Observer Design for Actuator Failure of a Quadrotor

Abstract

This article addresses the problem of fault estimation for a quadrotor unmanned aircraft vehicle (UAV). A robust $H_{\infty }$ observer is proposed to achieve fault and state estimation of a quadrotor UAV with actuator fault in the presence of external disturbances, parameter uncertainties and nonlinear terms. The observer can observe the system state and actuator fault simultaneously. The actuator fault estimation error is taken as an auxiliary state to transform the original system into an augmented generalized system, and a nonlinear robust $H_{\infty }$ observer is designed. Based on the Lyapunov stability theory, stability analysis was carried out and a sufficient condition for the stability of the observer was established, which is expressed as an LMI optimization problem to satisfy $H_{\infty }$ performance. Finally, the typical faults of two actuators of a quadrotor UAV are given, and the faults and states can be estimated by using the method proposed in this article. The results show that the proposed observer can accurately observe the system state and actuator fault before and after the occurrence of two typical faults.