- Vasile M. Popov
Vasile Mihai Popov (born 1928) is a leading systems theorist and
control engineering specialist. He is well known for having developed a method to analyzestability of nonlineardynamical systems , now known as Popov criterion.Biography
He was born in
Galaţi ,Romania on July 7 1928. He received the engineering degree in electronics from theBucharest Polytechnic Institute in 1950.He worked for a few years as Assistant Professor at the Bucharest Polytechnic Institute in the Faculty of Electronics. His main research interests during this period were in frequency modulation and parametric oscillations. In the mid 1950s, he joined the Institute for Energy of Romanian Academy of Science in Bucharest. In the 1960s, Popov headed the Control group at the Institute of Energy of the
Romanian Academy .In 1968 Popov left Romania. He was a visiting professor at the Electrical Engineering departments of
University of California, Berkeley , andStanford University , and then Professor in thedepartment of electrical engineering at theUniversity of Maryland College Park . In 1975 he joined the mathematics department ofUniversity of Florida Gainesville.He retired in 1993 and currently resides in
Gainesville , Florida, USA.Work
Qualitative theory of differential equations
Motivated by stability issues in nuclear reactors and by his participation in a seminar series on qualitative theory of
differential equations run byA. Halanay , Popov started working in stability of nonlinearfeedback systems, in particular on theLur'e-Postnikov problem .In 1958/59 he obtained, through a very original approach, the first frequency stability criterion for a class of nonlinear feedback control systems. He continued this work and obtained the equivalence between the
state space (Lyapunov function based) approach and the frequency domain approach for stability and obtained a very perceptive characterization ofpassive systems, nowadays known as the celebratedKalman-Yakubovich-Popov lemma .Hyperstability
In the early 1960s, Popov also conceived the notion of
hyperstability , a concept that he viewed as generalization ofabsolute stability . This introduced a new and a very fruitful point of view for the analysis and synthesis of nonlinear feedback systems.This research work was published in the first half of the sixties and led to the book "Hyperstability of Dynamic Systems", first published in Romania in 1966, and subsequently translated in French and English (Springer-Verlag, 1973). Popov was also the first to discover the geometric invariants of linear systems with respect to certain "transformation groups" and he introduced a "canonical" form for uniquely describing the multivariable systems.
References
*cite journal|first=B.D.O.|last= Anderson|coauthors=P. Kokotovic, I.D. Landau and J.C Willems|title=Dissipativity of dynamical systems: applications in control -- dedicated to Vasile Mihai Popov|issue=Special issue|journal=European Journal of Control|volume=8|year=2002.
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