Based On Singular Perturbation Of Three-axis Stabilized Flexible Satellite Attitude Control System

With the development of aerospace mission, more and more satellite adopts large scale flexible structure. However, rigid body motion of flexible spacecraft in orbit is strongly coupled with elastic vibration of flexible body. The dissertation, supported by a grant from National laboratory of space intelligent control, studies the design and realization of attitude control and vibration suppression for the three-axe stabilized satellite with flexible solar-array appendages.By model analyzing of a specific satellite with flexible solar-array appendages, it proved the importance of vibration suppression in attitude control of flexible satellite. Then, taking the flexible satellite as a singular perturbation system, a singular perturbation model is developed to reduce the order of dynamics model. The slow subsystem represents the rigid body motion while the fast subsystem describes the elastic vibrations.Based on the singular perturbation model, two composite controllers are adopted:one is PID and LQR composite controller and the other is SMC and LQR composite controller. The simulation results show that both of the two methods can approve the attitude control precise requirement and suppress the vibration of flexible solar-array appendages efficiently. However, there is small overshoot exists under the control of PID and LQR composite controller. The composite SMC and LQR controller improves it and has good robustness. The feasibility of singular perturbation method used in three-axe stabilized satellite attitude control is proved.