Functional Observer Design for Time-Delayed Systems With Application to Fault Diagnosis

This paper deals with the functional observer (FO)-based fault detection and isolation problem for time-delayed linear systems. First, a new method to design the low-order FO estimating the partial states for linear systems with time-varying delay is presented. Conditions for the existence of the proposed observer and the stability of resulting error dynamics are derived. Based on the proposed observer, a novel residual generator is constructed to detect actuator faults. Furthermore, a bank of residual generators for fault isolation is also constructed for time-delayed systems. The simulation results of the numerical example demonstrate that the proposed observer-based fault diagnosis scheme works effectively.