Predefined-Time Tracking Control for Quadrotor Unmanned Aerial Vehicle with Enhanced Disturbance Rejection

This work addresses the challenging problem of trajectory tracking for a quadrotor unmanned aerial vehicle (UAV) subject to model uncertainties and external disturbances. To this end, a unified controller for simultaneous position and attitude regulation is first built from the quadrotor dynamics. Specifically, the controller is constructed by integrating an adaptive disturbance observer, which enjoys predefined-time convergence, with a predefined-time fast terminal sliding-mode law that incorporates prescribed performance bounds. In this framework, the observer provides accurate estimates of lumped disturbances arising from both parametric uncertainty and exogenous perturbations, thereby enhancing system robustness. Meanwhile, the prescribed performance sliding-mode component serves to improve both transient performance and steady-state accuracy. Furthermore, a Lyapunov-based analysis is conducted to rigorously establish the predefined-time stability of the closed-loop system. Finally, numerical simulations are carried out, and the results consistently corroborate the effectiveness of the proposed approach.