Papers by Breno Braga Galvão
Revista Interdisciplinar de Pesquisa em Engenharia - RIPE, Feb 8, 2017
The success of a space mission where the satellite must perform rapid attitude maneuvers with gre... more The success of a space mission where the satellite must perform rapid attitude maneuvers with great angles is extremely dependent of a careful investigation of the nonlinear dynamics of the satellite. Since these big maneuvers imply in the dynamic coupling between the satellites angular motion and the actuators such as reaction wheels and/or gas jets. As a result, this coupling must be taking into account in the Attitude Control System (ACS) design. This paper presents the nonlinear model derivation of a rigid satellite and the performance comparison of two controllers designed by Lyapunov and LQR methods. The dynamics of the satellite is initially derived in the non-linear Euler equations form and the kinematics is based on the quaternion parametrization which represent the rotation and attitude motion, respectively. In the sequel, the linear model is obtained where linearization is about an operating point of the arbitrary angular velocity and the reaction wheel angular momentum. From this model, several simulations are performed in order to investigate the influence of the nonlinear dynamics in the in the SCA performance which is designed by trial and error and by the Linear Quadratic Regulator approaches. The ACS performance is evaluated considering the capacity of the reaction wheels to maintain the stability and to control the angular velocity and the attitude of the satellite. The stability is investigated comparing the location of the poles and zeros of the open and closed loops. The ACS performance is evaluated comparing the amount of energy spend by each control law. .
The Journal of Chemical Physics, 2003
We report on a global potential energy hypersurface for the lowest triplet state of H3+ based on ... more We report on a global potential energy hypersurface for the lowest triplet state of H3+ based on the double many-body expansion (DMBE) method and ab initio data points of V5Z quality. These data points are represented with a root mean square deviation of only 3.46 cm−1 in the energy region below the H2+(X2Σg+)+H(2S) dissociation threshold and with less than 15 cm−1 up to the three-particle breakup energy. As expected from a DMBE approach, all dissociation limits are represented accurately and are approached in a physically correct manner.
Proceedings of the 23rd ABCM International Congress of Mechanical Engineering, 2015
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Papers by Breno Braga Galvão