Observer based finite-time fault tolerant quadrotor attitude control with actuator faults

This paper investigates a nonlinear robust fault tolerant control method for rejecting wind disturbances and accommodating actuator faults in quadrotor attitude system. Actuator faults are modeled as a sudden loss of actuator effectiveness (LAE) in the rotor thrust. First, the lumped disturbances, including wind disturbances and LAE actuator faults, are estimated by a novel adaptive finite-time extended state observer (AFTESO). Additionally, a rigorous analysis for finite-time convergence of estimation errors is provided. Next, based on the estimated information from AFTESO, a continuous fast nonsingular terminal sliding mode controller (CFNTSMC) is proposed to achieve high-precision tracking and finite-time convergence. CFNTSMC provides faster convergence performance in both reaching and sliding phases. The proposed control scheme combines ESO-based and NTSM-based anti-disturbance mechanisms, which retains the advantages of the two control schemes and limits their drawbacks, thus achieving promising features, as finite-time convergence, fault tolerance and chattering suppression. The finite-time stability of the closed-loop system is supported by Lyapunov theory. Finally, extensive numerical simulations are carried out to demonstrate the effectiveness of the proposed method in different working regimes. (C) 2020 Elsevier Masson SAS. All rights reserved.