【报告摘要】Reset control systems for continuous-time plants were introduced in the 1950s by J.C. Clegg, then extended by Horowitz twenty years later and revisited using hybrid Lyapunov theory a few decades ago, to rigorously deal with the continuous-discrete interplay stemming from the reset laws. In this talk, we overview a recent research activity where suitable reset actions induce stability and performance of PID-controlled positioning systems suffering from nonlinear frictional effects. With the Coulomb-only effect, PID feedback produces a nontrivial set of equilibria whose asymptotic (but not exponential) stability can be certified by using a discontinuous Lyapunov-like function. With velocity weakening effects (the so-called Stribeck friction), the set of equilibria becomes unstable with PID feedback and the so-called ''hunting phenomenon'' (persistent oscillations) is experienced. Resetting laws can be used in both scenarios. With Coulomb friction only, the discontinuous Lyapunov-like function immediately suggests a reset action providing extreme performance improvement, preserving stability and increasing the convergence speed. With Stribeck, a more sophisticated set of logic-based reset rules recovers the global asymptotic stability of the set of equilibria, providing an effective solution to the hunting instability. We will discuss the Lyapunov-based proofs of these hybrid laws, requiring nontrivial derivations, such as building semi-global hybrid simulation models. The theoretical results will be illustrated by experiments carried out on an industrial nano-positioning system, showing the experimental advantages arising from our novel reset PID controllers.

【报告人简介】Luca Zaccarian received the Laurea and the Ph.D. degrees from the University of Roma Tor Vergata(Italy)in 1995 and 2000, respectively. He was Assistant Professor in control engineering at the University of Roma, Tor Vergata(Italy),from 2000 to 2006 and then Associate Professor. Since 2011 he is Directeur de Recherche at the LAAS-CNRS, Toulouse(France) and since 2013 he holds a part-time professor position at the University of Trento, Italy. Luca Zaccarian's main research interests include analysis and design of nonlinear and hybrid control systems, modeling and control of mechatronic systems. He has served in the organizing committee and TPC of several IEEE and IFAC conferences. He has been a member of the IEEE-CSS Conference Editorial Board and an associate editor for Systems and Control Letters and IEEE Transactions on Automatic Control. He is currently senior editor for nonlinear systems and control and deputy editor-in-chief for the IFAC journal Automatica, a member of the EUCA-CEB and an associate editor for the European Journal of Control. He served in the IEEE-CSS Board of Governors in2014(nominated member),and2017-2019(elected member).He has been nominated Director of Operations in the IEEE-CSS Executive Committee for the triennium2027-2029.He was a recipient of the 2001 O.Hugo Schuck(Best Paper Award given by the American Automatic Control Council. He is a fellow of the IEEE, class of 2016.