Metabolically efficient walking assistance using optimized timed forces at the waist

Authors

Prokopios Antonellis, Department of Neurology, Oregon Health & Science University, Portland, OR USAFollow
Arash Mohammadzadeh Gonabadi, University of Nebraska at OmahaFollow
Sara Myers, University of Nebraska at OmahaFollow
Iraklis Pipinos, University of Nebraska at OmahaFollow
Philippe Malcolm, Department of Biomechanics, University of Nebraska at Omaha, Omaha, NE USAFollow

Author ORCID Identifier

Myers - https://orcid.org/0000-0002-2934-2624

Pipinos - https://orcid.org/0000-0001-6873-6346

Antonellis - https://orcid.org/0000-0002-8927-1274

Gonabadi - https://orcid.org/0000-0002-4535-0325

Malcolm - https://orcid.org/0000-0003-4110-4167

Document Type

Article

Publication Date

3-16-2022

Abstract

The metabolic rate of walking can be reduced by applying a constant forward force at the center of mass. It has been shown that the metabolically optimal constant force magnitude minimizes propulsion ground reaction force at the expense of increased braking. This led to the hypothesis that selectively assisting propulsion could lead to greater benefits. We used a robotic waist tether to evaluate the effects of forward forces with different timings and magnitudes. Here, we show that it is possible to reduce the metabolic rate of healthy participants by 48% with a greater efficiency ratio of metabolic cost reduction per unit of net aiding work compared with other assistive robots. This result was obtained using a sinusoidal force profile with peak timing during the middle of the double support. The same timing could also reduce the metabolic rate in patients with peripheral artery disease. A model explains that the optimal force profile accelerates the center of mass into the inverted pendulum movement during single support. Contrary to the hypothesis, the optimal force timing did not entirely coincide with propulsion. Within the field of wearable robotics, there is a trend to use devices to mimic biological torque or force profiles. Such bioinspired actuation can have relevant benefits; however, our results demonstrate that this is not necessarily optimal for reducing metabolic rate.

Comments

“This is the author’s version of the work. It is posted here by permission of the AAAS for personal use, not for redistribution. The definitive version was published in Science Robotics on Vol 7 iss 64, DOI: 10.1126/scirobotics.abh1925

Journal Title

Science Robotics

Volume

7

Issue

64

Recommended Citation

Antonellis, Prokopios; Gonabadi, Arash Mohammadzadeh; Myers, Sara; Pipinos, Iraklis; and Malcolm, Philippe, "Metabolically efficient walking assistance using optimized timed forces at the waist" (2022). Journal Articles. 356.
https://digitalcommons.unomaha.edu/biomechanicsarticles/356