Modeling and control of UAV in fueling phase of automated aerial refueling

To slove the station-keeping control problem for the receiver in fueling phase of automated aerial refueling (AAR), the receiver is divided into the plane body and the fuel tank. The receiver nonlinear dynamics equations which reflect the mass and center of gravity (CG) variations of the fuel tank are established based on the variable-mass system theory. By transforming the fuel tank into unknown external disturbance, a compound controller based on the disturbance observer based control (DOBC) method is proposed. The compound controller consists of two parts: the station-keeping controller via linear quadratic regulator (LQR) method and the disturbance observer, which is composited by a proportional integral observer (PIO) and a compensation unit. Then, the stability of the compound controller is proved. The results of simulation demonstrate that the proposed control system is efficient and meets the station-keeping control requirements in fueling period.