Disturbance rejection-based adaptive non-singular fast terminal sliding mode control fora quadrotor under severe turbulent wind

This paper presents the design of a disturbance rejection-based control strategy fora quadrotor unmanned aerial vehicle subject to model uncertainties and external disturbances described by turbulent wind gusts of severe intensity. First, an extended state observer is introduced to supply full-state and total disturbance estimations within a fixed time regardless of initial estimation errors. Then, an adaptive non-singular fast terminal sliding mode controller with a single-gain structure is proposed to reduce the tuning complexity and drive the pose of the rotorcraft while providing practical finite-time convergence, robustness to bounded external disturbances, non-overestimation of its control gain, and chattering attenuation. Furthermore, the stability of the closed-loop system is guaranteed through homogeneity and Lyapunov theory. Simulation results obtained through the ROS/Gazebo framework demonstrate graphically and quantitatively that the proposed observer-based controller reduces the influence of perturbations and requires less torque effort than existing methods in the presence of sensor noise.