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Finite-Time Flight Control of Uncertain Quadrotor UAV based on Modified Non-Singular Fast Terminal Super-Twisting Control

This work tackles the problem of controlling quadrotor Unmanned Aerial Vehicles (UAVs) subject to model uncertainties and perturbations. The objective of the paper is to design a sliding mode controller capable of ensuring accurate position and attitude tracking performance while preventing singularity problem in the fast terminal sliding surface. To this end, a modified non-singular fast terminal second-order sliding mode, based on the robust continuous Super-Twisting algorithm, is proposed. First, a new exponential law is proposed to bypass the singularity problem in the conventional terminal sliding surface. Then, it is shown that the proposed modified Super-Twisting structure allows fast finite-time convergence of the switching function even if the trajectories of the considered system are relatively far from the selected function. Moreover, the proposed method reduces the chattering phenomenon. The stability of the closed-loop system is proved by means of a Lyapunov function. Finally, comparative simulation results are shown to demonstrate the effectiveness of the proposed controller.