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

Abstract

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.