Towards Variable Assistance for Lower Body Exoskeletons

This letter presents and experimentally demonstrates a novel framework for variable assistance on lower body exoskeletons, based upon safety-critical control methods. Existing work has shown that providing some freedom of movement around a nominal gait, instead of rigidly following it, accelerates t...

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Bibliographic Details
Published in:IEEE robotics and automation letters Vol. 5; no. 1; pp. 266 - 273
Main Authors: Gurriet, Thomas, Tucker, Maegan, Duburcq, Alexis, Boeris, Guilhem, Ames, Aaron D.
Format: Journal Article
Language:English
Published: Piscataway IEEE 01.01.2020
The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subjects:
Assistive devices
control architectures and programming
Control methods
Exoskeletons
Feedback
Gait
Leg
Legged locomotion
Perturbation
physically assistive devices
Prosthetics
Prosthetics and exoskeletons
Safety critical
Tubes
ISSN:2377-3766, 2377-3766
Online Access:Get full text
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Summary:This letter presents and experimentally demonstrates a novel framework for variable assistance on lower body exoskeletons, based upon safety-critical control methods. Existing work has shown that providing some freedom of movement around a nominal gait, instead of rigidly following it, accelerates the spinal learning process of people with a walking impediment when using a lower body exoskeleton. With this as motivation, we present a method to accurately control how much a subject is allowed to deviate from a given gait while ensuring robustness to patient perturbation. This method leverages control barrier functions to force certain joints to remain inside predefined trajectory tubes in a minimally invasive way. The effectiveness of the method is demonstrated experimentally with able-bodied subjects and the Atalante lower body exoskeleton.
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ISSN:2377-3766
2377-3766
DOI:10.1109/LRA.2019.2955946