LMI-based H−/H∞ observer design in low frequency domain with application in fault detection

This paper deals with the robust fault detection (FD) problem in low frequency domain for linear time-delay systems. The H_infin norm and H_- index are employed to measure the robustness to unknown inputs and the sensitivity to faults, respectively. The main results include derivation of a sufficient condition for the existence of a robust fault detection observer and a construction of it based on the linear matrix inequality (LMI) solution parameters. Finally, numerical simulation demonstrates the effectiveness of the presented methodology.