Robust Adaptation and Learning: Unfalsified Control and Cost-Detectability

Prof Michael G Safonov
Department of Electrical Engineering
University of Southern California

Friday, October 27
3:30pm - 4:30pm
Boelter Penthouse

Abstract

It has long been recognized that any adaptive controller can be characterized by an admissible controller set and a data-dependent cost function that partially orders these controllers. In this talk we discuss the unfalsified control concept, which involves expressing adaptive control cost functions in terms of certain controller-dependent 'fictitious' signals used to evaluate stability and performance. We also define a new plant-independent property for adaptive controllers called cost-detectability. We prove that when cost-detectable unfalsified controllers are constructed using hysteresis-type adaptive algorithms, then closed-loop stability of the adaptive control system is guaranteed with no assumption on the plant other than the trivial assumption of feasibility, i.e., that there exists a controller in the candidate controller set that would stabilize the plant if it were known. Cost detectable adaptive control designs circumvent the robustness problems and model-mismatch instability risks inherent with other popular adaptive design methods. Design studies and simulations demonstrate remarkably rapid convergence with unfalsified adaptive designs, often within a fraction of a plant time constant.

Bio: Michael G. Safonov was born in Pasadena, CA, on November 1, 1948. He received the B.S., M.S., Engineer, and Ph.D. degrees in electrical engineering from the Massachusetts Institute of Technology, Cambridge, MA in 1971, 1971, 1976 and 1977, respectively. From 1972 to 1975 he served with the U.S. Navy as Electronics Division Officer aboard the aircraft carrier USS Franklin D. Roosevelt (CVA-42). Since 1977 he has been with the University of Southern California where he is presently a Professor of Electrical Engineering. He has been a consultant to The Analytic Sciences Corp., Honeywell Systems and Research Center, Systems Control, Systems Control Technology, Scientific Systems, United Technologies, TRW, Northrop Aircraft, Hughes Aircraft and others. His consulting and university research activities have involved him flight control system design studies in which modern robust multivariable control techniques were applied to a variety of aircraft including the CH-47 Chinook helicopter (Analytic Sciences Corp., 1976), the NASA HiMAT aircraft (Honeywell/USC, 1980) and the F/A-18 Hornet (Northrop, 1987-1991). During the academic year 1983-1984 he was a Senior Visiting Fellow with the Department of Engineering, Cambridge University, England, and in summer 1987 he held a similar appointment at Imperial College of Science and Technology, London, England. In 1990-1991 he was a visiting faculty member at Caltech, Pasadena, CA. He has authored or co-authored more than one hundred and fifty journal and conference papers and the book Stability and Robustness of Multivariable Feedback Systems (Cambridge, MA: MIT Press, 1980). Additionally, he is co-author of the MATLAB Robust Control Toolbox (Natick, MA: MathWorks), a software package for use with MATLAB. His research interests include robust control, infinity-norm optimal control theory and nonlinear system theory with applications to aerospace control design problems. He served as an Associate Editor of the IEEE Trans. on Automatic Control from 1985- 1987 and is presently an editor of International Journal of Robust and Nonlinear Control and Systems and Control Letters. From 1993 to 1995, he was Chair of the AACC Awards Committee of the American Automatic Control Council. Dr. Safonov is a Senior Member of the AIAA and a Fellow of the IEEE.

Contact: Professor Jeff Shamma (shamma@ucla.edu)