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Mathematical Problems in Engineering
Volume 2012 (2012), Article ID 460430, 15 pages
http://dx.doi.org/10.1155/2012/460430
Research Article

Fisheye-Lens-Based Visual Sun Compass for Perception of Spatial Orientation

1College of Electronic Information and Control Engineering, Beijing University of Technology, Beijing 100124, China
2College of Information Science and Technology, Beijing Normal University, Beijing 100875, China
3College of Computing and Communication Engineering, Graduate University of the Chinese Academy of Sciences, Beijing 100049, China

Received 11 October 2011; Accepted 9 December 2011

Academic Editor: Sheng-yong Chen

Copyright © 2012 Liang Wang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

In complex aeronautical and space engineering systems, conventional sensors used for environment perception fail to determine the orientation because of the influences of the special environments, wherein geomagnetic fields are exceptional and the Global Positioning System is unavailable. This paper presents a fisheye-lens-based visual sun compass that is efficient in determining orientation in such applications. The mathematical model is described, and the absolute orientation is identified by image processing techniques. For robust detection of the sun in the image of the visual sun compass, a modified maximally stable extremal region algorithm and a method named constrained least squares with pruning are proposed. In comparison with conventional sensors, the proposed visual sun compass can provide absolute orientation with a tiny size and light weight in especial environments. Experiments are carried out with a prototype validating the efficiency of the proposed visual sun compass.