Academician B.N.Petrov

(to the 90-th Anniversary)

Yu.P.Portnov-Sokolov, V.Yu.Rutkovsky

 V.A. Trapeznikov Institute of Control Sciences RAS

65, Profsoyuznaya st., Moscow, 117997, Russia

 

Academician Boris Nikolaevich Petrov was borne on the 11-th March of 1913 year in Smolensk. His father was an accountant, mother was a physician. She was died in the 1919-th year catching typhus during her selfless fight on the epidemic of this terrible disease which was in our country at that years. Boris’ father was died in the 1929-th year. After that the sister of his father and the sister of his mother have taken over the task Boris’ upbringing. Boris Nikolaevich learned in school very well and willingly. He finished the school in the 1930-th year. After that he entered at the factory school of machine-tool construction plant by S Ordjonikidze. Then he worked during one year as a turner and in the 1933-th year he entered at Moscow Energetic Institute. He graduated from the Institute in the 1939-th year with distinction. As an able and talented student he was praised very high by his diploma supervise, prominent Russian scientist, “father” of aircraft electrotechnics, academician V.S. Kulebakin. He recommended of B.N.Petrov for entering at the Committee of Automatic and Remote Control of USSR Academy of Sciences, later the Institute of Automatic and Remote Control (IARC), now it is the Institute of Control Sciences of Russian Academy of Sciences. B.N.Petrov worked at this Institute until the last days of his life.

In the 1945-th year B.N.Petrov present in Scientific Council of IARC the thesis on the topic “Analysis of automatic copying systems”.The academic degree of engineering sciences doctor was confered to him eluding the degree of candidate. The prominent mathematician, the founder of scientific school on the function theory, academician N.N. Luzin wrote in his testimonial “Presented thesis … has high dignities enabling to consider it outstanding work … All author’s work in the whole and in the details is distinguished by high profundity, extraordinary thoughtfullity, caution and inquisitivity…” This words of the prominent scientists were as prophesy. All further B.N. Petrov’s activity in the field of automatic control theory was distinguished by new nature of solving problems, high profundity, outstanding results and boldness of the judgements and recommendations.Domain of his scientific interests wasvery wide. He suggested the method of structural transformation of automatic system’s diagrams and developed adequate mathematical means - algebra of structural transformations. Very profound investigations were carried out by B.N. Petrov on the domain of differential nonlinear equations’ integration (Petrov’s phenomena). He established the limits of academician S.A. Chaplygin results applicability.

B.N.Petrov is one of the founders of control systems invariance theory. He formulated and proved the physical realizability criterion of the invariance’s conditions which now is known as B.N.Petrov’s principle of two-channels. On the basis of the invariance theory many new principles and structures of different types of combined systems were developed and created.

High human and scientific qualities B.N. Petrov displayed when he gained scientific and civil rehabilitation of professor Georgy Vladimirovich Schipanov who was a collaborator of the IARC. In 1939-1940 years G.V. Schipanov was undergone for the first in the world paper about system’s invariance by destroying criticism. The special commission of USSR Academy of Sciences, central press and journal “Bolshevik” came out against him. G.V. Schipanov was dismissed from the IARC and he was forbidden to continue the investigations on this theory. In 1956 year B.N. Petrov gained of the recognition that the paper by G.V. Schipanov was true and the first. The Schipanov’s conditions were declared as a discovery, the author, who has died to that time, was rewarded by diploma and prize. B.N. Petrov organized the scientific school in which essentially graduates from Moscow Aviation Institute (MAI) were. In that Institute he was the head of the chair “Automatic control and stabilization of airplanes”. Boris Nikolaevich was distinguished by encyclopaedic knowledges and wide interests. Actively working on general theory of automatic control he always chose for mastering and developing the most urgent problems. Duping 50-60 years B.N. Petrov set up and carried out extensive investigations in the field of the theory and designing of nonlinear servomechanisms. He and the group of his colleagues developed the methods of analysis and investigations of the servomechanisms and past the results to specialized design bureaus for realizations.

From 1955 year B.N. Petrov was the leader of the scientists who suggested the systems with variable structure and developed their theory. From 1958 year Boris Nikolaevich and his colleagues were developing theory of nonsearching selfadjusted systems. The main results were generalized in the monograph by B.N. Petrov and his colleagues. For the first time in USSR under the guidance and participation Boris Nikolaevich selfadjusting control systems for the rockets by Chief Designer I.S. Seleznev were developed and created. Further development of the selfadjusting systems theory was a new perspective branch - the theory of coordinate-parametric control which was suggested by B.N. Petrov and his colleagues. The theory of this type of control was presented in their monograph.

Many papers by B.N. Petrov in which the tasks of nonstationary and multiconnected systems designing, of the sensitivity theory, of the synthesis of control algorithms as an inverse task of dynamics are well-known. We could write about many other interesting results by Boris Nikolaevich in the field of general theory automatic control. But the most important branch of his activity was the problem of the automatic control theory by aircrafts and vehicles. In particular this fact follows from considering aforementioned papers and monographs by B.N. Petrov. Sources of this can be found out in his pedagogical activity which he began in 1944 year at MAI. There he was the first who delivered the course of lectures “Automatic of an engine and a propeller”. The author created the course which contains the most important, the most new results ( results of journals papers, thesises ) of the automatic control theory of those years. B.N. Petrov’s results were brought to the engineering methods of designing and analysis of new control systems by turbocompressor boots, by piston engine propeller rate of rotation and others. At the first time mathematical description of the aviation piston engine and pressurized cabin as objects of control were obtained. The special laboratory by the chair was organized by B.N. Petrov. In that laboratory it was possible to study behaviour of the control system elements and regulator using mock-up and real control system. To the problem of control by engine installations of such vehicles as ballistic rockets B.N. Petrov spared intent attention all his life as the scientist and the engineer. The works in this domain enable him to enter in circle of the creators of practical cosmonautics. Obtained by him and his team results had founding character and were realized. On the basis of these results the control systems were created and they became as a part of all large liquid-propellant rockets by Chief Designers S.P. Korolev, M.K. Yangel, V.N. Chelomey, V.F. Utkin.

During all years of joint work with the designers of the rockets B.N. Petrov spared high attention to the problem of designing of on-board terminal control systems which increase energetic characteristics of the liquid-propellant rockets. Many years Boris Nikolaevich was as scientific leader of the terminal systems designing. Academician V.P. Glushko mentioned that in the process of that designing fundamental results for progress of native space engineering were obtained. In one of his last speech Boris Nikolaevich remembered that the designing of on-board control system began in the 50-th years. At that time he works with academician S.P. Korolev carrying out the investigations of the control systems for the first intercontinental ballistic missile (ICBM) R-7 and for its predecessor rocket-laboratory M5-RD. B.N. Petrov very often was a participant-consultant on meetings of the famous Councel of the Chief Designers being at the head of S.P. Korolev. The first dynamic’s investigations of the liquid-propellant engine (LPE) and its simulation on analog computer were obtained by Boris Nikolaevich and his collaborators in 1950-1951 years. This work was executed according to the request by V.P. Glushko for his engine of 100-tons thrust. The obtained results were reported at the meeting of the Commission of USSR Academy of Sciences Presidium.The head of the Commission was academician M.V. Keldysh. Outstanding authority in the problems of engine manufacturing academician B.S.Stechkin presented at this meeting too.

In 1954 year in accordance with the Decision of USSR Government the IARC it was charged to be at the head of the investigations for control by the engine installations of designed by S.P. Korolev intercontinental two-stage missile R-7. B.N. Petrov became the scientific leader of these works. The control systems designing problem of the LPE thrust and synchronization of tanks emptying was very important and was distinguished by absence of a prototype and similar investigations. As main tasks were the following:

∙            investigations of LPE as a control object and approximation of its mathematical model for different tasks of control;

∙            developing of the mathematical simulation methods for continuous and discrete on-board control systems;

∙            searching of principles’ designing of the fuel components level sensors with unique accuracy;

∙            realization of on-board high accuracy sensors of pressure in the LPE’s combustor;

∙            realization of actuators and control devices for control of the thrust and the fuel-oxidant ratio.

The investigations by B.N. Petrov and his colleagues in developing of the LPS’s mathematical model and the task of the LPE’s controllability had priority character and were included as a heading in the LPE’s general theory. Suggested by B.N. Petrov’s team procedures of the mathematical simulation on analog computers ( at that time there were not digital computers ) made it possible to quicken significantly search of methods for preventive of the rocket R-7 logitudinal instability. This instability was the cause which delayed the cosmonautics developing. It was in 1958 year when in our country they were preparing to fly to the Moon, but launching were broken down from the rocket explosion. Nature of this complicated process was founded out by efforts of big collective of the scientists and designers. LPE is the source of enormous quantity of energy. It is the unit of oscillating contour including pipelines and the rocket’s structure. The rocket was gone to ruin at resonance. B.N. Petrov suggested the method of the LPE’s imitative simulation which admitted to find out the causes of the resonance and to discover the means of its destruction. The knowledge of the LPE’s dynamic and justified simplification of its mathematical model made it possible to carry out the analog simulation of phantom velocity control system (PVCS) and to simplify full-scale development of the system and to decrease the duration of this development rather essentially. At the process of designing control systems of fuel-oxidant ratio ( CS FOR )it was found out that in the system auto-oscillations appeared because of nonlinear characteristics of some its elements. These dangerous event was eliminated after the simulation of the system with LPE in the closed contour. Subsequently this occurrence was investigated theoretically in detail. In this case the justified facilitations of the LPE’s mathematical model enabled the method of eliminating auto-oscillations to be found rather quickly too. B.N. Petrov was the leader of this investigations.

In 1954 year USSR Government issued some decisions for support of ballistic rocket creation. For creation of high-accuracy on-board non-float meters of fuel reactants many research-and-development institutes and institutes of USSR Academy of Sciences including IARC were drawn in. B.N. Petrov was appointed as the leader of this work. After examinations of the suggestions by ultrasonic sensors, radar-isotope sensors, endo-vibrator sensors it was chosen for the rocket-laboratory M5-RD the principle of designing of the discrete capacitance-type sensor for the creation of prototypes. Structure of the sensors for the rocket M5-RD and then for the rocket R-7 under the aegis of academician B.E. Chertok. Academician D.E.Okhotsimsky suggested original hydro-mechanical filter fir decreasing of liquid oscillations influence on the sensors’ data.

Many efforts were made by B.N. Petrov for designing of pressure transducer in the LPE’s combustion chamber (CC). V.P Glushko suggested very strict limitations on the accuracy of the pressure control in CC: ± 1% .So in the control system the pressure transducer might have an error not more than ± (0,4 ¸ 0,5)%. Under operating conditions on working LPE at wide spectrum and high intensity of vibrations, very high accelerations and at wide temperature range the creation of such on-board transducer was an enormous task. Only strongly attitude by B.N. Petrov made it possible to choose from many design bureau of Ministry of Aircraft Industry the organization which after long altercations agreed to do this work. The transducer was created for the rocket R-7 in experimental design bureau of Chief Designer R.G. Chachikyan. And this transducer helped to find out the nature of the longitudinal oscillations since resolving power of its output potentiometer was much higher than the same of telemetering one. B.N. Petrov team in IARC carried out the first works for searching a rational characteristics of control elements – throttles in the LPE’s supply lines of banks emptying system and CS FOR. The results formed the basis of these control elements which were created in the design bureaus of S.P. Korolev and V.P.Glushko.

Rather important research branch by B.N. Petrov from 1956 year was development of the theory and designing systems for artificial earth satellites (AES). Research in gravitational satellite orientation systems in Russia was initiated and guided by academician D.E. Okhotsimsky. These are passive systems that do not require the expenditure of some form of energy for creating restoring moments. However, the perturbations due to satellite separation required the development of a simple and inexpensive pre-damping system. The low fuel consumption of the relay pre-damping system elaborated at the IARC is attained by incorporating a special feedback to compensate the hysteresis loop of the relay characteristics and choosing an appropriate ration between the constraints of angular-rate sensor and attitude sensor. Control corrections were elaborated for suppressing the effect of the elastic vibrations of the gravitational stabilizer boom on the dynamics of the system and energy consumption.

Subsequent research in this direction resulted in the development of control theory and systems for flexible space constructs (satellites with large flexible solar battery panels and outrigger antennas). This problem arose in the early sixties when “Explorer –1” lost its stability soon after injection into orbit due to wrap energy dissipation induced by the elasticity of four spike antennas. Since them this problem has been attracting the earnest attention of scientists and engineers in many countries producing such satellites. A project on this topic was undertaken at the IARC in collaboration with the Scientific Production Division of Applied Mechanics (Academician M.F. Reshetnev, Chief Designer) in connection with the production of satellites for geosynchronized orbits and their orientation systems.

The flexibility of flexible space constructions creates new control problems, whose importance increases with decreasing degree of design rigidity and increasing intensity of inputs. A highly hazardous factor here is the interaction of a controller with the elastic vibrations of the flexible spacecraft under relay control in which periodically repeated “shock” loads of the control action may result in uncontrollable growth of the amplitude of elastic vibrations to the critical level at which the controller may be locked and consequently the spacecraft may become unstable. However, the relay control mode (hydrodyne discharge, stabilization of the angular orientation during orbital corrections, etc.) predominates over a considerable part of the flight time of virtually all types of flexible space vehicle with long active life. A physical –modal model of flexible vehicles was designed by B.N. Petrov and his collaborators. This model differs from the modal model in that all coordinates and coefficients have a distinct physical meaning. Therefore, it is best suited for studying that dynamics of flexible vehicles, helpful in delineating the “portrait” of the dynamics of the controlled object and simple in parameter identification and control synthesis. The method of analyzing the relay orientation system for one-modal flexible vehicles –the biplane phase method was suggested. It reveals the role of phase relations in the interaction of controls with the elsatic vibrations of the component parts of a flexible vehicle and the mechanism of loss of stability of motion due to these vibrations. It is a tool for determining the critical amplitude at which a controller is locked by the elastic vibrations, deriving the laws of distribution of random values of the elastic mode phase, and designing two types (amplitude and phase) of algorithms for damping elastic vibrations. The results obtained under the direction by B.N. Petrov and at his personal participation were used in designing control systems for the communication satellites onto the geosynchronized orbit of the series “Raduga”, of the series “Gorizont” and for television satellites of the series “Ekran”.

Essential scientific contribution B.N. Petrov introduced in the designing of multi-man orbited spacecraft’s, space stations launching to Moon, systems of vehicles safe lunar landing. It is not possible to mention about the International project “Soyuz - Apollon”. Big collectives of scientists, engineers, designers from USSR and USA more than five years worked under preparation of the flight according to this project. Council “Interkosmos” accomplished co-ordination of soviet collectives work and B.N. Petrov as the chairman of this Council introduced big personal contribution in the solving of many organization, scientific and technical problems. B.N. Petrov all his creative fife worked with leading workers of our rocket-space science and technique - S.P. Korolev, V.P. Glushko, M.K. Yangel, V.N. Chelomey, V.F. Utkin, M.F. Reshetnev, V.P. Mishin, B.E. Chertok, N.A Pilugin and other famous scientists and designers of our rocket manufactoring and cosmonautics. He assumed its right place among the founders of native cosmonautics. He participated in most launching in Kapustin Yar and Baiykonur during the period of the first works by S.P. Korolev under space mastering. He participated in the work of Government Commissions by launching very often. Of several years work connected Boris Nicolaevich with academician M.V. Keldish. He participated in the elaboration and discussions of our country space programs. At a period when our native multirepeated space system was elaborated B.N. Petrov participated in determination of the construction of the vehicle “Buran”. In 1966 year Boris Nicolaevich was honored with Lenin Prize for the development of space science.

Academician B.N. Petrov was engaged in legion size of scientific-organization and pedagogical work. Many years he was as the academician – secretary of Mechanics and Control Processes Department of USSR Academy of Sciences, he was elected as Vice-president of USSR Academy of Sciences, as a member of many foreign Academics including Academy of Astronautics. As well-know professor B.N. Petrov was the head of the chair in MAI, was leader of many Scientific Councils. Many of his post-graduate students, organized by him collectives work successfully in our country. Boris Nicolaevich was perfectly well man, was very kind and sympathetic. He always helped to his collaborators both in their scientific and in their living problems.

He died on the 23-th August of 1980 year. The name of Boris Nicolaevich Petrov will be in the science about control cosmonautics for ever.