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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Bibliographic Details
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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Summary: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.
ISSN:2159-6255
DOI:10.1109/AIM64088.2025.11175771