Adaptive Ankle Exoskeleton Control: Validation Across Diverse Walking Conditions

Safoura Sadegh Pour Aji Bishe, Thang Nguyen, Ying Fang, Zachary F. Lerner

Research output: Contribution to journalArticlepeer-review

28 Scopus citations


Ankle exoskeletons hold potential to augment human walking ability, yet their use in free-living environments has been limited by the absence of practical and effective control strategies that can appropriately adapt to variable terrain. To address this challenge, we derived a novel analytical ankle joint moment estimation model using custom wearable sensors and developed an exoskeleton control scheme to adapt assistance proportional to the biological plantar-flexor moment in real-time for unimpaired individuals and individuals with disabilities who are able to ambulate independently. We validated the controller during level, 5 incline and decline walking, each at multiple speeds; stair ascent; stair descent; and 90 turning (88 ± 3% average accuracy, R = 0.96 ± 0.01 average correlation coefficient). This study demonstrates the ability of the controller to accurately adapt assistance in unimpaired individuals across a wide variety of walking conditions without the need for walking condition classification or real-time assessment of muscle activity. Clinical feasibility testing in four individuals with cerebral palsy suggests that this control method holds promise for incline and stair walking in individuals with mild-to-severe impairment. This ankle-moment-adaptive control system can be used to prescribe ankle exoskeleton assistance that adapts in real-time across the tested conditions.

Original languageEnglish (US)
Pages (from-to)801-812
Number of pages12
JournalIEEE Transactions on Medical Robotics and Bionics
Issue number3
StatePublished - Aug 1 2021
Externally publishedYes


  • Wearable robotics
  • assistive device
  • control system
  • gait
  • rehabilitation
  • walking

ASJC Scopus subject areas

  • Biomedical Engineering
  • Human-Computer Interaction
  • Computer Science Applications
  • Control and Optimization
  • Artificial Intelligence


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