Honors Theses

Date of Award

Spring 5-9-2020

Document Type

Undergraduate Thesis


Electrical Engineering

First Advisor

Paul Mallette Goggans

Second Advisor

James Sabatier

Third Advisor

Joel Mobley

Relational Format



Collie Box is a medical device that measures the gait parameters of the person walk- ing in front of it. This device uses the Ultrasonic Doppler system to extract the heel-contact and toe-off times of a person walking within the range of 2-10 meters. These times are used to determine the leg’s swing phase and double stance times. The ultrasonic transducer of 10mm diameter is driven at 40kHz. At the time of the heel-contact and toe-off, foot velocity is zero while the torso part of the human body is still in motion. The wide directivity of 10mm diameter ultrasonic transducer cre- ates problems in reading the times at which the foot velocity is zero. For processing the received signal, we use Matlab algorithm to fit the measured foot velocity to a model in order to estimate these times. To narrow the directivity of the ultrasonic transducer, different sizes and arrangements of the ultrasonic transducer are com- pared. The linear array of ten 3.7mm diameter transducer is observed to have narrow directivity. Further, the comparison of the heel-contact and toe-off times is made be- tween force sensor and beamed 3.7mm diameter transducer arrays and single 10mm diameter ultrasonic transducer. As a result, the spectrogram view of unprocessed signal of a person walking in front of the beamed 3.7mm diameter transducer seems to have reduced torso velocity as compared to 10mm diameter ultrasonic transducer. However, when heel-contact and toe-off times of processed signal of a person walk- ing in front of beamed 3.7mm diameter transducer doesn’t seem to improve when compared with the force plate sensor.

Creative Commons License

Creative Commons Attribution 4.0 License
This work is licensed under a Creative Commons Attribution 4.0 License.



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