Profsoyuznaya, 65, Moscow, 117997,
Russia
e-mail: zeml@ipu.rssi.ru
The 5-th IFAC Symposium
“NONLINEAR CONTROL SYSTEMS” (NOLCOS’01) took place at St. Petersburg on July 4
– 6, 2001. The Symposium was jointly organized and sponsored by International
Federation on Automatic Control – Technical Committee on Nonlinear Systems
(IFAC-TC on NS), by Russian National Committee on Automatic Control (RNKAU), by
St. Petersburg Regional Group of RNKAU, by Institute for Problems of Mechanical
Engineering of Russian Academy of Sciences, by IFAC-TC on Optimal Control, by
Russian Academy of Sciences, by Russian Foundation for Basic Research (grant
01-01-10044).
Previous meetings were held at Capri (1989), Bordeaux (1992), Lace Tahoe
(1995), Enschede (1998).
Following the IFAC tradition, the Symposium presents latest
developments in the theory and applications of Nonlinear Control Systems and
related areas of research and engineering, as well as new design methodologies
for the control of nonlinear plants and their applications.
To the Symposium there were submitted 320 papers from 40 countries,
which was about two times more than at previous NOLCOS’98.
An important goal of the Symposium is to get the international community
better acquainted with recent achievements of Russian experts in nonlinear
dynamics and control, particularly those that were not published in English
before.
The Symposium was held in the historical city of St. Petersburg, in the famous Anichkov Palace, during the famous “White
Nights” season.
The great merit at the Symposium’s organization and conducting belongs
to the Chairman of the International Program Committee Alexander B.Kurzhanski
(Chairman of Russian National Committee on Automatic Control) and to the
Chairman of the National Organizing Committee Alexander L.Fradkov.
The Symposium official language was only English.
Once more special peculiarity for the Symposium in the whole was
particular attention to the works and memory of Anatoly Isakovich Lurie. In
July of 2001-th there is a centenary of A.I. Lurie. He died in 1980-th year.
A.I. Lurie made a great contribution into development of mechanics and theory
of control process, in particular, into the theory of the spacecrafts control.
The terms “Lurie system”, “Lurie problem”, “Lurie equations”, “Lyapunov-Lurie
function” are in common use of many experts in nonlinear control. The day
before the Symposium (on the 3-d of July) the National Organizing Committee
organized a special meeting dedicated to Centenary of A.I. Lurie. On the 4-th
of July at the Symposium was a special session, dedicated to Centenary of A.I.
Lurie. The both meeting and session were visited by a mass of people. But about
it a little bit later.
Three days (July 4 – 6) at the Symposium plenary, semiplenary or 6
regular sessions were working from 9 in the morning to 19 in the evening. Of
course today nonlinearity is a leading edge of control theory and engineering
but such a program at a glance the Symposium turns into the Conference. It was
not possible to hear simultaneously several papers what you are interesting in.
So I will mark papers in accord with my own perception.
The first plenary paper that has to be marked is the paper of well known
Italian scientist A. Isidori “The Differential Geometric Approach to Detection
of Faults in Nonlinear Systems”. The main result of the paper is a condition
for the existence of a solution of the problem which generalized all earlier
results and an appealing constructive procedure for the design of the detection
filter.
With great interest was accepted the plenary paper of N.M. Ivanov
(Russia) “Specific Features of “MIR” Orbital Complex Control Throughout the
Final Mission Phase”. The design to stop “MIR” orbital complex functioning and
to perform its splash down in the Pacific Ocean area was taken 3 years before
the practical implementation of this unique operation. However, the final
scenario of dynamic operations completely different from considered earlier was
adopted in very last days before the final stage.
As always the plenary paper of A. Linquist (Sweden) “A Global Analysis
Approach to Robust Control” was listened with great attention. Many important
problems in robust control can be formulated as analytic interpolation
problems. The author takes a global analysis approach where he considers
bijective transformations from spaces of tuning parameters to entire classes of
controllers.
The semiplenary paper of R. Gabasov, F.M. Kirilova (Belarus) “Optimal
Feedback Control for Nonlinear Dynamic System” was devoted to problems of
open-loop and closed-loop optimization of nonlinear systems. To optimize
nonlinear systems in large a solution of piecewise linear approximation of the
problem corrected by the asymptotic method is used. Results are illustrated by
examples.
The plenary paper of R.M. Murray (USA) “Future Directions in Control,
Dynamics and Systems” with such a strategic title was listened with intense
attention naturally. Under the sponsorship of the United State Air Force Office
of Scientific Research (AFOSR), a Panel on Future Directions in Control and
Dynamic Systems has been formed and was preparing a report to provide a renewed
vision of future challenges and opportunities in the field, along with
recommendations to government agencies, universities, and research
organizations for how to insure continued progress in areas of importance to
the industrial and defense base. In the paper the author summarized the
discussions of the panel and gives an overview of the panel report.
As was mentioned above the special session dedicated to Centenary of
A.I. Lurie was organized at the Symposium. The interested paper was represented
by V.A. Yakubovich (Russia) with the title “Lurie Method in Control Theory and
Its Development”. The author marked some very significant facts. For example
A.I. Lurie in his well known book (Some Nonlinear Problems of Control Theory,
1951) developed a method of establishing stability criteria for nonlinear
control systems. Stability criteria formulated as the condition of existence
real solution of some system of quadratic equations. Later it will be shown
that well known algebraic matrix Riccati equations differs from Lurie equations
only in a form of writing. In the paper V.A. Yakubovich briefly described the
main ideas of applying Lurie equations to different fields of modern control
theory.
The paper of M.R. Liberzon
(Russia) ”Lurie Problem of Absolute Stability – a Historical Essay” was devoted
to some facts from the history of research on the theory of absolute stability,
which was brought to life by the well-known Lurie Problem. Special attention
was paid to hypothesis and examples that accompanied the progress in this field
and exerted a significant influence on it.
With great attention was listened the paper of Konstantin A. Lurie (USA)
with the title “Some Recollections about Anatolii Isakovich Lurie”. The A.I.
Lurie’s son Konstantin A. Lurie told about the time of the Great Patriotic war.
At the end of August 1941 A.I. Lurie left Leningrad for Kazan where he met N.G.
Chebotarev. This meeting was very successful for the both great scientists: for
the outstanding algebraist N.G. Chebotarev and for the outstanding specialist
in Mechanics and in Control Theory. In November 1941 A.I. Lurie arrived in
Sverdlovsk and remained there until August 1944 when the Lurie’s family
returned to Leningrad. This period, lasting for almost three years, was the
time of major events related to the problem of absolute stability. K.A. Lurie
told a lot of very interesting moments from the scientific and human life of
our Russian great scientist. The main idea of
A.I. Lurie’s life was to serve to people and to mother country. And A.I.
Lurie has realized this idea by the development of Mechanics and Control theory
in Russia.
The paper by A. Astolfi (UK)
and R. Ortega (France) “Immersion and Invariance: A New Tool for stabilization
and Adaptive Control of Nonlinear Systems” was listened by the Symposium’s participants with the attention. The method
is well situated in situations where we know a stabilizing controller of a
nominal reduced order model, which we would like to robustify with respect to
high order dynamics.
With great attention was listened the paper of S.V. Emelyanov (Russia)
“A Role of Sliding Modes in Control Problems with Uncertain Parameters”. In the
paper it is emphasized that for a long time the high quality of variable
structure systems were directly connected with using a sliding mode in closed
loop. But it is not a single way. The author demonstrated that the high quality
system could be achieved by a new type of feedback.
A special section of nonlinear control systems in Aerospace was
organized at the Symposium. At this section with a particular attention was
listened the paper by V.N. Kalinichenko, A.V. Nebylov (Russia) and N. Tomita
(Japan) “Adaptive Controller in the Aerospace Plane to Ekranoplane handing
System”. At the paper the algorithm for adapting the controller in
accordance with the current bounds of disturbances is
proposed.
At the Closing Ceremony it was mentioned that the Symposium was visited
by 350 participants from 47 countries.