Three-dimensional measuring machines for
bodywork / assembly inspection.
Quantification of measurement uncertainty
EB40.69.135
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________________________________________
Standard
________________________________________
STATUS
EXECUTIVE
IMPORTANTE NOTE : This document has been translated from French. In the event of any dispute, only the
French version is referred to as the reference text and is binding on the parties.
Purpose
To define the uncertainty measurement quantification method to be applied upon:
Reception at the suppliers upon delivery at the stage: Delivery Technical Agreement (DTA),
Reception on the measurement site at the stage: End of Implementation Technical
Agreement (EITA),
Periodical verifications,
Verifications after interventions on the geometry of the machine,
Measurement machines:
Three-dimensional with orthogonal axes
Three-dimensional with central polar axes
designed for bodywork /assembly applications.
Three-dimensional measuring machines can be:
With horizontal arms, with a bridge, or with a gantry crane
Manual with digital controls
Stationary or mobile.
The specifications of the standard apply to reception and verifications, whether they be carried out
by internal personnel or subcontractors.
In the rest of the text, in order to avoid useless repetition, the term 3-D means is used instead of
three-dimensional measuring machine with orthogonal axes or central polar axes". When data
only applies to one type of machine with orthogonal axes or central polar axes) the machine type
of specified.
Field of application
Renault Group
Issuer
Confidentiality
67250
- Methods Design and Capitalization - Master Compliance and Process
Measures
Not confidential
Approved by
Function
L DIDIEZ
Manager of department 67250
RENAULT 2012
Signature
Origin: PEGI - Renault
Application date
07/2012
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EB40.69.135
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Version history
Version Update
A
F
01/1998
07/2012
Purpose of main modifications
Author
Creation
Update-Chapter 4.6: Acceptance criteria based on volume
measurement arm.
The main modifications are indicated by a vertical line.
J-M Le Bris
(1) M Davidou dpt 67250
JP Villot dpt 65306
M.Bentouati dpt 65306
Replaces
EB40.69.135 / E of 01/2011
Availability
Internally in Renault, on Intranet: http://gdxpegi.ava.tcr.renault.fr
Externally in Renault, on Internet: www.cnomo.com
E-mail:
norminfo.moyens@renault.com
Documents
mentioned
Regulations
International
European
French
CNOMO
Renault
DAM
Other external
documents
: ISO 10360-2.
:
:
:
:
: BMIR-V5805-2005-0007
:
Codification
ICS :
17.020 ; 17.040.30
Class
E40
Keywords
carrosserie, machine tridimensionnelle, mesure, contrle dimensionnel, 3d, incertitude de
mesure, mmt, capteur tactile, capteur optique (sans contact), bodywork, three dimensional
machine, measurement, dimensional check, uncertainty of measurement, touch probe,
optical probe (without contact)
Language
English
(1) Have participated in writing the document
Plant
Dept.
Name
TCR
68170
P. BOST
RENAULT 2012
Plant
Origin: PEGI - Renault
Dept.
Name
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EB40.69.135
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Table of Contents
Page
Preamble.................................................................................................................................... 4
1
Application rule for the standard ............................................................................................ 4
Principle of the quantification method ................................................................................... 4
3-D means with orthogonal axes............................................................................................. 4
3.1
Equipment used.......................................................................................................................................... 4
3.2
Recommendations for use ......................................................................................................................... 5
3.3
Preliminary operations................................................................................................................................ 5
3.4
Operating procedure .................................................................................................................................. 6
3.5
Processing of results .................................................................................................................................. 6
3.6
Acceptance criteria..................................................................................................................................... 9
3-D means with central polar axes........................................................................................ 10
4.1
Equipment used........................................................................................................................................ 10
4.2
Recommendations for use ....................................................................................................................... 10
4.3
Preliminary operations.............................................................................................................................. 10
4.4
Operating procedure ................................................................................................................................ 10
4.5
Processing of results ................................................................................................................................ 12
4.6
Acceptance criteria................................................................................................................................... 12
List of documents mentioned................................................................................................ 12
Appendix 1: Methodology of measurement ....................................................................................... 13
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Preamble
There are no directly applicable standard CNOMO for coordinate measuring machines used for the
control of body parts / assembly since the methodologies developed:
lead to lengthy trials,
do not provide a general indicator.
The standard ISO 10360-2 is not specific enough in terms of methodology and cannot therefore be
used.
Application rule for the standard
For 3-D means with orthogonal axes:
Reception by the supplier (DTA milestone)
Reception on the measurement site (EITA milestone)
Periodical verifications all verifications after interventions on the geometry of the machine
For 3-D means with central polar axes:
Reception by the supplier (DTA milestone)
Reception on the measurement site (EITA milestone)
Principle of the quantification method
The uncertainty of measurement is quantified from differences between the indications given by the 3-D
means in the value showed by the standard (reference distances). This is materialised by using the entire
measuring system (detector, measurement software, piloting software for 3-D means with digital control
and compensation software, etc.)
This method is to be applied:
Upon reception on the suppliers site
Upon reception at the measurement site
During recommended monitoring operations.
3-D means with orthogonal axes
3.1
Equipment used
Measure equipment with touch probe: The standard used is a simple notched ruler c, commonly
called notched ruler,
y Measure equipment with optical probe (without contact): The standard used is a double notched
ruler d, commonly called general-purpose notched ruler. Indeed this rule is appropriate for
the two kinds of probes.
Whatever the type of rule used, that is positioned in the measurement space of the 3-D means.
The use of a pivoting support helps maintain the ruler in place.
y
Notch for optical
probe
c Simple notched ruler(touch probe)
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Notch for touch
probe
d Double notched ruler (touch and optical probe)
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3.2
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Recommendations for use
Whatever the type of rule, this one is held as still as possible on the BESSEL points in order to minimise
bending (see diagram 1, example with simple notched ruler).
Diagram 1: Position of the notched ruler
The notched ruler must have been calibrated less than 24 months previously, by a metrological
department (* approval for measure), (e.g.: metrological department in Renault Technocentre).
The stability of the ruler mounted on its support is visually verified.
3.3
Preliminary operations
In all cases, the normal equipment of the means is conserved for the quantification of measurement
uncertainty.
3.3.1
On reception
Environmental conditions must comply with the specifications. The value or values noted will be written
down during verification.
The 3-D means equipment must comply with construct specifications and notably geometric conformity
that deals with:
Straightness and perpendicularity
Positioning errors
Evenness of the plate or the post
In the event of a DUPLEX reference configuration, the two machines must have been made parallel
and checked beforehand by the supplier and the results written down in the supplied inspection
report.
(*) It should be made sure that the metrological service has the technical skills and material which make it
possible to carry out the calibration (ex: uncertainty of calibration << uncertainty of the need)
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3.3.2
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Periodical verification and verification after intervention on the geometry of the machine
The temperature must be within the range specified for the 3-D means concerned.
If periodical verification happens following changes to bring about geometric compliance of the 3-D
means, the supplier presents an inspection report that shows the geometric parameters affected by the
new rules.
3.4
Operating procedure
The ruler is placed in a central position and is lined up in turn with the 4 diagonals of 3-D means.
Number of diagonals: d
Diagram 2: Position of the notched ruler in the effective volume
Positioning of the ruler in the
volume (see marker on the ruler
diagram 3.2)
AA
D4
D1
D3
D2
For each diagonal, by defining an origin 0 of the ruler, we measure 5 other notches in order to define 5
distances. The choice of notches is dictated by the measurement capacity of the 3-D means
Number of notches: i
The measurement of notches withheld is repeated a second time as per the following operating
procedure:
1st measurement from notch 0 to notch i
2nd measurement from notch 0 to notch i
Number of measurements per notch: m = 2
On the 3-D means whose measurement capacity on X is greater than 2 m, we repeat the measurements
mentioned above by moving the ruler + support unit following the X axis in order to cover at least of the
measurement volume. In this event the new effective volume is defined by the parameter P.
Number of positions: p
The processing of measurement results is carried out on PC software, whose formulas of computation
have been validated by the service 67250.
3.5
Processing of results
The following recommendations are valid for 3-D means with orthogonal axes and those with central polar
axes.
The approval criterion of the 3-D means is the uncertainty of measurement in the volume. Its threshold
value,
Ig max., is pointed our in paragraphs 3.6 and 4.6, unless specifically mentioned in specifications.
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3.5.1
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Prerequisite calculations by position
Calculation of deviation by measurement and by notch for a given diagonal
dim
(Xd,i, m - Xi Ref )
Xi Ref = Reference value engraved on the notched ruler (updated at each ruler calibration).
Average accuracy deviation per notch
Evaluation of the systematic average error of the 3D machine in all measurement conditions.
J=
d =1
(d , i, m)
2 D
Calculation of precision variation (on the m = 2 measurements)
The number of measurements being equal to 2, the standard precision deviation is estimated from the
spread.
2
(
X
d,i,1 - X d,i,2 ) W d , i
=
=
2
2
d ,i
Xd, i, 1 :
First measurement on notch i,
Xd, i, 2 :
Second measurement on notch i,
Wd, i :
Spread of measurements on notch i.
Standard precision deviation per notch
Evaluation of the faculty of the 3-D machine to give the same reading without changing the measurement
conditions:
Same position in the space
Same acquisition conditions
The standard precision deviation f i is obtained by:
f i =
D
f 2 d ,i
d =1
d
Standard repeatability deviation per notch
Evaluation of the faculty of the 3-D machine to give the same reading by changing the measurement
conditions:
Position in the space,
Acquisition conditions
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The standard repeatability deviation ri is obtained by:
d ,i,m - Ji
r =
2 D -1
3.5.2
Calculation of the uncertainty of measurement by position
It is determined with the criteria for accuracy, precision, and repeatability and furthermore, it is calculated
for each notch measured.
All of the results allow, for each notch (i), the calculation of:
An average accuracy deviation
A standard repeatability deviation
A standard precision deviation
i
i
f i
The incertitude of the notched ruler is negligible in the calculation of global incertitude:
3.5.3
Notch number
Diagonal number
Number of measurements per notch.
Uncertainty of measurement per notch and by position
It is obtained by
Igi =
+ 2
(f i + ri )
2
To facilitate reading and interpretation of results, a summary table must be drawn up.
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3.5.4
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Analysis of results table
1
2
3
4
5
6
POSITION 1
NOTCH
0
399.935
799.929
1199.936
1499.947
1799.953
Diagonal 1
Mes1 Mes 2
-0.028 -0.018
-0.037 -0.030
-0.022 -0.029
0.010 0.015
0.051 0.058
0.086 0.080
Diagonal 2
Mes1 Mes 2
0.007 0.011
-0.014 -0.002
-0.011 -0.006
-0.001 0.004
0.002 0.080
0.009 0.014
Diagonal 3
Mes1 Mes 2
-0.031 -0.031
-0.056 -0.070
-0.041 -0.058
-0.031 -0.042
-0.051 -0.034
-0.036 -0.046
Diagonal 4
Mes1 Mes 2
-0.020 -0.032
-0.016 0.001
0.023 0.042
0.076 0.089
0.097 0.097
0.113 0.125
Acc.
-0.018
-0.028
-0.013
0.015
0.038
0.043
Prec. Repet. Ig
0.005 0.017 0.054
0.008 0.025 0.081
0.009 0.033 0.080
0.006 0.046 0.108
0.025 0.058 0.164
0.006 0.067 0.177
1
2
3
4
5
6
POSITION 2
NOTCH
0
399.935
799.929
1199.936
1499.947
1799.953
Diagonal 5
Mes1 Mes 2
0.011 0.005
-0.005 -0.001
-0.011 -0.019
-0.031 -0.044
-0.042 -0.062
-0.055 -0.072
Diagonal 6
Mes1 Mes 2
0.019 0.019
0.022 0.019
0.004 0.004
0.040 0.040
0.069 0.076
0.087 0.088
Diagonal 7
Mes1 Mes 2
0.015 -0.008
-0.018 -0.017
-0.039 -0.045
-0.047 -0.046
0.003 0.002
0.041 0.030
Diagonal 8
Mes1 Mes 2
0.022 0.011
0.031 0.049
0.049 0.032
0.055 0.058
0.068 0.070
0.084 0.092
Acc.
0.012
0.010
-0.003
0.003
0.023
0.037
Prec. Repet. Ig
0.009 0.010 0.039
0.007 0.024 0.060
0.007 0.033 0.070
0.005 0.049 0.101
0.008 0.055 0.135
0.008 0.066 0.170
The value of the standard precision deviations per notch gives a good indication of:
The quality of the measurement on manual 3-D machines
The quality of servo-control on digital control 3-D machines
If the position number (p) is > 1, verify the homogeneity of results. The deviation between Ig max
observed on (p) positions must not exceed 0.05 mm.
3.6
Acceptance criteria
The maximum global incertitude withheld is:
Ig max. = maximum value of Igi calculated whatever the notch
Unless specific specifications are made to specifications, the 3-D means is accepted if, across all of the
notches and all of the positions:
Ig max. 0.2 mm
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3-D means with central polar axes
4.1
Equipment used
/F
See paragraph 3.1.
Nota: In the absence of suitable support, magnetic Vs and towers hold the ruler in place.
4.2
Recommendations for use
See paragraph 3.2.
4.3
Preliminary operations
The following must be checked:
4.4
The verification report given by the supplier of the polar axis means
Initialisation of the measure equipment (Example: visualisation on the screen, indication
variations of encoders in relation to a movement of the arm).
Operating procedure
For the polar equipments, other that poly-articulated arms, (example: tracker, scanner, ) please refer to
the useful zone of measurement recommended by the supplier.
4.4.1
Standard conditions for poly-articulated arms
The polart axis (or poly-articulated) arm is positioned on a tripod (e.g.: BRUNSON tripod model 231), so
that the pivoting base is located at height h1, as defined in the diagram below. 4 ruler positions (4
diagonals) that enable the best evaluation possible of the different encoders across all of the arm
measurement range are considered. Depending on the capacity of the polar axis 3-D means
(measurement sphere), the notched ruler is positioned following the diagram below and the distances that
are indicated in table 1:
Diagram 3: Positioning of the notched ruler and the poly-articulated arm
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Table 1: Ruler positioning value in relation to the polyarticulated arm
Polar arm
with a
spherical
diameter of
2900
Polar arm
with a
spherical
diameter of
> 2900
Ruler
position
h1
h2
X1
X2
X3
45
760
450
- 45
90
760
450
180
760
200
400
90
270
760
300
45
760
600
- 45
90
760
600
180
760
200
550
90
270
760
450
Notes:
: Angle of inclination of the ruler in respect to the horizontal plane
: Angle of rotation of the pivoting base of the arm between each position of the ruler
h 1 : Height of the pivoting base in respect to the plane of the plate
h 2 : Height of the ruler in respect to the plate for position 3
X1, X2, X3: Distance between the face of the notched ruler and the axis of the pivoting base.
If we consider the position of the polar axis arm in the centre of the base of a cube, the ruler is:
Either always positioned in a vertical plane that is parallel to the same side of the cube. In this
case, for each new position of the ruler, we must pivot the pivoting base of the polar axis arm by
an angle of +90 in relation to the previous position. ( gives the angular rotation value of the arm
in relation to a fixed point taken from the first position of the ruler)
Or is positioned in a vertical plane parallel to the side of a cube that is different for each ruler. In
this case, the polar axis arm remains in a fixed position (the value of angle indicated in the table
corresponds to the change of side of the cube for the successive positions of the ruler).
The choice is up to the operator, depending on which systems seems the most practical under the
circumstances..
Number of diagonals: d = Number of ruler positions = 4
For each diagonal, by defining an origin 0 for the ruler, we measure five other notches in order to define
five distances. The choice of notches is dictated by the measurement capacity of the 3-D means (see
recommendations below).
Number of notches: i
The measurement of notches withheld is repeated twice as per the following operating procedure:
2nd measurement from notch 0 to notch i
1st measurement from notch 0 to notch i
Number of measurements: m = 2
4.4.2
Specific conditions
For the 3-D means with central polar axes that are fitted with sensors with fixed stops (older
generations of appliance), a specific derogation allows the application of the following method:
The measurement of each notch is repeated successively twice taking care to miss the sensor by around
20 mm between the two measurements.
Order of measurements:
1st measurement Notch 0 then 2nd measurement Notch 0
1st measurement Notch i then 2nd measurement Notch i
Number of measurements: m = 2
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4.4.3
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Recommendations for the choice of notches
y
Touch probe
o of the measurement sphere 2000, notches: (0 ; 300 ; 600 ; 900 ; 1200 ; 1500),
o
of the measurement sphere 2200, notches: (0 ; 300 ; 700 ; 1000 ; 1400 ; 1700),
of the measurement sphere 2500, notches: (0; 400 ; 800 ; 1100 ; 1500 ; 1800). This
recommendation is also applied for other means (Tracker, etc).
Optical probe (without contact for all equipment)
o
Initial point 0,00
Notches 200; 600; 1000; 1400; 1700 (notch with 2 slopes)
The processing of measurement results is carried out by using PC software whose formulas of calculation
have been approved by the service 67250.
4.5
Processing of results
See paragraph 3.5.
4.6
Acceptance criteria
(See DISPLEASURE N BMIR-V5805-2005-0007)Unless specific specifications have been written in the
specification document, the polar axis3-D means is accepted if:
Ig max. 0.15 mm
Comments:
1. The measurement reference is determined on the notched ruler with the help of 6 points (see
appendix 1). A good definition of the reference is seen during the measurement of notch zero that
must indicate a deviation of < 0.05 mm compared to the real value.
2. For new poly-articulated arms the global uncertainty is:
- With tactile sensor
Ig max.< 0.10 mm if of measure < in 2500 mm.
Ig max.< 0.12 mm if in 2500 mm of measure 3000 mm.
Ig max. 0.15 mm if of measure > in 3000 mm.
- With optical sensor
Ig max.< 0.13 mm if of measure < in 2500 mm.
Ig max.< 0.15 mm if: 2500 mm of measure 3000 mm.
Ig max. 0.20 mm if of measure > in 3000 mm
(see MAF n BMIR-V5805-2005-0007)
List of documents mentioned
NOTE: For undated documents, the latest version in force applies.
ISO 10360-2
Geometrical Product Specifications (GPS) - Acceptance and
reverification tests for coordinate measuring machines (CMM) - Part 2 :
CMMs used for measuring linear dimensions.
BMIR-V5805-2005-0007 : Measurement Assurance File - Manual three-dimensional geometry
measurement machine CN & Polyarticulated arms.
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Annex 1 normative
Appendix 1: Methodology of measurement
1.
Geometrical reference of the rule
Point 2
Point 5
Point 6
Point 4
Point 1
Point 3
For measurement with optical probe, we carry out measurement of small plans at the same areas
2.
Positions of measurements on the notches
Measure point
Measured point
Measured point
Z
Y
X
e
Face A
h/2
h/2
e/2
Calculated point
Notch used for optical probe
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Notch used for touch probe
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