Gait Stability Under Hip Exoskeleton Assistance: A Phase-Dependent Analysis Using Gait Tube Methodology
This study aimed to evaluate how wearable hip exoskeleton assistance affects phase-dependent gait stability in healthy adults using a novel visualization technique known as gait tube analysis. Hip exoskeletons offer significant potential to enhance human locomotion through joint torque augmentation,...
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MDPI AG
2025-07-01
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| author | Arash Mohammadzadeh Gonabadi Farahnaz Fallahtafti |
| author_facet | Arash Mohammadzadeh Gonabadi Farahnaz Fallahtafti |
| author_sort | Arash Mohammadzadeh Gonabadi |
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| description | This study aimed to evaluate how wearable hip exoskeleton assistance affects phase-dependent gait stability in healthy adults using a novel visualization technique known as gait tube analysis. Hip exoskeletons offer significant potential to enhance human locomotion through joint torque augmentation, yet their effects on gait stability across the gait cycle remain underexplored. This study introduces gait tube analysis, a novel method for visualizing center of mass velocity trajectories in three-dimensional state space, to quantify phase-dependent gait stability under hip exoskeleton assistance. We analyzed data from ten healthy adults walking under twelve conditions (ten powered with varying torque magnitude and timing, one passive, and one unassisted), assessing variability via covariance-based ellipsoid volumes. Powered conditions, notably HighLater and HighLatest, significantly increased vertical variability (VT) during early-to-mid stance (10–50% of the gait cycle), with HighLater showing the highest mean ellipsoid volume (99,937 mm<sup>3</sup>/s<sup>3</sup>; z = 2.3). Conversely, the passive PowerOff condition exhibited the lowest variability (47,285 mm<sup>3</sup>/s<sup>3</sup>; z = –1.7) but higher metabolic cost, highlighting a stability-efficiency trade-off. VT was elevated in 11 of 12 conditions (<i>p</i> ≤ 0.0059), and strong correlations (r ≥ 0.65) between ellipsoid volume and total variability validated the method’s robustness. These findings reveal phase-specific stability challenges and metabolic cost variations induced by exoskeleton assistance, providing a foundation for designing adaptive controllers to balance stability and efficiency in rehabilitation and performance enhancement contexts. |
| format | Article |
| id | doaj-art-3f03cc4df5694a82a1e11700ad23c95f |
| institution | Matheson Library |
| issn | 2076-3417 |
| language | English |
| publishDate | 2025-07-01 |
| publisher | MDPI AG |
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| series | Applied Sciences |
| spelling | doaj-art-3f03cc4df5694a82a1e11700ad23c95f2025-07-11T14:36:55ZengMDPI AGApplied Sciences2076-34172025-07-011513753010.3390/app15137530Gait Stability Under Hip Exoskeleton Assistance: A Phase-Dependent Analysis Using Gait Tube MethodologyArash Mohammadzadeh Gonabadi0Farahnaz Fallahtafti1Institute for Rehabilitation Science and Engineering, Madonna Rehabilitation Hospitals, Omaha, NE 68118, USADepartment of Biomechanics and Center for Research in Human Movement Variability, University of Nebraska at Omaha, Omaha, NE 68182, USAThis study aimed to evaluate how wearable hip exoskeleton assistance affects phase-dependent gait stability in healthy adults using a novel visualization technique known as gait tube analysis. Hip exoskeletons offer significant potential to enhance human locomotion through joint torque augmentation, yet their effects on gait stability across the gait cycle remain underexplored. This study introduces gait tube analysis, a novel method for visualizing center of mass velocity trajectories in three-dimensional state space, to quantify phase-dependent gait stability under hip exoskeleton assistance. We analyzed data from ten healthy adults walking under twelve conditions (ten powered with varying torque magnitude and timing, one passive, and one unassisted), assessing variability via covariance-based ellipsoid volumes. Powered conditions, notably HighLater and HighLatest, significantly increased vertical variability (VT) during early-to-mid stance (10–50% of the gait cycle), with HighLater showing the highest mean ellipsoid volume (99,937 mm<sup>3</sup>/s<sup>3</sup>; z = 2.3). Conversely, the passive PowerOff condition exhibited the lowest variability (47,285 mm<sup>3</sup>/s<sup>3</sup>; z = –1.7) but higher metabolic cost, highlighting a stability-efficiency trade-off. VT was elevated in 11 of 12 conditions (<i>p</i> ≤ 0.0059), and strong correlations (r ≥ 0.65) between ellipsoid volume and total variability validated the method’s robustness. These findings reveal phase-specific stability challenges and metabolic cost variations induced by exoskeleton assistance, providing a foundation for designing adaptive controllers to balance stability and efficiency in rehabilitation and performance enhancement contexts.https://www.mdpi.com/2076-3417/15/13/7530gait stabilityhip exoskeletongait tube analysiscenter of mass variabilityphase-dependent variabilitywearable robotics |
| spellingShingle | Arash Mohammadzadeh Gonabadi Farahnaz Fallahtafti Gait Stability Under Hip Exoskeleton Assistance: A Phase-Dependent Analysis Using Gait Tube Methodology Applied Sciences gait stability hip exoskeleton gait tube analysis center of mass variability phase-dependent variability wearable robotics |
| title | Gait Stability Under Hip Exoskeleton Assistance: A Phase-Dependent Analysis Using Gait Tube Methodology |
| title_full | Gait Stability Under Hip Exoskeleton Assistance: A Phase-Dependent Analysis Using Gait Tube Methodology |
| title_fullStr | Gait Stability Under Hip Exoskeleton Assistance: A Phase-Dependent Analysis Using Gait Tube Methodology |
| title_full_unstemmed | Gait Stability Under Hip Exoskeleton Assistance: A Phase-Dependent Analysis Using Gait Tube Methodology |
| title_short | Gait Stability Under Hip Exoskeleton Assistance: A Phase-Dependent Analysis Using Gait Tube Methodology |
| title_sort | gait stability under hip exoskeleton assistance a phase dependent analysis using gait tube methodology |
| topic | gait stability hip exoskeleton gait tube analysis center of mass variability phase-dependent variability wearable robotics |
| url | https://www.mdpi.com/2076-3417/15/13/7530 |
| work_keys_str_mv | AT arashmohammadzadehgonabadi gaitstabilityunderhipexoskeletonassistanceaphasedependentanalysisusinggaittubemethodology AT farahnazfallahtafti gaitstabilityunderhipexoskeletonassistanceaphasedependentanalysisusinggaittubemethodology |