Metabolic Cost of Overground Walking Using a Motorized Walker-like Exoskeleton
Loading...
Date
2024-05
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
The Ohio State University
Abstract
Those with movement disorders commonly use exoskeletons and assistive walking devices. The purpose of most exoskeletons and assistive walking devices is to reduce the effort required to perform a task by providing mechanical assistance to the user. A way to measure effort is by studying metabolic cost. Thus, by providing mechanical assistance when performing a task, the metabolic cost of performing the task may decrease. Previous studies showed a passive walker-like exoskeleton cart in some configurations decreased the metabolic cost of walking [1]. Since such findings, a brushless DC motor was added to the cart to provide an adjustable assistive forward force on the user while walking. This research aims to determine the relationship between the intensity of the assistive forward force, metabolic cost, and walking speed when overground walking with the cart. To do so, metabolic and walking speed data was collected from five subjects using a COSMED K5 system and a video camera respectively. Each subject completed ten six-minute trials where nine of the trials were used to collect walking data. The trial order was randomized. One of the trials was used to collect normal walking data in which the subjects walked normally, without the cart. The metabolic cost and walking speed from this normal walking trial were used as the baseline metabolic cost and walking speed during data analysis.
When averaging across the five subjects, the cart was shown to decrease walking speed for all but the greatest assistance level (potentiometer setting 4.2, corresponding to large assistance). The cart increased the average metabolic cost per unit time from normal walking for all assistance levels except one (potentiometer setting 3.6, corresponding to medium assistance) and increased the average metabolic cost per unit distance from normal walking for all assistance levels. However, analyzing the data subject-wise, we found that the cart decreased metabolic rate below normal walking for four out of the five subjects and that the cart decreased the metabolic cost per unit distance for three out of the five subjects (with one subject showing a marginal increase). These decreases suggest that the cart may be promising. Further research will be required to determine how the cart can be modified or how much training the subjects need to be provided such that the cart becomes a more uniformly assistive walking device. Should the cart be modified and proven to reduce the metabolic cost of walking, the cart may replace other devices and provide a framework for future device designs.