Simultaneous maneuver and vibration suppression of flexible spacecraft

A method is described for the simultaneous large-angle maneuver and vibration suppression of flexible spacecraft. The control action is carried out in two independent systems, one system performing the maneuvers and the other system controlling the elastic motion. The vibration is suppressed using a natural control. It is shown that control of the elastic motion does not distort the maneuver because the spacecraft linear and angular momenta are conserved regardless of spacecraft modeling errors. Thus, the maneuver can be designed and performed independently of the elastic motion control.     

Comparison of two linearization methods for optimal attitude maneuver of a non-linear flexible spacecraft

^** Email: zhengjhluck{at}hotmail.com In this paper, we consider the optimal attitude maneuver designfor a non-linear flexible spacecraft with vibrating solar arrays.Two different linearization methods for the non-linear systemare compared in this study. One is the recursive approximatingsequence approach (RASA) to design a time-varying linear quadraticregulator (LQR) for the non-linear system and the other is todesign a LQR by linearizing the non-linear system at each locally‘frozen’ state in any sufficient small sphere alongthe trajectory. Numerical simulation shows that the later approachgives good design results quickly by scanning the time axisonly one time. The RASA method may scan the time axis severaltimes to get a good approach. Moreover, both linearization methodsgive satisfying control results in attitude maneuver and vibrationsuppression control for the non-linear flexible spacecraft.     

Stabilization of a class of hybrid systems arising in flexible spacecraft

We consider the problem of rigorous modelling of flexible spacecraft and their stabilization. It is shown that the dynamics of the flexible spacecraft can be described by a coupled system of ordinary differential equations and partial differential equations (hybrid system). Lyapunov's approach is used to prove the stabilizability of the system. Simple feedback controls are suggested for stabilization of flexible spacecraft.This work was supported in part by the Natural Science and Engineering Research Council of Canada under Grant No. A7109. The authors would like to thank Professor L. Meirovitch and the reviewers for some valuable suggestions.