Title page for ETD etd-05152009-221315


Type of Document Master's Thesis
Author Hager, Daniel Michael
Author's Email Address dhager@vt.edu
URN etd-05152009-221315
Title Situational Awareness of a Ground Robot From an Unmanned Aerial Vehicle
Degree Master of Science
Department Electrical and Computer Engineering
Advisory Committee
Advisor Name Title
Abbott, A. Lynn Committee Chair
Kochersberger, Kevin Bruce Committee Co-Chair
Athanas, Peter M. Committee Member
Keywords
  • Object Tracking
  • UAV
  • Obstacle Detection
  • Supervisory Control
  • Image Processing
Date of Defense 2009-05-04
Availability unrestricted
Abstract
In the operation of unmanned vehicles, safety is a primary concern. This thesis focuses on the use of computer vision in the development of a situational awareness system that allows for safe deployment and operation of a ground robot from an unmanned aerial vehicle (UAV). A method for detecting utility cables in 3D range images is presented. This technique finds areas of an image that represent edges in 3D space, and uses the Hough transform to find those edges that take the shape of lines, indicating potential utility cables. A mission plan for stereo image capture is laid out as well for overcoming some weaknesses of the stereo vision system; this helps ensure that all utility cables in a scene are detected. In addition, the system partitions the point cloud into best-fit planes and uses these planes to locate areas of the scene that are traversable by a ground robot. Each plane’s slope is tested against an acceptable value for negotiation by the robot, and the drop-off between the plane and its neighbors is examined as well. With the results of this analysis, the system locates the largest traversable region of the terrain using concepts from graph theory. The system displays this region to the human operator with the drop-offs between planes clearly indicated. The position of the robot is also simulated in this system, and real-time feedback regarding dangerous moves is issued to the operator.

After a ground robot is deployed to the chosen site, the system must be capable of tracking it in real time as well. To this end, a software routine that uses ARToolkit’s marker tracking capabilities is developed. This application computes the distance to the robot, as well as the horizontal distance from camera to the robot; this allows the flight controller to issue the proper commands to keep the robot centered underneath the UAV.

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