| || New Geo-location Approach Based on Camera Coordinates and Common Points on Multiple Images
Author : Jiaxiang, Yu;Deyun, Xiao;Ludong, Jiang;Rui, Guo
Source : Defence Science Journal ; Vol:59(1) ; 2009 ; pp 43-48
Subject : 533.6 Aerodynamics
Keywords : Geo-location;Camera coordinates;Unmanned aerial vehicle;UAV
Abstract : The accuracy of traditional unmanned aerial vehicle (UAV) geo-location based on single image is too low to meet the needs of precise strike. In this paper, a new UAV geo-location method is presented. The mathematical models are constructed by linearization of the collinearity equations to iteratively compute the pose angles and focal length of the camera. At least three images of the target, along with at least three identifiable common points among the images, are needed for reckoning camera pose angles and focal length. The three dimensional (3D) coordinates of ground target are calculated using forward intersection. The new method can get the target coordinates with no dependence on digital elevation model (DEM) and the measured values of camera pose angles, therefore two of the three primary error sources in the traditional UAV target location approach are eliminated. Simulation and real image experiment results show that the accuracy of the estimated target location is close to that of the UAV position, and that target location error is within 5m circular error probable (CEP) on condition that the UAV is navigated by differential global positioning systems (DGPS).
| || Design and Simulation of Blending Function for Landing Phase of a UAV
Author : Kumar, K. Senthil;Reddy, C. Sudhir;Shanmugam, J.
Source : Defence Science Journal ; Vol:58(3) ; 2008 ; pp 315-326
Subject : 629.7 Aeronautics
Keywords : UAV;Landing phase;Glide slope;Flare path;Blending function;Simulation;Unmanned air vehicle
Abstract : This paper aims to achieve the autonomous landing of unmanned air vehicle (UAV). It mainly deals with glide path design, flare path design, design of blending function, and interfacing the glide and flare paths with the blending function. During transition from glide slope to flare path, a UAV will tend to the unstable region. In a manned aircraft, the pilot controls the unstability that occurs during the change of phase from glide slope to flare, but which is impossible in UAV till now. A blending function has been formulated for use in a UAV to overcome this unstability during transition. This simulation is done with the Matlab Simulink and the results are reported.