Award Date

5-1-2020

Degree Type

Thesis

Degree Name

Master of Science in Electrical Engineering (MSEE)

Department

Electrical and Computer Engineering

First Committee Member

Sarah Harris

Second Committee Member

Emma Regentova

Third Committee Member

Venkatesan Muthukumar

Fourth Committee Member

David Lee

Number of Pages

137

Abstract

Upright bipedal walking is a complex balance of forces and actions that is almost taken for granted. How this system is modeled, how it affects a prosthesis, and how it can be implemented in the real world are topics that the proposed Dynamic Control Platform aims to address.

The Dynamic Control Platform (DCP) is a bipedal robot designed to test bio-inspired control algorithms with the aim to smooth out the walking experience for prosthetic legs. The main control paradigm that the DCP centers on the principle of orthogonal constraint, which aims to enforce a perpendicular relationship between the center of mass velocity and the ground reaction force so that mechanical cost is minimized.

The DCP is a circular hub with six ankles/feet equally distributed around the wheel. It is designed so that at most two of its ankles are touching the ground at any time, as in human walking. However, the ankles rotate around the central hub to eliminate the need for swinging of the leg – which simplifies the design and allows the focus to remain on control of the ankles. The ankles are controlled by a custom built motor controller which allows for servo-like angular control of a DC motor. The encoder counting, which allows for precise angular control, is completed by small microcontrollers, with one microcontroller dedicated to each ankle. This frees the main microcontroller to process incoming data and to enforce the desired control algorithms for walking.

In order to enforce the principle of orthogonal constraint – keeping center of mass force and velocity vectors parallel or nearly parallel, the robot needs to measure its force and velocity. To do so, we designed and built a force sensing trackway. The trackway converts sensed voltages into forces and transmit those wirelessly to the robot. The connection between the robot and the trackway is necessarily wireless because the robot must be able to move freely along the trackway and any contact with the ground must be sensed through the trackway.

The DCP can be used in the future to examine various ankle torque profiles for a powered prosthesis and the force trackway can be used to verify if the ankle profile has smooth redirections during each stride. This would allow researchers to hone in on desired ankle movement profiles without the need for human trials until much later in the process. These profiles, in turn, would help make the usage of prosthetic legs more comfortable and efficient for the wearer.

Disciplines

Computer Engineering | Electrical and Computer Engineering

File Format

pdf

File Size

4.4 MB

Degree Grantor

University of Nevada, Las Vegas

Language

English

Rights

IN COPYRIGHT. For more information about this rights statement, please visit http://rightsstatements.org/vocab/InC/1.0/

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