Adaptive Disturbance Observer-Based Trajectory Tracking Control for the Follower of Close Formation UAVs

This paper studies the trajectory tracking control problem of slave aircraft during close formation flight. The aerodynamic disturbances caused by the pilot aircraft are considered. In order to compensate for the disturbance in close formation, an uncertainty and disturbance estimator (UDE) based on low-pass filtering is considered. However, the estimation performance is determined by the constant parameters adjusted by the designer, which could make the performance unsatisfactory, especially under discontinuous disturbance. So the corresponding adaptive disturbance observer is designed for each channel of the aerodynamic model and compensated for in the controller design. In addition, the controller design is based on the idea of backstepping control to cope with matched and unmatched disturbances to ensure the performance of asymptotic tracking control. The stability of the system is demonstrated by Lyapunov theory. The effectiveness and performance advantages of the proposed strategy are verified by numerical simulation and simulation comparison. The result shows that both the transient time and steady-state errors are optimized by nearly three orders of magnitude, indicating superior performance of adaptive disturbance observer-based trajectory tracking controller.