Control System, Automated

Control System, Automated

 

(ACS), an aggregate of econometric methods, technical facilities (computers, communications facilities, information display equipment, and data transmission equipment), and organizational complexes that provides for the efficient control of a complex process or facility, such as a production process or enterprise. The most important objective in constructing any such system is a significant increase in the effectiveness of the control exercised over production, administration, and other areas, deriving from an increase in the productivity of the control work and an improvement in planning methods and flexible regulation of the controlled process. In the USSR automated control systems are constructed according to state plans for the development of the national economy.

Fundamental principles. The development, implementation sequence, and effective application of an ACS are governed by several principles first formulated by V. M. Glushkov.

PRINCIPLE OF NEW PROBLEMS. An ACS must provide solutions to new control problems rather than mechanize control procedures achieved by nonmechanized methods. In practice, this necessitates the solution of problems in multivariant optimization by means of large-scale econometric models. The particular composition of such problems depends on the nature of the controlled process. In machine-building and instrument-making enterprises, for example, the most important problems usually involve production and capacity planning. A significant effect is achieved when all the shift goals for both production and supply (as in material and technical supply) are coordinated in time, the optimum sizes for production batches have been determined, and equipment use has been optimized.

Similar problems occur in construction. In many cases the foremost problems include the technological preparation for production and the control of planning and design operations. In transportation the optimization of routes and the scheduling of movements and loading and unloading operations are the most important. In sectoral control systems the problems of primary importance are the optimum planning of operations for enterprises and the precise coordination of delivery times; the problems of future sectoral development and of forecasting are also important.

PRINCIPLE OF A SYSTEMS APPROACH TO ACS DESIGN. The design of an ACS should be based on a systems analysis of both the facility controlled and the control processes. This implies the necessity of defining goals and efficiency criteria for the operation of a facility and of the control system and of analyzing the structure of the control process. Such actions disclose the entire complex of problems that must be solved in order that the projected system conform to the specified goals and criteria in the most efficient way possible. These problems may be technical, economic, or organizational in nature. Therefore, in principle, the introduction of an ACS provides new possibilities for a radical improvement in the system of incentives and economic indicators chosen.

PRINCIPLE OF A PRIMARY DIRECTOR. The development of system requirements and the creation and installation of an ACS are managed by the primary director of the facility, for instance, the director of a plant, the head of a central administrative agency, or a state minister.

PRINCIPLE OF CONTINUOUS SYSTEM DEVELOPMENT. The fundamental concepts of the synthesis, structure, and specific realization of an ACS must permit the system to be adjusted with relative ease in order to solve problems that arise while the system is in service. Such problems may be due to the installation of new sections in the controlled facility or the extension and modernization of the system’s primary technical equipment or software. The software for an ACS is designed to permit convenient changes in individual programs and in the criteria that govern the control process.

PRINCIPLE OF UNITY FOR THE INFORMATION BASE. The information required to solve the entire set of control problems is stored and constantly updated on the computer’s information carriers (memories). This provides for the elimination of the unwarranted duplication of information in master files. This duplication inevitably occurs if primary data files are created for each separate problem.

The master files constitute an information model of the controlled facility or process. For example, at the enterprise level the master files should contain a very detailed description of all production factors: personnel data on all workers; information about fixed capital stock—land, buildings, and equipment with all the data needed to make decisions regarding use and redistribution; data on stocks held, including those in temporary warehouses and stocks of unfinished products; information regarding the condition of equipment; quotas for labor and materials and the sequences of production operations needed to fabricate parts, subassemblies, and finished products; plans, including requisitions for material and technical supplies; prices and evaluations; and information on the current status of an enterprise’s bank accounts.

The processing system for primary documents and the system of automatic data pickups must be organized in such a way that the data regarding any change in an enterprise are fed into the computer within the shortest possible time. Such data must be distributed periodically among the master files either automatically or by instruction of the operator in such a way as to ensure the system’s readiness to issue any information required about the facility or process. If necessary, files that are oriented toward specific production, products, or complexes of problems may be derived from the master files; in this case the derived files are considered secondary files.

PRINCIPLE OF INTEGRATION FOR PROBLEMS AND OPERATING PROGRAMS. Most control processes are interdependent and therefore cannot be reduced to a simple, independent set of separate problems. For example, the problems in material and technical supply are by their very nature associated with a whole complex of problems in production and capacity planning; their formulation depends on the tasks assigned to the planning of production, but if delivery times or item listings change, the plans must also be altered. If the problems of planning and material and technical supply are solved separately, the efficiency of an ACS may be substantially diminished. The principle of integration of problems and operating programs is incorporated in virtually all types of automated data-processing systems used in designing, testing, and other areas.

PRINCIPLE OF PROCESSING RATE MATCHING. The rate at which data are processed in the various interconnected circuits of an ACS must be matched in such a manner as to avoid blockages of information, when there is a physical possibility of losing data, or large information gaps, which lead to the inefficient use of some elements in the system. For example, there is no point in increasing the rate at which a computer performs arithmetic operations if, when specific ACS problems are being solved, data are introduced or information is exchanged between the external memory and the central processor via a bottleneck in the system.

PRINCIPLE OF STANDARDIZATION. When a designer develops an ACS equipment complex, the attendant software and operating programs, and the forms and structure for the associated data files, he must attempt to have his proposed solutions suit the widest possible range of customers. In each case it is necessary to establish a logical degree of standardization that ensures that attainment of this goal does not result in excessively complicated solutions to typical problems. Standardization of solutions provides the efficiency needed for the development of a complex ACS.

An ACS may be classified as one of two types, depending on its specific purpose: it may be designed to control a facility as a whole, with all its functions, or it may provide automation for a particular control function in a broad class of facilities (functional ACS’s). Systems in the first category are further classified according to the type of facility controlled: technological processes; shops; enterprises, such as factories, research institutes, and design offices; and sectors of the national economy, such as industry, communications, and transportation. Systems in the second category include those designed for planning calculations, for material and technical supply, and for statistical reporting.

Composition of an ACS. An ACS consists of a core and a functional section. A simplified block diagram of an ACS designed for enterprise control is shown in Figure 1.

Core. The core of an ACS comprises an information base, hardware (equipment base), software, and an organizational and economic base. It is used in the solution of all problems handled by the ACS.

INFORMATION BASE. The information base of an ACS is the aggregate of all data needed to automate the control of a facility or process; the data are stored in the computer’s memories. The information base is usually divided into three files: master, derived, and operational. The structure of the files and their fields—the method of data arrangement on the information carriers, the characteristics of the interdependence of data within a file, and the specific grouping of data—depend on the type of ACS and the general characteristics of the facilities for which it is designed. However, it is desirable to preserve a standardized structural design for a common class of facilities, such as machine-building enterprises.

A master file assembles the data common to all problems; it is structured according to a standardized design not limited to the execution of any single control function. A master file for a large facility contains hundreds of millions of symbols, occupies large volumes in memories, and is not always convenient to use for each specific task requiring specialized information. This problem becomes more complex when multiprogram data processing is used and the size of the internal computer memories is inadequate, which implies the use of external card or tape storages that are functionally isolated from the processors. For an actual ACS, it thus becomes necessary to generate derived files that take into account the specifics of a facility’s structure, the characteristics of the functions being executed in every period, the rate at which various problems are repeated, and several other factors associated with the current operation of the system. Usually, all the derived files are generated from the master file. Every permanent change in the characteristics of the facility being controlled should be accounted for in the master file.

An operational file holds current information and the intermediate results of calculations. It is also fed primary information on the condition of the facility being served; the information is received periodically through communications channels or is recorded on autonomous carriers, such as punched tapes, punched cards, or magnetic tapes. The processed and generalized data can then be inserted in the derived and master files or issued directly to a user.

EQUIPMENT BASE. The equipment base, or hardware, of an ACS includes means for processing, collecting and recording, displaying, and transmitting data, as well as actuating mechanisms that operate directly on the controlled facility, for example, automatic regulators and transducers. Actuating mechanisms also collect, store, and process information and produce control signals in all circuits that provide for automated production control. The principal components of the equipment base are computers that collect, store, and process the data circulating in the ACS. They

Figure 1. Structure of an automated control system for an enterprise

make it possible to optimize control parameters, simulate production processes, and prepare proposals for decision-making.

The computers used in ACS’s are usually divided into two classes according to function: information analyzers and local controllers. Information analyzers are located at the highest level of the control hierarchy, for example, at the coordinating computer center of a factory; they solve problems connected with the centralized control of the facility according to the basic planned economic, supply, and accounting functions—technical-economic and operational production planning, technical and material supply, and marketing. They feature high-speed operation, an interrupt system, syllabic data processing, variable word length, and multiprogram operation, and they are equipped with a large number of high-capacity memories—internal, buffer, external, read-only, and read-write storage with random and serial access. In the USSR in the 1970’s, the Unified Computer System was adopted for use as information analyzers.

Local controllers are usually operated at the lowest level of control. They are usually located in shops or sections, where they provide for the collection of information from the controlled facilities (machine tools, warehouses, and so on), primary processing of the information, and transmission of the data to an information analyzer and reception from the analyzer of instructional and planning information. In addition, local controllers perform local calculations, such as providing operating schedules for each machine tool and worker, charting the delivery of items and materials to be assembled, grouping parts into batches, and ensuring proper operating modes; they also are responsible for the application of control actions to the controlled facilities when operating conditions deviate from the nominal values.

Local controllers feature a highly developed input-output system for interfacing with a large number of information sources—data pickups and recorders—and with regulating equipment. Their arithmetic unit is less developed because the information subject to primary processing is transmitted to a higher-level computer for further use and long-term storage. Local controllers include the Dnepr and M-6000 models.

The means used to collect and record data with human assistance include various production recorders that perform the process directly at the operating sites (in a shop, in a section, or on a machine tool), data pickups (for registering temperature, the number of finished parts, and the operating time of equipment), and devices to halt operations in the event the established production and organization routines are interrupted (owing to a lack of workpiece blanks, tools, or materials; the incorrect setup of machine tools; or the absence of transportation facilities for shipping finished products). Examples of typical production recorders are the models RI-7501 (shop recorder) and RI-7401 (warehouse recorder).

Equipment for displaying information is designed to present the processed information in a form suitable for practical use. It includes various printers, typewriters, terminals, screens, signal boards, graph-plotting devices, and indicators. These devices are usually connected directly to a computer or to production recorders; they produce reference, command, or precautionary information on a regular schedule, on request, or in the event of an emergency.

Data transmission equipment is used for the exchange of information between the various elements of an ACS, for example, between the production recorders and the computer, and between the coordinating control center and the shop computers. It also provides for information exchange between an ACS and neighboring control levels, for example, between an ACS controlling an enterprise and one controlling a sector, or between territorial computer centers.

The equipment base of an ACS also includes office equipment, such as copying equipment, card files, and dictating machines, as well as auxiliary and monitoring-measuring devices that ensure that the technical facilities function normally in the prescribed modes.

SOFTWARE. The software for an ACS is a complex of programs in regular use that control the operation of equipment and the functioning of the information base; the programs also provide for the interaction of man and equipment.

The programming system translates a program for the solution of a problem as expressed in a convenient formal language into a machine language; the program is then debugged, edited, and incorporated into a software package. The programming system contains a description of the programming languages, a set of translators, a library of standard subroutines, linkage editors, and sets of programs that achieve programming continuity for computers of various types. In addition, it usually contains a collection of programs that facilitate interaction between the user and the machine and that permit the programming system to develop according to the nature of the problems being solved by the user. Typical programming languages adopted for ACS’s in the USSR are ALGOL-68, FORTRAN, COBOL, the universal high-level language PL/1, and assembler-type machine-oriented languages.

The operating systems ensure that all computer devices function in the required modes and that the sequence of tasks necessary for effecting various control procedures is executed. The operating systems constitute the indispensable components of the computer facilities of an ACS.

When an ACS is designed, it is often necessary to expand the operating systems in order to provide for special systems requirements, as when recorders and display systems unique to the process being controlled are connected to the system or when two-way communication is established between terminals and a central computer complex. Because of this flexibility requirement, a very important component of an ACS’s operating system is the generator program. This program is not a component of the active portion of the computer control package and is not directly associated with the control process; rather, it makes it possible to generate automatically a complex of control programs for systems of any configuration. This method proves particularly effective when a computer is used for a wide variety of ACS’s at various levels and for different facilities or when the design of a computer and the nature of the problems to be solved differ substantially.

A system software package includes a set of programs that control the operation of the computer system and the peripheral equipment, such as recorders and facilities for displaying the results of data processing. This package contains programs for the joint operation of several computers integrated at different memory levels as well as programs that handle communications channels, permit the use of time-sharing to solve problems at locations removed from the computer, and provide for the demarcation of access to information files. The system package also includes information retrieval systems that search specified files for a particular item or form needed files from fragments of data; the retrieval system then edits the material and presents the information to the user in the specified format or transmits the files to a memory for use by running operating programs. Other programs of the package handle facilities operating in real time, terminal equipment, and information display devices.

Packages of standard modules (standard subroutines) can be used in different combinations to solve various functional problems; examples are standard modules for sorting data, for the statistical processing of information, for plotting planning and control charts on graph paper, and for simulating real processes. The software of an ACS also frequently includes programs for the functional analysis of the system itself; these make the system convenient to use, and they are capable of making improvements in the system.

ORGANIZATIONAL AND ECONOMIC BASE. The organizational and economic base of an ACS is a set of economic principles, methods of organization production and control, and methods for the management problem interaction based on legal documents. It includes organizational and economic formats and methods for formulating technical and economic indicators of the facility being controlled, as well as basic principles for improving the efficiency of the facility’s operation and the location of the ACS in the overall system of planning, reporting, and regulation. Many other items are also classified under this heading: the organization of production, labor, and control, which establishes an efficient structure for the facility; the procedure for establishing production routing; the most favorable working conditions for maintaining high efficiency of workers and other employees; a scientifically sound management system for the facility; and precise regulations governing all subdivisions, the hierarchy of subdivisions, and the duties and responsibilities of employees.

The organizational and economic base includes a model that takes into account the interaction of the ACS’s primary tasks and information flow structure, and it provides for the monitoring of the order in which problems are handled and solutions are implemented. It also covers the legal principles and standards for the development and use of the ACS, the legal status of information circulating in the ACS, and the rights and responsibility of officials. The organizational and economic base also includes methodological and instructional materials that determine the effect of the ACS on the basic operating indexes of the facility, evaluate efficiency, and study methods for the further development of the ACS.

Functional section. The functional section of an ACS consists of a set of interrelated programs for the realization of specific management functions, such as planning, financial and bookkeeping operations, and so on. All the tasks of the functional section are based on the information files and technical equipment common to a given ACS. The addition of new tasks does not affect the basic structure of the system and is accomplished by means of a data format and procedural scheme that is standard for the ACS. The functional section is usually divided into subsystems that correspond to the basic control functions of the facility. The subsystems are divided in turn into complexes that contain sets of programs for solving specific control problems according to the general concept of the system.

The composition of the problems in the functional section depends on the type and state of the controlled facility and the kind of tasks the facility performs. For example, an ACS that controls an enterprise often contains the following subsystems: technological preparation for production, product quality control, technical and economic planning, operating plans, material and technical requirements, marketing, financial and bookkeeping operations, personnel operations, control of transportation, and control of auxiliary services. The division of the functional section into subsystems is quite arbitrary, inasmuch as the procedures in all subsystems are closely interrelated and in many cases it is impossible to delineate a precise boundary between different control functions, for example, between technical and economic planning, operating plans, and material and technical requirements. The separation of subsystems is used for convenience in distributing the work of developing the system and for interfacing the system with the corresponding organizational sections of the controlled facility.

The structure of the functional section depends on the formats for the control procedures, which determine the interrelation of all control elements and cover automated, partially mechanized, and manual procedures. The functional section is more flexible than the core; it allows changes in the composition and formulation of problems to be made as long as a standard interface with the basic system elements is ensured.

The future development of ACS’s centers on the creation of the proposed National Automated Control System, which will provide an interconnected network of control systems for all administrative, industrial, and other facilities in the country. The system is designed to ensure optimum, coordinated development rates in the national economy of the USSR, to develop intensive, balanced, and planned goals, and to ensure the attainment of such goals. The State Network of Computer Centers, which accomplishes the informational and functional coordination of the operation of all the country’s computer centers, will become the equipment base of the National Automated Control System.

REFERENCES

Glushkov, V. M. Vvedenie v ASU, 2nd ed. Kiev, 1974.
Zhimerin, D. G., and V. A. Miasnikov. Avtomatizirovannye i avtomaticheskie sistemy upravleniia. Moscow, 1975.

I. A. DANIL’CHENKO

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