Heel Down and Toe-off time measured with Ultrasonic Doppler System and Force Plate Sensor

Author

Sabin Timsina, University of MississippiFollow

Date of Award

Spring 5-9-2020

Document Type

Undergraduate Thesis

Department

Electrical Engineering

First Advisor

Paul Mallette Goggans

Second Advisor

James Sabatier

Third Advisor

Joel Mobley

Relational Format

Dissertation/Thesis

Abstract

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.

Recommended Citation

Timsina, Sabin, "Heel Down and Toe-off time measured with Ultrasonic Doppler System and Force Plate Sensor" (2020). Honors Theses. 1376.
https://egrove.olemiss.edu/hon_thesis/1376

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