BULETINUL INSTITUTULUI POLITEHNIC DIN IAŞI Publicat de Universitatea Tehnică „Gheorghe Asachi” din Iaşi Tomul LIV (LVIII), Fasc. 2, 2008 Secţia AUTOMATICĂ şi CALCULATOARE A UNIFIED ALGEBRAIC APPROACH TO RESIDUAL GENERATORS DESIGN BY ADRIAN MIHAIL STOICA Abstract. The paper presents a design methodology of residual generators used in fault detection applications. Two fundamental design objectives are considered, namely the fault detection and, the attenuation of the disturbances acting on the monitored plant. Using a unitary framework to characterize the performances of the residual generators, it is shown that the proposed methodology can be effective for various models of the monitored plants. Key words: fault detection, failure residuals, residual generators, multi-objective optimization, H ∞ control. 2000 Mathematics Subject Classification: 53B25, 53C15. 1. Introduction The study of Fault Detection and Isolation (FDI) systems received a major attention in the control community over the last three decades. This interest was stimulated by the continuous development of control systems and their use in complex applications demanding a high level of reliability and security. Thus, in such applications the capability to detect any malfunction and to provide prompt alarms in order to take the required decision is of maximum importance. A popular class of approaches to detect and identify faults occurring in the monitored plant is based on analytical redundancy and it consists in generating failure residuals which are zero or close to zero if the plant properly works and different from zero when a failure occurs (see for instance the pioneering papers [1], [2] and more recently, [3], [4], [5], [6]). The main difficulty arising when applying these methods consists in the possibility to confound the failure effects with the ones determined by inherent exogenous disturbances or by plant parameters variations. Therefore, a realistic formulation