Date of Award

1-1-2010

Document Type

Masters Thesis

Degree Name

M.S.

Organizational Unit

Daniel Felix Ritchie School of Engineering and Computer Science

First Advisor

Rahmat Shoureshi, Ph.D.

Second Advisor

Yun-Bo Yi

Third Advisor

Matthew Rutherford

Fourth Advisor

Stephen Albert

Keywords

Active, Biomedical, Control, Diabetic ulcers, Feedback, Mechatronics

Abstract

A pneumatic system with PID control for an actively controlled cast is designed. The cast is intended to aid healing of diabetic foot ulcers by relieving pressure from the sole of a patient's foot and distributing it to the calf. This is accomplished by a pneumatic system which maintains set pressure in multiple air bladders. The research began by defining an electrical circuit analogous to a single supply subsystem. Tests are performed to determine the coefficients for each component. These coefficients are used in a mathematical model to better understand the response of the system to pressure input. A controller is designed for a single subsystem using Ziegler-Nichols first method as a starting point. PID control is extended to each configuration option. Control theory is used to determine an optimal configuration of the bladder subsystems. Series, parallel, and a hybrid configuration are considered. The cost, complexity, and performance of each configuration is used in a weighted decision matrix to choose the best configuration. The parallel configuration is chosen as the optimal solution. Because the pump used in the design is capable of supplying all air bladders simultaneously, the parallel configuration can be simplified to a single subsystem. The model of the subsystem is validated against physical tests. The controller driving the single supply subsystem is used as a guideline for designing a modified duty cycle controller. This controller is implemented using simple pneumatic and electrical components.

Publication Statement

Copyright is held by the author. User is responsible for all copyright compliance.

Rights Holder

Susan Renee Mueller

Provenance

Received from ProQuest

File Format

application/pdf

Language

en

File Size

137 p.

Discipline

System Science, Electrical Engineering

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