ISO/TS 21002:2021
(Main)Road vehicles — Multidimensional measurement and coordinate systems definition
Road vehicles — Multidimensional measurement and coordinate systems definition
This document defines the measurement coordinate systems and presents the protocol to determine the sensor offsets to the chosen coordinate system. Finally, the method is presented how to process the sensor spherical coordinate system data to calculate the position of a dummy feature in three-dimensional space in the defined local orthogonal coordinate system.
Véhicules routiers — Mesurage multidimensionnel et définition des systèmes de coordination
General Information
Buy Standard
Standards Content (Sample)
TECHNICAL ISO/TS
SPECIFICATION 21002
First edition
2021-07
Road vehicles — Multidimensional
measurement and coordinate systems
definition
Véhicules routiers — Mesurage multidimensionnel et définition des
systèmes de coordination
Reference number
ISO/TS 21002:2021(E)
©
ISO 2021
---------------------- Page: 1 ----------------------
ISO/TS 21002:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/TS 21002:2021(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols . 6
5 Sensor calibration .10
6 Procedures zero-position verification .10
6.1 General .10
6.2 Verification acceptance limits .10
6.3 Zero-position data collection .11
6.4 Calculations .15
6.5 Zero-position verification with DAS parameters implemented . .16
7 Coordinate system transformation .17
7.1 Conditions .17
7.2 Sensor data processing spherical to orthogonal coordinate system .17
Annex A (informative) Measurement orthogonal coordinate systems .19
Annex B (informative) Zero-position fixture and data collection examples .26
Annex C (informative) Mathematical background data processing .37
Annex D (informative) Applicable sensors .42
Annex E (informative) Suggestions for generic workflow - parameter implementation in
data acquisition systems and verification of post processing software.43
Annex F (informative) ISO MME code examples .47
Annex G (informative) Expected outputs multidimensional sensors mounted in dummy .49
Bibliography .52
© ISO 2021 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO/TS 21002:2021(E)
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.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 22, Road Vehicles, Subcommittee SC 36,
Safety aspects and impact testing.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2021 – All rights reserved
---------------------- Page: 4 ----------------------
ISO/TS 21002:2021(E)
Introduction
This document provides a unified method to handle and process various types of multidimensional
displacement sensors for use in crash dummies and automotive crash testing. The content covers
existing sensors and dummies, but the document also offers a generic method to handle future new
dummies and/or sensors.
Multidimensional measurement systems are used in crash dummies (ATD, or anthropomorphic test
device) to monitor the position of dummy features (e.g. ribs, abdomen, etc.) for injury assessment. The
dummy feature position is typically expressed in an orthogonal coordinate system which is fixed to
the thoracic spine of the dummy, see Annex A. The systems covered in this document are an assembly
of one distance sensor and one or two angle sensors, the axes of which are organised in a (rotating)
spherical coordinate system, see Figure C.1. Other 2- and 3-dimensional position measurement systems
are outside the scope of this document. Although in this document a suit of ATD’s and their features are
discussed to explain the methodology, its scope is not limited to these examples and can be applied to
any other ATD and its features.
© ISO 2021 – All rights reserved v
---------------------- Page: 5 ----------------------
TECHNICAL SPECIFICATION ISO/TS 21002:2021(E)
Road vehicles — Multidimensional measurement and
coordinate systems definition
1 Scope
This document defines the measurement coordinate systems and presents the protocol to determine
the sensor offsets to the chosen coordinate system. Finally, the method is presented how to process
the sensor spherical coordinate system data to calculate the position of a dummy feature in three-
dimensional space in the defined local orthogonal coordinate system.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology 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
multidimensional measurement system
system that measures spatial position of a crash dummy feature (e.g. rib, abdomen, etc.) with respect to
a defined reference feature (e.g. dummy spine) and its local coordinate system origin.
Note 1 to entry: Examples of multidimensional sensors and applications are given in the NOTES of Figure 1,
Figure 2 and Figure 3.
3.2
radius
distance between the centre of rotation at spine interface and centre of rotation at feature interface
(e.g. dummy rib)
[2]
Note 1 to entry: The parameter radius (R) is associated with the ISO MME Code DC for Distance, ISO/TS 13499 .
3.3
sensor Y-angle
angle of the multidimensional sensor along Y-axis with respect to local orthogonal coordinate system
Note 1 to entry: The positive rotation direction is defined following SAE sign convention right hand rule.
3.4
sensor Z-angle
angle of the multidimensional sensor along Z-axis with respect to local orthogonal coordinate system
Note 1 to entry: The positive rotation direction is defined following SAE sign convention right hand rule.
Note 2 to entry: Examples of the angle definitions are given in the NOTES of Figure 1, Figure 2 and Figure 3.
© ISO 2021 – All rights reserved 1
---------------------- Page: 6 ----------------------
ISO/TS 21002:2021(E)
Key
1 radius, R
i
NOTE Two examples for WorldSID application are shown: left image 2D IR-TRACC, right image S-Track.
Figure 1 — Two-dimensional sensor mounted in right-hand side WorldSID 50M dummy
NOTE Two examples for THOR application are show: left image IR-TRACC, right image S-Track.
Figure 2 — Three-dimensional sensors mounted in THOR 50M right-hand view and global
coordinate system.
2 © ISO 2021 – All rights reserved
---------------------- Page: 7 ----------------------
ISO/TS 21002:2021(E)
Key
1 radius, R
i
NOTE Two informative examples for THOR application are shown: left image 3D IR-TRACC, right image 3D
S-Track).
Figure 3 — Three-dimensional sensors for THOR lower right-hand thorax and their local
orthogonal coordinate system
3.5
zero-position
condition of multidimensional sensor when mounted by the spine interface and the distance sensor is
aligned with (parallel to) the local orthogonal coordinate system axes and the feature interface is fixed
at an accurately defined distance from the coordinate system origin
Note 1 to entry: By definition the angles of the multidimensional position sensor are zero.
3.6
zero-position fixture
tool to set up a multidimensional position sensor in its zero-position (3.5)
Note 1 to entry: A zero-position fixture has accurately machined reproducible mountings to simulate the dummy
spine and the feature mountings. These sensor mountings of the fixture are accurately positioned in (2D- and
3D) space such that the sensor is in its zero-position condition, called position 0 (position zero). The fixture has
additional mounting positions for the feature interface, which are translated from zero position over a defined
distance in a direction perpendicular to the distance sensor axis and parallel to at least one of the local orthogonal
coordinate system axes.
Note 2 to entry: The fixture is considered adequately accurate if the overall dimensional tolerance stack ups of
the sensor mountings are within ±0,3mm in all directions.
Note 3 to entry: Examples of 2D and 3D zero-position fixtures are given in Annex B.
Note 4 to entry: The zero-position fixtures are used in subsequent steps of the zero-position verification
procedure:
a) to find the offset of the sensors with respect to the local orthogonal coordinate system;
b) to remove offsets (by adjustment or compensation in a data acquisition system);
c) to check if sensor offsets are removed with a live data acquisition system;
© ISO 2021 – All rights reserved 3
---------------------- Page: 8 ----------------------
ISO/TS 21002:2021(E)
d) to check sensor polarities with respect to global orthogonal coordinate system;
e) to check if calculations for coordinate system transformation are reproducing the design positions of the
fixture in 2D or 3D space. See paragraph 7 and Annex B.
3.7
offset angle
output in degrees of the angle sensor(s) when the multidimensional position sensor is in its zero-position
(3.5) condition
Note 1 to entry: If the angle sensor has a positive offset according to the local orthogonal coordinate system, the
offset angle is defined positive.
3.8
orientation angle
correction angle for multidimensional sensors that can be mounted in sensor orientation for left hand
and right-hand side impact operation, as well as for frontal impact operation
Note 1 to entry: Typically the two-dimensional sensors can be mounted in various orientations inside the dummy.
In side impact dummies the sensors can be set up for left hand and right-hand impact (even simultaneously), and
the Q10 child dummies can be set up for both frontal and lateral impacts.
Note 2 to entry: The two-dimensional sensors can be oriented inside the dummy with a rotated coordinate
system about the Z-axis. The orientation angle can be implemented in Data Acquisition Systems Z-angle data
channels as a fixed offset to correct for a rotated coordinate system, see Table 1.
Table 1 — Orientation angle definition per orientation in the dummy
Sensor orientation for impact operation
Left Lateral Frontal Right Lateral
Orientation angle -90° 0° +90°
3.9
reference angle
orientation angle minus the offset angle (3.7)
Note 1 to entry: Calculate the reference angle with Formula (1).
ϕϕ =− ϕ (1)
REF ORIENTOSZ
Note 2 to entry: The reference angle can be used with data acquisition systems that can handle only one fixed
offset parameter, see example in Figure 4.
4 © ISO 2021 – All rights reserved
---------------------- Page: 9 ----------------------
ISO/TS 21002:2021(E)
Figure 4 — Angle sensor parameter examples seen from top of dummy (looking over dummy
shoulder)
Table 2 — Examples for φ and φ when offset angle is +3°, for left side, frontal and right-
REF ORIENT
side impact dummy set up, see Figure 4
Left lateral impact Frontal impact Right lateral impact
φ -90 0 +90
ORIENT
φ +3 +3 +3
OSZ
φ -93 -3 +87
REF
3.10
angle sensor polarity
direction of rotation of the sensor shaft with reference to its fixed body in relation to its electrical
(digital) signal output and sensor body and shaft orientation to the relevant coordinate system
Note 1 to entry: The polarity is defined positive when the far end of the shaft points in the positive orthogonal
direction and the shaft (or internal wiper) is rotated in the positive rotation direction according to the relevant
coordinate system, see example Figure 5.
Note 2 to entry: The value of the polarity can only be +1 or -1.
Note 3 to entry: Depending of the sensor assembly orientation in the dummy some sensors need to change the
polarity sign to get a positive output in accordance with the relevant coordinate system.
© ISO 2021 – All rights reserved 5
---------------------- Page: 10 ----------------------
ISO/TS 21002:2021(E)
Figure 5 — Positive polarity for angle sensors
4 Symbols
Table 3 — List of symbols
Parameter Symbol Unit Definition/description Application
X-axis x - Global orthogonal coordinate system
X-axis
Y-axis y - Global orthogonal coordinate system
Y-axis
Z-axis z - Global orthogonal coordinate system
Z-axis
Origin of local orthogo- O - Origin upper thoracic spine
UTS
nal coordinate systems
O Origin lower thoracic spine
LTS
O Origin lumbar spine
LS
O Origin distance sensor
DC
x - Local X-axis upper thoracic spine 3D-THOR
UTS
y - Local Y-axis upper thoracic spine 3D-THOR
UTS
z - Local Z-axis upper thoracic spine 3D-THOR
UTS
x - Distance sensor axis 3D-THOR
DC
y Position sensor Y-pivot axis 3D-THOR
DC
z - Position sensor Z-pivot axis 3D-THOR
DC
x - Local X-axis lower thoracic spine 3D-THOR
LTS
y - Local Y-axis lower thoracic spine 3D-THOR
LTS
z - Local Z-axis lower thoracic spine 3D-THOR
LTS
x - Local X-axis lumbar spine 3D-THOR
LS
y - Local Y-axis lumbar spine 3D-THOR
LS
z - Local Z-axis lumbar spine 3D-THOR
LS
6 © ISO 2021 – All rights reserved
---------------------- Page: 11 ----------------------
ISO/TS 21002:2021(E)
Table 3 (continued)
Parameter Symbol Unit Definition/description Application
Distance D mm Design distance on zero-position fixture 2D
from 2D sensor origin to rib interface
Distance position 0 D
ZERO
centre in position-0, position-1, posi-
tion-2
Distance position 1 D
P1
Distance position 2 D
P2
Distance positions mm Design distance on zero-position fixture 3D
from origin O , O , or O to rib
UTS LTS LS
ZERO-L, ZERO-R, D
ZERO
interface centre in position ZERO, posi-
PZL, PZR, D tion PZ (L and R), position PY (L and R),
PZ
position PYZ (L and R)
PYL, PYR D
PY
PYZL, PYZR D
PYZ
Z-angle Θ degrees Design Z-angles on zero-position fixture 2D
Z
2D sensor origin to rib interface centre
Angle position 0 Θ
Z ZERO
in zero-position, position-1, position-2
Angle position 1 Θ
Z1
Angle position 2 Θ
Z2
Y-angle positions Θ degrees Design Y-angles on zero-position fixture 3D
Y
origin O , O , or O to rib interface
UTS LTS LS
ZERO-L, ZERO-R, Θ
Y ZERO
centre in position ZERO, position PZ (L
PZL PZR, Θ and R) , position PY (L and R), position
Y PZ
PYZ (L and R)
PYL, PYR Θ
Y PY
PYZL, PYZR Θ
Y PYZ
Z-angle positions Θ degrees Design Z-angles on zero-position fixture 3D
Z
origin O , O , or O to rib interface
UTS LTS LS
ZERO-L, ZERO-R, Θ
Z ZERO
centre in position ZERO, position +Z,
position +Y, position PYZ (L and R)
PZL PZR, Θ
Z PZ
PYL, PYR Θ
Z PY
PYZL, PYZR Θ
Z PYZ
Calibration range d mm Distance between starting and end point
E
of displacement calibration
Distance sensor output U V, LSB Distance sensor output
DC
Tubes-IN output U V, LSB Output at certain displacement with all IR-TRACC only
DC IN
floating tubes pushed IN
Tubes-OUT output U V, LSB Output at certain displacement with all IR-TRACC only
DC OUT
floating tubes pushed OUT
Linearization exponent EXP [-] Optimized linearization exponent IR-TRACC only
Linearized voltage U V IR-TRACC output to power of exponent; IR-TRACC only
LIN lin
calculated parameter
LSB
LIN
Distance sensor calibra- C mm/V and linear sensor mm displacement per Ratiometric
DC
tion factor mm/LSB mm/ output sensor
V
LIN
IR-TRACC mm displacement per line- IR-TRACC
mm/LSB arized output
LIN
Distance sensor sensi- S V/mm and linear sensor output per mm displace- Ratiometric
DC
tivity LSB/mm ment sensor
V /mm and IR-TRACC linearized output per mm IR-TRACC
LIN
displacement
LSB /mm
LIN
Angle sensor calibration C degrees/V/V Angle sensor degrees rotation at 1V out-
ANY
factor put per 1V excitation or degree rotation
C degrees/LSB
ANZ
per digital output
© ISO 2021 – All rights reserved 7
---------------------- Page: 12 ----------------------
ISO/TS 21002:2021(E)
Table 3 (continued)
Parameter Symbol Unit Definition/description Application
Angle sensor sensitivity S V/V/degrees Angle sensor output per degree rotation
ANY
at 1V excitation or
S LSB/degrees
ANZ
digital output per degree
Angle sensor polarity P [-] The value can be either +1 or -1 2D-3D
Distance sensor Pos0 U V, LSB Distance sensor average output at zero 2D-3D
DC0
output position on Zeroing Fixture
Distance sensor Pos0 U V, LSB Distance sensor output at zero position IR-TRACC
DC0 IN
output tubes-IN tubes IN
Distance sensor Pos0 U V, LSB Distance sensor output at zero position IR-TRACC
DC0 OUT
output tubes-OUT tubes OUT
Distance sensor Pos1 U V, LSB Distance sensor output at position 1 2D
DC1
output
Distance Sensor Pos2 U V, LSB Distance sensor output at position 2 2D
DC2
output
Distance sensor output U V, LSB Distance sensor output at position PY 3D
DC PY
position PY
Distance sensor output U V, LSB Distance sensor output at position PZ 3D
DC PZ
position PZ
Distance sensor output U V, LSB Distance sensor output at position PYZ 3D
DC PYZ
position PYZ
Radius R mm Distance from O to rib interface 2D 3D
DC
rotation centre, see Figure 3. Distance
R
0
sensor output in mm at t , at t .
0 i
R
i
Radius Pos0 R mm Radius at zero position on zeroing 2D-3D
IO
fixture calculated using average IN-OUT
output
Radius Pos0 tubes-IN R mm Radius at zero position calculated using IR-TRACC
IN
tubes IN output
Radius Pos0 tubes-OUT R mm Radius at zero position calculated using IR-TRACC
OUT
tubes OUT output
Radius Pos0 R mm Radius at zero-position 2D-3D
ZERO
2D
Radius Pos1 R Radius at position-1
1
2D
Radius Pos2 R Radius at position-2
2
3D
Radius PY R Radius at position PY
PY
3D
Radius PZ R Radius at position PZ
PZ
3D
Radius PYZ R Radius at position PYZ
PYZ
Excitation U V Excitation voltage angle sensor during
EX
zero-position verification
Y-angle sensor output U V, LSB Y-axis angle sensor voltage 3D
ANY
Z-angle sensor output U V, LSB Z-axis angle sensor voltage
ANZ
Z-Angle output 0 U V, LSB Z-Angle sensor average output at posi- 2D & 3D
ANZ0
(ZERO) tion-0 (ZERO)
Z-Angle output 0-Near U V, LSB Z-Angle sensor output at position-0 pull 2D & 3D
ANZ NEAR
Near (3D away from spine)
Z-Angle output 0-Far U V, LSB Z-Angle sensor output at position-0 pull 2D & 3D
ANZ FAR
Far (3D towards spine)
8 © ISO 2021 – All rights reserved
---------------------- Page: 13 ----------------------
ISO/TS 21002:2021(E)
Table 3 (continued)
Parameter Symbol Unit Definition/description Application
Z-Angle output 1 U V, LSB Z-axis angle sensor output at position-1 2D
ANZ1
Z-Angle output 2 U V, LSB Z-axis angle sensor output at position-2 2D
ANZ2
Z-Angle output PZR U V, LSB Z-Angle sensor output at position PZ 3D
ANZ PZ
Y-Angle output zero U V, LSB Y- Angle sensor average output at posi- 3D
ANY0
tion-zero
Y-Angle output zero- U V, LSB Y- Angle sensor output at position-zero 3D
ANY DOWN
Down pull Down
Y-Angle output zero-Up U V, LSB Y- Angle sensor output at position-0 pull 3D
ANY UP
Up
Y-Angle output PY U V, LSB Y-Angle sensor output at position PY 3D
ANY PY
Y-Offset Angle φ degrees Y-angle sensor average offset between
OSY
extremes (Up-Down) when at fixture
zero-position
Z-Offset Angle φ degrees Z-angle sensor average offset between
OSZ
extremes (Near-Far) when at fixture
zero-position
Sensor Y-angle φ degrees Distance sensor angle along y-axis with
Y
respect to local orthogonal coordinate
φ
Y0
system, see Figure 3, and at t and at t .
0 i
φ
Yi
Sensor Z-angle φ degrees Distance sensor angle along z-axis with
Z
respect to local orthogonal coordinate
φ
Z0
system, see Figure 3, and, at t and at t .
0 i
φ
Zi
Distance intercept I mm Distance sensor offset in mm from coor-
DC
dinate system origin.
Distance intercept I V, V Calculated (linearized) output at 0mm
DCV LIN
voltage radius
LSB
LIN
Axis offset δ mm Mechanical offset distance between O 3D thoracic
DC
distance sensor origin and coordinate
system origin, see Figure 3.
Orientation angle φ degrees Orientation angle of 2D position sensor 2D
ORIENT
assembled inside dummy. For definition
see also Figure 4 and Table 1.
Reference angle φ degrees Orientation angle minus offset angle. For 2D
REF
definition see also Figure 4 and Table 1.
Time t s time
t time zero, start of the test
0
t time i
i
x coordinate x, x , x mm Feature interface rotation centre x-
0 i
coordinate, x at t , x at t , see NOTES of
0 i
Figure 1, Figure 2 and Figure 3.
y coordinate y, y , y mm Feature interface rotation centre y-
0 i
coordinate, y at t , y at t , see NOTES of
0 i
Figure 1, Figure 2 and Figure 3.
z coordinate z, z , z mm Feature interface rotation centre z-
0 i
coordinate, z at t , z at t , see NOTES of
0 i
Figure 1, Figure 2 and Figure 3.
© ISO 2021 – All rights reserved 9
---------------------- Page: 14 ----------------------
ISO/TS 21002:2021(E)
Table 3 (continued)
Parameter Symbol Unit Definition/description Application
x deflection Dx mm Feature deflection in x direction at t
i i
y deflection Dy mm Feature deflection in y direction at t
i i
z deflection Dz mm Feature deflection in z direction at t
i i
Resultant deflection D mm Resultant deflection of the feature inter-
i
face centre at t
i
5 Sensor calibration
Individual angle and displacement or distance sensors are calibrated according to accepted standards
before conducting the zero-position verification procedure. (Recommended: calibrate non-linear
[3] [4]
Infrared distance sensor IR-TRACC according to ISO/TS 21476 and calibrate ratio metric distance
[5]
sensor according to ISO/TS 23521 ).
6 Procedures zero-position verification
6.1 General
This clause describes procedures to obtain reproducible data from multidimensional position sensors
on zero-position fixtures. Example sensors and fixtures are used in the procedures to describe the
method, but the procedures should also be applicable to other sensors and fixtures. The sequences for
2D and 3D zero-position verification are generally following the same principle.
6.2 Verification acceptance limits
The acceptance limits of the zero-position verification procedure are based on an uncertainty analysis
[6]
conducted according to procedures outlined in JCGM_100_2008 applying four components of
variation. The components identified are
a) variation introduced by the operator (assembly of the sensor on the fixture, system play in the
mountings),
b) imperfection of the sensor, like system play, friction and non-linearity,
c) voltage measurement uncertainty, and
d) manufacturing tolerances of fixtures.
To quantify the operator component of variation a round robin was conducted in 2018-2019, involving
one 2D sensor and fixture and one 3D sensor and fixture. The round robin included eleven qualified test
labs on three continents. The other three components of uncertainty, b), c), and d), were accounted for in
the uncertainty analysis based on the specifications of the equipment used. The total uncertainty was
calculated from the square root of the sum of squares of standard deviation, σ, of the four components,
and a multiplier of three was applied to define acceptance limits (3σ ≡ 99,7 % confidence limits). The
verification acceptance limits are defined based on these studies as follows:
— For angles: ±3 % of mechanical range of ±45°: ±1,35°. (Example max error: with distance sensor at
140mm radius, 1,35° corresponds to 1,35π/180 × 140 = 3,3mm).
— For distance: ±3 % of calibration range of distance sensor. (Example max error: calibration range
80mm, 3 % corresponds to 2,4mm).
10 © ISO 2021 – All rights reserved
---------------------- Page: 15 ----------------------
ISO/TS 21002:2021(E)
6.3 Zero-position data collection
Zero-position verification data collection sequences are given in Table 4 for 2D sensors and Table 5
for 3D sensors. The sensors are connected to measurement systems according adequate and accepted
laboratory practise standards to measure the sensor outputs.
The zero-position verification procedure are conducted in a temperature controlled environment
between 20 °C to 25 °C.
A 120 s warm up time after powering the sensors is observed before data collection starts.
The sensor assembly are setup on the zero position fixture in its zero position. Measurements and
calculations are conducted according to the sequences given in Table 4 and Table 5 and formulae given
in 6.4. Measurements taken under conditions of controlled lateral loading to find the extreme sensor
offsets are conducted with a ballast 0,44 kg to 0,47kg; finally the rib interface are manipulated in
multiple positions to verify the sensor polarities and pass criteria are applied for the expected sensor
outputs in these positions. See also Annex B for example fixtures and data collection examples.
© ISO 2021 – All rights reserved 11
---------
...
TECHNICAL ISO/TS
SPECIFICATION 21002
First edition
Road vehicles — Multidimensional
measurement and coordinate systems
definition
Véhicules routiers — Mesurage multidimensionnel et définition des
systèmes de coordination
PROOF/ÉPREUVE
Reference number
ISO/TS 21002:2021(E)
©
ISO 2021
---------------------- Page: 1 ----------------------
ISO/TS 21002:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii PROOF/ÉPREUVE © ISO 2021 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/TS 21002:2021(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols . 6
5 Sensor calibration .10
6 Procedures zero-position verification .10
6.1 General .10
6.2 Verification acceptance limits .10
6.3 Zero-position data collection .11
6.4 Calculations .15
6.5 Zero-position verification with DAS parameters implemented . .16
7 Coordinate system transformation .17
7.1 Conditions .17
7.2 Sensor data processing spherical to orthogonal coordinate system .17
Annex A (informative) Measurement orthogonal coordinate systems .19
Annex B (informative) Zero-position fixture and data collection examples .26
Annex C (informative) Mathematical background data processing .37
Annex D (informative) Applicable sensors .42
Annex E (informative) Suggestions for generic workflow - parameter implementation in
data acquisition systems and verification of post processing software.43
Annex F (informative) ISO MME code examples .47
Annex G (informative) Expected outputs multidimensional sensors mounted in dummy .49
Bibliography .52
© ISO 2021 – All rights reserved PROOF/ÉPREUVE iii
---------------------- Page: 3 ----------------------
ISO/TS 21002:2021(E)
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.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 22, Road Vehicles, Subcommittee SC 36,
Safety aspects and impact testing.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
iv PROOF/ÉPREUVE © ISO 2021 – All rights reserved
---------------------- Page: 4 ----------------------
ISO/TS 21002:2021(E)
Introduction
This document provides a unified method to handle and process various types of multidimensional
displacement sensors for use in crash dummies and automotive crash testing. The content covers
existing sensors and dummies, but the document also offers a generic method to handle future new
dummies and/or sensors.
Multidimensional measurement systems are used in crash dummies (ATD, or anthropomorphic test
device) to monitor the position of dummy features (e.g. ribs, abdomen, etc.) for injury assessment. The
dummy feature position is typically expressed in an orthogonal coordinate system which is fixed to
the thoracic spine of the dummy, see Annex A. The systems covered in this document are an assembly
of one distance sensor and one or two angle sensors, the axes of which are organised in a (rotating)
spherical coordinate system, see Figure C.1. Other 2- and 3-dimensional position measurement systems
are outside the scope of this document. Although in this document a suit of ATD’s and their features are
discussed to explain the methodology, its scope is not limited to these examples and can be applied to
any other ATD and its features.
© ISO 2021 – All rights reserved PROOF/ÉPREUVE v
---------------------- Page: 5 ----------------------
TECHNICAL SPECIFICATION ISO/TS 21002:2021(E)
Road vehicles — Multidimensional measurement and
coordinate systems definition
1 Scope
This document defines the measurement coordinate systems and presents the protocol to determine
the sensor offsets to the chosen coordinate system. Finally, the method is presented how to process
the sensor spherical coordinate system data to calculate the position of a dummy feature in three-
dimensional space in the defined local orthogonal coordinate system.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions 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 http:// www .electropedia .org/
3.1
multidimensional measurement system
system that measures spatial position of a crash dummy feature (e.g. rib, abdomen, etc.) with respect to
a defined reference feature (e.g. dummy spine) and its local coordinate system origin.
Note 1 to entry: Examples of multidimensional sensors and applications are given in the NOTES of Figure 1,
Figure 2 and Figure 3.
3.2
radius
distance between the centre of rotation at spine interface and centre of rotation at feature interface
(e.g. dummy rib)
[2]
Note 1 to entry: The parameter radius (R) is associated with the ISO MME Code DC for Distance, ISO/TS 13499 .
3.3
sensor Y-angle
angle of the multidimensional sensor along Y-axis with respect to local orthogonal coordinate system
Note 1 to entry: The positive rotation direction is defined following SAE sign convention right hand rule.
3.4
sensor Z-angle
angle of the multidimensional sensor along Z-axis with respect to local orthogonal coordinate system
Note 1 to entry: The positive rotation direction is defined following SAE sign convention right hand rule.
Note 2 to entry: Examples of the angle definitions are given in the NOTES of Figure 1, Figure 2 and Figure 3.
© ISO 2021 – All rights reserved PROOF/ÉPREUVE 1
---------------------- Page: 6 ----------------------
ISO/TS 21002:2021(E)
Key
1 radius, R
i
NOTE Two examples for WorldSID application are shown: left image 2D IR-TRACC, right image S-Track.
Figure 1 — Two-dimensional sensor mounted in right-hand side WorldSID 50M dummy
NOTE Two examples for THOR application are show: left image IR-TRACC, right image S-Track.
Figure 2 — three-dimensional sensors mounted in THOR 50M right hand view and global
coordinate system.
2 PROOF/ÉPREUVE © ISO 2021 – All rights reserved
---------------------- Page: 7 ----------------------
ISO/TS 21002:2021(E)
Key
1 radius, R
i
NOTE Two informative examples for THOR application are shown: left image 3D IR-TRACC, right image 3D
S-Track).
Figure 3 — Three-dimensional sensors for THOR lower right hand thorax and their local
orthogonal coordinate system
3.5
zero-position
condition of multidimensional sensor when mounted by the spine interface and the distance sensor is
aligned with (parallel to) the local orthogonal coordinate system axes and the feature interface is fixed
at an accurately defined distance from the coordinate system origin
Note 1 to entry: By definition the angles of the multidimensional position sensor are zero.
3.6
zero-position fixture
tool to set up a multidimensional position sensor in its zero-position (3.5)
Note 1 to entry: A zero-position fixture has accurately machined reproducible mountings to simulate the dummy
spine and the feature mountings. These sensor mountings of the fixture are accurately positioned in (2D- and
3D) space such that the sensor is in its zero-position condition, called position 0 (position zero). The fixture has
additional mounting positions for the feature interface, which are translated from zero position over a defined
distance in a direction perpendicular to the distance sensor axis and parallel to at least one of the local orthogonal
coordinate system axes.
Note 2 to entry: The fixture is considered adequately accurate if the overall dimensional tolerance stack ups of
the sensor mountings are within ±0,3mm in all directions.
Note 3 to entry: Examples of 2D and 3D zero-position fixtures are given in Annex B.
Note 4 to entry: The zero-position fixtures are used in subsequent steps of the zero-position verification
procedure:
a) to find the offset of the sensors with respect to the local orthogonal coordinate system;
b) to remove offsets (by adjustment or compensation in a data acquisition system);
c) to check if sensor offsets are removed with a live data acquisition system;
© ISO 2021 – All rights reserved PROOF/ÉPREUVE 3
---------------------- Page: 8 ----------------------
ISO/TS 21002:2021(E)
d) to check sensor polarities with respect to global orthogonal coordinate system;
e) to check if calculations for coordinate system transformation are reproducing the design positions of the
fixture in 2D or 3D space. See paragraph 7 and Annex B.
3.7
offset angle
output in degrees of the angle sensor(s) when the multidimensional position sensor is in its zero-position
(3.5) condition
Note 1 to entry: If the angle sensor has a positive offset according to the local orthogonal coordinate system, the
offset angle is defined positive.
3.8
orientation angle
correction angle for multidimensional sensors that can be mounted in sensor orientation for left hand
and right hand side impact operation, as well as for frontal impact operation
Note 1 to entry: Typically the two-dimensional sensors can be mounted in various orientations inside the dummy.
In side impact dummies the sensors can be set up for left hand and right hand impact (even simultaneously), and
the Q10 child dummies can be set up for both frontal and lateral impacts.
Note 2 to entry: The two-dimensional sensors can be oriented inside the dummy with a rotated coordinate
system about the Z-axis. The orientation angle can be implemented in Data Acquisition Systems Z-angle data
channels as a fixed offset to correct for a rotated coordinate system, see Table 1.
Table 1 — Orientation angle definition per orientation in the dummy
Sensor orientation for impact operation
Left Lateral Frontal Right Lateral
Orientation angle -90° 0° +90°
3.9
reference angle
orientation angle minus the offset angle (3.7)
Note 1 to entry: Calculate the reference angle with Formula (1).
ϕϕ =− ϕ (1)
REF ORIENTOSZ
Note 2 to entry: The reference angle can be used with data acquisition systems that can handle only one fixed
offset parameter, see example in Figure 4.
4 PROOF/ÉPREUVE © ISO 2021 – All rights reserved
---------------------- Page: 9 ----------------------
ISO/TS 21002:2021(E)
Figure 4 — Angle sensor parameter examples seen from top of dummy (looking over dummy
shoulder)
Table 2 — Examples for φ and φ when offset angle is +3°, for left side, frontal and right
REF ORIENT
side impact dummy set up, see Figure 4
Left lateral impact Frontal impact Right lateral impact
φ -90 0 +90
ORIENT
φ +3 +3 +3
OSZ
φ -93 -3 +87
REF
3.10
angle sensor polarity
direction of rotation of the sensor shaft with reference to its fixed body in relation to its electrical
(digital) signal output and sensor body and shaft orientation to the relevant coordinate system
Note 1 to entry: The polarity is defined positive when the far end of the shaft points in the positive orthogonal
direction and the shaft (or internal wiper) is rotated in the positive rotation direction according to the relevant
coordinate system, see example Figure 5.
Note 2 to entry: The value of the polarity can only be +1 or -1.
Note 3 to entry: Depending of the sensor assembly orientation in the dummy some sensors need to change the
polarity sign to get a positive output in accordance with the relevant coordinate system.
© ISO 2021 – All rights reserved PROOF/ÉPREUVE 5
---------------------- Page: 10 ----------------------
ISO/TS 21002:2021(E)
Figure 5 — Positive polarity for angle sensors
4 Symbols
Table 3 — List of symbols
Parameter Symbol Unit Definition/description Application
X-axis x - Global orthogonal coordinate system
X-axis
Y-axis y - Global orthogonal coordinate system
Y-axis
Z-axis z - Global orthogonal coordinate system
Z-axis
Origin of local orthogo- O - Origin upper thoracic spine
UTS
nal coordinate systems
O Origin lower thoracic spine
LTS
O Origin lumbar spine
LS
O Origin distance sensor
DC
x - Local X-axis upper thoracic spine 3D-THOR
UTS
y - Local Y-axis upper thoracic spine 3D-THOR
UTS
z - Local Z-axis upper thoracic spine 3D-THOR
UTS
x - Distance sensor axis 3D-THOR
DC
y Position sensor Y-pivot axis 3D-THOR
DC
z - Position sensor Z-pivot axis 3D-THOR
DC
x - Local X-axis lower thoracic spine 3D-THOR
LTS
y - Local Y-axis lower thoracic spine 3D-THOR
LTS
z - Local Z-axis lower thoracic spine 3D-THOR
LTS
x - Local X-axis lumbar spine 3D-THOR
LS
y - Local Y-axis lumbar spine 3D-THOR
LS
z - Local Z-axis lumbar spine 3D-THOR
LS
6 PROOF/ÉPREUVE © ISO 2021 – All rights reserved
---------------------- Page: 11 ----------------------
ISO/TS 21002:2021(E)
Table 3 (continued)
Parameter Symbol Unit Definition/description Application
Distance D mm Design distance on zero-position fixture 2D
from 2D sensor origin to rib interface
Distance position 0 D
ZERO
centre in position-0, position-1, posi-
tion-2
Distance position 1 D
P1
Distance position 2 D
P2
Distance positions mm Design distance on zero-position fixture 3D
from origin O , O , or O to rib
UTS LTS LS
ZERO-L, ZERO-R, D
ZERO
interface centre in position ZERO, posi-
PZL, PZR, D tion PZ (L and R), position PY (L and R),
PZ
position PYZ (L and R)
PYL, PYR D
PY
PYZL, PYZR D
PYZ
Z-angle Θ degrees Design Z-angles on zero-position fixture 2D
Z
2D sensor origin to rib interface centre
Angle position 0 Θ
Z ZERO
in zero-position, position-1, position-2
Angle position 1 Θ
Z1
Angle position 2 Θ
Z2
Y-angle positions Θ degrees Design Y-angles on zero-position fixture 3D
Y
origin O , O , or O to rib interface
UTS LTS LS
ZERO-L, ZERO-R, Θ
Y ZERO
centre in position ZERO, position PZ (L
PZL PZR, Θ and R) , position PY (L and R), position
Y PZ
PYZ (L and R)
PYL, PYR Θ
Y PY
PYZL, PYZR Θ
Y PYZ
Z-angle positions Θ degrees Design Z-angles on zero-position fixture 3D
Z
origin O , O , or O to rib interface
UTS LTS LS
ZERO-L, ZERO-R, Θ
Z ZERO
centre in position ZERO, position +Z,
position +Y, position PYZ (L and R)
PZL PZR, Θ
Z PZ
PYL, PYR Θ
Z PY
PYZL, PYZR Θ
Z PYZ
Calibration range d mm Distance between starting and end point
E
of displacement calibration
Distance sensor output U V, LSB Distance sensor output
DC
Tubes-IN output U V, LSB Output at certain displacement with all IR-TRACC only
DC IN
floating tubes pushed IN
Tubes-OUT output U V, LSB Output at certain displacement with all IR-TRACC only
DC OUT
floating tubes pushed OUT
Linearization exponent EXP [-] Optimized linearization exponent IR-TRACC only
Linearized voltage U V IR-TRACC output to power of exponent; IR-TRACC only
LIN lin
calculated parameter
LSB
LIN
Distance sensor calibra- C mm/V and linear sensor mm displacement per Ratiometric sen-
DC
tion factor mm/LSB mm/ output sor
V
LIN
IR-TRACC mm displacement per line- IR-TRACC
mm/LSB arized output
LIN
Distance sensor sensi- S V/mm and linear sensor output per mm displace- Ratiometric sen-
DC
tivity LSB/mm ment sor
V /mm and IR-TRACC linearized output per mm IR-TRACC
LIN
displacement
LSB /mm
LIN
Angle sensor calibration C degrees/V/V Angle sensor degrees rotation at 1V out-
ANY
factor put per 1V excitation or degree rotation
C degrees/LSB
ANZ
per digital output
© ISO 2021 – All rights reserved PROOF/ÉPREUVE 7
---------------------- Page: 12 ----------------------
ISO/TS 21002:2021(E)
Table 3 (continued)
Parameter Symbol Unit Definition/description Application
Angle sensor sensitivity S V/V/degrees Angle sensor output per degree rotation
ANY
at 1V excitation or
S LSB/degrees
ANZ
digital output per degree
Angle sensor polarity P [-] The value can be either +1 or -1 2D-3D
Distance sensor Pos0 U V, LSB Distance sensor average output at zero 2D-3D
DC0
output position on Zeroing Fixture
Distance sensor Pos0 U V, LSB Distance sensor output at zero position IR-TRACC
DC0 IN
output tubes-IN tubes IN
Distance sensor Pos0 U V, LSB Distance sensor output at zero position IR-TRACC
DC0 OUT
output tubes-OUT tubes OUT
Distance sensor Pos1 U V, LSB Distance sensor output at position 1 2D
DC1
output
Distance Sensor Pos2 U V, LSB Distance sensor output at position 2 2D
DC2
output
Distance sensor output U V, LSB Distance sensor output at position PY 3D
DC PY
position PY
Distance sensor output U V, LSB Distance sensor output at position PZ 3D
DC PZ
position PZ
Distance sensor output U V, LSB Distance sensor output at position PYZ 3D
DC PYZ
position PYZ
Radius R mm Distance from O to rib interface 2D 3D
DC
rotation centre, see Figure 3. Distance
R
0
sensor output in mm at t , at t .
0 i
R
i
Radius Pos0 R mm Radius at zero position on zeroing 2D-3D
IO
fixture calculated using average IN-OUT
output
Radius Pos0 tubes-IN R mm Radius at zero position calculated using IR-TRACC
IN
tubes IN output
Radius Pos0 tubes-OUT R mm Radius at zero position calculated using IR-TRACC
OUT
tubes OUT output
Radius Pos0 R mm Radius at zero-position 2D-3D
ZERO
2D
Radius Pos1 R Radius at position-1
1
2D
Radius Pos2 R Radius at position-2
2
3D
Radius PY R Radius at position PY
PY
3D
Radius PZ R Radius at position PZ
PZ
3D
Radius PYZ R Radius at position PYZ
PYZ
Excitation U V Excitation voltage angle sensor during
EX
zero-position verification
Y-angle sensor output U V, LSB Y-axis angle sensor voltage 3D
ANY
Z-angle sensor output U V, LSB Z-axis angle sensor voltage
ANZ
Z-Angle output 0 U V, LSB Z-Angle sensor average output at posi- 2D & 3D
ANZ0
(ZERO) tion-0 (ZERO)
Z-Angle output 0-Near U V, LSB Z-Angle sensor output at position-0 pull 2D & 3D
ANZ NEAR
Near (3D away from spine)
Z-Angle output 0-Far U V, LSB Z-Angle sensor output at position-0 pull 2D & 3D
ANZ FAR
Far (3D towards spine)
8 PROOF/ÉPREUVE © ISO 2021 – All rights reserved
---------------------- Page: 13 ----------------------
ISO/TS 21002:2021(E)
Table 3 (continued)
Parameter Symbol Unit Definition/description Application
Z-Angle output 1 U V, LSB Z-axis angle sensor output at position-1 2D
ANZ1
Z-Angle output 2 U V, LSB Z-axis angle sensor output at position-2 2D
ANZ2
Z-Angle output PZR U V, LSB Z-Angle sensor output at position PZ 3D
ANZ PZ
Y-Angle output zero U V, LSB Y- Angle sensor average output at posi- 3D
ANY0
tion-zero
Y-Angle output ze- U V, LSB Y- Angle sensor output at position-zero 3D
ANY DOWN
ro-Down pull Down
Y-Angle output zero-Up U V, LSB Y- Angle sensor output at position-0 pull 3D
ANY UP
Up
Y-Angle output PY U V, LSB Y-Angle sensor output at position PY 3D
ANY PY
Y-Offset Angle φ degrees Y-angle sensor average offset between
OSY
extremes (Up-Down) when at fixture
zero-position
Z-Offset Angle φ degrees Z-angle sensor average offset between
OSZ
extremes (Near-Far) when at fixture
zero-position
Sensor Y-angle φ degrees Distance sensor angle along y-axis with
Y
respect to local orthogonal coordinate
φ
Y0
system, see Figure 3, and at t and at t .
0 i
φ
Yi
Sensor Z-angle φ degrees Distance sensor angle along z-axis with
Z
respect to local orthogonal coordinate
φ
Z0
system, see Figure 3, and, at t and at t .
0 i
φ
Zi
Distance intercept I mm Distance sensor offset in mm from coor-
DC
dinate system origin.
Distance intercept I V, V Calculated (linearized) output at 0mm
DCV LIN
voltage radius
LSB
LIN
Axis offset δ mm Mechanical offset distance between O 3D thoracic
DC
distance sensor origin and coordinate
system origin, see Figure 3.
Orientation angle φ degrees Orientation angle of 2D position sensor 2D
ORIENT
assembled inside dummy. For definition
see also Figure 4 and Table 1.
Reference angle φ degrees Orientation angle minus offset angle. For 2D
REF
definition see also Figure 4 and Table 1.
Time t s time
t time zero, start of the test
0
t time i
i
x coordinate x, x , x mm Feature interface rotation centre x-
0 i
coordinate, x at t , x at t , see NOTES of
0 i
Figure 1, Figure 2 and Figure 3.
y coordinate y, y , y mm Feature interface rotation centre y-
0 i
coordinate, y at t , y at t , see NOTES of
0 i
Figure 1, Figure 2 and Figure 3.
z coordinate z, z , z mm Feature interface rotation centre z-
0 i
coordinate, z at t , z at t , see NOTES of
0 i
Figure 1, Figure 2 and Figure 3.
© ISO 2021 – All rights reserved PROOF/ÉPREUVE 9
---------------------- Page: 14 ----------------------
ISO/TS 21002:2021(E)
Table 3 (continued)
Parameter Symbol Unit Definition/description Application
x deflection Dx mm Feature deflection in x direction at t
i i
y deflection Dy mm Feature deflection in y direction at t
i i
z deflection Dz mm Feature deflection in z direction at t
i i
Resultant deflection D mm Resultant deflection of the feature inter-
i
face centre at t
i
5 Sensor calibration
Individual angle and displacement or distance sensors are calibrated according to accepted standards
before conducting the zero-position verification procedure. (Recommended: calibrate non-linear
[3] [4]
Infrared distance sensor IR-TRACC according to ISO/TS 21476 and calibrate ratio metric distance
[5]
sensor according to ISO/TS 23521 ).
6 Procedures zero-position verification
6.1 General
This clause describes procedures to obtain reproducible data from multidimensional position sensors
on zero-position fixtures. Example sensors and fixtures are used in the procedures to describe the
method, but the procedures should also be applicable to other sensors and fixtures. The sequences for
2D and 3D zero-position verification are generally following the same principle.
6.2 Verification acceptance limits
The acceptance limits of the zero-position verification procedure are based on an uncertainty analysis
[6]
conducted according to procedures outlined in JCGM_100_2008 applying four components of
variation. The components identified are
a) variation introduced by the operator (assembly of the sensor on the fixture, system play in the
mountings),
b) imperfection of the sensor, like system play, friction and non-linearity,
c) voltage measurement uncertainty, and
d) manufacturing tolerances of fixtures.
To quantify the operator component of variation a round robin was conducted in 2018-2019, involving
one 2D sensor and fixture and one 3D sensor and fixture. The round robin included eleven qualified test
labs on three continents. The other three components of uncertainty, b), c), and d), were accounted for in
the uncertainty analysis based on the specifications of the equipment used. The total uncertainty was
calculated from the square root of the sum of squares of standard deviation, σ, of the four components,
and a multiplier of three was applied to define acceptance limits (3σ ≡ 99,7 % confidence limits). The
verification acceptance limits are defined based on these studies as follows:
— For angles: ±3 % of mechanical range of ±45°: ±1,35°. (Example max error: with distance sensor at
140mm radius, 1,35° corresponds to 1,35π/180 × 140 = 3,3mm);
— For distance: ±3 % of calibration range of distance sensor. (Example max error: calibration range
80mm, 3 % corresponds to 2,4mm).
10 PROOF/ÉPREUVE © ISO 2021 – All rights reserved
---------------------- Page: 15 ----------------------
ISO/TS 21002:2021(E)
6.3 Zero-position data collection
Zero-position verification data collection sequences are given in Table 4 for 2D sensors and Table 5
for 3D sensors. The sensors are connected to measurement systems according adequate and accepted
laboratory practise standards to measure the sensor outputs.
The zero-position verification procedure are conducted in a temperature controlled environment
between 20 °C to 25 °C.
A 120 s warm up time after powering the sensors is observed before data collection starts.
The sensor assembly are setup on the zero position fixture in its zero position. Measurements and
calculations are conducted according to the sequences given in Table 4 and Table 5 and formulae given
in 6.4. Measurements taken under conditions of controlled lateral loading to find the extreme sensor
offsets are conducted with a ballast 0,44 kg to 0,47kg; finally the rib interface are manipulated in
multiple positions to verify the sensor polarities and pass
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.