Date Approved

8-2020

Graduate Degree Type

Thesis

Degree Name

Engineering (M.S.E.)

Degree Program

Biomedical Sciences

First Advisor

Samhita Rhodes

Second Advisor

Gordon Alderink

Third Advisor

Blake Ashby

Academic Year

2019/2020

Abstract

The body’s postural control mechanism is responsible for responding to perturbations of balance and keeping the body upright. One of the main ways that this is completed during quiet standing, where both feet are planted on the ground, is through center of pressure oscillations. In these oscillations, the center of pressure circles around the center of mass, constantly counteracting any lean that exists in the body. These oscillations can be recorded with floorembedded force plates and center of mass can be recorded with a motion capture system. In this research, these signals were recorded for stances with feet together and feet tandem with eyes opened and eyes closed with neurotypical subjects. Center of pressure and center of mass were compared to determine if they provide the same information as one another. Through different correlation measures, it was shown that they generally have a very strong relationship to one another, and that COP provides as much information as COM.

From there, center of pressure was further analyzed using approximate entropy, velocity measures, and regression. This analysis showed evidence of increased irregularity, increased velocity, and increased frequency content in center of pressure oscillations during standing conditions with lower stability. ApEn indicated significant differences between the most stable eyes open, feet together condition and all of the less stable feet tandem trials for eyes open and eyes closed in nearly every subject. Velocity, however, only indicated significant differences between the most stable condition and the least stable eyes closed, feet tandem trials. Regression analysis showed a decrease in the content that could be explained by the model as stability decreased. Regression also provided a general illustration of what each stability condition may be expected to look like, which can be used to compare future data against. The results of this study will be useful to compare non-neurotypical subject data to moving forward.

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