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In this paper, a fault diagnosis method is developed for systems described by multimodels. The main contribution consists in the design of a new Fault Detection and Isolation scheme (FDI) through an adaptive filter for such systems. Based on the assumption that dynamic behavior of the process is described by a multi-model approach around different operating points, a set of residual is established in order to generate weighting functions robust to faults. These robust weighting functions are directly linked with the adaptive filter effectiveness which provides multiple fault magnitude estimations for the whole operating range of the system. Stability conditions of the adaptive filter are studied and its performances are tested using an hydraulic system.

An important issue in fault diagnosis research is the design of methods for robust residual generation. In this framework, systems described by uncertain models and subject to unknown input disturbances are studied in this article. A nominal model of the system is first considered for residual generation using an H∞ parameterized output observer. The design procedure is based on the optimization of a performance index which is solved via linear matrix inequalities (LMI). Unstructured uncertainties due to parameter variations are then considered in the system model. In order to take the worst effect of uncertainties into account, the determination of an optimal threshold depending on the operating conditions is suggested for residual evaluation. This is achieved via the introduction of Kharitonov polynomials and the associated geometry of uncertain polytopic families. A simulation example illustrates the proposed approach. Copyright © 2000 John Wiley & Sons, Ltd.

This paper deals with a Fault Tolerant Control (FTC) strategy for polytopic Linear Parameter Varying (LPV) systems. The main contribution consists in the design of a Static Output Feedback (SOF) dedicated to such systems in the presence of multiple actuator faults/failures. The controllers are synthesized through Linear Matrix Inequalities (LMIs) in both faultfree and faulty cases in order to preserve the system closed-loop stability. Hence, this paper provides a new sufficient (but not necessary) condition for the solvability of the stabilizing output feedback control problem. An example illustrates the effectiveness and performances of the proposed FTC method.