ISO 10068:2012
(Main)Mechanical vibration and shock — Mechanical impedance of the human hand-arm system at the driving point
Mechanical vibration and shock — Mechanical impedance of the human hand-arm system at the driving point
ISO 10068:2012 specifies the mechanical impedance of the human male hand-arm system at the driving point. Values of the impedance, expressed as modulus and phase, are provided for three orthogonal, translatory directions of excitation that correspond to the xh-, yh- and zh-axes of the basicentric coordinate system. The xh-, yh- and zh-components of impedance are defined as a function of frequency, from 10 Hz to 500 Hz, for specified arm positions, grip and feed forces, handle diameters, and intensities of excitation. The components of impedance in the three directions are treated as being independent. ISO 10068:2012 can be used to define typical values of the mechanical impedance of the hand-arm system at the driving point, applicable to males under the circumstances specified. ISO 10068:2012 can provisionally be applied to females. Reference values of the mechanical impedance at the driving point are provided as a function of frequency for a specified grip and feed force. These impedance values are intended for the determination of the transmissibility of resilient materials when loaded by the hand-arm system. Mathematical representations of the hand-arm system that model the mean values of apparent mass or impedance are provided. A gloved hand-arm model is described, and the frequency dependence of vibration power absorption in the hand-arm system is also provided. To help conduct further measurement of the mechanical impedance, especially for circumstances that are not specified in ISO 10068:2012, information on the measurement of mechanical impedance is provided.
Vibrations et chocs mécaniques — Impédance mécanique du système main-bras au point d'entrée
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INTERNATIONAL ISO
STANDARD 10068
Second edition
2012-12-01
Mechanical vibration and shock —
Mechanical impedance of the human
hand-arm system at the driving point
Vibrations et chocs mécaniques — Impédance mécanique du système
main-bras au point d’entrée
Reference number
©
ISO 2012
© ISO 2012
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ii © ISO 2012 – All rights reserved
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Terms and definitions . 2
3 Mechanical impedance of the hand-arm system at the driving point .2
4 Applicability of values of impedance . 8
5 Applications .10
5.1 General .10
5.2 Evaluation of the transmissibility of resilient materials when loaded by the hand-
arm system .10
5.3 Models of the hand-arm system .11
5.4 Estimation of power absorbed in the hand-arm system and its frequency dependence .11
Annex A (normative) Reference values for the z -component of the mechanical impedance of the
h
hand-arm system .12
Annex B (informative) Model 1.14
Annex C (informative) Model 2 .19
Annex D (informative) Model 3 .24
Annex E (informative) Model of the gloved hand-arm system .29
Annex F (informative) Examples of frequency dependence derived from vibration
power absorption .32
Annex G (informative) Measurement of the mechanical impedance of the hand-arm system .36
Bibliography .37
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International
Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies
casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 10068 was prepared by Technical Committee ISO/TC 108, Mechanical vibration, shock and condition
monitoring, Subcommittee SC 4, Human exposure to mechanical vibration and shock.
This second edition cancels and replaces the first edition (ISO 10068:1998), of which it constitutes a
technical revision. The second edition includes the results of measurements of hand-arm impedance
conducted since publication of the first edition, and it includes new models for apparent mass and
mechanical impedance. The models now possess anatomic compatibility, and identify components for the
fingers, palm, wrist and arm, and upper body. A model of the hand-arm system is provided when a glove
is worn to estimate the transmissibility of vibration from a vibrating handle to the surface of the hand.
The frequency dependency of the vibration power absorbed by the hand-arm system and by structures
within the hand-arm system (i.e. fingers, palm and wrist, and arm) is also included. Information on
methods for measuring the mechanical impedance of the hand-arm system is also provided in an annex.
iv © ISO 2012 – All rights reserved
Introduction
The mechanical impedance of the human hand-arm system at the driving point provides a measure of
the overall biodynamic properties of the hand-arm system in specified conditions. When the hands are
coupled to a vibrating tool or machine, the dynamic behaviour of the tool or machine could be affected
by the biodynamic properties of the hand-arm system. Therefore, the mechanical impedance can be
used to help design or develop:
a) power tools, and tool handles;
b) vibration-reducing and protective devices;
c) testing apparatus with which to measure the handle vibration of power tools.
Values of the mechanical impedance can be used to establish mechanical-equivalent models of the hand-
arm system. The models can be used to analyse the vibration of tools and anti-vibration devices, and
to guide the construction of testing apparatus. The models can also be used to estimate biodynamic
responses such as vibration power absorption and biodynamic forces acting at the hand-tool interfaces.
Such knowledge can be used to help understand the mechanisms of vibration-induced disorders and
discomfort, and to help develop frequency weightings for assessing these effects. The establishment of
typical values for human hand-arm impedance will foster these applications.
The response of the hand-arm system to vibration depends not only on the mechanical properties of the
hand and arm, but also on the coupling between the hand and the vibrating surface. The major factors
that could influence the response are as follows:
— direction of vibration with respect to the hand-arm system;
— geometry of the object grasped;
— forces exerted by the hand on the object;
— hand and arm postures;
— individual differences, such as tissue properties and anthropometric characteristics of the
hand-arm system;
— vibration magnitude, because of the nonlinear properties of tissues.
The forces exerted by the hand are usually described in terms of the grip force and feed force. The latter
is often called the “thrust”, “push” or “press” force.
In this International Standard, typical values for the mechanical impedance of the hand-arm system
measured at the driving point of one bare hand are provided. They have been derived from the results
of impedance measurements performed on groups of live male subjects by different investigators.
Insufficient data are available from independent sources to specify hand-arm impedances for females.
There are large differences between the mean values of impedance reported in studies conducted
independently, under nominally equivalent conditions. The variations have dictated the form in which
the standardized male hand-arm impedance is presented. The most probable values of impedance
modulus and phase are defined, as a function of frequency, by upper and lower envelopes, which
encompass the mean values of all accepted data sets at each frequency. The envelopes have been
constructed from segmental cubic spline functions, and define, at each frequency, the range of accepted
values of the male hand-arm impedance. The mean of the accepted data sets, and standard deviation of
the mean, are defined as a function of frequency, and represent the target values for all applications of
this International Standard.
No impedance modulus or phase presented as a function of frequency in this International Standard
corresponds precisely to the mean value measured in a single investigation involving human subjects,
at all frequencies.
INTERNATIONAL STANDARD ISO 10068:2012(E)
Mechanical vibration and shock — Mechanical impedance
of the human hand-arm system at the driving point
1 Scope
This International Standard specifies the mechanical impedance of the human male hand-arm system
at the driving point. Values of the impedance, expressed as modulus and phase, are provided for three
orthogonal, translatory directions of excitation that correspond to the x -, y - and z -axes of the
h h h
basicentric coordinate system.
[2] [5]
NOTE 1 The basicentric coordinate system is defined in ISO 5349-1 and ISO 8727.
The x -, y - and z -components of impedance are defined as a function of frequency, from 10 Hz to
h h h
500 Hz, for specified arm positions, grip and feed forces, handle diameters, and intensities of excitation.
The components of impedance in the three directions are treated as being independent.
This International Standard can be used to define typical values of the mechanical impedance of the
hand-arm system at the driving point, applicable to males under the circumstances specified. This
International Standard can provisionally be applied to females.
Reference values of the mechanical impedance at the driving point are provided as a function of
frequency for a specified grip and feed force.
NOTE 2 See Annex A.
These impedance values are intended for the determination of the transmissibility of resilient materials
when loaded by the hand-arm system.
Mathematical representations of the hand-arm system that model the mean values of apparent mass or
impedance are provided.
NOTE 3 See Annexes B to D.
A gloved hand-arm model is described, and the frequency dependence of vibration power absorption in
the hand-arm system is also provided.
NOTE 4 See Annexes E and F.
To help conduct further measurement of the mechanical impedance, especially for circumstances
that are not specified in this International Standard, information on the measurement of mechanical
impedance is provided.
NOTE 5 See Annex G.
2 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
2.1
mechanical impedance of the hand-arm system at the driving point
Z
h
complex ratio of the dynamic force F acting on the hand contact surface and the vibration velocity input
v to the hand, given by the equation Z (ω) = F(ω)/v(ω) [Equation (1)], where ω is the vibration frequency
h
in radians per second
NOTE 1 The mechanical impedance can be derived from the apparent mass M of the hand-arm system, which
h
is defined as the complex ratio of the dynamic force and the vibration acceleration a and is expressed by the
equation M (ω) = F(ω)/a(ω) [Equation (2)].
h
NOTE 2 The relationship between the mechanical impedance and the apparent mass can be expressed by the
equation Z (ω) = jω·M (ω) [Equation (3)], where
h h
j=−1
NOTE 3 These biodynamic response functions are generally complex, i.e. they possess real and imaginary
parts, which can be expressed as modulus and phase.
3 Mechanical impedance of the hand-arm system at the driving point
The modulus and phase of the mechanical impedance of the hand-arm system at the driving point are
given in Tables 1 to 3 and (for illustration) in Figures 1 to 3 at one-third-octave band centre frequencies,
for three orthogonal directions of excitation. The directions correspond to the x -, y - and z -axes of
h h h
the basicentric coordinate system for the hand (see Figure 5). Each table and figure contains three
values of modulus and phase at each frequency, for each direction of motion, to reflect the range of
values measured on male hands. The upper and lower values define the range of most probable values of
impedance. The third value represents an overall mean of the human data, and defines the target value
for all applications. The upper and lower limiting values at each frequency encompass the mean values
of all data sets selected, and are shown by bold continuous curves in Figures 1 to 3. The central value at
each frequency, shown by dashed curves in Figures 1 to 3, provides an estimate of the mean of all data
sets selected, and forms the target value for all applications.
Numerical values are quoted up to three significant figures for the purposes of calculation, and do not
reflect the precision of knowledge of the hand-arm impedance. Linear interpolation is permitted to
obtain impedance values at frequencies other than those listed in Tables 1 to 3.
Applications that generate or employ values of impedance between the upper and lower limits at any
frequency satisfy the requirements of this International Standard, and represent the group mean of the
male hand-arm mechanical impedance at that frequency, or frequencies.
If an application only satisfies the requirements of this International Standard at certain frequencies,
then those frequencies should be stated in any description of the application.
NOTE Because each set of the selected data represents the group mean of the individuals participating in the
study, the impedance for a specific individual could be beyond the limits.
2 © ISO 2012 – All rights reserved
Table 1 — Values of the mechanical impedance of the hand-arm system at the driving point in
the x -direction
h
Modulus Phase
Frequency
N·s/m degrees
Hz
Lower limit Mean Upper limit Lower limit Mean Upper limit
10 24 38 59 36 53 68
12,5 30 49 71 38 53 69
16 33 54 80 38 53 70
20 36 64 84 38 54 71
25 43 72 104 38 57 72
31,5 51 80 125 38 53 73
40 62 95 154 37 53 73
50 74 112 189 36 51 70
63 90 140 233 33 47 66
80 109 172 280 29 43 63
100 120 199 300 23 37 60
125 124 211 302 18 31 57
160 123 210 294 11 29 52
200 120 208 287 7 23 48
250 119 189 287 6 24 45
315 120 207 302 6 25 44
400 134 224 360 8 26 45
500 168 292 442 10 29 47
Table 2 — Values of the mechanical impedance of the hand-arm system at the driving point in
the y -direction
h
Modulus Phase
Frequency
N·s/m degrees
Hz
Lower limit Mean Upper limit Lower limit Mean Upper limit
10 21 55 80 20 39 55
12,5 23 62 90 15 35 54
16 26 70 106 11 32 52
20 30 86 119 6 31 49
25 35 96 128 1 23 44
31,5 40 88 132 –6 18 39
40 48 102 135 −12 7 30
50 55 101 130 −18 −1 22
63 61 93 117 −22 −2 16
80 64 86 106 −23 −5 10
100 63 86 106 −23 −9 7
125 60 80 106 −22 −11 6
160 54 77 107 −19 −7 7
200 49 71 108 −16 −6 9
250 45 67 110 −11 0 17
315 45 69 113 −7 8 30
400 51 71 118 −4 16 45
500 66 79 134 1 22 56
4 © ISO 2012 – All rights reserved
Table 3 — Values of the mechanical impedance of the hand-arm system at the driving point in
the z -direction
h
Modulus Phase
Frequency
N·s/m degrees
Hz
Lower limit Mean Upper limit Lower limit Mean Upper limit
10 120 145 200 15 29 45
12,5 80 149 225 10 29 46
16 133 181 250 5 31 48
20 141 217 325 0 31 49
25 200 266 361 0 26 44
31,5 275 311 365 −2 16 27
40 240 315 358 −13 −1 6
50 220 263 321 −33 −13 3
63 140 216 285 −47 −15 1
80 95 170 240 −37 −11 −2
100 85 158 239 −12 −1 6
125 100 156 240 −5 6 20
160 108 163 247 5 16 30
200 113 184 271 10 21 34
250 150 212 320 13 21 29
315 150 235 363 5 20 30
400 190 243 365 2 21 32
500 185 254 362 7 21 30
Key
X frequency (Hz)
Y1 modulus (N·s/m)
Y2 phase (degrees)
Figure 1 — Values of the mechanical impedance of the hand-arm system
at the driving point in the x -direction (schematic)
h
6 © ISO 2012 – All rights reserved
Key
X frequency (Hz)
Y1 modulus (N·s/m)
Y2 phase (degrees)
Figure 2 — Values of the mechanical impedance of the hand-arm system
at the driving point in the y -direction (schematic)
h
Key
X frequency (Hz)
Y1 modulus (N·s/m)
Y2 phase (degrees)
Figure 3 — Values of the mechanical impedance of the hand-arm system
at the driving point in the z -direction (schematic)
h
4 Applicability of values of impedance
The values of impedance are applicable to human males under the following conditions, all of which shall
be met. The limits of applicability approximately correspond to the range of measurement conditions
over which data were obtained.
a) The position of the arm relative to the torso falls within the ranges defined in Figure 4.
b) The wrist is in the neutral position, that is, the position involving no flexion or extension
(tolerance ±15°), as shown in Figure 5.
c) One bare hand grasps a handle that is between 19 mm and 45 mm in diameter. The values of
impedance are applicable to handles with non-circular cross-sections, provided that the largest and
smallest cross-section dimensions are between 19 mm and 45 mm.
8 © ISO 2012 – All rights reserved
d) The hand grip force is between 25 N and 50 N. The feed force applied by the hand is not greater than
50 N.
NOTE 1 The impedance values are mainly based on data obtained from the right hand, and can be provisionally
applied to the left hand.
NOTE 2 The impedance values can be provisionally applied to females. Research has shown the modulus of
impedance for females to be up to 20 % less than the corresponding value for males.
NOTE 3 An increase in grip force has been reported to result in an increase in impedance modulus, especially
at frequencies in excess of about 50 Hz.
NOTE 4 The impedance modulus and phase do not appear to be substantially influenced by feed force at
frequencies above 100 Hz. An increase in impedance modulus with increased feed force has been reported at
lower frequencies. The values can be expected to change by less than 10 % for feed forces of up to 100 N.
NOTE 5 The impedance can be marginally influenced by the magnitude of the acceleration of the handle,
especially when the dominant components of the vibration are at frequencies less than 100 Hz. The values in this
International Standard are believed to be applicable to unweighted r.m.s. accelerations of up to 50 m/s in the
frequency range 10 Hz to 500 Hz.
NOTE 6 It is anticipated that clothing marginally increases the low frequency impedance (<25 Hz). The
impedance values were measured in various laboratories at room temperature when the subjects wore normal
working clothes.
NOTE 7 Wearing a glove generally increases the impedance or apparent mass at low frequencies (<25 Hz), but
could reduce the impedance at higher frequencies.
15° < α < 120°; −15° < β < 75°; −15° < γ < 15°; α + β < 120°
NOTE Angles are positive in sign when measured in a clockwise direction.
Figure 4 — Ranges of allowable arm positions
NOTE 1 Origin: The centre or midpoint of the axis of the instrumented handle used for measuring biodynamic
response functions of the hand-arm system.
NOTE 2 Orientation: The z -axis approximates the principal functional axis of the instrumented handle; it
h
passes through the origin of the handle and is parallel to, or aligned with, the forearm centreline when the wrist is
in the neutral position; the y -axis is along the centreline of the handle, and the x -axis passes through the origin
h h
and is mutually perpendicular to y - and z -axes.
h h
Figure 5 — Basicentric coordinate system for the measurement of biodynamic response
functions of the hand-arm system
5 Applications
5.1 General
The mechanical impedance of the entire hand-arm system at the driving point is the vector summation
of the distributed impedance at the hand-object interface. In the design and analysis of many tools and
anti-vibration handles, the total impedance is likely to be of concern, and the impedance values listed in
Tables 1 to 3 can be directly applied. A doubled value of the impedance at each frequency can be used if
both hands are coupled on the vibrating object with similar hand-arm postures and interacting conditions.
In some cases, such as estimates of the vibration transmissibility of an anti-vibration glove at the palm
and the vibration power input to the palm, only a portion of the distributed impedance is involved in
the interaction or response. Only the impedance distributed at the location effectively involved in the
response of concern shall be used in applications.
5.2 Evaluation of the transmissibility of resilient materials when loaded by the
hand-arm system
Reference values for the z -component of the mechanical impedance of the hand-arm system at the
h
driving point and its distribution at the palm and the fingers are given in Annex A as a function of
frequency for a grip force of 30 N, a feed force of 50 N, and an elbow angle of 90°. The impedance values
are provided for evaluating the transmissibility of resilient materials, when loaded by the hand-arm
[7]
system (details are given in ISO 13753 ). To compare the predicted transmissibility with that measured
[6]
with the method defined in ISO 10819, the impedance distributed at the palm shall be used.
When the equivalent stiffness, damping, and mass of a resilient material are measured or estimated,
the vibration transmissibility of the material at the fingers and palm may also be estimated using the
modelling method described in Annex E.
10 © ISO 2012 – All rights reserved
5.3 Models of the hand-arm system
Models of the hand-arm system that comply with the provisions of this International Standard are
provided in Annexes B to D. The models possess varying degrees of complexity for different applications.
Annexes B to D are provided to facilitate mathematical modelling, and the construction of mechanical
analogues of the hand-arm system for use in testing apparatus.
NOTE 1 The selection of the biodynamic function (mechanical impedance or apparent mass) for the model
development depends primarily on the application. Because the dynamic force is directly associated with the
apparent mass, it is more suitable to use the apparent mass when the interacting dynamic force is of primary
concern. Because the apparent mass generally decreases with an increase in frequency, a mechanical equivalent
model based on the apparent mass emphasizes the low frequency response. Therefore, apparent mass-based
models are more suitable for the design, analysis, and testing of tools and anti-vibration devices. On the other
hand, impedance-based models are more suitable for estimating the vibration power absorption because the
impedance is directly associated with the vibration power absorption.
NOTE 2 The biodynamic models can provisionally be used to predict hand-arm impedance up to 1 kHz.
5.4 Estimation of power absorbed in the hand-arm system and its frequency dependence
The mechanical power P absorbed in the hand-arm system at each frequency ω can be estimated from
h
the real part of the mechanical impedance Re Z and the vibration acceleration input a to the hand as:
h
a ω
()
PZ()ωω=Re (4)
()
hh
ω
The frequency dependence w of the vibration power absorption in one-third octave bands is
P
expressed as follows:
ReZ ωω
()
h
w ()ω =0,958 (5)
P
ReZ ωω
()
hRef Ref
where ω is the reference frequency for normalization and 0,958 is the maximum weighting in the one-
Ref
[2]
third octave band centre frequencies in ISO 5349-1.
NOTE The hand-arm system is assumed to be a linear system in these estimations, but the system is actually
nonlinear. Therefore, this assumption could introduce errors. The estimated frequency dependence can only be
used for identifying the basic trend of the power absorption as a function of frequency.
The power absorbed in a substructure P can be estimated from a model for a given vibration spectrum.
s
The frequency dependence of the substructure-specific power absorption w can be estimated from
P
s
Paωω
() ()
s
w ()ω =0,958 (6)
P
s
Paωω
() ()
sRef Ref
Examples of the frequency dependency are given in Annex F.
Annex A
(normative)
Reference values for the z -component of the mechanical
h
impedance of the hand-arm system
Reference values for the z -component of the mechanical impedance are given in Table A.1 as a function
h
of frequency, from 10 Hz to 500 Hz. The values have been derived from impedance measurements
conducted on human male subjects and are intended for the evaluation of the transmissibility of resilient
[7]
materials when loaded by the hand
...
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