Practical finite time adaptive robust flight control system for quad-copter UAVs

This paper investigates the practical finite time control problem with uncertain parameters, external disturbances, and input saturation for quad-copter unmanned aerial vehicle systems. Firstly, an adaptive robust controller based on backstepping with fast terminal sliding mode control is designed for the major control loops. Secondly, only four adaptation laws are used to estimate the quad-copter uncertain parameters while a projector algorithm is used to guarantee the estimation within a prescribed range. Thirdly, an adaptive switching gain is developed to compensate the lumped disturbances. Finally, a compensator term is introduced in control design to reduce the adverse effect caused by the input saturation. The proposed control scheme can attenuate chattering phenomenon and guarantee that all states of the closed-loop system are practical finite time stable. The validity of the proposed flight control system is confirmed by using several flight scenarios under various conditions and a comparison study with other works is made showing the effectiveness, robustness, adaptiveness, and energy efficiency of the proposed approach. (C) 2020 Elsevier Masson SAS. All rights reserved.