Airborne Image Navigation for Ocean Wave Motion Analysis

John P. Dugan, Alan E. Evans and Udayan V. Bhapkar

Abstract:	A GPS/INS guided airborne framing camera has been designed, constructed and tested for imaging the ocean. The objective is to navigate the frames of data accurately enough so that they can be mapped onto a rectilinear grid on the mean ocean surface. A temporal sequence of these frames, then, is utilized for analyzing the propagation of surface waves on the ocean. This paper describes the system, the tests which have been undertaken to evaluate its pointing performance, and preliminary results. The system consists of a turret that is attached to the underside of the nose cowling of a small aircraft, the framing camera, an integrated INS/GPS processor that measures its location and attitude, and a computer that controls the pointing of the camera. The camera is commanded to point at a GPS location, and the GPS and inertia data for the turret are used by the controller to drive the turret to maintain its orientation to the target no matter what the motions of the aircraft. The accuracy has been evaluated by pointing the camera at an array of surveyed targets on the ground. The rms pointing error is shown to be about 3 mrad, which translates into an error of 20 m (1 ó ) at nominal range of 6 km, and this is improved by a factor of about 3 by utilizing more precise post-flight solutions for the turret position and attitude. The mapped imagery is utilized for studies of ocean wave phenomena which also are described.
Published in:	Proceedings of the 2000 National Technical Meeting of The Institute of Navigation January 26 - 28, 2000 Pacific Hotel Disneyland Anaheim, CA
Pages:	317 - 322
Cite this article:	Dugan, John P., Evans, Alan E., Bhapkar, Udayan V., "Airborne Image Navigation for Ocean Wave Motion Analysis," Proceedings of the 2000 National Technical Meeting of The Institute of Navigation, Anaheim, CA, January 2000, pp. 317-322.
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