The improved extrapolated center of mass enhances the safety of exoskeleton system

Abstract Maintaining the balance and safety of the exoskeleton human–robot coupling system is a prerequisite for realizing the rehabilitation training function. Therefore, research on the balance of lower limb exoskeleton robots has attracted much attention. When the exoskeleton human–robot coupling...

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Main Authors: Chang Wang, Jian Cao, Jianhua Zhang, Junhui Wang, Qiang Yang, Song Men
Format: Article
Language:English
Published: Nature Portfolio 2025-04-01
Series:Scientific Reports
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Online Access:https://doi.org/10.1038/s41598-025-93299-5
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author Chang Wang
Jian Cao
Jianhua Zhang
Junhui Wang
Qiang Yang
Song Men
author_facet Chang Wang
Jian Cao
Jianhua Zhang
Junhui Wang
Qiang Yang
Song Men
author_sort Chang Wang
collection DOAJ
description Abstract Maintaining the balance and safety of the exoskeleton human–robot coupling system is a prerequisite for realizing the rehabilitation training function. Therefore, research on the balance of lower limb exoskeleton robots has attracted much attention. When the exoskeleton human–robot coupling system reaches the critical state of falling, there is an issue with inaccurate detection in the extrapolated center of mass (XCoM) balance index. This paper firstly establishes an inverted pendulum model after the system is disturbed, fully considering that the external environment may exert a disturbance force on the system at any time, and proposes an improved extrapolated center of mass(PXCoM) balance index based on XCoM. Secondly, we aim to the problem of balance recovery in the critical state of the human-exoskeleton system falling. Using an ankle joint under-actuated exoskeleton robot as a research object, we study the balance recovery method of the exoskeleton based on active stepping strategies under large disturbance states. Finally, a lower limb exoskeleton robot experimental platform was built, on which the balance sensing method and balance recovery mechanism studied in this article were transplanted, and its feasibility was verified. The experiment results show that the PXCoM balance evaluation index proposed in this paper has a better perceptual effect than the XCoM balance evaluation index in the critical state of the human-exoskeleton system falling. The proposed gait recovery strategy can effectively restore the balance of the human-exoskeleton system under significant disturbances, thereby ensuring safety under disturbances while wearing the exoskeleton.
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spelling doaj-art-b722b596e36d42a9a937348c3672e72a2025-08-20T02:11:46ZengNature PortfolioScientific Reports2045-23222025-04-0115112010.1038/s41598-025-93299-5The improved extrapolated center of mass enhances the safety of exoskeleton systemChang Wang0Jian Cao1Jianhua Zhang2Junhui Wang3Qiang Yang4Song Men5School of Mechanical Engineering, University of Science and Technology BeijingSchool of Mechanical Engineering, Hebei University of TechnologySchool of Mechanical Engineering, University of Science and Technology BeijingSchool of Mechanical Engineering, Hebei University of TechnologyDepartment of Spine Surgery, Tianjin HospitalInspur Yunzhou Industrial Internet Co., Ltd.Abstract Maintaining the balance and safety of the exoskeleton human–robot coupling system is a prerequisite for realizing the rehabilitation training function. Therefore, research on the balance of lower limb exoskeleton robots has attracted much attention. When the exoskeleton human–robot coupling system reaches the critical state of falling, there is an issue with inaccurate detection in the extrapolated center of mass (XCoM) balance index. This paper firstly establishes an inverted pendulum model after the system is disturbed, fully considering that the external environment may exert a disturbance force on the system at any time, and proposes an improved extrapolated center of mass(PXCoM) balance index based on XCoM. Secondly, we aim to the problem of balance recovery in the critical state of the human-exoskeleton system falling. Using an ankle joint under-actuated exoskeleton robot as a research object, we study the balance recovery method of the exoskeleton based on active stepping strategies under large disturbance states. Finally, a lower limb exoskeleton robot experimental platform was built, on which the balance sensing method and balance recovery mechanism studied in this article were transplanted, and its feasibility was verified. The experiment results show that the PXCoM balance evaluation index proposed in this paper has a better perceptual effect than the XCoM balance evaluation index in the critical state of the human-exoskeleton system falling. The proposed gait recovery strategy can effectively restore the balance of the human-exoskeleton system under significant disturbances, thereby ensuring safety under disturbances while wearing the exoskeleton.https://doi.org/10.1038/s41598-025-93299-5Lower limb exoskeletonHuman–robot coupling systemBalance perceptionImproved extrapolated center of mass
spellingShingle Chang Wang
Jian Cao
Jianhua Zhang
Junhui Wang
Qiang Yang
Song Men
The improved extrapolated center of mass enhances the safety of exoskeleton system
Scientific Reports
Lower limb exoskeleton
Human–robot coupling system
Balance perception
Improved extrapolated center of mass
title The improved extrapolated center of mass enhances the safety of exoskeleton system
title_full The improved extrapolated center of mass enhances the safety of exoskeleton system
title_fullStr The improved extrapolated center of mass enhances the safety of exoskeleton system
title_full_unstemmed The improved extrapolated center of mass enhances the safety of exoskeleton system
title_short The improved extrapolated center of mass enhances the safety of exoskeleton system
title_sort improved extrapolated center of mass enhances the safety of exoskeleton system
topic Lower limb exoskeleton
Human–robot coupling system
Balance perception
Improved extrapolated center of mass
url https://doi.org/10.1038/s41598-025-93299-5
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