An LMI approach to H_ index and mixed H_/H∞ fault detection observer design

Using the newly developed worst-case fault sensitivity measure, the H(-) index, and the well-known worst-case robustness measure, the H(infinity) norm, this paper addresses the problem of H(-) index fault detection observer design and multiobjective H(-)/H(infinity) fault detection observer design problems. Necessary and sufficient conditions for the existence of such a fault detection observer are given in terms of matrix inequalities. Both infinite frequency range case [0, infinity) and finite frequency range case [0, (omega) over bar) are considered. Iterative linear matrix inequality (ILMI) algorithms are given to obtain the solutions. The effectiveness of the proposed approaches is shown by numerical examples. (C) 2007 Elsevier Ltd. All rights reserved.