Robust adaptive dynamic surface attitude control of flexible spacecraft

The nonlinear attitude motion equations of flexible spacecraft are described by the Modified Rodrigues Parameters (MRPs). Based on Lyapunov stability theory, a robust dynamic surface controller is designed for the attitude tracking and active vibration suppression of flexible spacecraft in the presence of external disturbance torques. Then, this controller is redesigned with an adaptive update law such that the controller can be used without the known inertial moments of the attitude control system. Lyapunov analyses show that the two controllers can guarantee the asymptotical stability of attitude control system. The undesirable vibration is also actively suppressed by the modal velocity feedback (MVF) control method. Finally, simulations verified the effectiveness of the presented control algorithms.