Investigation of multivariable control techniques for attitude control of a rigid satellite - flexible / Investigação de técnicas de controle multivariáveis no controle de atitude de um satélite rígido - flexível

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

The main objective of this work is the investigation of multivariable control techniques for attitude control of a Rigid Satellite - Flexible. For this investigation, a satellite model was developed consisting of a rigid body and two flexible panels. The investigated techniques are Linear Quadratic Regulator (LQR) method, Linear Quadratic Gaussian (LQG) method and H Infinity method. The satellite modeling was built following the Lagrangean approach and the discretization was done using the assumed-modes method. The equations of motion obtained were written in its modal state space form. In this phase one works with three modes of vibration, in order to inquire its influence in the performance of the system. In LQR method, the control law shows a good performance, however the method is only applied for system with absence of disturbances and where all the states are available. In reality that does not happen. On the other hand, the LQG method is more realistic, because nor all the states are available and the system presents noises. The LQG controller (Kalman filter + LQR) is better for damping the modes of vibration of panels. However, the performance of the system decays due to presence of the Kalman filter. The disadvantage of both the methods is the absence of a systematic procedure in the choice of weights matrix Q and R, and noises w and v. The H∞ method has a distinct systematic with respect to the other two methods here applied. In comparison with LQR and LQG the H∞ results in this work had been superior. However its great disadvantage is in the need of great ability and necessary experience to build the weights that are associated to the performance of the method H∞. Regarding to the flexion modes of vibration, the influences were verified for the controller and were more perceptible in the levels of panel vibration.

ASSUNTO(S)

lqr control design controle h-infinito controle lqr h-control design controle lqg controle multivatiável estruturas flexíveis lqg control design flexíble structures multivariable control

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