Evgeny S. Pyatnitskiy

Evgeny S. Pyatnitskiy


Wednesday, July 22, 1936

Passed away: 

Thursday, April 3, 2003

Evgeny Pyatnitskiy, in full Evgeny Serafimovich Pyatnitskiy (also transliterated as Pyatnitskii or Pyatnitsky), was a remarkable man, a famous scientist, Corresponding Member of the Russian Academy of Sciences, Dr. Sci. (Eng.), Professor, and Head of Laboratory No. 16 at the Institute of Control Sciences, the Russian Academy of Sciences. He passed away in the prime of his creative powers, full of ideas, and with unexhausted scientific potential.

Pyatnitskiy was born in the village of Podbelevets (Mtsensk district, the Orel Region) in a family of rural teachers. After graduating from Mtsensk high school, he entered the Moscow Institute of Physics and Technology (MIPT), graduating with a diploma in aerodynamics (1960, with honors). In the same year, he began working as an Assistant at the Department of Theoretical Mechanics in MIPT. During that period, Felix R. Gantmakher, Head of the Department, an outstanding mathematician and mechanical engineer, played a great role in Pyatnitskiy’s life. Gantmakher became the scientific supervisor of his postgraduate studies at MIPT. In 1963, Pyatnitskiy defended his candidate’s dissertation on the structural stability of control systems at the Institute of Automation and Remote Control (IARC), the USSR Academy of Sciences.

In 1964, by the invitation of Professor Mark A. Aizerman, Pyatnitskiy began combining his teaching activities at MIPT with research in Aizerman’s Laboratory No. 25. Gantmakher and Aizerman, two great persons and outstanding scientists, much affected the research interests and further creative destiny of Pyatnitskiy. In 1972, Pyatnitskiy defended his doctoral dissertation on the absolute stability of control systems. In 1974, he received a professorship at the Department of Theoretical Mechanics in MIPT. Pyatnitskiy taught courses on control theory, theoretical mechanics, stability theory, engineering cybernetics, nonlinear oscillation theory, and finite automata theory.

In 1982, on Aizerman’s initiative, the Laboratory of Dynamics of Nonlinear Control Processes (Laboratory No. 16) was established at IARC. Pyatnitskiy headed this laboratory until his last day of life. He actively participated in the famous IARC seminar on the theory of automatic control, led by Aizerman. Jointly with V.F. Krotov, Pyatnitskiy organized and chaired the Moscow Seminar on Control Theory of Dynamical Systems. Researchers and engineers from many organizations and institutions in Moscow and other cities took part in those seminars. Pyatnitskiy also organized and chaired the International Seminar on Stability and Oscillations in Nonlinear Control Systems (Moscow, 1992; Samara, 1994; Moscow, 1996, 1998, 2000). He was Chairman of the Organizing Committee of other regular conferences: Robots and Flexible Production Systems; Stability and Oscillations of Nonlinear Control Systems.

Pyatnitskiy was a well-known scientist in theoretical mechanics, control, and stability theory, as well as in robot control and biomechanical systems. He was one of the world’s leaders in the theory of stability of nonlinear systems.

Pyatnitskiy established a new principle of classical mechanics, i.e., the minimax principle. He justified the decomposition principle for constructing universal control systems for mechanical plants. Pyatnitskiy developed computer-oriented methods for the stability analysis and design of control systems for nonlinear plants with complete and incomplete information about the state vector. He proposed and justified the variation method for solving stability problems of nonlinear control systems; derived stability criteria for nonlinear dynamic systems in a matrix equation different from the Lyapunov equation; developed a method for determining slow variables in dynamic systems without small parameters. Pyatnitskiy obtained several results in the theory of discontinuous systems, the harmonic balance method, and the structural stability of control systems. He developed the goal potential method for designing control systems for mechanical plants. Pyatnitskiy completely solved the control problem for the black box of mechanical nature. As a result, a conceptual model of motion control in biomechanics was developed, and the book Theoretical Biomechanics was written.

Pyatnitskiy was a fascinating man: if he was interested in some topic, he could drop everything and start dealing only with it, with the problem that seemed to him the most important today. But in everything and at all times, he remained a control theory fundamentalist who observed everything through the prism of general properties of dynamic systems and from the standpoint of their stability. In the last years of his life, Pyatnitskiy “discovered” a theoretical justification of quantum mechanics, as he believed. As it turned out, for a heavy oscillator with small dissipation, stability conditions lead to a classical mechanical plant with a “quantum,” or discrete, nature. (Such an oscillator has only discrete orbits stable.) Following this line of research, Pyatnitskiy obtained other analogs of the main quantum-mechanical relations (the Schrödinger equation, the uncertainty relation, and others). Thus, according to Pyatnitskiy, the basic postulates of quantum mechanics turned out to be a consequence of stability. Many physicists took these results critically, and Pyatnitskiy had no time to argue with them. What a pity!

Pyatnitskiy authored and coauthored over 170 scientific publications, including four books. His Workbook in Analytical Mechanics (coauthors N.M. Trukhan, Yu.I. Khanukaev, and G.N. Yakovenko) has been the basic textbook on theoretical mechanics for students at MIPT and many other universities for over 25 years. It has undergone several editions, in the USSR and abroad. Pyatnitskiy trained 12 candidates and 3 doctors of sciences.

Pyatnitskiy was Member of the National Committee on Automatic Control, a member of the editorial board of the RAS journal Automation and Remote Control and other journals: Proceedings of the Institute of Mechanical Engineers and Stability and Control. Theory and Applications. He was Chairman of the Scientific Council Section of the Institute of Control Theory and Vice-Chairman of the Dissertation Council of the Institute of Control Sciences, the Russian Academy of Sciences.

In 2000, Pyatnitskiy was elected Corresponding Member of the Russian Academy of Sciences.

Until his last days, Pyatnitskiy actively worked and was full of energy and creative plans. Pyatnitskiy’s exceptional work capacity and power inspired his colleagues and employees. An authoritative scientist, infinitely kind and attentive to people, he was always ready to help in word and deed, advise on scientific and everyday problems, and generously share his numerous ideas.

Pyatnitskiy’s main monographs are as follows:

  1. Izbrannye trudy. Teoreticheskaya biomekhanika. Kontseptsiya upravleniya dvizheniem v usloviyakh neopredelennosti (Selected Proceedings. Theoretical Biomechanics. The Concept of Motion Control under Uncertainty), Moscow: Fizmatlit, 2006. — 400 p.;
  2. Izbrannye trudy. Teoriya upravleniya (Selected Proceedings. Control Theory), Moscow: Fizmatlit, 2005. — 316 p.;
  3. Izbrannye trudy. Teoriya upravleniya (Selected Proceedings. Control Theory), Moscow: Fizmatlit, 2004. — 384 p.;
  4. Mark Aronovich Aizerman (1913—1992), Moscow: Fizmatlit, 2003. — 318 p. (coauthors F.T. Aleskerov, A.A. Dorofeyuk, I.B. Muchnik, L.I. Rozonoer, A.L., Chernyavskii, and A.N. Shubin);
  5. Sbornik zadach po analiticheskoi mekhanike (Workbook in Analytical Mechanics), Moscow: Fizmatlit, 2002. — 400 p. (coauthors N.M. Trukhan, Yu.I. Khanukaev, and G.N. Yakovenko).

They are presented in the Institute’s database:

The list of journal papers by Pyatnitskiy is available at Math-Net.Ru:

His publications, including inventions, can be also found at:

Articles about E.S. Pyatnitskiy

1. Evgenii Serafimovich Pyatnitskii (July 22, 1936 — March 3, 2003)Autom. Remote Control64:6 (2003), 1016—1019.

In addition, see the Wikipedia page devoted to Pyatnitskiy:

Scopus Author ID: 6602874017, 6506099803, 7003292744, 14122262100