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Published January 2020 | Submitted
Journal Article Open

Towards Variable Assistance for Lower Body Exoskeletons

Abstract

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.

Additional Information

© 2019 IEEE. Manuscript received: 09, 11, 2019; Accepted 11, 06, 2019. Manuscript received September 10, 2019; accepted November 5, 2019. Date of publication November 26, 2019; date of current version December 11, 2019. This work was supported in part by the National Science Foundation, National Robotics Initiative under Award 1724464, in part by the Caltech Big Ideas and ZEITLIN Funds, and in part by the Wandercraft. The authors would like to thank the participants that took part in the presented experiments. The authors would also like to thank the entireWandercraft team that designed Atalante and continues to provide technical support for this project. Thiswork was conducted under IRB No. 16-0693.

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Created:
August 19, 2023
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October 18, 2023