Finite-Time Nonsingular Terminal Sliding Mode Control for 3D Trajectory Tracking of a Quadrotor UAV under Exogenous Disturbances
This paper presents a nonsingular terminal sliding mode control (NTSMC) strategy for robust three-dimensional (3D) trajectory tracking of a quadrotor unmanned aerial vehicle (UAV) operating in the presence of external disturbances and modeling uncertainties. The proposed controller is designed using the full nonlinear dynamics of the quadrotor and ensures finite-time convergence of the sliding variables and tracking errors without introducing singularities in the control law. A Lyapunov-based stability analysis is provided to demonstrate finite-time stability of the closed-loop system. The effectiveness of the proposed approach is evaluated through comparative simulations against representative state-of-the-art sliding mode control strategies. Numerical simulations are conducted under multiple operating scenarios, including large initial deviations and persistent external perturbations. The results demonstrate that the proposed NTSMC scheme achieves improved tracking accuracy, enhanced robustness, and a more favorable transient response compared to the considered benchmark controllers.