Adaptive fast nonsingular terminal sliding mode control for attitude tracking of flexible spacecraft with rotating appendage

This paper investigates the attitude tracking problem for the flexible spacecraft composed of a rigid platform with a rotating appendage. Two robust attitude controllers, each matched to the platform and the appendage, are constructed simultaneously. First, the relative kinematic models are presented, and the dynamic model describing the translation, rotation, and vibration of the spacecraft is proposed using the Lagrange Method. Then, a novel fast nonsingular terminal sliding mode surface is designed, and control strategies are proposed by integrating the aforementioned sliding manifold with the adaptive methodology. The adaptive update laws are employed to estimate the boundaries of various uncertainties, which do not require a priori disturbance information. Finally, illustrative numerical simulations are conducted to demonstrate the performance of the proposed control technique in terms of fast convergence and robustness compared to existing control schemes.