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Mathematical Problems in Engineering
Volume 2014 (2014), Article ID 820586, 8 pages
Research Article

Satellite Attitude Control System Design Taking into Account the Fuel Slosh and Flexible Dynamics

1National Institute for Space Research (INPE), Avenida dos Astronautas 1758, 12227-010 São José dos Campos, SP, Brazil
2Brasília University, Campus Gama, Área Especial de Indústria-A-UnB, 72444-240 Brasilia, DF, Brazil

Received 31 March 2014; Revised 23 July 2014; Accepted 29 July 2014; Published 10 September 2014

Academic Editor: Antonio F. Bertachini A. Prado

Copyright © 2014 Alain G. de Souza and Luiz C. G. de Souza. 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 design of the spacecraft Attitude Control System (ACS) becomes more complex when the spacecraft has different type of components like, flexible solar panels, antennas, mechanical manipulators and tanks with fuel. The interaction between the fuel slosh motion, the panel’s flexible motion and the satellite rigid motion during translational and/or rotational manoeuvre can change the spacecraft center of mass position damaging the ACS pointing accuracy. This type of problem can be considered as a Fluid-Structure Interaction (FSI) where some movable or deformable structure interacts with an internal fluid. This paper develops a mathematical model for a rigid-flexible satellite with tank with fuel. The slosh dynamics is modelled using a common pendulum model and it is considered to be unactuated. The control inputs are defined by a transverse body fixed force and a moment about the centre of mass. A comparative investigation designing the satellite ACS by the Linear Quadratic Regulator (LQR) and Linear Quadratic Gaussian (LQG) methods is done. One has obtained a significant improvement in the satellite ACS performance and robustness of what has been done previously, since it controls the rigid-flexible satellite and the fuel slosh motion, simultaneously.