Preferred walking speeds and metabolic costs while using a walking-assistive walker-like exoskeleton
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Date
2021-12
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The Ohio State University
Abstract
Humans have a sophisticated neuro-muscular system which helps them walk in a smooth and well-balanced manner. Movement disorders are mostly caused by abnormalities in central and peripheral nervous systems. Such disorders cause recurrent involuntary motions or an inability to move despite the usage of adequate strength. Better understanding of walking biomechanics has the potential to inform development of assistive devices that can aid humans with movement disorders, a way to walk better. The devices used today for physical therapy and rehab have not been able to explain how the human body interacts with them as they are complex to model and have additional variables to compute. Moreover, these devices often fall short in providing the metabolic reduction that it should produce. Hence, a simplified version of these complex setups is necessary to get a better understanding of how humans interact in detail with an external powered device. This study used a simplified Zimmerman's powered walker-like exoskeleton cart that was built at Ohio State's Movement Lab to focus on how external assistance from such an exoskeleton reduces the metabolic energy for walking and to characterize the human-exoskeleton coupled dynamics. To begin with, the prototype was improved for better data acquisitions to conduct two types of trials: (1) measure the preferred overground walking speeds for different fixed motor assistance levels and (2) measure metabolic cost on a treadmill-exoskeleton setup for different fixed motor assistance levels. We concluded that the device can substantially increase over ground walking speeds. Using a simple mathematical model, we showed that the device may decrease the energy cost of walking but only up to a certain assistance level, beyond which it would increase the cost. This pursuit can also give us a better insight of the neuro-muscular interactions with an exoskeleton and help improve current assistive walking devices to aid people with gait disorders.