A Shank Angle-Based Control System Enables Soft Exoskeleton to Assist Human Non-Steady Locomotion

Fuente: arXiv
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Autori principali: Tan, Xiaowei, Jiang, Weizhong, Zhang, Bi, Chen, Wanxin, Zhao, Yiwen, Li, Ning, Liu, Lianqing, Zhao, Xingang
Natura: Preprint
Pubblicazione: 2025
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author Tan, Xiaowei
Jiang, Weizhong
Zhang, Bi
Chen, Wanxin
Zhao, Yiwen
Li, Ning
Liu, Lianqing
Zhao, Xingang
author_facet Tan, Xiaowei
Jiang, Weizhong
Zhang, Bi
Chen, Wanxin
Zhao, Yiwen
Li, Ning
Liu, Lianqing
Zhao, Xingang
contents Exoskeletons have been shown to effectively assist humans during steady locomotion. However, their effects on non-steady locomotion, characterized by nonlinear phase progression within a gait cycle, remain insufficiently explored, particularly across diverse activities. This work presents a shank angle-based control system that enables the exoskeleton to maintain real-time coordination with human gait, even under phase perturbations, while dynamically shaping assistance profiles to match the biological ankle moment patterns across walking, running, stair negotiation tasks. The control system consists of an assistance profile online generation method and a model-based feedforward control method. The assistance profile is formulated as a dual-Gaussian model with the shank angle as the independent variable. Leveraging only IMU measurements, the model parameters are updated online each stride to adapt to inter- and intra-individual biomechanical variability. The profile tracking control employs a human-exoskeleton kinematics and stiffness model as a feedforward component, reducing reliance on historical control data due to the lack of clear and consistent periodicity in non-steady locomotion. Three experiments were conducted using a lightweight soft exoskeleton with multiple subjects. The results validated the effectiveness of each individual method, demonstrated the robustness of the control system against gait perturbations across various activities, and revealed positive biomechanical and physiological responses of human users to the exoskeleton's mechanical assistance.
format Preprint
id arxiv_https___arxiv_org_abs_2508_09876
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A Shank Angle-Based Control System Enables Soft Exoskeleton to Assist Human Non-Steady Locomotion
Tan, Xiaowei
Jiang, Weizhong
Zhang, Bi
Chen, Wanxin
Zhao, Yiwen
Li, Ning
Liu, Lianqing
Zhao, Xingang
Robotics
Systems and Control
I.2.9
Exoskeletons have been shown to effectively assist humans during steady locomotion. However, their effects on non-steady locomotion, characterized by nonlinear phase progression within a gait cycle, remain insufficiently explored, particularly across diverse activities. This work presents a shank angle-based control system that enables the exoskeleton to maintain real-time coordination with human gait, even under phase perturbations, while dynamically shaping assistance profiles to match the biological ankle moment patterns across walking, running, stair negotiation tasks. The control system consists of an assistance profile online generation method and a model-based feedforward control method. The assistance profile is formulated as a dual-Gaussian model with the shank angle as the independent variable. Leveraging only IMU measurements, the model parameters are updated online each stride to adapt to inter- and intra-individual biomechanical variability. The profile tracking control employs a human-exoskeleton kinematics and stiffness model as a feedforward component, reducing reliance on historical control data due to the lack of clear and consistent periodicity in non-steady locomotion. Three experiments were conducted using a lightweight soft exoskeleton with multiple subjects. The results validated the effectiveness of each individual method, demonstrated the robustness of the control system against gait perturbations across various activities, and revealed positive biomechanical and physiological responses of human users to the exoskeleton's mechanical assistance.
title A Shank Angle-Based Control System Enables Soft Exoskeleton to Assist Human Non-Steady Locomotion
topic Robotics
Systems and Control
I.2.9
url https://arxiv.org/abs/2508.09876