Disturbance Separation-Based Antidisturbance Attitude Control for Flexible Liquid-Filled Spacecrafts

Tightly coupled disturbances such as flexible vibration and liquid sloshing reduce the attitude control accuracy and stability of spacecrafts. The separation and thereby compensation of tightly coupled disturbances are crucial for improving attitude control performance. This paper investigates disturbance separation-based antidisturbance attitude control for flexible liquid-filled spacecrafts. First, based on the rigid-flexible-liquid interaction mechanism of spacecrafts, the flexible vibration disturbance and liquid sloshing disturbance are finely characterized, and a tightly coupled attitude dynamics model of a flexible liquid-filled spacecraft is established. Then, a disturbance separability criterion is established and two disturbance separability observers are designed to estimate the flexible vibration disturbance and the liquid shaking disturbance, respectively. Furthermore, a tightly coupled antidisturbance attitude control law is designed to accurately compensate for the flexible vibration disturbance and the liquid sloshing disturbance, thereby improving the attitude control accuracy and stability of spacecrafts. Finally, a numerical simulation is given to verify the validity of the proposed methodology.