Adaptive nonlinear actuator fault diagnosis for uncertain nonlinear systems with time-varying delays

An actuator fault diagnosis method is presented in this paper for a class of time-delayed nonlinear systems via the use of adaptive updating rules. The considered system is represented by a dynamic state space model where the time delays are embedded into the state vector. Model parameters are not perfectly known, which lead us to consider norm bounded uncertainties. An adaptive fault diagnosis observer is designed where the Lyapunov stability theory is used to obtain the required adaptive tuning rule for estimation of the nonlinear actuator fault. A simulated numerical example is included to demonstrate the effectiveness of the proposed approach. © 2013 Chinese Automatic Control Society and Wiley Publishing Asia Pty Ltd.