Closed-Loop Torque and Kinematic Control of a Hybrid Lower-Limb Exoskeleton for Treadmill Walking.

Autor:	Chang CH; Department of Mechanical and Aerospace Engineering, Syracuse University, Syracuse, NY, United States., Casas J; Department of Mechanical and Aerospace Engineering, Syracuse University, Syracuse, NY, United States., Brose SW; Department of Physical Medicine and Rehabilitation, SUNY Upstate Medical University, Syracuse, NY, United States.; Spinal Cord Injury and Disabilities Service, Syracuse VA Medical Center, Syracuse, NY, United States., Duenas VH; Department of Mechanical and Aerospace Engineering, Syracuse University, Syracuse, NY, United States.
Jazyk:	angličtina
Zdroj:	Frontiers in robotics and AI [Front Robot AI] 2022 Jan 20; Vol. 8, pp. 702860. Date of Electronic Publication: 2022 Jan 20 (Print Publication: 2021).
DOI:	10.3389/frobt.2021.702860
Abstrakt:	Restoring and improving the ability to walk is a top priority for individuals with movement impairments due to neurological injuries. Powered exoskeletons coupled with functional electrical stimulation (FES), called hybrid exoskeletons, exploit the benefits of activating muscles and robotic assistance for locomotion. In this paper, a cable-driven lower-limb exoskeleton is integrated with FES for treadmill walking at a constant speed. A nonlinear robust controller is used to activate the quadriceps and hamstrings muscle groups via FES to achieve kinematic tracking about the knee joint. Moreover, electric motors adjust the knee joint stiffness throughout the gait cycle using an integral torque feedback controller. For the hip joint, a robust sliding-mode controller is developed to achieve kinematic tracking using electric motors. The human-exoskeleton dynamic model is derived using Lagrangian dynamics and incorporates phase-dependent switching to capture the effects of transitioning from the stance to the swing phase, and vice versa. Moreover, low-level control input switching is used to activate individual muscles and motors to achieve flexion and extension about the hip and knee joints. A Lyapunov-based stability analysis is developed to ensure exponential tracking of the kinematic and torque closed-loop error systems, while guaranteeing that the control input signals remain bounded. The developed controllers were tested in real-time walking experiments on a treadmill in three able-bodied individuals at two gait speeds. The experimental results demonstrate the feasibility of coupling a cable-driven exoskeleton with FES for treadmill walking using a switching-based control strategy and exploiting both kinematic and force feedback. Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. (Copyright © 2022 Chang, Casas, Brose and Duenas.)
Databáze:	MEDLINE
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