This paper deals with the Robust Fault Detection (RFD) problem with the aid of the H norm and H− index optimization techniques and the LMI approach. First, a necessary and sufficient condition<BR>is proposed for the design of RFD observers in the nominal case. Then, the RFD problem for systems with structured uncertainties in the system matrices is considered. Approaches are proposed to<BR>design robust fault detection observers to enhance the fault detection and to attenuate the effects due to
