State Committee Russian Federation for standardization and metrology

All-Russian Research Institute of Metrological Service (VNIIMS)

GSI. The choice of methods and means of measurement in the development of methods for performing measurements. General provisions

MI 1967-89

Moscow, 1989

INFORMATION DATA

DEVELOPEDAll-Union Research Institute of Metrological Service (VNIIMS)

PERFORMERS

M.A. Zemelman, Ph.D. tech. sciences (topic leader),

THEM. Tronova

APPROVED VNIIMS 09.02.89

REGISTERED VNIIMS 13.02.89

I. GENERAL PROVISIONS

2. PRELIMINARY CHOICE OF MEASUREMENT METHODS AND INSTRUMENTS

3. GENERAL RULES AND CONDITIONS FOR DETERMINING CHARACTERISTICS OF MEASUREMENT ERROR

4. DETERMINATION OF CHARACTERISTICS OF DIRECT MEASUREMENT ERROR

5. DETERMINATION OF CHARACTERISTICS OF THE ERROR OF INDIRECT MEASUREMENTS

6. FINAL CHOICE OF MEASUREMENT METHODS AND INSTRUMENTS

APPLICATION

With regard to the choice of types of measuring instruments, this recommendation concerns only their metrological characteristics. This recommendation does not provide requirements regarding the degree of automation of measurements, the complexity of metrological maintenance of measuring instruments and other factors related to operational, ergonomic, etc. properties of MVI.

The choice of methods and measuring instruments according to the given initial data is determined by highly qualified personnel who are well acquainted with physical foundations measurements, methods for normalizing metrological characteristics and calculating the errors of measuring instruments based on them in real conditions of their use, with methods for presenting and using results and measurement errors, methods for calculating results and errors of indirect measurements. Normative-technical and methodological documents, which lay the foundations of these methods, are:

GOST 8.009-84 “GSI. Standardized metrological characteristics of measuring instruments”;

"Methodological material on the application of GOST 8.009-84";

RD 50-453-84 " Guidelines. Characteristics of the error of measuring instruments in real operating conditions. Methods of calculation”;

MI 1317-86 “Guidelines. GSI. Results and characteristics of measurement errors. Presentation forms. Methods of use in testing product samples and monitoring their parameters”;

MI 1730-87 “Guidelines. GSI . Errors of indirect measurements of process parameters. Methods of calculation".

This recommendation is intended to serve as a guide for the development of private instructions or other documents (industry, enterprises, etc.) that regulate, in relation to specific types of products or processes, the rules for choosing methods and measuring instruments used in research, development, testing, control and other operations, including into itself measurements.

All documents presented in the catalog are not their official publication and are intended for informational purposes only. Electronic copies of these documents can be distributed without any restrictions. You can post information from this site on any other site.

State Committee of the Russian Federation for Standardization and Metrology

All-Russian Research Institute of Metrological Service (VNIIMS)

GSI. The choice of methods and means of measurement in the development of methods for performing measurements. General provisions

MI 1967-89

Moscow, 1989

INFORMATION DATA

DEVELOPEDAll-Union Research Institute of Metrological Service (VNIIMS)

PERFORMERS

M.A. Zemelman, Ph.D. tech. sciences (topic leader),

THEM. Tronova

APPROVED VNIIMS 09.02.89

REGISTERED VNIIMS 13.02.89

The choice of methods and measuring instruments according to the given initial data is determined by highly qualified personnel who are well acquainted with the physical foundations of measurements, methods for standardizing metrological characteristics and calculating the errors of measuring instruments in real conditions of their use, with methods for presenting and using results and measurement errors, methods for calculating results and errors of indirect measurements. Normative-technical and methodological documents, which lay the foundations of these methods, are:

Where T- the time interval at which the effective value of the voltage is determined;t- current time.

Based on a priori information about the generator circuit, it is necessary to refine the functional (1) in order to be able to choose the type of voltage measuring instrument (in particular, in terms of the operating frequency range). It may be possible to model the generator output voltage as a sinusoidal time-varying process. Then, for an approximate choice of the type of voltage measuring instrument, the functional(1)can be written in the form

,(2)

Where U m And ω - amplitude and circular frequency of the sinusoidal voltage. When calculating the measurement error, it must be taken into account that in reality the output voltage may differ from purely harmonic and represent the sum of harmonics (if the generator output voltage model is chosen correctly, the first harmonic should prevail). Therefore, when calculating the measurement error, it must be assumed that the measured value should actually be expressed by the functional

.(3)

As a result, the error of the measuring instrument may contain an additional "frequency" component caused by the influence of higher harmonics of the generator voltage on the output signal of the measuring instrument.

2.1.6. Make up a connection diagram of measuring instruments with the object of measurement, among themselves (if there are several), with other technical means.

3.6. Depending on what are known (from the given initial data) the temporal or spectral characteristics of the measured value or signal, the informative parameter of which is the measured value, and the dynamic characteristics of the measuring instruments used in the MMI (from the regulatory and technical documents for the measuring instruments of the applied types), different characteristics of the dynamic error of measuring instruments can be calculated (see "Methodological material on the application of GOST 8.009-84").

3.6.1. If the settling time of the readings of the measuring device is known, then it is possible to determine: a) the time interval (starting from the moment of change in the measured value, close in nature to the jump), after which it is allowed to take a reading on the scale of the measuring device; b) the largest possible value of the measurement error component due to the dynamic properties of the measuring device, subject to condition a).

3.6.2. If the frequency spectrum of the signal is known, the informative parameter of which is the measured value, and the full dynamic characteristics of the measuring instruments, then it is possible to determine the probabilistic characteristics of the dynamic error of the measuring instruments.

3.7. When analyzing the first draft of the MIM, it is necessary to check whether there are any specific features of the MIM (for example, due to the use of auxiliary technical means, the presence of communication channels between the technical means of MVI, etc.), additional components of the measurement error, except for those considered in and. They should be taken into account in the calculation if they cause an increase in the calculated characteristics of measurement errors by at least 15-20%.

When analyzing the first project of MIM, if necessary (there is no sufficient information about the properties of methods and measuring instruments), experimental studies to get the required data. To do this, it is necessary to carry out (make) a model of the implementation of the MMI, corresponding to the first project of the MMI, or, if there is no information about the properties of measuring instruments, select specimens of measuring instruments for research.

4. DETERMINATION OF CHARACTERISTICS OF DIRECT MEASUREMENT ERROR

4.1. When calculating the characteristics of the error of direct measurements, it is recommended to divide this error into three groups of components: methodical, instrumental, personal.

4.2. Based on initial data; analysis of the connection scheme in MMI of measuring instruments with the object of measurements, between themselves and with other technical means used in MVI; taking into account the MVI factors indicated V - , identify and determine the characteristics of the following possible main methodological errors of direct measurements.

Where n\u003d 2 - the number of cross sections of the sleeve, in each of which T diameter measurementsd(A i.) an ellipse having an angular coordinatea ij = 360/2t(i-1); i=1,...m .

dcircle in any cross section of the sleeve leads to a methodological error equal to

∆1 = d-D*.(8)

2. Under conditions the sleeve is in fact a distorted truncated elliptical cone: the generators of the inner surface of the sleeve are not straight lines, but curves, for example, parabolas of small curvature. Therefore, we can assume that the task of measurement corresponds to the adoption as a measured value, for example, a functional of the form

. (9)

Acceptance as a measured value of the diameterdthe inner circle in any cross section of the sleeve leads in this case to a methodological measurement error equal to

∆2 = d-D**.(10)

Characteristics of methodological errors (8) and (10) can be calculated on the basis of initial information about possible deviations of the shape of the inner surface of the sleeve from a straight circular cylinder. If necessary, these errors can be reduced if, instead of a direct measurement of the diameter of the inner circle, an indirect measurement is used, taking the functional or . This would lead to the complication of the MIM - to the complication of the algorithm for determining the result of measurements, but would allow to reduce the methodological error of measurements.

Note . Methods for determining the methodological measurement error due to the inadequacy of the adopted model measurement object , belong to the least developed areas of metrology. This is due to the practical absence of formal methods for establishing such models of measurement objects that are strictly adequate to the objects and tasks of measurements, therefore, the determination of this methodological measurement error requires not only high qualifications, but also the experience and engineering intuition of MIM developers.

4.2.2. The error due to possible deviations from the nominal values of the parameters of the function of the dependence of the informative parameter of the secondary process on the measured value (when using the secondary process in MIM) ().

Example.Informative parameter dependency function at secondary process from the measured value x y = f (λ, x)has an uninformative parameter λ. His change Δλ relatively nominal value λ 0 , causes a change in the informative parameter at secondary process (i.e. the corresponding methodological measurement error) equal to Δy=df/dλΔλ .It is taken into account here that the changes Δλ are small enough so that in the expression for Δy members containing (Δλ) kat k> 1 can be neglected.

On this stage of the development of MVI, the characteristics of additional and dynamic errors of measuring instruments are determined by calculation according to the normalized metrological characteristics of measuring instruments of selected types and according to the initial data (). The general approach to calculating the error characteristics of measuring instruments in real conditions of their use is described in ""; calculation methods - in RD 50-453-84.

Note . Methods for calculating the errors of indirect measurements are also set out in MI 1730-87.

An example of calculating the characteristics of the error of one of the types of indirect measurements - determining, according to the results of direct measurements, the difference in instantaneous values of a function for different values of its argument - taking into account the autocorrelation of the error of direct measurements, is given in the "Methodological material for the application of GOST 8.009-84".

6. FINAL CHOICE OF MEASUREMENT METHODS AND INSTRUMENTS

6.1. The calculated characteristics of the measurement error under given conditions are compared with the given limits of their allowable values. In this case, four cases can be distinguished.

6.1.1 . The values of the characteristics of the measurement error are in the range from about 20 to 60% of the corresponding limits of permissible values.

6.1.2 . The values of the characteristics of the measurement error are in the range from about 60 to 100% of the limits of permissible values.

6.1.3 . The values of the measurement error characteristics go beyond their allowable values.

6.1.4 . The values of the measurement error characteristics are less than 20% of the limits of their permissible values.

6.2. In the case referred to in, the choice of methods and means of measurement can be considered complete, i.e. it is expedient to accept the first draft MVI as the final MVI.

6.3 . In the case referred to in); personal measurement error (), decide what changes it is advisable to introduce into the MIM in order to increase the characteristics of the measurement error to about 50-60% of the limits of their permissible values with the greatest benefit while satisfying all other requirements for the MIM.

6.6 . After making any changes to the MVI, it is necessary to check whether the conditions and all other requirements for the MVI are satisfied.

If the results of this check are positive, i.e. conditions are satisfiedand other requirements for MMI, it is necessary to normalize for this MMI the limits of permissible values of the MMI error characteristics, i.e. errors of any measurement results that will be obtained when using implementations of this MIM under given conditions.

It is expedient to set the standards in such a way that they exceed the obtained calculated values of the largest possible values of the measurement error characteristics by 10-20%, but do not exceed the specified requirements for the MVI error characteristics.

After that, the choice of methods and measuring instruments and the development of MIM can be considered complete. MVI can be recommended for use, i.e. for standardization (if the standardization of this MIM is recognized as useful), for the development and production of implementations of this MVI.

6.7. If the results of the test specified in, negative, then it is necessary to reconsider the issue of appropriate changes in the MIM that ensure the satisfaction of the conditionand all other requirements for MVI. This procedure must be repeated until a positive result of the test specified in.

If you cannot select from existing type measuring instruments, it is necessary to develop the necessary measuring instruments or, if possible, to change (simplify) the initial requirements specified for the development of MIM. If necessary, it is allowed to make changes to the applied measuring instruments that do not affect their main mode of operation. Before use, such a measuring instrument must be certified as a non-standardized measuring instrument.

6.8. In the process of developing the MMI, it is necessary to establish methods and means of monitoring the compliance of the characteristics of the error of the MMI implementations with the standards adopted for it (). The document regulating the MVI (standard, description, passport, etc.) must indicate the required frequency of control, acceptable characteristics of the reliability of control and recommended methods of control.

APPLICATION
Reference

EXPLANATION OF THE TERMS USED

1 . SECONDARY PROCESS - a process excited by the measurement object, which differs in physical nature from the measured quantity, at least one parameter of which is associated with the measured quantity by a known functional dependence.

The secondary process is used as an input signal of measuring instruments in those cases when primary measuring transducers or sensitive elements of measuring instruments that react directly to the measured value are not used for any reason.

That parameter of the secondary process (affecting the input of the measuring instrument), which is functionally related to the measured value, is called the informative parameter of the secondary process. The secondary process may also have other, non-informative parameters, changes in which affect the informative parameters of the output signals of measuring instruments, i.e. on the measurement results.

The appointment of a secondary process can be performed by a secondary quantity that differs in physical nature from the measured quantity, associated with the measured quantity by a known functional dependence. In this case, the secondary value is the value to which the measuring instrument connected to the measurement object directly responds.

Example.When measuring the temperature of a medium using an optical pyrometer, the secondary process is the thermal radiation of the medium (in the optical wavelength range), and the informative parameter of the secondary process is the intensity of thermal radiation affecting the pyrometer. The dependence function of the informative parameter (intensity) of the secondary process (thermal radiation) on the measured value (ambient temperature) has a non-informative parameter - the radiation wavelength.

Note. Cm. to the explanation of the term "indirect measurement".

2. MEASURED VALUE - a parameter (or functional of parameters) of the measurement object model, reflecting the property of the measurement object, the definition of which is the measurement task.

3. INSTRUMENTAL MEASUREMENT ERRORS - components of measurement errors due to the influence of the properties of the measuring instruments used (including the basic error; the sensitivity of the measuring instruments to the properties of the measurement object that are not determined by this MIM, to the non-informative parameters of the signal affecting the input of the measuring instrument, to external conditions; dynamic characteristics of measuring instruments; spatial resolution of the measuring instrument; interaction of the measuring instrument with the object of measurement).

4. INDIRECT MEASUREMENT - determination of the value of the measured quantity, which is a known function (functional) of other quantities, by calculating the value of this function (functional) based on the results of direct measurements of quantities - the arguments of the function.

Notes:

1. It is advisable to include indirect measurements of functionals of functions of one argument, carried out by direct measurements of the function and subsequent calculation of the functional based on the results of direct measurements. For example, it is convenient to refer to indirect measurements of the effective value of electric voltage if it is carried out by direct measurements of instantaneous voltage values at discrete times and the subsequent calculation of the square root of the quotient from dividing the sum of squares of the results of direct measurements by the number of terms in the sum, i.e. by the number of discrete time points at which direct voltage measurements were made.

2. Aggregate and joint measurements are also classified as indirect, since their results are calculated from the results of direct measurements of the arguments of known functions. Specific features of calculating the characteristics of the error of the result of indirect measurement of a function expressed by one equation are also inherent in the calculation of the characteristics of measurement errors of functions expressed by systems of equations.

3 . According to their physical principles, measurements using the "secondary process" could be included in the group of indirect measurements. However, it is advisable to separate measurements in which the measurement result is calculated (by the operator or automatically) based on the results of direct measurements, and measurements in which the functional dependence of the measured quantity on another quantity by physical nature is used, but calculations are not used when determining the measurement result, and the functional dependence between the measured value and the informative parameter of the secondary process is taken into account in the nominal conversion function of the measuring instruments used in this measurement. When measuring using a secondary process, there is no need to take into account specific methodological errors that affect the measurement error when the measurement result is determined by calculation from the results of direct measurements. For practical calculations, measurements using a secondary process should be classified as direct if the measurement results are determined directly from the indicators of measuring instruments.

5. METHOD OF PERFORMING MEASUREMENTS (MTI) - a set of techniques (procedure) for the use of certain types of measuring instruments and other technical means connected to the object and among themselves, designed to obtain measurement results

Note . For a given group of measurement objects; the given measured value and its values in the given range; the rate (frequency) of change of the measured value in the given range or the given frequency spectrum of the signal, the informative parameter of which is the measured value; given external conditions - MVI should provide measurement results of the measured quantity with an error, the characteristics of which do not go beyond the specified allowable limits. MVI is a kind of "technological process" of measurements.

6. METHODOLOGICAL MEASUREMENT ERRORS - components of measurement errors due to:

The difference between the accepted model of the measurement object and the model that adequately reflects its property, determined by measurements;

The influence of changes in the parameters of the function of the dependence of the informative parameter of the secondary process (or secondary value) on the measured value (when using a secondary process or secondary value);

Influence of methods of application in MVI of measuring instruments;

Influence of algorithms (formulas) for calculating measurement results (for indirect measurements);

The influence of other factors not related to the properties of the measuring instruments used.

The methodical measurement error does not depend on the properties of the measuring instruments. It is identically equal to the measurement error when hypothetical "ideal" measuring instruments are used in MIM. The methodological error characterizes the potential properties of a given MIM, which it would have when using "ideal" measuring instruments.

Note. “Ideal” is a measuring instrument that has the following properties: its error in real conditions of use is zero; its interaction with the measurement object, with another measuring instrument, with a technical device connected to its output, does not affect the measurement error; its spatial resolution (if it makes sense for it) is infinitely large (i.e., when measuring quantities that are functions of spatial coordinates, the measuring instrument distinguishes changes in the measured quantity caused by infinitesimal changes in the arguments - spatial coordinates).

7. MIM ERROR - a generalized concept that combines the measurement errors inherent in all measurement results obtained using the implementation of this MIM, under the conditions specified for this MIM.

8. IMPLEMENTATION OF MIM - practical implementation of MIM: a specialized measuring installation corresponding to this MIM;

connection (maybe temporarily assembled) of the measurement object, measuring instruments and other technical means provided for by this MVI;

for the simplest MIM - one measuring instrument that allows you to carry out the procedure (techniques) provided for by this MVI and obtain the measurement result.

Note . If the conditions for using the MIM implementation correspond to the specified conditions for using the MIM, then the characteristics of the measurement errors performed using this MIM implementation should not go beyond the limits normalized for this MIM.

9. RESULT OF MEASUREMENT - assessment (implementation random variable) the true value of the measured quantity, obtained "by measurement".

Note . Here, a random variable is a set of measurement results of a certain measurable quantity, which can be obtained using a certain implementation of the MVI.

(with change #1)

State Committee of the Russian Federation for Standardization and Metrology

All-Russian Research Institute of Metrological Service (VNIIMS)

GSI. CHOICE OF METHODS AND MEASUREMENT INSTRUMENTS IN THE DEVELOPMENT OF MEASUREMENT TECHNIQUES. GENERAL PROVISIONS

MI 1967-89

Moscow, 1989

INFORMATION DATA

DEVELOPED All-Union Research Institute of Metrological Service (VNIIMS)

PERFORMERS

M.A. Zemelman, Ph.D. tech. sciences (topic leader),

THEM. Tronova

APPROVED VNIIMS 09.02.89

REGISTERED VNIIMS 13.02.89

I. GENERAL PROVISIONS

2. PRELIMINARY CHOICE OF MEASUREMENT METHODS AND INSTRUMENTS

3. GENERAL RULES AND CONDITIONS FOR DETERMINING CHARACTERISTICS OF MEASUREMENT ERROR

4. DETERMINATION OF CHARACTERISTICS OF DIRECT MEASUREMENT ERROR

5. DETERMINATION OF CHARACTERISTICS OF THE ERROR OF INDIRECT MEASUREMENTS

6. FINAL CHOICE OF MEASUREMENT METHODS AND INSTRUMENTS

APPLICATION

GOST 8.009-84 “GSI. Standardized metrological characteristics of measuring instruments”;

"Methodological material on the application of GOST 8.009-84";

RD 50-453-84 “Guidelines. Characteristics of the error of measuring instruments in real operating conditions. Methods of calculation”;

MI 1317-86 “Guidelines. GSI. Results and characteristics of measurement errors. Presentation forms. Methods of use in testing product samples and monitoring their parameters”;

MI 1730-87 “Guidelines. GSI . Errors of indirect measurements of process parameters. Methods of calculation".

I. GENERAL PROVISIONS

1.1. The choice of methods and means of measurement in the process of developing MIM is carried out on the basis of the following given initial data:

type and, if necessary, description of: measurement objects; properties of the object, which must be determined in accordance with the task of measurement; other properties of the measurement object that can affect measurement errors;

the type of the measured quantity, the range of its possible values, the highest possible frequency (rate) of its change, the type (a certain deterministic function, random function etc.) and the frequency spectrum of the process (signal), the informative parameter of which is the measured value (if it is a parameter or functional of any process).

The latest data are accepted as initial in cases where, in accordance with the task of measurement and the type of measurement object, there are no difficulties in choosing the value that should be taken as the measured one. If this choice is not obvious, on the basis of the remaining given initial data, a model of the measurement object should be formed and a certain parameter or functional of the parameters of the model of the measurement object should be selected as a measured quantity. After that, the characteristics of the measured quantity necessary for the choice of methods and measuring instruments are established;

characteristics of the external conditions for the measurement and operation modes of the measurement objects (hereinafter referred to as the external conditions) that can affect the measurement errors;

limits of permissible characteristics of measurement error, which must be satisfied by all (any) measurement results obtained by applying the implementations of the developed MIM (requirements for MIM errors) under given conditions.

The degree of specificity of the specified initial data significantly affects the proximity of the characteristics of the measurement error, determined by calculation in the process of choosing methods and measuring instruments, to the actual characteristics of the measurement error inherent in a given MIM under given conditions.

Note. MVI can be intended for use in more general than measurements, operations for obtaining certain final results (test results, product control, technical diagnostics of machines, etc.). In this case, the measurement results are intermediate results, according to which the final results are determined based on the known functional relationships of the final results with the measurement results. The requirements for the errors of such MIM are established on the basis of the known functional relationships between the indicators of the degree of correctness of the final results with measurement errors and the specified allowable values of these indicators.

For the operations of testing product samples and monitoring the parameters of product samples, the corresponding functional relationships, as well as engineering methods for determining the errors in testing product samples and the reliability indicators for monitoring the parameters of product samples according to known characteristics of measurement errors are given in MI 1317-86. Using the formulas and graphs given in MI 1317-86, it is also possible to solve the inverse problem: to determine the limits of the permissible characteristics of measurement errors according to the given permissible characteristics of errors in testing product samples or the permissible indicators of reliability of monitoring the parameters of product samples.

1.2. The choice of methods and means of measurement according to the given initial data is a multivariate problem, an acceptable metrological solution of which can be obtained with different ratios of the components of the measurement error, i.e. with different MVI. It is necessary to consider such a solution to this problem as rational, which minimizes the costs of measurements (including metrological maintenance of measuring instruments) provided that the specified limits of permissible characteristics of the measurement error under given conditions are ensured, taking into account all, not only metrological, requirements for MIM.

1.3. The choice of methods and means of measurement should be based on taking into account the following factors specific to measurement tasks and to MIM.

1.3.1. The measured value corresponds to a certain model of the object of measurement, taken as adequately reflecting the properties of the object, which should be studied by measurements (MI 1317-86). Meanwhile, any accepted model practically only approximately reflects the studied properties of the measurement object.

Examples:

1. When planning electrical output voltage measurements And (t) generator in order to study the power released in the load, the effective (effective) voltage value should be taken as a measured value

Where T- the time interval at which the effective value of the voltage is determined; t- current time.

2. When planning measurements of the inner diameter of the bushing to study the possible degree of sealing of the joint of the bushing with the shaft passing through it, based on a priori information about the design of the bushing, a model of the inner surface of the bushing in the form of a straight circular cylinder was adopted. In this case, the internal diameter of the sleeve in any of its cross sections at any angular coordinate can be taken as a measured value.

In fact, the inner surface of the sleeve, due to the peculiarities of its manufacturing technology, may differ somewhat from a straight circular cylinder, for example, it may have a certain taper, and the cross sections may differ slightly from a circle. Therefore, the accepted measured value - the diameter in any cross section at any angular coordinate - does not fully correspond to the properties of the sleeve itself, and the task for which measurements are taken, and to determine the possible degree of sealing of the sleeve-shaft joint.

1.3.2. It is possible to use a secondary process (see Appendix). The process is characterized by a certain functional dependence of its informative parameter on the measured value. This function, in the general case, contains a number of parameters that do not depend on the measured value, but changes in which can affect the measurement error. These parameters can change spontaneously or under the influence of any factors within the limits that must be established during the analysis of the MIM errors.

1.3.3. The measured quantity (for indirect measurements - the quantity subjected to direct measurements) is transferred from the measurement object to the measuring instrument (means) in the general case so that strict equality of the dimensions of the measured quantity at the measurement object and at the input of the measuring instrument is not ensured.

Example. When directly measuring the inner diameter of the sleeve, the measuring instrument cannot be practically installed in such a way as to perceive strictly the length of exactly the segment that is taken "by definition" for the diameter of the sleeve: it is practically impossible to install the measuring instrument strictly in the plane of the cross section and along the diameter; it is practically installed in a plane only close to the plane of the cross section, and along a chord only close to the diameter.

1.3.4. With indirect measurements, the measurement result is calculated from the results of direct measurements. If in this case the measured value is a function of several arguments, these arguments are subjected to direct measurements. If the measured value is the functional of a function of one argument, the function is subjected to direct measurements for different values of the argument.

1.3.5. With indirect measurements, the measurement result is calculated (automatically or by the operator) according to a certain algorithm (formula), which is not always strictly identical to the accepted “definition” of the measured quantity.

1.3.6. Indirect measurements of the functionals of continuous functions can be carried out using direct measurements of functions for discrete values of their arguments.

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USSR STATE COMMITTEE ON STANDARDS

STATE SYSTEM FOR ENSURING THE UNIFORMITY OF MEASUREMENTS.

CHOICE OF METHODS AND MEASUREMENT INSTRUMENTS DURING DEVELOPMENT
MEASUREMENT TECHNIQUES

GENERAL PROVISIONS

2.1.6. Make up a connection diagram of measuring instruments with the object of measurement, among themselves (if there are several), with other technical means.

2.1.7. If it is assumed that in order to meet the requirements for the MIM error, it will be necessary to reduce the influence of random components of the measurement error during measurements, the number of measurements (observations) and the corresponding algorithm for processing their individual results are preliminarily set.

2.1.8. If it is assumed that in order to meet the requirements for the MVI error, it will be necessary to reduce the systematic components of the measurement error during measurements, a method for eliminating (reducing) the systematic components of the error is chosen.

2.2. As a result of the work under paragraphs. 2.1.1 - 2.1.8 the preliminary selection of methods and measuring instruments is completed, i.e. developed the first draft MVI.

3. GENERAL RULES AND CONDITIONS FOR DETERMINING CHARACTERISTICS OF MEASUREMENT ERROR

3.1. Based on the given initial data and the analysis of the first MIM project, the calculation of the characteristics of measurement errors is carried out, which may be inherent in any measurement results obtained using implementations of this MIM under given conditions.

When calculating the characteristics of measurement errors corresponding to the first draft of the MVI, their normalized values are taken as the metrological characteristics of measuring instruments.

3.2. It is precisely those characteristics of the total (total) measurement error that should be determined, the limits of the permissible values of which are indicated in the initial data for the selection of methods and measuring instruments (clause 1.1). Types of characteristics of measurement errors are specified in MI 1317-86. Those characteristics (dispersions or modules of the largest possible values) of the components are selected, the summation of which determines the desired characteristic of the total (total) measurement error.

Note. When summing up the characteristics that make up the measurement errors, the same methods that are recommended in " methodological material on the application of GOST 8.039 -84 "and in RD 50-453-84 for summing the error components of measuring instruments, as well as other summation methods justified in each specific case.

3.3. If the TIM provides for a decrease in the influence of the random component of the error of direct measurement by multiple direct measurements (clause 2.1.7), then instead of its characteristic, the characteristic of the random error of the arithmetic mean of the result of multiple direct measurements (with their accepted number) is introduced into the calculation. In this case, the indicated arithmetic mean is taken as the final result of direct measurement.

3.4. If the systematic component of the measurement error (Sec. 2.1.8) includes components whose values are constant and known (or can be determined), the latter can be excluded from the measurement error, i.e. corrections can be made to the measurement result. If the MVI assumes the introduction of amendments to the measurement results, then instead of the characteristics of the systematic component of the measurement error as characteristics of a random variable (see “Methodological material for the application of GOST 8.009-84”), the characteristics of the non-excluded residual of the systematic error are introduced into the calculation as characteristics of a random variable. Then, when making measurements using this MIM, it is obligatory to introduce corrections into the measurement results.

3.5. Depending on what characteristics of the external measurement conditions are given, different characteristics of the measurement error in real measurement conditions can be calculated.

3.5.1. If specific values of influencing quantities with negligibly small possible deviations are specified and used in the calculation (for example, temperature environment(20 ± 2) °С; supply voltage (220 ± 5) V), then the calculated characteristics of measurement errors correspond to the use of MVI implementations precisely at these values of the influencing quantities.

3.5.2. If the lower and upper limits of the possible values of the influencing quantities are specified and used in the calculation (for example, ambient temperature from minus 30 to plus 50 °C; supply voltage from 180 to 230 V), then only the largest characteristics of measurement errors that correspond to the boundary conditions for the use of MVI.

3.5.3. If the characteristics of the influencing quantities as random processes are given (or assumed) and the calculation uses the characteristics of the measurement error as a function of the random argument (influencing quantities). The methodology for such a calculation of the characteristics of the errors of measuring instruments (it is they who contribute to the measurement error, depending on the influencing quantities) is set out in the Appendix "Methodological material for the application of GOST 8.009-84".

3.6. Depending on what are known (from the given initial data) temporary or spectral characteristics of the measured value or signal, the informative parameter of which is the measured value, and the dynamic characteristics of the measuring instruments used in the MVI (from the regulatory and technical documents for the measuring instruments of the applied types), different characteristics of the dynamic error of the measuring instruments can be calculated (see "Methodological material for the application GOST 8.009-84 ").

3.7. When analyzing the first MIM project, it is necessary to check whether, due to any features of the MIM (for example, due to the use of auxiliary technical means, the availability of communication channels between the MVI technical means, etc.), additional components of measurement errors, except those considered in sections 4 and 5. They should be taken into account in the calculation if they cause an increase in the calculated characteristics of measurement errors by at least 15 - 20%.

During the analysis of the first MIM project, if necessary (there is no sufficient information about the properties of methods and measuring instruments), experimental studies can be carried out to obtain the required data. To do this, it is necessary to carry out (make) a model of the implementation of the MMI, corresponding to the first project of the MMI, or, if there is no information about the properties of measuring instruments, select specimens of measuring instruments for research.

4. DETERMINATION OF CHARACTERISTICS OF DIRECT MEASUREMENT ERROR

4.1. When calculating the characteristics of the error of direct measurements, it is recommended to divide this error into three groups of components: methodical, instrumental, personal.

4.2. Based on initial data; analysis of the connection scheme in MMI of measuring instruments with the object of measurements, between themselves and with other technical means used in MVI; taking into account the MVI factors specified in paragraphs. 1.3.1 - 1.3.3, identify and determine the characteristics of the following possible main methodological errors of direct measurements.

4.2.1. The error due to the difference between the accepted model of the measurement object and the (unknown) model that would adequately reflect the properties of the measurement object studied by measurements, and (or) the difference between the parameter (functional) of the model, taken as the measured value, and the parameter (functional) , "more adequately" reflecting the studied property of the measurement object (clause 1.3.1).

Examples:

1. Under the conditions of example 2, clause 1.3.1, the inner surface of the sleeve is actually a truncated elliptical cone somewhat different from a straight circular cylinder. Therefore, we can assume that the task of measurement corresponds to the adoption as a measured quantity not the diameter d the inner circle in any cross section of the sleeve (as is customary in example 2 of clause 1.3.1), and for example, a functional of the form

Where n\u003d 2 - the number of cross sections of the sleeve, in each of which m diameter measurements d(a i) of an ellipse having angular coordinate a i = 360/2m(i - 1); i = 1,..., m.

d circle in any cross section of the sleeve leads to a methodological error equal to

2. Under the conditions of Example 2, Section 1.3.1, the sleeve is actually a distorted truncated elliptical cone: the generatrix of the inner surface of the sleeve are not straight lines, but curves, for example, parabolas of small curvature. Therefore, we can assume that the task of measurement corresponds to the adoption as a measured value, for example, a functional of the form

Acceptance as a measured value of the diameter d the inner circle in any cross section of the sleeve leads in this case to a methodological measurement error equal to

Characteristics of methodological errors (8) and (10) can be calculated on the basis of initial information about possible deviations of the shape of the inner surface of the sleeve from a straight circular cylinder. If necessary, these errors can be reduced if, instead of a direct measurement of the diameter of the inner circle, an indirect measurement is used, taking functional (7) or (9) as the measured value. This would lead to the complication of the MMI - to the complication of the algorithm for determining the measurement result, but would reduce the methodological measurement error.

Note. Methods for determining the methodological error of measurements, due to the inadequacy of the accepted model of the measurement object, belong to the least developed areas of metrology. This is due to the practical absence of formal methods for establishing such models of measurement objects that are strictly adequate to the objects and measurement tasks. Therefore, the determination of this methodological measurement error requires not only high qualifications, but also the experience and engineering intuition of the MMI developers.

4.2.2. Error due to possible deviations from the nominal values of the parameters of the function of dependence of the informative parameter of the secondary process on the measured value (when using the secondary process in MIM) (clause 1.3.2).

Example. The dependence function of the informative parameter of the secondary process on the measured value has a non-informative parameter l. Its change Dl relative to the nominal value l 0 causes a change in the informative parameter at secondary process (i.e. the corresponding methodological measurement error), equal to. Here it is taken into account that the changes in Dl are sufficiently small, so that in the expression for D at members containing (Dl) k at k> 1 can be neglected.

4.2.3. The error in the transmission of quantities subjected to direct measurements from the object of measurement to measuring instruments (clause 1.3.3).

Note. This error does not include the measurement error component due to the interaction of measuring instruments with the object of measurements (see "Methodological material on the application of GOST 8.009-84"), which depends on the properties of measuring instruments and, therefore, by definition, refers to instrumental measurement errors.

Example. Under the conditions of example 2 of clause 1.3.1, to measure the inner diameter of the sleeve, the sensitive element of the measuring instrument (for example, the legs of the inside gauge) should be installed in a plane strictly perpendicular to the axis of the sleeve. In fact, almost always the sensitive element of the measuring instrument is installed in a plane constituting an angle with the axis of the sleeve that is close, but not equal to exactly 90°. As a result, the size of the measured value, perceived by the measuring instrument, differs from the size of the diameter d bushings by an amount (by the corresponding methodological measurement error) equal to D d » d a/2, where a is a small angle between the plane perpendicular to the axis of the sleeve and the plane in which the sensitive element of the measuring instrument is located.

4.3. In accordance with the "Methodological material for the application of GOST 8.009-84", instrumental errors of direct measurements include errors that depend on the properties of measuring instruments: errors of measuring instruments; components of the measurement error, due to the interaction of measuring instruments with the object of measurement; component of the measurement error, due to the finite spatial resolution of the measuring instruments.

4.3.1. The error of measuring instruments, as a rule, is divided into the following components: basic error; additional errors; dynamic error. Accordingly, in regulatory and technical documents, as metrological characteristics of measuring instruments, they normalize: characteristics of the basic error of measuring instruments; characteristics of the sensitivity of measuring instruments to influencing quantities; dynamic characteristics of measuring instruments (GOST 8.009-84).

At this stage of the development of the TIM, the characteristics of the additional and dynamic errors of measuring instruments are determined by calculating according to the normalized metrological characteristics of measuring instruments of selected types and according to the initial data (clause 1.1). The general approach to calculating the error characteristics of measuring instruments in the real conditions of their use is set out in the "Methodological material for the application of GOST 8.009-84"; calculation methods - in RD 50-453-84.

4.3.2. The characteristics of the error component of direct measurements, due to the interaction of the measuring instrument with the object of measurement, are determined by calculation according to the corresponding normalized metrological characteristic of measuring instruments of this type (GOST 8.009-84) and the characteristic of the output circuit of the measurement object.

For the case of a linear output circuit of the measurement object and the input circuit of the measuring instrument that consumes energy from the measurement object, the method for calculating this component of the measurement error is set out in the "Methodological material for the application of GOST 8.009-84".

4.3.3. In direct measurements of quantities that are a function of spatial coordinates, the characteristics of the component of the measurement error, due to the final spatial resolution of the measuring instruments, are determined by calculation according to the resolution characteristic, normalized for measuring instruments of the selected type, and according to the approximate form of the measured function of spatial coordinates, which (at the need to take into account this component of the measurement error) should be given as part of the initial data for the selection of methods and measuring instruments.

Note. The basics for calculating the instrumental error of direct measurements in real conditions of using measuring instruments according to their normalized metrological characteristics are given in the "Methodological material for the application of GOST 8.009-84". See also RD 50-453-84.

4.4. The personal measurement error includes the component of the error of direct measurements, due to the error in reading the indications by the operator on the scales of measuring instruments, according to the diagrams of recording instruments, etc. The characteristics of personal error are determined on the basis of the normalized (GOST 8.009-84) nominal price of the scale divisions of the measuring instrument (or chart paper of the recording instrument) of the selected type, taking into account the ability of the "average" operator to interpolate within the scale division.

Example. The nominal value of division of the uniform scale of the voltmeter is X cases[IN]. The division length is l cases[mm]. For example, it is assumed that the "average" operator can interpolate within a division in steps of 0.2 divisions, i.e. by 0.2 l cases. Then highest value personal error is calculated by the formula

4.5. The calculation of the error characteristics of direct measurements is carried out in the following sequence.

Note. The characteristics of the components of the total (total) error of direct measurements are expressed on a scale and in units of measured values.

4.5.1. The characteristics of three (clauses 4.2.1 - 4.2.3) methodological errors of direct measurements are determined separately.

4.5.2. The characteristics of three (clause 4.3.1) error components of measuring instruments and two other (clauses 4.3.2, 4.3.3) instrumental errors of direct measurements are determined separately.

If a measuring system is used as a measuring instrument, the metrological characteristics of which as a whole are not standardized, but the metrological characteristics of its components (primary and intermediate measuring transducers, switches, secondary measuring instruments) are normalized, the metrological characteristics of the measuring channels of the measuring system must first be calculated according to the normalized metrological the characteristics of its components (the approach to such calculations and the principles for regulating the metrological characteristics of the measuring channels of measuring systems are set out in the “Methodological material for the application of GOST 8.009-84” and in MI 202-80).

4.5.3. Determine the characteristics of personal (clause 4.4) measurement errors.

4.5.4. The characteristics of the error of direct measurements under given conditions are determined by summing (clause 3.2) the characteristics of all its components.

5. DETERMINATION OF CHARACTERISTICS OF THE ERROR OF INDIRECT MEASUREMENTS

5.1. When calculating the characteristics of the error of indirect measurements, based on the selected procedure and technical means of the MMI, taking into account the factors of the MMI specified in paragraphs. 1.3.4 - 1.3.6, one should take into account, in addition to the errors of direct measurements, according to the results of which the results of indirect measurements are calculated, also the methodological errors of indirect measurements and the possible correlation of errors of direct measurements.

Note. The characteristics of the components of the total (total) error of indirect measurements are expressed on a scale and in units of measured values.

5.1.1. The error in calculating the results of indirect measurements can be due to: the difference between the algorithm (formula) of calculations and the strict function (functional) of the dependence of quantities determined by indirect measurements on quantities subjected to direct measurements; a finite number of digits of the results of direct and indirect measurements, etc. (clauses 1.3.4; 1.3.5).

Example. It is required to measure the mass of oil delivered to the consumer through the pipeline over time T. On the basis of a priori information about the conditions of production, treatment, transportation of oil, a random process is adopted as a model of the oil flow. The measured value should be taken as the integral

Where q- instantaneous oil consumption, i.e. the mass of oil flowing through the cross section of the pipeline per unit of time; t- current time.

An indirect measurement of the measured value is carried out by counting the number of revolutions of the turbine flow meter sensor installed in the cross section of the oil pipeline, and multiplying this number by the coefficient K, equal to the mass of oil flowing through this oil pipeline during one revolution of the turbine flow meter sensor. The result of this indirect measurement is calculated by the formula

Where nT- the number of revolutions of the sensor, counted over the time T.

The methodological measurement error, due to the fact that the measurement result is calculated by a formula that differs from the formula that determines the measured value, is equal to

5.2. In indirect measurements, measurement error components (as a rule, instrumental ones) may arise due to the correlation (mutual or autocorrelation) of direct measurement errors (Sec. 1.3.7).

Accounting for these components makes it possible to refine the values of the measurement error characteristics, i.e. bring their calculated values closer to the actual values.

The cross-correlation of errors in direct measurements can be determined, as a rule, only through an experimental study of MIM implementations. If this study shows that the cross-correlation coefficient can be significant, then the document regulating this MIM (standard, description, passport, etc.) should indicate the conditions under which the component of the measurement error due to the cross-correlation of errors of straight lines measurements, does not exceed a certain norm.

The autocorrelation function of the error of direct measurements (or its parameters) can be determined by an experimental study of the implementation of the MVI or from the normative and technical document for the selected type of measuring instruments, if this document normalizes the autocorrelation function (or its parameters) of the error of measuring instruments of this type (GOST 8.009 -84).

5.3. The characteristics of the total (total) error D of indirect measurements are determined by calculating, on the basis of formula (15), the total error as the sum (combination) of partial errors: the weighted sum (combination) of errors D X i direct measurements of arguments X i functions f(X i,..., X m) the dependence of the measured quantity on the quantities Х i subjected to direct measurements; methodological error D alg, due to the difference in the algorithm for calculating the result of indirect measurement from the true function f(X i,..., X m) (clause 5.1.1); methodological error D a due to the discreteness of the arguments by which the result of indirect measurement is calculated (clause 5.1.2)

Notes:

1. Formula (15) is a symbolic record of the union of the components of the error of indirect measurements of the function f(X 1 ,..., X m). Based on this formula, it is possible to calculate the mathematical expectation, dispersion and other necessary characteristics of the error of indirect measurements.

2. For such indirect measurements, the results of which are calculated using systems of equations (cumulative, joint measurements) or as functionals, the total (total) measurement errors should be determined on the basis of formulas that take into account, like formula (15), all the necessary components, but specified depending on on the type of specific systems of equations and functionals, the solution of which determines the measurement result.

5.4. Calculation of the characteristics of the error of indirect measurements is carried out taking into account the instructions in paragraph 3.2 in series.

5.4.1. Determine the characteristics of the error of each of the direct measurements provided for in the TIM (clauses 4.5.1 - 4.5.4).

5.4.2. Determine the characteristics of methodological errors, indirect measurements (clause 5.1.1).

5.4.3. The characteristics of the total (total) error of indirect measurements are determined based on formula (15).

5.5. If it is possible to experimentally determine the cross-correlation between the errors of direct measurements, the variance of the error of indirect measurements based on formula (15) is calculated by the formula

Here and are the centered random components of the corresponding errors; - dispersion;

Mathematical expectation of products of errors and: their mutual correlation moment.

If there is no cross-correlation between direct measurement errors or is not taken into account, the indirect measurement error variance is determined by the first two terms of formula (16).

Note. Methods for calculating the errors of indirect measurements are also set out in MI 1730-87.

6. FINAL CHOICE OF MEASUREMENT METHODS AND INSTRUMENTS

6.1. The calculated characteristics of the measurement error under given conditions are compared with the given limits of their allowable values. In this case, four cases can be distinguished.

6.1.1. The values of the characteristics of the measurement error are in the range from about 20 to 60% of the corresponding limits of permissible values.

6.1.2. The values of the characteristics of the measurement error are in the range from approximately 60 to 100% of the limits of permissible values.

6.1.3. The values of the measurement error characteristics go beyond their allowable values.

6.1.4. The values of the characteristics of the measurement error are less than 20% of the limits of their permissible values.

6.2. In the case specified in clause 6.1.1, the choice of methods and measuring instruments can be considered complete, i.e. it is expedient to accept the first draft MVI as the final MVI.

6.3. In the case specified in clause 6.1.2, it is advisable to consider the issue of reducing the MIM error, since the calculation is inevitably approximate, and the errors in the calculated measurement error characteristics can reach 20-30%.

Comparing methodological (clauses 4.2.1 - 4.2.3; 5.1.1) and instrumental (clauses 4.3.1 - 4.3.3) errors; components of the error of indirect measurements, due to the correlation of errors of direct measurements (clauses 5.2; 5.3; 5.5); personal measurement error (clause 4.4), decide what changes should be introduced into the MMI in order to reduce the characteristics of the measurement error to approximately 50 - 60% of the limits of their permissible values at the lowest cost, while satisfying all other requirements for the MVI.

6.4. In the case specified in clause 6.1.3, it is necessary to introduce changes in the MMI to ensure a decrease in the characteristics of the measurement error. In this case, one should be guided by the recommendations of clause 6.3.

6.5. In the case specified in clause 6.1.4, it is possible, by means of some simplifications of the MIM, to provide lower costs for the implementation of the MIM, while satisfying all the requirements for them. Comparing methodological (clauses 4.2.1 - 4.2.3; 5.1.1) and instrumental (clauses 4.3.1 - 4.3.3) errors; components of the error of indirect measurements, due to the correlation of errors of direct measurements (clauses 5.2; 5.3; 5.5); personal measurement error (clause 4.4), decide what changes it is advisable to introduce into the MIM in order to most advantageously increase the characteristics of the measurement error to approximately 50 - 60% of the limits of their allowable values while satisfying all other requirements for the MVI.

6.6. After making any changes to the TIM, it is necessary to check whether the conditions of clause 6.1.1 and all other requirements for the TIM are satisfied.

If the results of this check are positive, i.e. the conditions of clause 6.1.1 and other requirements for the MMI are satisfied, it is necessary to normalize for this MMI the limits of permissible values of the MMI error characteristics, i.e. errors of any measurement results that will be obtained when using implementations of this MIM under given conditions.

It is expedient to set the norms in such a way that they exceed the obtained calculated values of the largest possible values of the measurement error characteristics by 10–20%, but do not exceed the specified requirements for the measurement error characteristics.

6.7. If the results of the verification specified in clause 6.6 are negative, then it is necessary to reconsider the issue of appropriate changes in the TIM that ensure the satisfaction of the condition of clause 6.1.1 and all other requirements for the TIM. This procedure must be repeated until positive results of the verification specified in clause 6.6 are obtained.

If it is not possible to select a type of measuring instruments from the existing ones, it is necessary to develop the necessary measuring instruments or, if possible, change (facilitate) the initial requirements specified for the development of MIM. If necessary, it is allowed to make changes to the applied measuring instruments that do not affect their main mode of operation. Before use, such a measuring instrument must be certified as a non-standardized measuring instrument.

6.8. In the process of developing the MIM, it is necessary to establish methods and means of monitoring the compliance of the error characteristics of the MIM implementations with the standards adopted for it (clause 6.6). The document regulating the MVI (standard, description, passport, etc.) must indicate the required frequency of control, acceptable characteristics of the reliability of control and recommended methods of control.

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Reference

EXPLANATION OF THE TERMS USED

1. SECONDARY PROCESS - a process excited by the measurement object, which differs in physical nature from the measured value, at least one parameter of which is associated with the measured value by a known functional dependence.

Example. When measuring the temperature of a medium using an optical pyrometer, the secondary process is the thermal radiation of the medium (in the optical wavelength range), and the informative parameter of the secondary process is the intensity of thermal radiation affecting the pyrometer. The dependence function of the informative parameter (intensity) of the secondary process (thermal radiation) on the measured value (ambient temperature) has a non-informative parameter - the radiation wavelength.

Note. See note 3 for an explanation of the term "indirect measurement".

2. MEASURED VALUE - a parameter (or functional of parameters) of the measurement object model, reflecting the property of the measurement object, the definition of which is the measurement task.

Notes:

3. According to their physical principles, measurements using the "secondary process" could be included in the group of indirect measurements. However, it is advisable to separate measurements in which the measurement result is calculated (by the operator or automatically) based on the results of direct measurements, and measurements in which the functional dependence of the measured quantity on another quantity by physical nature is used, but calculations are not used when determining the measurement result, and the functional dependence between the measured value and the informative parameter of the secondary process is taken into account in the nominal conversion function of the measuring instruments used in this measurement. When measuring using a secondary process, there is no need to take into account specific methodological errors that affect the measurement error when the measurement result is determined by calculation from the results of direct measurements. For practical calculations, measurements using a secondary process should be classified as direct if the measurement results are determined directly from the indicators of measuring instruments.

5. METHOD OF PERFORMING MEASUREMENT (MP) - a set of techniques (procedure) for the use of certain types of measuring instruments and other technical means connected to the object and among themselves, designed to obtain measurement results.

Note. For a given group of measurement objects; the given measured value and its values in the given range; the rate (frequency) of change of the intended value in a given range or a given frequency spectrum of the signal, the informative parameter of which is the measured value; given external conditions - MVI should provide measurement results of the measured quantity with an error, the characteristics of which do not go beyond the specified allowable limits. MVI is a kind of "technological process" of measurements.

6. METHODOLOGICAL MEASUREMENT ERRORS - components of measurement errors due to:

the difference between the accepted physical model of the measurement object and the model that adequately reflects its property, determined by measurements;

the influence of changes in the parameters of the dependence function of the informative parameter of the secondary process (or secondary quantity) on the measured quantity (when using a secondary process or secondary quantity);

the influence of methods of using measuring instruments in MVI;

the influence of algorithms (formulas) for calculating the measurement results (for indirect measurements);

the influence of other factors not related to the properties of the measuring instruments used.

8. IMPLEMENTATION OF MVI - practical implementation of MVI:

specialized measuring installation corresponding to this MVI;

connection (maybe temporarily assembled) of the measurement object, measuring instruments and other technical means provided for by this MVI;

for the simplest MIM - one measuring instrument that allows you to carry out the procedure (techniques) provided for by this MVI and obtain the measurement result.

Note. If the conditions for using the MIM implementation correspond to the specified conditions for using the MIM, then the characteristics of the measurement errors performed using this MIM implementation should not go beyond the limits normalized for this MIM.

9. RESULT OF MEASUREMENT - assessment (implementation of a random variable) of the true value of the intended value, obtained "by measuring".

Note. Here, a random variable is a set of measurement results of a certain measurable quantity that can be obtained using a certain implementation of the MVI.

4. DETERMINATION OF CHARACTERISTICS OF DIRECT MEASUREMENT ERROR

6. FINAL CHOICE OF MEASUREMENT METHODS AND INSTRUMENTS

APPLICATION Reference

I. GENERAL PROVISIONS

3. GENERAL RULES AND CONDITIONS FOR DETERMINING CHARACTERISTICS OF MEASUREMENT ERROR

4. DETERMINATION OF CHARACTERISTICS OF DIRECT MEASUREMENT ERROR

5. DETERMINATION OF CHARACTERISTICS OF THE ERROR OF INDIRECT MEASUREMENTS

6. FINAL CHOICE OF MEASUREMENT METHODS AND INSTRUMENTS

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EXPLANATION OF THE TERMS USED

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