by Vladislav RUTKOVSKY, Dr. Sc. (Tech.), Laboratory Head of the Trapeznikov Institute of Control Sciences, Russian Academy of Sciences (Moscow)

In March of 2013 the scientific community of our country will mark the centennial birth anniversary of the outstanding scientist in the field of automatic control Boris Petrov (1913-1980), Vice-President of the USSR Academy of Sciences (1979-1980), Hero of Socialist Labor (1969), winner of Lenin (1966) and State prizes (1972). Working in close creative cooperation with leaders of the national rocket-and-space science and technology, such as Sergei Korolev, Valentin Glushko, Mikhail Yangel, Vladimir Chelomey, Vladimir Utkin, Mikhail Reshetnyov, Vasily Mishin, Boris Chertok and Nikolai Pilyugin, he joined by rights a cohort of founders of national astronautics and was one of the organizers of international cooperation in near-Earth space. Petrov's activity received wide recognition in the world. He was a member of the International Academy of Astronautics, foreign member of Czechoslovak, Hungarian, Bulgarian and Polish academies of sciences, was awarded a number of foreign orders and a gold medal of the National Space Research Center of France.

Petrov was born on March 11, 1913, in Smolensk. His mother was a physician who devoted all her efforts to control of the typhoid epidemy broken out soon after the October Revolution of 1917 and died when her son was 6 years old. In 1929 died his father, and Petrov's relatives took care of him and his younger sister.

He left school in February of 1930, was a bookkeeper in a collective farm for some time and in autumn of that year left for Moscow where he entered a factory school

attached to Ordzhonikidze Machine-Tool Construction Plant and acquired a profession of lathe operator. However, he was eager to study. Yet as a boy, he preferred reading to children's games, he liked books on travels and adventures and was carried away by drawing.

In 1933 he entered in the Moscow Power-Engineering Institute (MPI) and brilliantly completed his training there. His graduation work prepared under the supervision of Academician Viktor Kulebakin was recognized as outstanding.

In 1939, upon graduation from the MPI Petrov was sent to work, on the suggestion of his instructor, at the Committee for Telemechanics and Automatics of the USSR Academy of Sciences, and on its basis Kulebakin created an Institute of Automatics and Telemechanics of the USSR Academy of Sciences (today RAS Trape-znikov Institute of Control Sciences) that same year. Petrov headed the institute in the hard years of its formation (1947-1951) and remained committed to it till the last days of his life covering the path from engineer to academician.

The first works of the young scientist were devoted to the automation process of continuous metal casting from open-hearth furnace. When the World War II broke out, the scientist tackled the problem of automatic rejection of products. The Energetik (Power-Engineering Specialist) large edition newspaper of the MPI wrote in November of 1945: "The old professionals showed distrust when examining Petrov's projects, and experienced designers lost heart considering his ideas impracticable. But Petrov believed in himself... He checked his calculations over and over again, verified drawings and designed new appliances... By the end of 1942 the first mount was put into operation, which sorted and rejected bad cartridge-cases. The cartridge-case local measuring machine LOG designed by the professor Trapeznikov and the engineer Petrov was included into the country's armament."

The scientific bases for development of automatic control devices was described in the monograph "Automatic Control of Dimensions" published by Petrov in coauthorship with Vadim Trapeznikov, Iosif Gorodetsky and Alexander Feldbaum in the Oborongiz publishing house already after the war, in 1947. It was the first work in the world scientific literature, generalizing the achievements in the sphere of automation of control of dimensions and a geometric form of mass-production items.

Six years after graduation from the MPI, Petrov defended a thesis on the "Analysis of Automatic Copying Systems", and was given the degree of Doctor in technical sciences. The 32-year-old competitor for the degree suggested an original theory of creation of automatic copying systems of a wide class and new principles for construction of high-precision machines for production

of sophisticated products. In his comment on the thesis, the well-known Soviet mathematician Nikolai Luzin wrote: "The submitted thesis... has high merits, which allow recognizing it as an outstanding phenomenon among other works."

Petrov's merit is in the fact that he created a method of structural transformations of automatic system schemes and developed an adequate mathematical apparatus. Well after, already in the last years of his life, he returned again to this problem in his work implemented together with his students from the Aviation Institute in Ufa (Bashkortostan).

The scientist carried out profound research in integration of nonlinear differential equations, which resulted in a discovery called "Petrov's Phenomenon" by Luzin.

Petrov is one of the founders of the invariance theory (independence of a system from applied external actions), whose ideas are used in automatic control devices of flight vehicles. Professor of the Institute of Automatics and Telemechanics Georgi Shchipanov was a pioneer in this field. In 1939 he published in the Automatics and Telemechanics journal an article, which aroused severe criticism, in the spirit of Stalin, of the invariance theory in the scientific and political press (the Bolshevik journal). The theory was declared harmful and idealistic and the author's ideas unrealizable in any physical systems. Shchipanov was discharged from the institute, and all works on the invariance theory were scaled down. But in 1953, when there was even no trace of the Khrushchev Thaw, Petrov had courage to address the 2nd All-Union Conference on the Automatic Control Theory confirming physical feasibility of invariant systems. He stated that for their realizability it was necessary to have at least two transmission channels of disturbing action between the point of its application and the point of a coordinate measuring, for which invariance was achieved. The said criterion became a platform in the design of automatic controlled systems and is now widely known in world literature as "Petrov's two-channel principle". Many-sided research in the field of invariance resulted in creation of new principles and structures of different types for combined systems.

Petrov displayed excellent qualities as an individual and a scientist when he together with Academician Alexander Ishlinsky succeeded in scientific and civil rehabilitation of Shchipanov. In 1966 results of his work were recognized as a scientific discovery with a priority of April 1939. Unfortunately, the author was no longer alive.

In the 1950s-1960s Petrov conducted theoretical and experimental works on nonlinear servomechanisms (devices providing remote control to bring mechanisms into action). Together with his disciples, he formed bases of the theory of this class of automatic systems, suggested calculation methods for them and passed the obtained results to specialized design offices for subsequent realization.

From 1955 Petrov headed development of design methods for a new class of nonlinear systems with a variable structure, which provided high static and dynamic accuracy of automatic control of aircraft.

In 1957, the scientist took charge of work on the theory of self-adjusting control systems and their creation, generalizing the main achievements in this field in the monograph Principles of Construction and Design of Self-Adjusting Control Systems (1972). First developed in the USSR under supervision of Petrov, they were suggested for several classes of rockets of the well-known designer Igor Seleznev, Dr. Sc. (Tech.). Further elaborating this problem, Petrov with his disciples laid the foundation for a new promising line, i.e. the theory of coordinate-parametric control. In his monograph Adaptive Coordinate-Parametric Control of Non-Stationary Objects, which the scientist saw only in galley proof (it was published in 1980 after his death), Petrov analyzed principles of constructing, algorithm synthesis of object parameters rearrangement, capabilities and growth perspectives of this class of systems.

Other works, namely Information and Semantic Problems in the Processes of Control and Work Organization (1977) and The Model Theory in Control Processes (1978) written by the scientist jointly with other authors, discuss information and thermodynamic aspects in analyzing complex control systems, which cleared the way to a new line in the control theory associated with information approach.

Widely known are Petrov's works devoted to non-stationary systems, the sensitivity theory and synthesis of control algorithms as an inverse task of dynamics.

Problems of automatic control of mobile objects held a prominent place in Petrov's activities, which, in particular, is confirmed by the monograph Design of Automatic Control Systems of Gas-Turbine Engines (1980), in which he and his coauthors described adequate and, at the same time, rather simple mathematical models of gas-turbine engines and structures of high-efficiency dual invariance control systems. Interest in this subject originated in the course of his pedagogical activities at the Moscow Aviation Institute, where in 1944 at the chair of Automatic Control and Aircraft Stabilization he created a new course of lectures Automation of the Engine and the Screw, whose significance went beyond the scope of technical presentation. The author organized a set of lectures on the most important and recent results (according to the materials of scientific papers and theses) in the theory of automatic regulation. Moreover, he developed and brought them up to engineering methods of designing and calculation of new at that time regulation systems of turbocompressor pressurization and screw rotation speed of piston engine.

Petrov was the first to give a mathematical description of aircraft piston engines as an object of regulation and also a description of pressurized cockpit as an object of its pressure maintenance. He set up a laboratory under the said chair headed by him from 1950 till the last days of his life, where one could study behavior of control devices using models and prototypes. It should be noted that Petrov's lectures were always a success among students. Thanks to his permanent and laborious work, a highly qualified scientific and teaching work group was formed at the chair, whose curriculum became a standard for many universities of the country.

As a brilliant engineer, Petrov paid intent attention to control problems of aircraft engines, in particular, ballistic rockets. This work drew him closer to the creators of practical astronautics. The results obtained by him and his team were of fundamental character, and the control systems realized on their basis became a component element of all large liquid-propellant rockets by chief designers Korolev*, Yangel, Chelomey and Utkin. By the way, he participated in most launchings of aircraft from Kapustin Yar military range (constructed in 1946 for testing of the first Soviet ballistic rockets) located in the north-western part of the Astrakhan Region, and also from the Baikonur cosmodrome** in the territory of Kazakhstan during the first operations on outer space exploration. He was included many times in the State Commission for launching.

His work with rocket engineers brought him to handling problems of construction of airborne terminal control systems of liquid-propellant rockets, which improved power characteristics of the equipment. Products of his work in this field were described in his monograph Airborne and Terminal Control Systems published in 1983 after his death. Academician Valentin Glushko noted their fundamental significance for progress of national space engineering.

Petrov and Sergei Korolev met in the 1950s, when they created a control system for the first intercontinental ballistic missile R-7*** and the laboratory missile M5-RD. Petrov often came out as a consultant at meetings of the well-known Council of Chief Designers headed by Korolev. In 1950-1951 he and his colleagues received the first positive research results of studies of dynamics of liquid-propellant jet engines and their analog simulation. They were reported at the committee meeting at the Presidium of the USSR Academy of Sciences chaired by Academician Mstislav Keldysh****, where they were approved, in par-

* See: N. Koroleva, "His Name and Cosmos Are Inseparable", Science in Russia, No. 1, 2007; N. Sevastyanov, "The Cause of Legendary Designer Lives On", Science in Russia, No. 1, 2007.-Ed.

** See: Yu. Markov, "Baikonur: 50 Years of Serving Mankind", Science in Russia, No. 3, 2005.--Ed.

*** See: G. Grechko, "Satellite Going Into Orbit", Science in Russia, No. 5, 2007.--Ed.

**** See: B. Chetvemshkin, K. Brushlinsky, "Our Director"; L. Zelyony, O. Zakutnyaya, "Chief Theorist and Strategist of National Cosmonautics", Science in Russia, No. 1, 2011.-Ed.

ticular, by the major specialist in engine-building Academician Boris Stechkin, who actively participated in the discussion.

It is natural that in 1954 Petrov was appointed supervisor of works on the engine unit of R-7 missile at the Institute of Automatics and Telemechanics.

Creation of radically new rocket systems of such sophisticated design, starting from the zero level, without any background and with a complete lack of prototypes and literary material, was accompanied by great difficulties. Hence their high research intensity. The contribution of Petrov and his students to the development of mathematical models and solution of the problem of controllability of liquid-propellant engines was of priority nature and made up a special section of the theory of liquid-propellant jet engines, which covered a number of landmark problems arising in the process of creation of R-7 missiles and subsequent large missiles of this class.

The method of electronic simulation of liquid-propellant engines using analog computers (there were no digital computers at that time) suggested by Petrov's team accelerated essentially the finding of a remedy for longitudinal instability of R-7 missile, a problem, which was considered terra incognita and hindered the advance of space exploration. In 1958 the country was preparing to launch the first automatic interplanetary station Mechta to the Moon*, but an official start was postponed again and again due to explosions of missiles at test launchings. By efforts of a large team of scientists and designers it was managed to solve the problem of the

* See: Yu. Avsyuk, "Focus on Lunar Studies", Science in Russia, No. 6, 2006.-Ed.

complicated process. The liquid-propellant engine as a source of colossal energy was a part of oscillating circuit including the piping and design of the missile proper, which was destroyed under resonance. The method of engine simulation modeling developed by Petrov essentially accelerated search for reasons of catastrophes and helped to find means of their counteracting.

But there arose another problem. When developing a regulation system of fuel component ratio of a liquid-propellant engine, the specialists revealed self-induced vibrations of a constrictor (restrictor, regulator). This dangerous phenomenon was removed after simulation of the system with an engine in a closed circuit. Petrov as head of this work displayed his ability to approximate (substitute some objects by others similar to initial ones but simpler) intricate equations of the engine, which substantially reduced the time of achieving of the desired result, i.e. finding of methods to prevent self-induced vibrations of a constrictor.

In 1954, the Government passed a number of regulations on the main blocks of R-7. In particular, it was required to create high-precision floatless airborne depth gauge of propellant components. The Central Research Institute of Mechanical Engineering (NII-88, Korolev, Moscow Region), the Acoustic Institute of the USSR Academy of Sciences and the Institute of Automatics and Telemechanics (Moscow) were drawn to solve this problem. Petrov carried on general direction and managed to attract a wide circle of researchers for this purpose. After analyzing a number of proposals for ultrasonic, radioisotope and endovibrator sensors received from different institutes, the research supervisor decided to construct prototypes of a capacitance discrete sensor for the laboratory missile M5-RD. Trial experiments were headed by the scientist at his institute, which was later reflected in his monograph Principles of Invariance in Measuring Technology (1976). The approved design of a capacitance sensor for a system of tank drainage of the rocket M5-RD (and then also R-7) was developed in NII-88 under the direction of Academician Boris Cher-tok. The well-known specialist in space flight dynamics Dmitry Okhotsimsky (Acad, since 1991) developed a special hydromechanical filter for reduction of slush effect in flight on sensor readings.

Petrov's team made a lot of efforts to create a precision airborne pressure sensor in a combustion chamber of liquid-propellant engine. The chief designer Glushko put strict limitations on pressure control error, i.e. ±1 percent. Besides, the sensor was to have error not more than ±0.4-0.5 percent. In the conditions of a wide range of extreme vibrations and high accelerations, to design such airborne device with a considerable temperature range was an unheard-of and difficult task. And only Petrov's tough attitude made it possible to choose an organization among design offices of the USSR Ministry of Aviation Industry, which consented to implement this work after long heated technical discussions. The sensor for R-7 was developed at the Experimental Design Bureau (EDB) No.133 (Moscow) headed by the chief designer Ruben Chachikyan. It should be noted that it was just that device which helped guess the nature of longitudinal vibrations of the rocket, as resolving capacity of its output potentiometer (an instrument for measurement of electromotive force and tensions by compensation method) was much higher than that of telemetric sensor of pressure.

Petrov and his colleagues curried out search for rational characteristics of control organs, i.e. constrictors in the main lines of liquid-propellant engines and passed

the findings to the EDB headed by Korolev and Glush-ko, where efficient devices were made.

As a whole, Petrov accepted a responsibility for an idea of creation of principally new terminal control systems for fuel consumption of liquid-propellant engines, which substantially increased rocket power at the expense of drastic reduction of guarantee reserves of fuel. He was a research supervisor of similar systems for all large liquid-propellant rockets starting from Korolev's R-7 and subsequent combat ballistic missiles and carrier rockets of space vehicles.

Petrov made substantial contribution to the development of the theory and systems of control of the Earth (ASE) artificial satellites*. In the mid-1950s, in our country on the initiative of Dmitry Okhotsimsky works started on creation of gravitation systems of attitude control of ASE, which did not require consumption of any energy for restoring moments. But significant disturbances arose during satellite separation from the carrier rocket. An original relay system of its preliminary stabilization, whose high efficiency was achieved by introduction of a special downlink, was developed at the Institute of Control Sciences headed by Petrov.

The further development of this trend was connected with elaboration of the theory and systems of control of deformable space vehicles. The latter include artificial satellites with attached flexible elements (large-area solar battery panels, outboard radio aerials). Such necessity appeared early in the 1960s when the Ameri-

* See: B. Chertok, "The First Artificial Satellite"; G. Grechko, "Satellite Going Into Orbit", Science in Russia, No. 5, 2007.-Ed.

can satellite Explorer-1 lost stability soon after its putting into orbit due to scattering of twisting energy, caused by elasticity of 4 rod antennas. Since that time up till now this problem is in the center of attention of scientists and engineers in many countries of the world where similar artificial satellites are being developed. The Institute of Control Sciences tackled this problem jointly with the Moscow Science and Production Association of Applied Mechanics headed by the chief designer Acad. Mikhail Reshetnyov. Petrov and his team suggested a modally physical form of the mathematical model of a deformable space vehicle, which in scientific literature was called "a method of analysis of

a relay orientation system of a single-mode deformable space vehicle" or "a phase biplane method". It allowed to comprehend and study the mechanisms of a loss of a space vehicle stability and also to determinate a critical amplitude of bending vibrations. Finally, the scientists suggested 2 types of algorithms (amplitude and phase) of their damping. The obtained results were applied in the course of designing of control systems of communication satellites (Raduga and Gorizont series), TV satellites (Ekran series) and telecommunication relay station satellites Luch-1 and Luch-2.

Petrov made substantial contribution also to the creation of multi-seater piloted satellite vehicles, automatic stations launched to the Moon and systems for soft lunar landing of automatic space vehicles.

Petrov's participation in preparation of the first Soviet-American Apollo-Soyuz flight* (1975) also cannot be disregarded. This project involved efforts of large teams of scientists, engineers and designers of 2 space powers for more than 5 years. The Interkosmos Council coordinated works of our specialists, and Petrov as its chairman made major personal contribution to the solution of numerous organizational and scientific and technical problems of the joint flight.

* See: Yu. Markov, "Russia-USA: Space Cooperation", Science in Russia, No. 3, 2008.--Ed.

In the course of creation of the national reusable space system Buran (starting from 1973), Petrov took active participation in forming of a space vehicle look. Unfortunately, he did not see the only space flight of this vehicle (on November 15, 1988) and its landing, which took place in the automatic mode under on-board computer control.

Petrov's heritage is really great: he wrote round 200 publicistic and popular science papers on major scientific problems associated with the development of automatics, computer engineering, automation of the experiment and programmed control of space exploration. He supported all new and perspective ideas and stressed not once the importance of developing a mathematical or abstract theory of systems, which, as he used to say, extended horizons of control science.

From 1963 the scientist held permanently the office of academic secretary of the Department of Mechanics and Control Processes of the USSR Academy of Sciences and in 1979-1980 that of Vice-President of the USSR Academy of Sciences. In this walk of life he worked hard for the development of space programs of our country and participated in their elaboration and discussions. He cooperated for many years with Mstislav Keldysh, President of the USSR Academy of Sciences (1961-1975).

Under his supervision grew up large groups of specialists. His scientific school is successfully working on urgent problems of modern control theory. His numerous disciples have defended theses and have become known scientists and engineers, head university chairs, scientific and industrial organizations.

It should be noted that both students and teachers alike were fond of the scientist. He was treated with great warmth by the founder and first director of the Institute of Automatics and Telemechanics Acad. Viktor Kulebakin and the outstanding mathematician and creator of the Moscow scientific school of the theory of functions Acad. Nikolai Luzin; Petrov and his family members were always welcome guests in their homes. Luzin's letter to Petrov of August 23, 1949, has been preserved: "Having heard nothing from you for long I thought that your administrative duties (at that time Petrov headed the institute.-Auth.) drew you away from scientific work and I really felt sorry for you as bureaucratic administration dries out people and makes them older than they actually are, while science and artistic works make them younger. But you are young!" The teacher was afraid that his favorite talented student would move away from big science but his fears were vain. Petrov was an outstanding researcher, and his "administrative duties" by no means diverted him from "scientific work". Besides, he was a man with a wide range of interests and very knowledgeable about many spheres of science, fiction and arts. Leisure time he devoted to drawing. In addition, he was an excellent family man, he treated his wife Irene, a true friend and partner in life, with deep tenderness.

Petrov's name will remain forever in the annals of national science and space exploration. In 1980, the Presidium of the USSR Academy of Sciences instituted Gold Medal named after B. Petrov (the Petrov Prize since 1993) conferred for outstanding works in the automatic control theory and systems, experimental studies in space exploration. One of the research vessels of the Academy of Sciences was given the name Academician Boris Petrov. His memorial plates are placed on buildings of the Trapeznikov Institute of Control Sciences and the Moscow Aviation Institute.