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Proceedings Paper

Computer vision sensor for autonomous helicopter hover stabilization
Author(s): Carl-Henrik Oertel
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Paper Abstract

Sensors for synthetic vision are needed to extend the mission profiles of helicopters. A special task for various applications is the autonomous position hold of a helicopter above a ground fixed or moving target. A computer-vision based system, which is able to observe the helicopter flight state during hover and low speed, based on the detection and tracking of significant but arbitrary features, has been developed by the Institute of Flight Mechanics of DLR Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V. The approach is as follows: A CCD camera looks straight downward to the ground and produces an image of the ground view. The digitized video signal is fed into a high performance on- board computer which looks for distinctive features in the image. Any motion of the helicopter results in movements of these patterns in the camera image. By tracking the distinctive features during the succession of incoming images and by the support of inertial sensor data, it is possible to calculate all necessary helicopter state variables, which are needed for a position hold control algorithm. This information is gained from a state variable observer. That means that no additional information about the appearance of the camera view has to be known in advance to achieve autonomous helicopter hover stabilization. The hardware architecture for this image evaluation system mainly consists of several PowerPC processors which communicate with the aid of transputers and an image distribution bus. Feature tracking is performed by a dedicated 2D-correlator subsystem. The paper presents the characteristics of the computer vision sensor and demonstrates its functionality.

Paper Details

Date Published: 26 June 1997
PDF: 9 pages
Proc. SPIE 3088, Enhanced and Synthetic Vision 1997, (26 June 1997); doi: 10.1117/12.277229
Show Author Affiliations
Carl-Henrik Oertel, DLR Institut fuer Flugmechanik (Germany)

Published in SPIE Proceedings Vol. 3088:
Enhanced and Synthetic Vision 1997
Jacques G. Verly, Editor(s)

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