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On the 5th of February 2002 at 15:00 in room 4.2,

prof. Thomas Parisini,

from the University of Trieste (Italy), will give a seminar titled

Fault detection, isolation and accomodation
for nonlinear uncertain dynamic systems.

Everyone is invited.

Abstract: This talk presents a robust fault diagnosis scheme for abrupt an incipient faults in nonlinear uncertain dynamic systems. A detection and approximation estimator is used for on-line health monitoring. Once a fault is detected, a bank of isolation estimators are activated for the purpose of fault isolation. A key design issue of the proposed fault isolation scheme is the adaptive residual threshold associated with each isolation estimator. A fault that has occurred can be isolated if the residual associated with the matched isolation estimator remains below its corresponding adaptive threshold, whereas at least one of the components of the residuals associated with all the other estimators exceeds its threshold at some finite time. Based on the class of nonlinear uncertain systems under consideration, an isolation decision scheme is devised and fault isolability conditions are given, characterizing the class of nonlinear faults that are isolable by the robust fault isolation scheme. The non-conservativeness of the fault isolability conditions is illustrated by deriving a subclass of nonlinear systems and of faults for which these conditions are also necessary for fault isolability. Moreover, the analysis of the proposed fault isolation scheme provides rigorous analytical results concerning the fault isolation time. Based on the fault information obtained during the fault diagnosis procedure, a fault-tolerant control component is designed to compensate the effects of faults. In the presence of a fault, a nominal controller guarantees the boundedness of all the system signals until the fault is detected. Then the controller is reconfigured after fault detection and after fault isolation, respectively, to mprove the control performance using the fault information generated by the diagnosis module. Under certain assumptions, the stability of the close-loop system is rigorously investigated. It is shown that the system signals always remain bounded and the output tracking error converges to a neighborhood of zero. Simulation examples are given to show the effectiveness of the fault diagnosis and accomodation methodology.

Speaker biography: Thomas Parisini was born in Genoa, Italy, in 1963. He received the "Laurea" degree (Cum Laude) in electronic engineering from the University of Genoa in 1988 and the Ph.D. degree in electronic engineering and computer science in 1993. From 1988 to 1995, he was with DIST, University of Genoa. In 1995, he joined DEEI, University of Trieste, as an assistant professor, and in 1998, he joined DEI, Politecnico di Milano, as associate professor. In 2001 he was appointed full professor and Danieli Endowed Chair of Automation Engineering at DEEI, University of Trieste. He is the present Chairman of the IEEE CSS Technical Committee on Intelligent Control and a member of the IEEE CSS Board of Governors. He is currently serving as an Associate Editor of the IEEE Trans. on Automatic Control, of Automatica, of the Int. J. of Control, and as the Subject Editor on Intelligent Control of the Int. J. of Adaptive Control and Signal Processing. His research interests include neural-network approximations for optimal control and filtering problems, fault diagnosis for nonlinear systems, and hybrid control systems.

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