Actuator fault reconstruction based on a robust adaptive observer

A fault reconstruction method based on a robust adaptive observer is proposed to handle the actuator additive faultsthat exist in a non-linear descriptor system that satisfies the Lipschitz conditions. First, a robust adaptive fault reconstructionobserver is proposed. This method has the desired robust performance and can achieve accurate reconstructions of both abruptand time-varying faults in the presence of an external unknown disturbance. Then, to improve the transition process of faultreconstruction, an improved robust adaptive fault reconstruction observer is proposed. The improved robust adaptive faultreconstruction algorithm, which uses different coefficients for the proportion output errors and the derivative output errors, canenhance the rapidity and accuracy of fault reconstruction. The robust adaptive and improved robust adaptive observers arebased on the linear matrix inequality technique. According to the Lyapunov stability theory, the stability conditions of themethods are derived. Additionally, the influence of an external unknown disturbance on the actuator fault reconstruction issuppressed using a robust method. Finally, two different examples are used to demonstrate the effectiveness of the proposedfault reconstruction methods.