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Mathematical Problems in Engineering
Volume 2012 (2012), Article ID 985429, 12 pages
Research Article

Unscented Kalman Filter Applied to the Spacecraft Attitude Estimation with Euler Angles

1Space Mechanic and Control Division, INPE, 12227-010 São José dos Campos, SP, Brazil
2Department of Mathematics, FEG, UNESP, 12516-410 Guaratinguetá, SP, Brazil

Received 8 July 2011; Accepted 18 September 2011

Academic Editor: Antonio F. Bertachini A. Prado

Copyright © 2012 Roberta Veloso Garcia 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.


The aim of this work is to test an algorithm to estimate, in real time, the attitude of an artificial satellite using real data supplied by attitude sensors that are on board of the CBERS-2 satellite (China Brazil Earth Resources Satellite). The real-time estimator used in this work for attitude determination is the Unscented Kalman Filter. This filter is a new alternative to the extended Kalman filter usually applied to the estimation and control problems of attitude and orbit. This algorithm is capable of carrying out estimation of the states of nonlinear systems, without the necessity of linearization of the nonlinear functions present in the model. This estimation is possible due to a transformation that generates a set of vectors that, suffering a nonlinear transformation, preserves the same mean and covariance of the random variables before the transformation. The performance will be evaluated and analyzed through the comparison between the Unscented Kalman filter and the extended Kalman filter results, by using real onboard data.