Title page for ETD etd-06262009-141905


Type of Document Master's Thesis
Author Murtha, Justin Fortna
Author's Email Address jmurtha@vt.edu
URN etd-06262009-141905
Title An Evidence Theoretic Approach to Design of Reliable Low-Cost UAVs.
Degree Master of Science
Department Aerospace and Ocean Engineering
Advisory Committee
Advisor Name Title
Woolsey, Craig A. Committee Chair
Kochersberger, Kevin Bruce Committee Member
Marchman, James F. III Committee Member
Keywords
  • Fault Tree Analysis
  • Reliability
  • SPAARO
  • UAV
  • Dempster-Shafer Theory
  • Evidence Theory
Date of Defense 2009-06-18
Availability unrestricted
Abstract
Small unmanned aerial vehicles (SUAVs) are plagued by alarmingly high failure rates. Because these systems are small and built at lower cost than full-scale aircraft, high quality components and redundant systems are often eschewed to keep production costs low. This thesis proposes a process to ``design in'' reliability in a cost-effective way. Fault Tree Analysis is used to evaluate a system's (un)reliability and Dempster-Shafer Theory (Evidence Theory) is used to deal with imprecise failure data. Three unique sensitivity analyses highlight the most cost-effective improvement for the system by either spending money to research a component and reduce uncertainty, swap a component for a higher quality alternative, or add redundancy to an existing component. A MATLAB$^{\circledR}$ toolbox has been developed to assist in practical design applications. Finally, a case study illustrates the proposed methods by improving the reliability of a new SUAV design: Virginia Tech's SPAARO UAV.
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