Title: Adaptive Feedforward Compensation of Harmonic Disturbances for Convergent Nonlinear Systems
Abstract: Rejecting periodic disturbances occurring in dynamical systems is a fundamental problem in control theory, with numerous technological applications such as control of vibrating structures, active noise control, and control of rotating mechanisms. From a theoretical standpoint, any design philosophy aimed at solving this problem reposes upon a specific variant of the internal model principle, which states that regulation can be achieved only if the controller embeds a copy of the exogenous system generating the periodic disturbance. In the classic internal model control (IMC), the plant is augmented with a replica of the exosystem, and the design is completed by a unit which provides stability of the closed loop. In a somewhat alternative design methodology, referred to as adaptive feedforward compensation (AFC), a stabilizing controller for the plant is computed first and then an observer of the exosystem is designed to provide asymptotic cancelation of the disturbance at the plant input. In particular, the parameters of the feedforward control are computed adaptively by means of pseudo-gradient optimization, using the regulated error as a regressor. Contrary to IMC, which has been the focus of extensive investigation, application of AFC methods to nonlinear systems has remained so far elusive. This talk aims at presenting results that set the stage for a theory of AFC for nonlinear systems by providing a nonlinear equivalent of the condition for the solvability of the problem in the linear setting, and by re-interpreting classical linear schemes in a fully nonlinear setting. To this end, the problem is approached by combining methods from output regulation theory with techniques for semi-global stabilization.
Bio: Andrea Serrani received the Laurea (B.Eng.) degree in Electrical Engineering, summa cum laude, from the University of Ancona, Italy, in 1993, and the Ph.D. degree in Artificial Intelligence Systems from the same institution in 1997. From 1994 to 1999, he was a Fulbright Fellow at Washington University in St. Louis, MO, where he obtained the M.S. and D.Sc. degrees in Systems Science and Mathematics in 1996 and 2000, respectively. Since 2002, he has been with the Department of Electrical and Computer Engineering of The Ohio State University, where he is currently a Professor and Interim Chair.
He has held visiting positions at the Universities of Bologna and Padua, Italy, and multiple summer faculty fellowships at AFRL. The research activity of Prof. Serrani lies at the intersection of methodological aspects of nonlinear, adaptive and geometric control theory with applications in aerospace and marine systems, fluidic systems, robotics and automotive engineering. His work has been supported by AFRL, NSF, Ford Motor Co. and NASA, among others. Prof. Serrani has authored or co-authored more than 150 articles in journals, proceedings of international conferences and book chapters, and is the co-author of the book Robust Autonomous Guidance: An Internal Model Approach, published by Springer-Verlag. Prof. Serrani was a Distinguished Lecturer of the IEEE CSS. Prof. Serrani is the Editor-in-Chief of the IEEE Transactions on Control Systems Technology, and a past Associate Editor for the same journal (2010-2016), Automatica (2008-2014) and the International. Journal of Robust and Nonlinear Control} (2006-2014). He serves on the Conference Editorial Boards of IEEE CSS and IFAC, served as Program Chair for the 2019 ACC, and currently serves as General Co-chair for the 2022 CDC.