Robust dynamic surface sliding mode control for attitude tracking of flexible spacecraft with an extended state observer

The nonlinear attitude motion equations of flexible spacecraft described by the Euler angles are expressed in the vector form. Based on dynamic surface control, a new robust dynamic surface sliding mode controller is proposed for the attitude tracking and active vibration suppression of flexible spacecraft in the presence of parameter uncertainty and external disturbances. Then, a novel robust dynamic surface finite time sliding mode controller is proposed with an extended state observer such that the uncertainties can be estimated. Lyapunov stability analyses show that the two controllers can guarantee the asymptotical stability of the attitude control system. The undesirable vibration of flexible spacecraft is also actively suppressed by the modal velocity feedback approach. Finally, simulation results verified the effectiveness of the presented control algorithms.