Modeling and predefined-time anti-disturbance control for the aerial refueling phase of receiver aircraft

Aiming at the relative position-holding and velocity-holding control problems during the refueling phase of autonomous aerial refueling (ARR) missions, this paper proposes a predefined-time anti-disturbance control (PTADC) structure for receiver aircraft. First, a 6-degree-of-freedom (6-DOF) rigid model of the receiver in the refueling phase is established, with the time-varying mass, time-varying inertia, time-varying unbalanced moment, multiwind disturbances, and model uncertainties explicitly considered. Moreover, to facilitate the design of a nonlinear controller, the affine nonlinear form of the 6-DOF receiver model is formulated. Then, fixed-time extended state observers (FTESOs) are designed for each subsystem to estimate the lumped disturbances. By compensating for these estimated lumped disturbances, a backstepping-based PTADC structure with disturbance resistance and predefined-time convergence is developed to complete the refueling task. The performance of the entire closed-loop system is rigorously proven through Lyapunov functions. Finally, the effectiveness of the proposed refueling control framework is validated through numerical simulations.