WHAT ARE MEASUREMENT--COMPUTATION
COMPLEXES?
G. I. Kavalerov, S. M. Mandel'shtam, G. N. Solopchenko, M. P. Tsapenko, and E. I. Tsvetkov
UDC 681.3:53:62-501.7
Recently the scientific and technical community has shown considerable interest in a new trend in measurement technique: measurement-computation complexes (MCC), the development of their scientific principles of construction, and their metrological provision, and also consideration of various aspects of their design and use. However, in the press and in conference reports by a number of specialists, in our opinion, they unwarrantedly apply the name "measurement-computation complex" to certain types of apparatus and measurement systems which include in their composition means of measurement and computers but do not have all the functions and properties of MCC. A quite comprehensive definition of the MCC appeared in the literature and was discussed at the conference "IIS-77" in Baku. It is expedient to define the "measurement-computation complex" as an automated means of measurement and information treatment, intended for investigation (control, tests) of complicated objects, constituting an aggregate of program-controllc technical means (measurement, computation, auxiliary), having a modular structure, a definite organization, and connections which provide the gathering, conversion, accumulation, treatment and delivery of measurement, command, and other information in an appropriate form, including the form for action on the object of investigation. Actually, MCC also contain means of programming [I]. At the present stage, it is important to determine quite clearly the purposes of assembling MCC, their principal functions and characteristics, and the fields in which they can be used most efficiently. Since this new type of means of measurement is quite complicated and relatively expensive, minimization of functions and maximization of the metrological characteristics of MCC is also an important technical and economic task which ultimately will justify going over to such means of measurement. Hence, the formulation of a general approach to the definition of MCC, a uniform interpretation of this concept, and valid use of the term in normativetechnical documents, in our opinion, is not merely a matter of terminological discussion.~ In view of the above, it is expedient to turn once more to the definition of MCC and explain the characteristic peculiarities of this type of means of measurement. First we note that the MCC is not a system but a universal nucleus of digital measuring information systems (MIS). It does not have a fixed structure but consists of an aggregate of program-controlled measurement, computation, and auxiliary means. The use of the modular principle of construction of MCC with respect to functions and execution and the presence of a special organization of switching connections between modules enables one to realize some finite set of systems with one MCC. Such flexibility of structure is necessary, since MCC are intended for creating systems of automation of a measurement experiment and experimental investigations of new examples of technique or materials, as well as complicated engineering equipment. The capacity for structural reorganization required varies with the field of application. However, its flexibility is characteristic of this type of product. It is interesting to compare MCC with controlling computer complexes (CCC). These groups constitute a type of industrial production, and based on them, one may construct the systems: automatic control system technical regulations (ACSTR),and from CCC and automated systems of tests and investigations irom MCC. In this case, other instruments are also used to construct the systems: in ACSTR, primary measurement transducers and devices acting on the object being controlled, and in automated systems of scientific investigation, scientific instruments (spectrometers, analyzers, and the like), primary measurement transducers, and devices acting on the object of the tests or investigations. Translated from Izmeritel naya Tekhnika, No. 2, pp. 13-14, February, 1979o
0543-1972/79/2202-0135507.50
9 1979 Plenum Publishing Corporation
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As compared with ACSTR, automated systems of scientific investigation must be far more flexible in structure and functions. Often, even in a single laboratory, it is necessary to revamp the structure of the system and the character of the experiment, during a relatively short time, whereas technical processes are relatively stable. Thus, automated systems of scientific investigation and ACSTR are created and developed by the user, whereas MCC and CCC are manufactured by instrument-making concerns and are intended for the construction of ACS, MIS, or automated systems of scientific investigation, based on them. It is no less important that the MCC is set up as a program-controlled means of measurement, a necessary component of which is a freely programmable processor, usable for both control of functioning of the system, and computations if required. By using a processor, the structure of the system is partly or wholly revamped. In many cases, based on computation treatment of the results of observations (measurements), the plan of experiment is revised, i.e., the principle of adaptivity of investigations is embodied. In MCC, individual modules of the complex and the system based on it also may be supplied with memory and logic elements. The transfer of part of the functions of control and computation in the MCC from the central processor to satellite microprocessors enables one to increase substantially the speed of the system and also to increase the stability when the reliability of the modules and elements is limited. In this case it becomes possible, e.g., to combine the main and sequential (cascade) principles of control in a single complex. An essential component of the MCC is the standard modular applied programming provision for treating the results of measurements and control of experiments, which is based on the overall (system) programming provision of the computer used. In many cases, appropriate further improvement or revision of the "base" will be required. For instance, when the language FOKAL is used, it is expedient to work out a version of this high-level algorithmic language which will permit inclusion of units written on an assembler, including driver modules for control of component instruments of the MCC. When setting up an MCC, one should not expect the user to have a staff of programmers available for servicing the system. Hence, the plant turning out the MCC should incorporate in it a developed modular programming provision for carrying out the principal functions (in this case, treatment of measurement results and control of experiments), oriented on use by an experimenter who need not know programming. The driver programming provision should be constructed on the modular principle and should use unified procedures. Naturally, all the other components of the program provision are logically united by a common principle of construction. Like any means of measurement, the MCC must have a certain set of standardized metrological charecteristics for the complex as a whole. By virtue of the specific character of this type of means of measurement, its metro!ogical provision also has a number of peculiarities. Since the MCC may be used to create systems of varied structure, a number of testing schemes must first be specified. Since it is impossible to foresee all possible types of instruments, transducers, and devices for acting on the object of investigation, the plant which turns out the MCC is only in a position to guarantee the metrological characteristics of some of the most typical forms of combination of MCC modules. Secondly, the presence of a computer built into the complex affords ample opportunity for automation of testing. In this case it may be used as both a special technological installation in the plant when the MCC is turned out, and built-in technical and programming means of self-calibration and error correction. It follows from the above that MCC must be constructed from aggregated standard modules of the appropriate technical means. Each such module must consist of a functionally and constructively finished article meeting its technical specifications. The technical and organizational prerequisites for constructing MCC on the indicated principles, now exist, since Soviet ihdustry has acquired a broad range of the technical means entering into aggregate complexes of state instrument systems (GSP), and the work of selecting unified interfaces is finished. To provide informational, design, and working compatibility of functional MCC modules, one must use a common interface for the given type of MCC. In principle, one may set up an MCC by using system (e.g., KAMAK), machine (e.g., OSh), and instrumental (e.g., the recommended IEC) interfaces [2].
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According to the method of setting up, MCC may be divided into: universal ones for creating systems for automating scientific experiments and tests on various articles and materials (this type of production of instrument-making concerns is distinguished by special flexibility of the structure to be rearranged and its highly developed algoritl~nic-programming provision); problem-oriented, intended for a specific user or users (these MCC may also be a type of production of specialized plants); MCC specified for highly critical applications, created in specialized concerns by using unified modules and a stock of programming provision (basic and applied); and specialized MCC, created during some period of functioning, directly by the user for his own needs. The last two types of MCC are not mass-produced, but are often created by planned layout by using commercial unified modules of means of measurement and computation and the basic programming provision of computers and microprocessors. In view of the fact that in 1978, the first models of MCC underwent interdepartmental tests and their mass production began, the preparation and publication of the appropriate normative-technical documents must be accelerated. LITERATURE CITED l,
2.
G. I. Kavalerov, Prib. Sist. Upr., No. ii (1977). S. M. Mandel'shtam et al., Izmer. Kontrol, Avtom., No. 2 (1978).
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