Date of Award

Spring 1997

Document Type

Thesis - Restricted

Degree Name

Master of Science (MS)

Department

Biomedical Engineering

First Advisor

Prieto, Thomas

Second Advisor

Jeutter, Dean C.

Third Advisor

Myklebust, Joel

Abstract

Extensive research has been conducted to characterize the postural control system, which is instrumental in maintaining standing balance. A thorough understanding of the postural control system may allow early diagnosis of conditions associated with diseases and aging that can lead to an increased risk of falling. Most studies concentrate on the analysis of the center of pressure measured by either a single or dual force-plate platform. Force distribution measurements can provide information on weight distribution, foot position and orientation, as well as foot-ground contact area. These measurements may be enhance our understanding of the postural control system when used in conjunction with center of pressure measurements. The purpose of this thesis was to develop and validate a microcontroller-based · system to measure force distribution under the feet using commercially available sensors. The system was designed to complement an existing dual force-plate platform so that center of pressure and force distribution can be measured simultaneously. The Force Distribution Measurement System (FDMS) was developed and integrated with a dual force-plate platform. Custom electronic circuitry and programming were developed for the system. The characteristics of the force sensors and the performance of the circuits used in the system were evaluated. An apparatus was also designed and developed to calibrate the sensors. A study was conducted to validate the system. Ten healthy young adults performed four balance tests on the integrated FDMS and dual force-plate platform: 1) normal stance with eyes open, 2) normal stance with eyes closed, 3) forward and then backward lean with eyes open, and 4) forward and then backward lean with eyes closed. The data from the first test was used to validate the use of the FQMS to reliably measure force distribution, foot position and orientation. The data collected from the balance study were used to illustrate potential applications for the FDMS in postural control studies. Lateral weight distribution asymmetry was analyzed, and a significant difference was found between the eyes-open and eyes-closed conditions during normal stance. The results of the leaning tests demonstrated the utility of the FDMS to determine the maintenance of foot-ground contact during stability limit testing.

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