Robust nonlinear observer design for actuator fault detection in diesel engines

• Published in: International journal of applied mathematics and computer science Vol. 23; no. 3; pp. 557 - 569
• Main Authors: Boulkroune, Boulaid, Djemili, Issam, Aitouche, Abdel, Cocquempot, Vincent
• Format: Journal Article
• Language: English
• Published: Zielona Góra Versita 01.09.2013; De Gruyter Poland
• Subjects: Actuators; diesel engine; Disturbances; Dynamical systems; Fault detection; fault diagnosis; LMI; Mathematical models; Nonlinear dynamics; nonlinear unknown input observers; Nonlinearity; Observers
• ISSN: 1641-876X; 2083-8492
• DOI: 10.2478/amcs-2013-0042

This paper is concerned with actuator fault detection in nonlinear systems in the presence of disturbances. A nonlinear unknown input observer is designed and the output estimation error is used as a residual for fault detection. To deal with the problem of high Lipschitz constants, a modified mean-value theorem is used to express the nonlinear error dynamics as a convex combination of known matrices with time-varying coefficients. Moreover, the disturbance attenuation is performed using a modified H criterion. A sufficient condition for the existence of an unknown input observer is obtained using a linear matrix inequality formula, and the observer gains are obtained by solving the corresponding set of inequalities. The advantages of the proposed method are that no a priori assumption on the unknown input is required and that it can be applied to a large class of nonlinear systems. Performances of the proposed approach are shown through the application to a diesel engine model.