Adaptive Rejection of Unknown Narrow Band Disturbances in LTI Systems

January 30, 2015, Webb 1100

Petros Ioannou

USC, Electrical Engineering Systems


The suppression of unknown narrow band disturbances with time-varying characteristics has many industrial applications. The narrow band disturbances get mixed up with broadband noise of lower amplitude and usually appear at the output of the system. The objective is to use feedback to attenuate or reject the narrow band disturbances without amplifying the broadband noise. In this talk we present   the design and analysis of an effective adaptive scheme that achieves the following: Rejects the narrow band disturbances whose characteristics can change with time without amplifying the output noise.  It uses an overparametrized robust adaptive filter that provides enough freedom to adaptively search for parameters that achieve both objectives namely disturbance rejection and no noise amplification. In addition a feed forward filter is used to increase the gain of the system over the frequency range of the narrow band disturbances and therefore allow the zeros of the plant to be closer to those of the internal model of the disturbance without sacrificing on performance. Simulation results based on a model of a laser beam device are used to demonstrate the results.

Speaker's Bio

Petros A. Ioannou received the B.Sc. degree with First Class Honors from University College, London, England, in 1978 and the M.S. and Ph.D. degrees from the University of Illinois, Urbana, Illinois, in 1980 and 1982, respectively. During the period 1975-1978, he held a Commonwealth Scholarship from the Association of Commonwealth Universities, London, England. He was awarded several prizes, including the Goldsmid Prize and the A. P. Head Prize from University College, London. From 1979 to 1982 he was a research assistant at the Coordinated Science Laboratory at the University of Illinois. In 1982, Dr. Ioannou joined the Department of Electrical Engineering-Systems, University of Southern California, Los Angeles, California. He is currently a Professor in the same Department and the Director of the Center of Advanced Transportation Technologies. His research interests are in the areas of control and applications, adaptive and nonlinear systems, vehicle dynamics and control, intelligent transportation systems, marine transportation, congestion control of computer networks and neural networks. He was visiting Professor at the University of Newcastle, Australia in the Fall of 1988, the Technical University of Crete in summer of 1992 and served as the Dean of the School of Pure and Applied Science at the University of Cyprus in 1995. In 1984 he was a recipient of the Outstanding Transactions Paper Award for his paper, An Asymptotic Error Analysis of Identifiers and Adaptive Observers in the Presence of Parasitics, which appeared in the IEEE Transactions on Automa! tic Control in August 1982. Dr. Ioannou is also the recipient of a 1985 Presidential Young Investigator Award for his research in Adaptive Control. He has been an Associate Editor for the IEEE Transactions on Automatic Control, the International Journal of Control and Automatica. He is currently an Associate Editor of the IEEE Transactions on Intelligent Transportation Systems, Associate Editor at Large of the IEEE Transactions on Automatic Control, Member of the Control System society on IEEE ITS Council Committee and Vice-Chairman of the IFAC Technical Committee on Transportation Systems. Dr. Ioannou is a Fellow of IEEE and the author/co-author of 5 books and over 150 research papers in the area of controls, neural networks, nonlinear dynamical systems and intelligent transportation systems.