ISO/TS 22704:2022

TECHNICAL ISO/TS
SPECIFICATION 22704
First edition
2022-04
Mechanical vibration — Uncertainty
of the measurement and evaluation of
human exposure to vibration
Vibrations mécaniques — Incertitude de mesure et évaluation de
l'exposition humaine aux vibrations
Reference number
© ISO 2022
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ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Considerations regarding the uncertainty of vibration measurements .7
4.1 Measurement objectives and fixed parameters . 7
4.2 Types of uncertainties . 8
4.3 Measurement instrumentation uncertainty sources . 8
5 Evaluation of the uncertainty .9
5.1 Evaluation of the uncertainty through mathematical modelling . 9
5.2 Determination of the uncertainty from interlaboratory tests . 10
5.3 Determination (estimation) of uncertainties from field measurements . 10
6 Presentation of results .11
7 Use of uncertainties .13
7.1 General .13
7.2 Use of uncertainties in comparisons . 13
Annex A (informative) Uncertainty in the measurement of hand-arm vibration at the
workplace — Example for determination of the measurement uncertainty of the
vibration exposure during task-based measurements according to ISO 5349-2 .14
Annex B (informative) Example for determination of the measurement uncertainty of
emission measurements on hand-held and hand-guided machines .25
Annex C (informative) Typical errors .28
Annex D (informative) Statistical background.30
Bibliography .31
iii
Foreword
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This document was prepared by Technical Committee ISO/TC 108, Mechanical vibration, shock and
condition monitoring, Subcommittee SC 4, Human exposure to mechanical vibration and shock.
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iv
Introduction
This document takes the form of a guide and describes how to deal with the uncertainty of vibration
quantities associated with human exposure to vibrations.
The uncertainty arises from various sources. These uncertainties need to be distinguished from errors,
such as when using measuring instruments or selecting the measurement strategy, which may falsify
the measurand. Errors are not considered in this guide.
Calculations of measurement uncertainty are meaningful and valid only if all significant mistakes have
been identified.
This document is intended to be used as a reference document for other standards. Examples of
the application of the individual methods in practical situations are provided in the annexes. These
examples are related to hand-arm vibration but the principles also apply for whole-body vibration.
v
TECHNICAL SPECIFICATION ISO/TS 22704:2022(E)
Mechanical vibration — Uncertainty of the measurement
and evaluation of human exposure to vibration
1 Scope
This document specifies methods for determining the uncertainty of the measurement and evaluation
of human exposure to vibration. It applies to measurements of vibration quantities (measurands),
calculated following a relevant measurement model on the basis of directly measured values, to
evaluate
a) human exposure to hand-transmitted vibration at the workplace,
b) vibration emission of hand-held and hand-guided machinery in a laboratory setting,
c) human exposure to whole-body vibration at the workplace, and
d) whole-body vibration emission of vehicles.
Examples of the application of the individual methods in practical situations are provided in the
annexes.
In this document a measurement error is defined as the difference between a measured and a reference
quantity value.
In this document “uncertainty” does not include errors that result from bad measurement strategies,
faulty use of measurement equipment or other mistakes.
2 Normative references
The following document is referred to in the text in such a way that some or all of it’s content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO/IEC Guide 99, International vocabulary of metrology — Basic and general concepts and associated
terms (VIM)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO/IEC Guide 99 and the
following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
input quantity in a measurement model
input quantity
X
quantity that must be measured, or a quantity, the value of which can be otherwise obtained, in order
to calculate a measured quantity value of a measurand
EXAMPLE When evaluating the daily vibration exposure, vibration magnitude and exposure time are input
quantities of a measurement model.
Note 1 to entry: An input quantity in a measurement model is often an output quantity of a measuring system.
Note 2 to entry: Indications, corrections and influence quantities can be input quantities in a measurement
model.
Note 3 to entry: An estimated value for X is x.
[SOURCE: ISO/IEC Guide 99:2007, 2.50, modified — example adapted and Note 3 added]
3.2
output quantity in a measurement model
output quantity
Y
quantity, the measured value of which is calculated using the values of input quantities in a measurement
model
Yf= (,XX ,.) (1)
Note 1 to entry: An estimated value for Y is y.
[SOURCE: ISO/IEC Guide 99:2007, 2.51, modified — Formula and Note 1 added]
3.3
arithmetic mean value
x
best estimated value for the expected value of the individual measured values when N independent
observations xx,, …, x are available for the input quantity (3.1), X :
ii,,12 iN, i
N
x = x (2)
ii∑ ,k
N
k=1
Note 1 to entry: The arithmetic mean value of the output quantity for N independent observations is
N
y= y (3)
∑
k
N
k=1
3.4
variance
s
measure for the scattering of the measured values when N individual measured values are available for
the variable X :
i
N
s = xx− (4)
()
ii∑ ,ki
N −1
k=1
Note 1 to entry: This Formula produces an estimated value for the variance of the measured values.
Note 2 to entry: An estimated value for the variance of the mean value is
s
i
sx()= (5)
i
N
Note 3 to entry: The variance of the mean value is always smaller than the variance of the measured values.
3.5
standard deviation
s
positive square root of the variance (3.4)
Note 1 to entry: The standard deviation of the individual measured values is therefore
N
s = xx− s (6)
()
ii∑ ,ki i
N−1
k=1
The standard deviation of the measured values is a measure for the scattering of the measured values in a sample
(measurement series) around their (arithmetic) mean value. It is also referred to as s in standards to determine
n–1
vibration emission values of machines (see Annex A).
Note 2 to entry: The standard deviation of the mean value is
N
1 2
sx()= xx− (7)
()
ii,ki
∑
NN()−1
k=1
The standard deviation of the mean value is a measure for the accuracy of repeated measurements. Formula (7)
is used when Type A evaluation is applied (see A.2).
3.6
sensitivity coefficient
c
i
partial derivative of the output quantity (3.2) according to X at the location of the estimated values of
i
the input quantities (3.1):
∂f
c = (8)
i
∂X
i
xx,.,
1 N
Note 1 to entry: If the output quantity has a linear relation to the input quantity, c is a constant that can have any
i
greater or lesser value. The X relation can also be selected in the model so that c = 1.
i i
3.7
uncertainty
parameter assigned to the result of a measurement or calculation which identifies the scattering of the
values that can sensibly be assigned to the measured or calculated variable
Note 1 to entry: The uncertainty does not necessarily have to be a standard deviation.
3.8
standard uncertainty
u
uncertainty (3.7) of the result of a measurement or calculation expressed as a standard deviation (3.5)
Note 1 to entry: The standard uncertainty u(x) of a variable x has the same unit as x. The relative standard
uncertainty u(x)/(x) is dimensionless.
3.9
combined standard uncertainty
u
c
standard uncertainty (3.7) of a result y that is obtained from L values of other variables, X
i
Note 1 to entry: The combined standard uncertainty is equal to the positive square root of a sum of terms,
whereby the terms are variances or co-variances of these other variables X , weighted according to the sensitivi
...