:IEEE/ASME International Conference on Advanced Intelligent Mechatronics pp. 1 - 6
Main Authors: Zhuang, Wenbing, Luo, Zining, Li, Xinying, Yu, Shiquan, Leng, Yuquan, Fu, Chenglong
Format: Conference Proceeding
Language:English
Published: IEEE 14.07.2025
Subjects:
Adaptive control
Ankle
Asymmetric load
Exoskeleton
Exoskeletons
gait symmetry
Human in the loop
human-in-the-loop optimization
Limbs
Loading
Mechatronics
Muscles
Optimization
Real-time systems
ISSN:2159-6255
Online Access:Get full text
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Abstract Asymmetric weight-bearing frequently disrupts gait symmetry and increases muscular effort. This paper presents the development of a lightweight ankle exoskeleton and a human-in-the-loop (HIL) adaptive control strategy to mitigate these effects. The exoskeleton employs a modular design with remote actuation to minimize distal limb mass. The hierarchical control strategy estimates ankle joint moments in real-time using plantar pressure for proportional assistance, while a high-level Bayesian optimization algorithm iteratively adjusts bilateral assistance parameters to maximize a center of mass (CoM) velocity-based symmetry index (SI). Experiments with three healthy participants carrying a unilateral 15% body weight load demonstrated that the HIL optimization converged rapidly (average 2.8 min) to subject-specific, asymmetric assistance levels. Compared to unassisted loaded walking, the optimized assistance improved CoM velocity SI by 13.16%. Concurrently, bilateral plantar flexor muscle activation showed reductions of up to approximately 28%. These results highlight the potential of adaptive, personalized exoskeleton control to restore gait symmetry under asymmetric loading conditions.
AbstractList Asymmetric weight-bearing frequently disrupts gait symmetry and increases muscular effort. This paper presents the development of a lightweight ankle exoskeleton and a human-in-the-loop (HIL) adaptive control strategy to mitigate these effects. The exoskeleton employs a modular design with remote actuation to minimize distal limb mass. The hierarchical control strategy estimates ankle joint moments in real-time using plantar pressure for proportional assistance, while a high-level Bayesian optimization algorithm iteratively adjusts bilateral assistance parameters to maximize a center of mass (CoM) velocity-based symmetry index (SI). Experiments with three healthy participants carrying a unilateral 15% body weight load demonstrated that the HIL optimization converged rapidly (average 2.8 min) to subject-specific, asymmetric assistance levels. Compared to unassisted loaded walking, the optimized assistance improved CoM velocity SI by 13.16%. Concurrently, bilateral plantar flexor muscle activation showed reductions of up to approximately 28%. These results highlight the potential of adaptive, personalized exoskeleton control to restore gait symmetry under asymmetric loading conditions.
Author Li, Xinying
Yu, Shiquan
Luo, Zining
Leng, Yuquan
Zhuang, Wenbing
Fu, Chenglong
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  surname: Luo
  fullname: Luo, Zining
  organization: Southern University of Science and Technology,Department of Mechanical and Energy Engineering,Shenzhen,China
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  surname: Li
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  organization: Southern University of Science and Technology,Department of Mechanical and Energy Engineering,Shenzhen,China
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  organization: Southern University of Science and Technology,Department of Mechanical and Energy Engineering,Shenzhen,China
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  givenname: Chenglong
  surname: Fu
  fullname: Fu, Chenglong
  email: fucl@sustech.edu.cn
  organization: Southern University of Science and Technology,Department of Mechanical and Energy Engineering,Shenzhen,China
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Snippet Asymmetric weight-bearing frequently disrupts gait symmetry and increases muscular effort. This paper presents the development of a lightweight ankle...
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SubjectTerms Adaptive control
Ankle
Asymmetric load
Exoskeleton
Exoskeletons
gait symmetry
Human in the loop
human-in-the-loop optimization
Limbs
Loading
Mechatronics
Muscles
Optimization
Real-time systems
Title Human-in-the-Loop Adaptive Control of an Ankle Exoskeleton for Gait Symmetry under Asymmetric Loading
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