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Guide to the 3 D pattern fitting in coordinate metrology

Abstract

The guide provides a comprehensive overview to the application of 3D hole pattern fitting in coordinate metrology. Its focus is the development of mathematical models for a simulation of product assembly. Inspection tasks of workpieces with Maximum material condition according to the international standard ISO 2692 are subject to these models. Among general recommendations, the guide provides detailed informations for three example application. These are the fitting of flange rings with associated datum systems, the fit of mixed patterns with cylinder elements and pairs of planes as well as the general 3D fit of non parallel cylinder patterns.

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Guide to the 3 D pattern fitting in coordinate metrology

Author: Hutzschenreuter, Daniel
Publisher: Physikalisch-Technische Bundesanstalt (PTB)
Year: 2017
DOI: 10.7795/530.20170606EN
Source: https://oar.ptb.de/files/download/681c518053218de84f08e6c6
Physikalisch-Technische Bundesans al
Na ional Me ology Ins i u e
Guide o 3 D pa e n i ing
in coo dina e me ology
Ve sion 1 | 2017-05-23
DOI 10.7795/530.20170606EN
Physikalisch-Technische Bundesans al B aunschweig u. Be lin
Guide o 3D pa e n i ing in coo dina e me ology
1
Guide
To 3 D pa e n i ing in coo dina e me ology
Ve sion 1
2017-05-23
Table o Con en s
1. In oduc ion ..................................................................................................................................... 2
2. Gene al Requi emen s .................................................................................................................... 4
2.1. Hole pa e n i in s anda diza ion .......................................................................................... 4
2.2. De e mina ion o he CAD pa ame e s o gauging ................................................................ 6
2.3. Deg ees o eedom o i ing and da um ea u es................................................................ 8
2.4. Gauging wi h coo dina e measu emen sys ems .................................................................... 8
2.5. In luence o measu emen unce ain ies on he i ing esul .............................................. 14
3. Applica ion example 1: langes ..................................................................................................... 15
3.1. Inspec ion acco ding o he s anda d ........................................................................................ 15
3.2. Ma hema ical modelling o da um ea u es and i ing ........................................................... 17
3.4 Gene aliza ion o he es ask o he simula ion o assembly .................................................. 25
4. Applica ion example 2: conical discs ............................................................................................. 26
4.1. Inspec ion acco ding o he s anda ds .................................................................................. 27
4.2. Ma hema ical model o da um c ea ion and i .................................................................... 28
5. Applica ion example 3: cubes ........................................................................................................ 35
5.1. Inspec ion acco ding o he s anda d ................................................................................... 37
5.2. Ma hema ical model o he 3D hole pa e n i .................................................................... 37
5.3. Gene aliza ion o he inspec ion ask o he simula ion o assembly .................................. 41
Re e ences ............................................................................................................................................. 42
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1. In oduc ion
Physical gauges a e e y impo an o he inspec ion o p oduc s, as hey we e al eady used p io o
he de elopmen o ini ial coo dina e measu ing machines (CMM). The inspec ion p inciple is called
he Taylo p inciple. The gauge used – also called unc ional gauge [1] – consis s o wo pa s. A go
gauge de e mines he maximum pe missible limi de ia ions o he shape o p oduc ea u es. Fo
he inspec ion o a hole, his is, o example, a cylind ical gauge pin which is o be en i ely inse ed in
he manu ac u ed hole. I he pin ge s jammed du ing inse ion, he hole is a ejec . The second
ea u e o gauging is he no-go gauge. Wi h his ea u e, local measu es a e inspec ed o
pe missibili y, in con as o he go gauge. Fo holes, his includes pins o he inspec ion o maximum
pe missible wo-poin measu es o he hole's inne su ace. In a simila way, snap gauges a e used o
he inspec ion o sha s. The inspec ion by means o unc ional gauges is no limi ed o indi idual
geome ic elemen s, bu can also include pa e ns o se e al unc ional ea u es o one p oduc .
In mode n p oduc ions, he componen s o se e al p oduc s a e usually manu ac u ed a di e en
si es o by supplie s. The pe missible shape de ia ions o wo kpieces a e ag eed upon by means o
echnical d awings wi h ole ance ames in acco dance wi h he ISO s anda ds 1101 [2], ASME
Y14.5M [3] o o he speci ic in-house s anda ds. The ease o assembly o he componen s can be
ensu ed la e on, only i he ole ances in he echnical d awings a e in e p e ed in a consis en
manne by he clien and by he supplie . The e o e, a p oduc ion which is adap ed o he unc ion
indispensably equi es he inspec ion o he i ing capabili y p io o he assembly. This p oblem is
illus a ed by he lange in Figu e 1.
Figu e 1 Ou line o he assembly equi emen s o a lange connec ion wi h a bol .
Figu e 1 shows a lange wi h 16 equidis an holes. This lange is o be connec ed wi h a second
lange ia indi idual bol s in he o m o sc ews. I is e iden ha he indi idual bol s o di e en
diame e s i in o he appu enan holes. Howe e , lange connec ions equi e all bol s o i in o he
appu enan holes a he same ime. The igh side o he igu e makes he p oblem e en mo e
ob ious, as holes and he appu enan bol s can also be skew o each o he . Gene ally, all shape
de ia ions o he p oduc s ha e an in luence on he i ing capabili y. This includes size, o m and
posi ion de ia ions. I he equi emen s on accu acy a e e y high, in luences by ipple and oughness
o he wo kpiece su ace a he ma ing su aces mus also be aken in o accoun .
The implemen a ion o gauging ia CMMs is gene ally called " i ual" o a i hme ical gauging.
He e, he physical unc ional gauge is eplaced by a CAD model. The CMM is also used o measu e
he wo kpiece su ace by p obing a ini e numbe o poin s wi h he CMM. These da a a e also
e e ed o as ex ac ed wo kpiece geome y. Finally, he i ual gauging is implemen ed by he
p ocedu e o he 3D i ing o hole pa e ns be ween he ex ac ed geome y and a CAD model o he
gauge. The eby, he e m "hole pa e n" e e s o he 3D elemen s o size "cylinde " (hole, sha ) and
pai s o pa allel planes (slo , oung).
When i ing and associa ing single geome ic elemen s, he e is a wide ange o s anda ds o a
uni o m speci ica ion o p ocedu es, obus e e ence algo i hms and es s o indus y ([4], [5]). In
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con as o his, he geome ic i ing wi h se e al elemen s in he o m o hole pa e ns and he 3D
i ing o hole pa e ns ha e ha dly been uni o mly documen ed and egula ed by s anda ds wi h
ega d o me ological and compu ing p ocesses. Al hough d awing speci ica ions a e de ined o he
ole ancing o he 3D hole pa e n i in ISO s anda diza ion o geome ic p oduc speci ica ion
(GPS), he necessa y s anda d pa s o he implemen a ion in a uni o m es p ocedu e a e lacking
en i ely. Guidelines on he co ec use o di e en senso s o he me ological de ec ion o
measu emen poin s a e equi ed, so ha he highes poin s o he elemen s conside ed a e e y
likely o be measu ed. They a e signi ican o he calcula ion o he quan i ies and hus o he
quali y and eliabili y o p oduc inspec ion. Wi h his backg ound, op ical and CT measu emen
p ocedu es a e o pa icula impo ance o he 3D i ing o hole pa e ns ia i ual gauging, as hey
a e sui able o de ec he en i e su ace o a p oduc e y apidly. Howe e , a la ge pa o oday's
exis ing s anda ds is only designed o ac ile senso s which gene ally de ec a p oduc su ace much
mo e slowly.
Mos o he inspec ion asks which a e deal wi h by physical gauging o a i hme ical gauging wi h
se e al geome ic elemen s e e o he ole ancing acco ding o ISO 2691 [6]. This s anda d speci ies
he maximum ma e ial condi ion (MMC) and leas ma e ial condi ion (LMC) o componen s. The
guideline o he applica ion o he s anda d is ha a manu ac u ed wo kpiece mus be able o ma e
wi h a coun e pa de ined by d awing speci ica ions. The implemen a ion o he inspec ion by MMC
and/o LMC in a simula ion o assembly is no documen ed. Consequen ly, li e a u e p o ides
di e en app oaches (e.g.: [7], [8], [9]) o a i hme ical hole pa e n i . The di e si y o he
algo i hms is also e lec ed in he measu ing machine so wa e. Solu ions by a ious manu ac u e s
a e incompa ible i di e en algo i hms a e used o i he p ocedu es o be used ha e no been
de e mined in he o e on . The gene al co ec p ocedu e is he i ing wi h all measu emen poin s
o he i ual coun e pa . Fu he mo e, e y la ge da a se s occu in s a e-o - he-a coo dina e
measu ing sys ems using mul i-senso echnology, op ical- ac ile measu ing senso s o also CT
measu ing sys ems. I , o easons o e iciency, he so wa e eaches i s limi s o economic bene i ,
il e s a e o en used o educe he measu emen da a p io o he e alua ion. In addi ion o he
i ing algo i hm, hey also ha e an in luence on he measu emen esul s du ing hole pa e n i . The
ask o his Guide o 3D hole pa e n i ing is he use -o ien ed p esen a ion o inspec ion p ocesses
o he a i hme ical simula ion o assembly wi h i ual gauging. The eby, he undamen al
equi emen s o classical physical gauging acco ding o ISO 1101 a e ans e ed o coo dina e
me ology and ecommenda ions o a so wa e-based implemen a ion a e p esen ed. Va ious
coo dina e me ology sys ems wi h di e en senso s a e conside ed. P oduc measu emen s wi h
dimensional compu e omog aphy (CT) a e o special in e es , as hey allow he en i e p oduc
su ace o be e icien ly ex ac ed. Apa om he desc ip ion o a gene al p ocedu e in Sec ion 2, he
ecommenda ions also comp ise de ails o h ee special applica ion examples. The i s example is a
lange which, e.g., has o be manu ac u ed du ing he cons uc ion o wind engines. This lange is
p esen ed in Sec ion 3. Based on a echnical d awing in which se e al pa allel holes ha e a common
posi ion ole ance wi h maximum ma e ial condi ion, a o a o y hole pa e n i ia cylinde s is
desc ibed. In he sense o he ISO GPS s anda diza ion, a geome ic ideal da um sys em is a ibu ed
o he lange which de e mines a o a ion axis o he gauge o i ing.
In addi ion, Sec ion 4 deals wi h asks whe e miscellaneous geome ic elemen s a e i ed
simul aneously. The example which is p esen ed he e is a conical disc wi h a slo consis ing o pa allel
planes and se e al pa allel holes. A da um is also a ailable. The hi d applica ion example in Sec ion 5
speci ies he i ing o a gauge made o cylinde elemen s in se e al holes in a cube whose axes a e
pe pendicula o each o he . He e, he case o a ee i will be conside ed, i.e. da um ea u es which
limi he i ing o he gauge geome y a e no speci ied.
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2. Gene al Requi emen s
The 3D hole pa e n i is used o he inspec ion o speci ic o m and posi ion ole ances o
unc ional p oduc ea u es. This mainly includes he inspec ion o comple e geome ies wi h
a i hme ical gauging.
In addi ion, he e is a whole ange o u he applica ions whe e in eg al geome ic elemen s, e.g.
axes o median planes, can also be inspec ed acco ding o he o mal p inciples o 3D hole pa e n i .
These p inciples a e e e ed o in a la e sui able sec ion o his Guide. Howe e , his will no be
deal wi h in g ea e de ail as he necessa y p ocedu es and equi emen s o he inspec ion a e
su icien ly co e ed by he s anda diza ion o can simply be aken o e by a i hme ic gauging.
In Subsec ions 2.1, 2.2 and 2.3, he mos impo an equi emen s placed on he hole pa e n i
a e p esen ed which mus be ul illed when applying he ISO 1101 and ISO 2962 s anda ds. The
p inciple in e p e a ion and supplemen o hole pa e n i ing o coo dina e me ology a e shown in
Sec ion 2.4. I also includes equi emen s placed on he e alua ion so wa e and ele an nume ical
p ocedu es. Finally, Sec ion 2.5 deals wi h he measu emen de ia ions occu ing du ing 3D hole
pa e n i . These measu emen de ia ions a e signi ican o he consis ency o inconsis ency
be ween a i hme ical gauging and an inspec ion du ing eal physical gauging.
2.1. Hole pa e n i in s anda diza ion
The subsequen conside a ions s a wi h he echnical d awings o p oduc s whe e he ole ancing
acco ding o he ISO 8015 [10] p inciple has been inse ed. He eby, he applica ion o ISO 1101 and
all a ibu ed indi idual s anda ds will be implied o he inspec ion o ole ances. The examples
gi en in Figu es 2-1 and 2-2 show a pla e wi h wo holes ha a e ole a ed in ou di e en ways. Fo
each example, a 3D hole pa e n i will be used o inspec ion.
Figu e 2-1 (le ) (Example a) shows a posi ion ole ancing o he median lines o he holes.
DIN EN ISO 14660 Pa 2 [11] egula es he p ocedu e o he ex ac ion o hese lines o cylind ical
geome ic elemen s. The ole ance ame is used o de ine wo cylind ical ole ance zones which a e
ep esen ed below he echnical d awing. These cylind ical egions ha e an ideal shape. Thei axes
a e pa allel wi h a nominal dis ance o 20 mm. In addi ion, bo h cylinde s a e o hogonal o he
da um plane A. When inspec ing he pla e, i s he la e al su ace A and he holes a e ex ac ed in
o de o a ibu e he da um su ace and he median lines o he holes. Du ing i ing, he ole ance
zones a e allowed o be shi ed along he planes A and o be o a ed o hogonally o A. The
wo kpiece is pe missible i bo h median lines a e wi hin he ole ance zones a he same ime. As he
median lines o he holes a e cons uc ed, i.e. a e no a ailable as di ec ly measu able geome y a
he manu ac u ed p oduc , he inspec ion can only be ca ied ou by means o a i hme ical hole
pa e n i .
Example b) (Figu e 2-1, on he igh ) inspec s he posi ion o he holes acco ding o he maximum
ma e ial condi ion. This has been speci ied wi h he aid o he d awing speci ica ion Ⓜ which is
di ec ly behind he alue o he posi ion’s ole ance. No ma i ely, he equi emen s o he
inspec ion ia MMC a e egula ed in ISO 2962. Nex , he pla e mus be i able by means o a
geome ically ideal coun e pa which is shown below he enginee ing d awing. The coun e pa is
composed o a le el con ac plane. Two bol s a e o hogonal o he con ac plane. The axes o he
bol s ha e he nominal dis ance o he holes and a e pa allel. The bol diame e o 4.9 mm is
calcula ed on he basis o he lowe size limi o a 5.0 mm hole and he posi ion ole ance. The
inspec ion aims o e i y whe he he holes o he pla e lie wi hin he admissible ole ance. Physical
gauging as well as a i hme ical gauging can be applied. Fo he a i hme ical hole pa e n i , he le el
con ac su ace o he gauging is aligned o he da um su ace A o he pla e and/o an ideal plane is
assigned. A he same ime, he wo bol s o he gauge mus i in he holes o he pla e.

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Figu e 2-1 Two examples o ole ancing a pla e wi h wo holes. The i ual inspec ion o he
ole ances p esupposes he 3D hole pa e n i in bo h cases (Tole ance p inciple ISO 8015).
Se e al p oduc s ha e speci ic unc ional equi emen s. In hese cases, da um elemen s wi h he
speci ica ion Ⓜ o he MMC a e also occasionally en e ed in d awings. Figu e 2-2 shows wo
examples o his.
Figu e 2-2 Tole ances wi h da um ea u es including d awing speci ica ions Ⓜ.
In example c), he con ac su ace A is he p ima y da um. The le hole is de ined as seconda y
da um B. The igh hole has a posi ion ole ance wi h he speci ica ion Ⓜ o he ole ance zone and
he da um B. The o m o hole B o i s o ien a ion o A is no ole a ed. Fo his eason, he quan i ies
a e neglec ed du ing he ole a ion. The compliance wi h he ole ance can be inspec ed again by
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classical physical gauging o a i hme ical hole pa e n i . The nominal geome y o he go gauge
assigned o i consis s o a plane which is aligned o he da um su ace A. On his da um su ace, a
gauge cylinde o he da um B is loca ed ha ing a diame e o 5.0 mm which is he lowe size limi o
he da um hole. The second gauge cylinde has a diame e o 4.4 mm which esul s om he lowe
limi o he hole minus he posi ion ole ance. I s ands o he posi ion o he hole. Bo h cylinde s
a e o hogonal o Plane A and hei axes ha e he nominal dis ance o 20 mm. The classical
inspec ion wi h physical gauging and he hole pa e n i in coo dina e me ology can be applied in
he example.
Example d) in Figu e 2-2 shows ha da um elemen s wi h he speci ica ion Ⓜ can be iden i ied o
he MMC, bu ha he ole a ed elemen will no be inspec ed acco ding o he MMC. These d awing
speci ica ions only occu in a e applica ions. The inspec ion o he ole ance equi es an a i hme ical
3D hole pa e n i as he ex ac ed median line a he ole a ed elemen does no exis a he eal
p oduc as di ec ly measu able geome y. A gauge cylinde in da um hole B and he cylind ical
posi ion ole ance zone o he median line will be i ed oge he o his pu pose. The cylind ical
ole ance zone has a diame e o 0.1 mm. The gauge pin has a diame e o 5.0 mm ( he lowe size
limi o he da um hole). The bol s and he ole ance zone o he ex ac ed axis a e o hogonal on
he da um plane A. The axes o gauge bol and ole ance zone o he median line ha e a nominal
dis ance o 20 mm.
In each o he ou examples shown, he 3D hole pa e n i o ole ance inspec ion has h ee
deg ees o eedom. They include wo o hogonal ansla ions and one o a ion wi hin he da um
su ace A.
Fu he explana ions e e o applica ions wi h he d awing speci ica ion Ⓜ o posi ion ole ances
and da a. The ollowing basic equi emen s apply o he co ec applica ion o d awing speci ica ions
acco ding o ISO 2962.
 Only o m and posi ion ole ances can be supplemen ed by he speci ica ion Ⓜ.
 Tole ances and da um elemen s wi h he speci ica ion Ⓜ mus e e o in eg al geome ic
elemen s om elemen s o size, such as he axis o a cylinde o o he median plane o a
slo .
 Fu he elemen s o size include sphe es and – in he wo-dimensional case – ci cles and
pai s o pa allel lines. In his con ex , cones and wedges a e no elemen s o size.
 Da um ea u es can be supplemen ed by he speci ica ion Ⓜ. In he case o da um sys ems,
indi idual da um elemen s can occu wi h and wi hou he speci ica ion Ⓜ, as long as a Ⓜ
elemen is no ollowed by an elemen which is no iden i ied by Ⓜ a he e alua ion
sequence acco ding o he d awing speci ica ion wi hin he ole ance (jus i ica ion acco ding
o ISO 5459 [12] o da um e alua ion – uniqueness equi emen ).
2.2. De e mina ion o he CAD pa ame e s o gauging
The de e mina ion o go gauge geome ic pa ame e s is ele an o he hole pa e n i ing. This
means ha he CAD model o a geome ically ideal coun e pa mus be cons uc ed and
manu ac u ed as co ec ly as possible. When inspec ing he i ing capabili y, an a emp is made o
i his pa in o he p oduc wi hou jamming. In Figu e 2, hese gauges a e shown as ske ches in he
lowe pa o he pic u e, using he elemen a y example o he hole pla e.
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When de ining geome ically ideal coun e pa s o gauging acco ding o ISO 2692 in he case o
d awing speci ica ions nume ous ules mus be conside ed. The c ea ed ideal geome ic elemen s
which o m a CAD model o a gauge a e deno ed as maximum ma e ial i ual condi ion (MMVC).
The size o a geome ic elemen o he gauge is e e ed o as maximum ma e ial i ual size (MMVS).
Size, o m and posi ion ole ances can be equally in eg a ed in he calcula ion o he MMVS. The
ollowing hand ules can be applied o he de e mina ion o he pa ame e s equi ed o he
cons uc ion o he gauge:
 Gauge geome y o o m and posi ion ole ances wi h Ⓜ
o Ex e nal elemen s o size (sha , oung):
The MMVS o he gauge geome y will be o med as sum om he uppe size
limi o he ole a ed geome ic elemen Go and he ole ance o he o m o
likewise posi ion de ia ion .
MMVS = Go +
o In e nal elemen s o size (hole, slo ):
The MMVS o he gauge geome y will be o med as a di e ence om he
lowe limi o he ole a ed geome ic elemen Gu and he ole ance o o m
o likewise posi ion de ia ion .
MMVS = Gu -
 Gauge geome y o da um elemen s wi h Ⓜ
o Ex e nal elemen s o size (sha , oung):
 The MMVS o he gauge geome y is he uppe size limi Go o he da um
elemen o negligible o m de ia ions.
MMVS = Go
 I he da um elemen has an addi ional o m o posi ion ole ance ( ole ance
alue e e ed o as ) i mus be aken in o accoun o he MMVC o he
da um elemen .
MMVS = Go +
o In e nal elemen o size (hole, slo ):
 The MMVS o he gauge geome y is he lowe size limi Gu o he da um
elemen o negligible o m de ia ions.
MMVS = Gu
 I he da um elemen has an addi ional o m o posi ion ole ance ( ole ance
alue e e ed o as ) i mus be aken in o accoun o he MMVC o he
da um elemen .
MMVS = Gu -
The alue o MMVS only de e mines he measu es o he geome ic elemen s which a e plugged
in o o ha e o enci cle he p oduc du ing he gauging. As a gauge gene ally accoun s o se e al o
such coupling elemen s, he posi ions o each o he and o a gauge coo dina e sys em mus be
de e mined in he ollowing.
The dis ances be ween cen e poin s, axes and median planes o he gauge’s geome ic elemen s
a e clea ly de e mined in he echnical d awing by means o exac local measu es. Howe e , he
assignmen o a gauge coo dina e sys em is no always ob ious and he decision is le o he use . I
da um elemen s a e a ailable acco ding o ISO 5459 hey can be used o de e mine he x, y and z
axes o Ca esian coo dina es, as local measu es e e o he da um ea u es in case o a co ec
d awing. I da um sys ems a e incomple e o i no da a a e a ailable, indi idual deg ees o eedom
emain a ailable o he posi ioning o he gauge. Fo example, a single da um plane only de ines he
di ec ion o one axis and one ze o poin on his axis. The use can hen a bi a ily de e mine wo
u he coo dina e axes in he da um plane and hei posi ion. Howe e , i mus be ensu ed ha – in
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he coo dina e sys em p o isions – he nominal dis ances be ween he gauge elemen s comply wi h
he equi emen s in he echnical d awing. Only hen is i ensu ed ha he i ing esul s be ween he
di e en coo dina e sys ems a e s ill compa ible wi h each o he .
Fu he in o ma ion o he use o he MMC including he d awing speci ica ion Ⓜ as well as he
co ec calcula ion o gauge complying wi h he s anda ds a e p esen ed in Jo den [1], o example.
2.3. Deg ees o eedom o i ing and da um ea u es
So a , he ques ion o how he e m " i ing" ("coupling" o "plugging oge he ") o a p oduc and
gauge can be o mally in e p e ed has no been answe ed. Fo his pu pose, he classical physical
gauging is ini ially conside ed. A es e will y o plug he p oduc oge he wi h he gauge. The eby,
he/she pu s he p oduc on he edges o he gauge and by simply "shaking" and " il ing" he causes
bo h pa s o slide in o each o he . I a p oduc and a gauge can be plugged oge he by his
p ocedu e o such an ex en ha he equi emen s o he inspec ion a e complied wi h, he p oduc
is wi hin he ole ance which is e e ed o as comple e i ing capabili y.
The CAD model o he i ual coun e pa o a i hme ical 3D gauging is a ailable in he gauge
coo dina e sys em (𝑥𝐺,𝑦𝐺,𝑧𝐺). The measu emen poin s o he ex ac ed p oduc a e gi en in he
wo kpiece coo dina e sys em(𝑥𝑊,𝑦𝑊,𝑧𝑊). Bo h sys ems a e Ca esian coo dina es. The i ing o he
gauge o he ex ac ed geome y is desc ibed by a linea ans o ma ion.
𝑇:(𝑥𝐺,𝑦𝐺,𝑧𝐺)⟶(𝑥𝑊,𝑦𝑊,𝑧𝑊)
This ans o ma ion maps he gauge geome y in o he wo kpiece coo dina e sys em. O e lapping
o emp y space can be quan i ied be ween he ex ac ed p oduc geome y and he ans o med
gauge. The i ual gauge and he ex ac ed geome y a e comple ely i ed i he e is a
ans o ma ion which ep esen s a plugged s a e whe e he e is s ill emp y space be ween gauge
geome y and he measu emen poin s.
In he h ee-dimensional case, he ans o ma ion is de ined by o a ions – e.g. by means o he
Eule angle – and ansla ions owa ds he h ee coo dina e axes 𝑥𝐺,𝑦𝐺 and 𝑧𝐺. Gene ally, six
pa ame e s a e a ailable o he ans o ma ion o gauge geome y. The un es ic ed selec ion o a
pa ame e alue is e e ed o as deg ee o eedom o he i ing. I he e a e no es ic ions o he
pa ame e selec ion, hey a e e e ed o as ull deg ees o eedom o de e mine he ans o ma ion
T.
In many cases, he ans o ma ion pe mi ed o he i ing is limi ed by cons ain s. In he con ex
o posi ion ole ancing including hole pa e n i he e a e da um elemen s which block he deg ees
o eedom du ing ans o ma ion. I , o example, a da um axis o he wo kpiece is gi en, he
wo kpiece coo dina e sys em is ini ially o ien ed owa ds his. The o a ion a ound and a ansla ion
along he da um axis hen emain as deg ees o eedom o he i ing. An excep ion o he
es ic ion o he deg ees o eedom is he da um elemen s labelled wi h he symbol Ⓜ.
2.4. Gauging wi h coo dina e measu emen sys ems
In Figu e 3, eigh indi idual s eps a e ep esen ed o he implemen a ion o gauging o – in gene al –
3D hole pa e n i by means o coo dina e measu emen sys ems. They a e spli up in wo g oups.
The i s g oup is he wo kpiece measu emen . I comp ises he s eps o ex ac ion ia he eco ding
o measu emen poin s a he unc ional su aces o he p oduc , pa i ioning and/o a educ ion o
he measu emen poin s. The second g oup comp ises all s eps o he a i hme ical e alua ion o he
hole pa e n i by means o gi en measu emen poin s. He eby, da a and da um sys ems a e ini ially
se up which a e equi ed o he de ini ion o p oduc and gauge coo dina e sys ems. By means o
ans o ma ion o he measu emen poin s in o he nominal posi ion o he gauge he p ocedu e
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3. Applica ion example 1: langes
The example o "assembly o a lange", as i occu s du ing he cons uc ion o wind engines shows
ha a seemingly simple geome ical p oduc canno always be ea ed in a i ial way. Cha ac e is ic
o he lange a mode n acili ies a e he la ge dimensions o mo e han 5 m o lange diame e as
well as he high numbe o holes on he lange. The a i hme ical simula ion o assembly equi es he
ex ac ion o almos he en i e ex e nal su ace o he lange. This is possible, o example wi h he
aid o su ace measu ing op ical senso s. Due o he geome y, he a ising da a amoun is pa icula ly
la ge and oo complex o a desc ip ion o he hole pa e n i .
To show he co e equi emen s o he a i hme ical assembly simula ion o he lange including
3D hole pa e n i we he e o e eso o he simpli ied model in Figu e 6. The p incipal se -up is
equi alen o a lange o wind engines. The measu es and he numbe o he holes a e clea ly
smalle . Fu he mo e, di e en measu ing sys ems can be used o he ex ac ion o his ype o
p oduc s.
Figu e 6 Applica ion example o lange
The applica ion example o he lange is shown in Figu e 6. The op su ace o he lange is
desc ibed by wo pa allel planes a a dis ance o 8.0 mm. The ex e nal su ace ep esen s a cylinde
wi h a diame e o 70.0 mm. The in e nal su ace o he lange is desc ibed as cylinde wi h a
diame e o 50.0 mm. Bo h cylinde s a e coaxial and pe pendicula o bo h op su aces. On he bol
ci cle wi h a diame e o 58.0 mm he e a e 5 indi idual holes. Each o hem is s agge ed by 72°.
Each hole has a diame e o 4.0 mm.
3.1. Inspec ion acco ding o he s anda d
In o de o be able o plug he lange, he con ac su ace (assembly su ace) mus be le el.
Fu he mo e, he holes a e equi ed o be o hogonal o he assembly su ace. In addi ion, he bol
ci cle is concen ical o he axis o he cylinde o he ex e nal la e al su ace. The eby, he e will be
no eccen ici y du ing ope a ion la e on which would lead o an inc eased wea o mobile pa s o
wind engines.
Top su ace
(Assembly
su ace)
Bol ci cle
In e nal la e al
su ace
Ex e nal la e al
su ace
Hole o
assembly wi h
bol s

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Figu e 7 ISO 1101 complian inspec ion o he lange.
Acco ding o hese equi emen s, an unambiguous unique es ask including ole ances o he
manu ac u ed lange can be de i ed. Figu e 7 shows a echnical d awing acco ding o ISO 1101. The
a i hme ical inspec ion esul s in he ollowing ask: An ideal geome ical plane – iden i ied as da um
A – mus be aligned o he eal assembly su ace a a minimum dis ance. Da um B speci ies an ideal
cylinde ha is o hogonal o plane A and whose diame e is he smalles possible diame e whe e
he ex e nal la e al su ace o he p oduc is comple ely enclosed, i.e. all measu emen poin s lie
wi hin he assigned cylinde . The da um assignmen is ep esen ed in Figu e 8.
Finally, he size and posi ion o he indi idual holes o he da um su ace (da um poin ) and o he
axes o he da um cylinde mus be inspec ed. This is shown in Figu e 9. The ole ance om Figu e 7
wi h he symbol o he maximum ma e ial condi ion he eby de ines 5 gauge cylinde s wi h he
diame e o 3.8 mm (MMVS). The axes o he cylinde a e pa allel o he da um axis B. They a e
egula ly a anged on a bol ci cle wi h a diame e o 58,0 mm a a dis ance o 72° segmen s. The
bol ci cle is pa allel o he da um plane A. I s cen e poin lies on he da um axis B. A ans o ma ion
is allowed o he i ing which o a es he gauge a ound he axis o he da um cylinde . One mus
check i he e is a o a ion angle whe e all gauge bol s a e wi hin he holes wi hou o e lapping wi h
he ma e ial o he lange ing. In his case, he p oduc is wi hin he ange o ole ance. On he o he
hand, he p oduc canno be assembled due o he inspec ion esul .
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Figu e 8 Da um assignmen a he manu ac u ed lange.
Figu e 9 3D hole pa e n i o he lange (on he le : pe spec i e iew, on he igh : op iew); he
gauge cylinde highligh ed in ed o e laps wi h he hole. By o a ing all gauge cylinde s a ound he
da um axis, no posi ion is ound whe e all cylinde s lie wi hin he holes.
3.2. Ma hema ical modelling o da um ea u es and i ing
In o de o be able o ca y ou he 3D hole pa e n i a i hme ically, a co ec and eliable
ma hema ical modelling is undamen al in o de o mee he equi emen s and a ge s o he
inspec ion. Figu e 10 gi es an o e iew a he p ocess o he 3D hole pa e n i o he lange. He e,
he calcula ion o measu ands on he basis o he ex ac ed da a is shown. The 3D hole pa e n i is
ca ied ou in six consecu i e s eps. E e y s ep is indi idual and equi es an independen calcula ion
me hod o he inaliza ion.
The s a ing poin is he calcula ion o he da um elemen s 𝐴 and 𝐵. They include single geome ic
elemen s ha a e assigned o he ex ac ed lange acco ding o he Chebyshe and likewise
Minimum ci cumsc ibed condi ion. A wo kpiece coo dina e sys em is de i ed om he da um
elemen s which – apa om a o a ion a he wo kpiece – is uniquely de e mined. The lacking
deg ee o eedom is de e mined by a special ans o ma ion o he measu emen poin s a he ini ial
posi ion in o he wo kpiece coo dina e sys em. The modelling a he hole pa e n i includes he
calcula ion o he gauge geome y (ideal coun e pa o he hole pa e n i ), he calcula ion o an
ini ial solu ion o he i ing and, inally, he implemen a ion o he hole pa e n i . The goal is o
de e mine he posi ion o he i ual gauge in such a way ha maximum emp y space and/o
minimum o e lapping is achie ed be ween he gauge geome y and measu emen poin s. By means
o he Gaussian me hod o he calcula ion o he ini ial solu ion, his a ge is a ained only oughly.
The desi ed posi ion a he gauge can only ac ually be de e mined by applying he Chebyshe
c i e ion.
Manu ac u ed p oduc
wi h de ia ions
Da um su ace A
Assigned cylinde
o da um B
Da um poin
(posi ion)
Da um axis
(di ec ion)
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Figu e 10 Flowcha o he 3D hole pa e n i o he lange.
The ollowing subsec ions p esen de ails on he ma hema ical modelling and on he asks o be
sol ed o each o he 6 s eps.
3.2.1. Assignmen o he da um plane
The da um plane is assigned o he ex ac ed op su ace o he lange as an adjacen Chebyshe
plane (minimum zone c i e ion). The inpu da a o he calcula ion o he plane a e he ex ac ed
poin s o he op su ace. 𝑃≔{𝑃1,…,𝑃𝑚}, 𝑃𝑖∈ℝ3
E e y poin has he o m 𝑃𝑖=(𝑥𝑖,𝑦𝑖,𝑧𝑖)𝑇. The coo dina es 𝑥,𝑦 and 𝑧 a e speci ied in he
measu emen poin coo dina e sys em. The assigned plane has an ideal geome ical o m. I has
been pa ame e ized ia he no mal ec o
𝑣=(𝑣𝑥,𝑣𝑦,𝑣𝑧)𝑇∈ℝ3
and a poin on he plane. 𝐶=(𝐶𝑥,𝐶𝑦,𝐶𝑧)𝑇∈ℝ3
Wi h his de ini ion, he ep esen a ion o an ideal plane is no ye unambiguous. Fo example, o
𝐶, e e y a bi a y poin o he plane is possible. Thus, u he cons ain s a e made on he
pa ame e s. On he one hand, he no mal ec o is supposed o ha e he leng h 1.
〈𝑣,𝑣〉=1. (3)
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On he o he hand, he poin o he plane mus be loca ed so ha he dis ance o he cen oid 𝐺
o he da a 𝑃 is a a minimum. Fo his pu pose, 𝑣1,𝑣2∈ℝ3 shall be wo ec o s wi h a leng h o 1
which a e o hogonal o he no mal 𝑣. Fo hose, 〈𝑣1,𝑣2〉=0 applies. Then, poin 𝐶 is he p ojec ed
cen oid, i 〈𝐺−𝐶,𝑣1〉=0
〈𝐺−𝐶,𝑣2〉=0 (4)
is me . The cen oid is calcula ed as an a i hme ic mean.
𝐺=1
𝑚∑𝑃𝑖
𝑚
𝑖=1 .
Fo he co ec assignmen o he da um plane he o hogonal dis ances be ween he ideal plane
and he measu emen poin s a e conside ed. These a e as ollows:
𝑓𝑖(𝐶,𝑣)=〈𝑃𝑖−𝐶,𝑣〉
The assignmen inally akes place acco ding o he ollowing ma hema ical model.
Assignmen ask: Chebyshe plane as adjacen da um plane
I 𝑃 is he ex ac ed geome y o a plane su ace. The assigned Chebyshe plane has he pa ame e s 𝐶
and 𝑣 which sol e 𝑚𝑖𝑛
𝐶,𝑣 𝑚𝑎𝑥
𝑖|𝑓𝑖(𝐶,𝑣)| (5)
and mee he cons ain s (3) and (4). Fo 𝑠=𝑚𝑎𝑥
𝑖|𝑓𝑖(𝐶,𝑣)|, he adjacen Chebyshe da um plane
wi h he pa ame e s 𝐶󰆹,𝑣 is calcula ed by means o he ansla ion
𝐶󰆹=𝐶+𝑠∙𝑣. (6)
The sign o 𝑣 mus be de e mined in such a way ha his ec o poin s away om he ma e ial side o
he ex ac ed geome y o he calcula ion o (6).
3.2.2. Assignmen o he da um cylinde
The inpu da a o he cylinde calcula ion a e he poin s measu ed a he ou e lange su ace. In he
case o he planes, hey a e simply called 𝑃. The assigned cylinde has a geome ically ideal o m. I is
pa ame e ized by a pa ame e o he di ec ion o he cylinde axis
𝑣=(𝑣𝑥,𝑣𝑦,𝑣𝑧)𝑇∈ℝ3,
a pa ame e o he posi ion o he cylinde axis
𝐶=(𝐶𝑥,𝐶𝑦,𝐶𝑧)𝑇∈ℝ3
and he adius o he cylinde la e al su ace 𝑟>0
As he cylinde is assigned as seconda y da um elemen , he ollowing cons ain s apply o he
pa ame e s. The di ec ion o he cylinde axis co esponds o he no mal ec o o he da um plane
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p e iously de e mined. Fo he unambiguous calcula ion o he posi ion, a u he c i e ion o he
posi ion o he poin on he cylinde axis mus be gi en. This poin can be he in e sec ion be ween
he axis and he da um plane.
The assignmen o he cylinde pa ame e s is ca ied ou acco ding o he minimum ci cumsc ibed
elemen c i e ion. Fo i s ma hema ical o mula ion he o hogonal dis ances
𝑓𝑖(𝐶,𝑣,𝑟)=‖(𝑃𝑖−𝐶)×𝑣‖−𝑟
be ween he measu emen poin s om 𝑃 and he la e al su ace o he ideal cylinde a e conside ed.
The ollowing ask mus be sol ed o he co ec calcula ion o he cylinde pa ame e s.
Assignmen ask: en elope cylinde as seconda y da um e ically o a plane:
De e mine he poin 𝐶 and he adius 𝑟 in such a way ha
𝑚𝑖𝑛
𝐶,𝑟 𝑟 𝑠.𝑡. 𝑓𝑖(𝐶,𝑣,𝑟)≤0 𝑓𝑜𝑟 1≤𝑖≤𝑚 (7)
is ob ained.
3.2.3. Wo kpiece coo dina e sys em and i ual gauge
In he case o he lange conside ed he e, he i ual gauge o he hole pa e n i mus only be
o a ed a ound he axis o he da um cylinde . As he axis can gene ally be il ed in space, his can
only be sol ed wi h g ea echnical e o . By sui ably assigning a wo kpiece coo dina e sys em and
he sui able geome y o he i ual gauge, he i ing can be echnically ealized mo e easily.
Assignmen o he wo kpiece coo dina e sys em
The axis o he en elope cylinde (7) is he basis o he de ini ion o he wo kpiece coo dina e
sys em. This example speci ies ha he di ec ion ec o 𝑣 de ines he z axis 𝑧𝑊 o he wo kpiece.
Likewise, poin 𝐶 om (7) is de ined as he cen e poin o he wo kpiece coo dina e sys em. The
emaining axes 𝑥𝑊 and 𝑦𝑊 a e no clea ly de e mined by he da um sys em. I is only du ing he
ans o ma ion o he ex ac ed geome y in o he wo kpiece coo dina e sys em – which is s ill
incomple e a ha poin in ime – ha hey a e speci ied. The ans o ma ion shown he e is a
possible a ian o his. The e a e also o he app oaches which lead o he same i ing esul la e
on, howe e , hey will no be discussed he e.
The con e sion o poin coo dina es 𝑃𝑖∈ℝ3 in o he wo kpiece coo dina e sys em is
implemen ed by he linea ans o ma ion 𝑃𝑖=𝑅(𝑃𝑖−𝐶).
The 3x3 ma ix 𝑅 de ines a o a ion which map he di ec ion ec o 𝑣 o he da um cylinde on
he basis ec o 𝑒𝑧=(0,0,1)𝑇. As 𝑣 co esponds o he z axis o he coo dina e sys em, he
ollowing mus be alid 𝑅𝑣=𝑒𝑧.
By means o he Tai -B yan angles o o a ions a ound he x and/o y axis
𝑅𝑥=(1000
cos(𝛼)
sin(𝛼)−0
sin(𝛼)
cos(𝛼)) and 𝑅𝑦=(cos(𝛽)
0
−sin(𝛽)010sin(𝛽)
0
cos(𝛽))

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𝑅≔𝑅𝑦𝑇𝑅𝑥𝑇
is c ea ed. The poin coo dina es 𝑃𝑖 hen lie in he wo kpiece coo dina e sys em wi h he o igin poin
𝑊0=(0,0,0)𝑇, x axis 𝑥𝑤=(1,0,0)𝑇, y axis 𝑦𝑤=(0,1,0)𝑇 and z axis 𝑧𝑤=(0,0,1)𝑇.
The ollowing algo i hm p o ides a nume ically mo e s able p ocedu e o he calcula ion o he
wo Eule o a ion angles 𝛼 and 𝛽.
Algo i hms o he calcula ion o he o a ion angles o he
coo dina e ans o ma ion
S ep 0: Se a posi i e accu acy 𝜀≪1.
S ep 1: Calcula e 𝑡=√𝑣𝑦2+𝑣𝑧2
I 𝑡<𝜀, se 𝑐𝑜𝑠(𝛼)=1 and sin(𝛼)=0.
I no , se 𝑐𝑜𝑠(𝛼)=𝑣𝑧
𝑡, sin(𝛼)=𝑣𝑦
𝑡 and 𝑣𝑧′= .
S ep 2: Calcula e 𝑡=√𝑣𝑥2+𝑣′𝑧2
I 𝑡<𝜀, se 𝑐𝑜𝑠(𝛽)=1 and sin(𝛽)=0.
I no , se 𝑐𝑜𝑠(𝛽)=𝑣′𝑧
𝑡 and sin(𝛽)=𝑣𝑥
𝑡.
The limi o he p ecision 𝜀 de e mines when a componen o a ec o 𝑣 al eady lies close enough
o he di ec ion achie ed o he z axis. In his case, no u he o a ion o he da a is done.
The ans o ma ion mus be implemen ed o all measu emen poin s which ha e been assigned
o he cylind ical holes on he lange. Each hole is a ailable wi h i s own se o measu emen poin s.
𝑃(1)={𝑃1(1),…,𝑃𝑚1
(1)},
𝑃(2)={𝑃1(2),…,𝑃𝑚2
(2)},
𝑃(3)={𝑃1(3),…,𝑃𝑚3
(3)},
𝑃(4)={𝑃1(4),…,𝑃𝑚4
(4)},
𝑃(5)={𝑃1(5),…,𝑃𝑚5
(5)}
Fo simpli ica ion easons, he index 𝑘 wi h 1≤𝑘≤5 will be in oduced o he assignmen o
he measu emen poin se s o he indi idual holes in he ollowing. I is w i en as 𝑃(𝑘) and/o 𝑃𝑖(𝑘)
wi h he coo dina e alues 𝑃𝑖(𝑘)=(𝑥𝑘𝑖,𝑦𝑘𝑖,𝑧𝑘𝑖)𝑇. Fu he mo e, he alues 𝑚𝑘 s and o he numbe
o poin s o he ex ac ed geome ic elemen wi h he index k. The ans o ma ion o he
measu emen da a is 𝑃𝑖(𝑘)=𝑅(𝑃𝑖(𝑘)−𝐶). The ex ac ed geome y is ou lined wi h he wo kpiece
coo dina e sys em in Figu e 11.
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Figu e 11 Wo kpiece coo dina e sys em and ex ac ed geome y a he lange.
To simpli y hings, he u he no a ion 𝑃𝑖(𝑘) is used ins ead o 𝑃𝑖(𝑘) o he poin coo dina es in
he wo kpiece coo dina e sys em e e ing o he espec i e con ex .
Speci ica ion o he i ual gauge:
The i ual gauge consis s o 5 cylinde s wi h an ideal geome ical o m. All cylinde axes a e pa allel
wi h he common di ec ion ec o 𝑣=(0,0,1)𝑇. Likewise, e e y cylinde has he same adius 𝑟=1.9
mm. Howe e , he posi ions o he indi idual cylinde axes
𝐶1,…,𝐶5
a e di e en . They a e also e e ed o as 𝐶𝑘 (𝑘=1,…,5). The nominal posi ion is ca ied ou by
means o he speci ied bol ci cle wi h he adius 𝑟𝐿=29 mm and he angula dis ance 𝜏=72° o
𝐶𝑘=(𝐶𝑘𝑥
𝐶𝑘𝑦
𝐶𝑘𝑧)=(𝑟𝐿cos(𝑘𝜏)
𝑟𝐿sin(𝑘𝜏)
0)
The ollowing ma ix o mula ion is sui able o he s o age o he geome ic pa ame e s o he
gauge.
𝑀=
(
𝐶1𝑥 𝐶1𝑦 𝐶1𝑧 𝑣𝑥𝑣𝑦𝑣𝑧𝑟
𝐶2𝑥 𝐶2𝑦 𝐶2𝑧 𝑣𝑥𝑣𝑦𝑣𝑧𝑟
𝐶3𝑥 𝐶3𝑦 𝐶3𝑧 𝑣𝑥𝑣𝑦𝑣𝑧𝑟
𝐶4𝑥 𝐶4𝑦 𝐶4𝑧 𝑣𝑥𝑣𝑦𝑣𝑧𝑟
𝐶5𝑥 𝐶5𝑦 𝐶5𝑧 𝑣𝑥𝑣𝑦𝑣𝑧𝑟
)
(8)
No e: The o mula ion o (8) equi es ha he no mal ec o o he da um plane A poin s owa ds
he ma e ial side o he lange. Howe e , i he da um di ec ion is u ned, i.e. i he no mal ec o
poin s away om he ma e ial, hen he sequence o he en ies in he pa ame e ma ix changes.
Then, 𝐶5 o 𝐶1 mus be en e ed ins ead o 𝐶1 o 𝐶5.
3.2.4. Ini ial alue and 3D hole pa e n i o he lange
The s a ing poin o he modelling o he 3D hole pa e n i o he lange a e he measu emen
poin s o he holes 𝑃(1),…,𝑃(5) in he wo kpiece coo dina e sys em and he ma ix wi h he
pa ame e s o he gauge geome y 𝑀.
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The ee pa ame e o he i ing is he o a ional angle 𝜑 which u ns he gauge o , likewise, he
gauge pa ame e a ound he z axis in he coo dina e o igin o he coo dina e sys em. The angle
de e mines a special o a y ma ix 𝐻. 𝑀(𝜑)=𝑀∙𝐻(𝜑)
The e is
𝐻(𝜑)=
(
𝑐𝑜 𝑠𝑖 0000 0
−𝑠𝑖 𝑐𝑜 0000 0
0 0 1 000 0
0 0 0 100 0
0 0 0 010 0
0 0 0 001 0
0 0 0 000 1
)
(9)
wi h he alues 𝑠𝑖=sin(𝜑) and 𝑐𝑜=cos(𝜑). In addi ion,
𝐶𝑘(𝜑)=(𝐶𝑘𝑥,𝐶𝑘𝑦,𝐶𝑘𝑧)𝑇∙(𝑐𝑜
−𝑠𝑖
0𝑠𝑖
𝑐𝑜
0001)
is used o he o a ed posi ion poin s o he gauge cylinde s in o de o simpli y he no a ion o he
ma hema ical modelling o he i ing ask.
In he ollowing subsec ions, he ma hema ical models a e desc ibed o a consis en 3D hole
pa e n i . The p ocedu e s a s wi h a Gaussian- ype coa se i ing which is used as he s a ing
solu ion o he exac i acco ding o he Chebyshe c i e ion (1).
S a ing solu ion wi h a Gaussian i ing
In a i s s ep, he cen oid 𝑄𝑘=(𝑞𝑘𝑥,𝑞𝑘𝑦,0)𝑇 is calcula ed o e e y poin se 𝑃(𝑘). The eby he
ollowing applies:
𝑞𝑘𝑥=1
𝑚𝑘∑𝑥𝑘𝑖
𝑚𝑘
𝑖=1
and 𝑞𝑘𝑦=1
𝑚𝑘∑𝑦𝑘𝑖
𝑚𝑘
𝑖=1 .
The calcula ion is also e icien o la ge da a se s. In o de o de e mine he s a ing posi ion o
he gauge, he angle 𝜑0 is calcula ed by means o a bes i ing which sol es he minimiza ion
p og am min
φ0 12∑ ‖𝐶𝑘(𝜑0)−𝑄𝑘‖2
5𝑘=1 (10)
The sum o he dis ance squa es be ween he cen e poin o he gauge cylinde axes and he
poin cloud cen oids is he eby minimized. This coa se i ing is shown in Figu e 12.
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Figu e 12 Coa se i ing a he lange
On he le , he ini ial si ua ion whe e he wo kpiece coo dina e sys em and he gauge a e
supe imposed is shown. Measu emen poin s and gauge cylinde s a e shown in he op iew on he
x-y-plane. The gauge cylinde s colou ed in blue a e clea ly s agge ed o he black do ed ex ac ed
holes. On he igh side o he igu e, he dis ances be ween he gauge cen e poin s and he poin
cloud cen oids we e minimized. The eby, he gauge coo dina e sys em was o a ed a ound he
angle 𝜑0.
Calcula ion o he 3D hole pa e n i
The measu emen poin s a he 5 indi idual holes desc ibe cylinde s which – due o measu emen
and manu ac u ing de ia ions – do no ha e an ideal geome ic shape. In gene al, he e a e
de ia ions o measu e, shape and posi ion. They in luence he esul o he p e ious Gaussian i . The
angle 𝜑0 calcula ed om he ini ial alue (10) is no ye he angle wi h he smalles possible o e lap
o la ges possible emp y space be ween he gauge cylinde s and he measu emen poin s a ailable.
Fo he calcula ion o he 3D hole pa e n i , he o hogonal dis ances be ween he gauge
cylinde s and he measu emen poin s o he holes a e de ined as ollows:
𝑓𝑘𝑖(𝑀(𝜑))=𝑟−‖(𝑃𝑖(𝑘)−𝐶𝑘(𝜑))×𝑣‖
Index 𝑘 is he numbe o he hole and index 𝑖 speci ies he numbe o he measu emen poin s o
he hole 𝑘. The no m is he Euclidean s anda d no m in he ℝ3.
The applica ion o he gene al i ing p og am (2) om Chap e 2.4 he eby p o ides he 3D hole
pa e n i o he lange (11).
min
φ∈ℝ,𝑠∈ℝ𝑠 𝑠.𝑡. 𝑓𝑘𝑖(𝜑)≤𝑠 ∀ 𝑘=1,..,5 𝑎𝑛𝑑 ∀ 𝑖=1,…,𝑚𝑘 (11)
The o a ion angle 𝜑 calcula ed om his p og am and he maximum dis ance 𝑠 is he
de e mina ion o he quan i y sea ched – minimum o e lapping o maximum emp y space – and
easy o ealize. The ollowing s a emen s a e alid
 I 𝑠>0, he e is an o e lap be ween he gauge and he measu emen poin s. I has he alue
𝑠.
 I 𝑠<0, he e is emp y space be ween he gauge and he measu emen poin s. I has he
alue 𝑠.
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pa ame e is iden ical o he p ocedu e in sec ion 3 (algo i hm o he calcula ion o he o a ion
angle o he coo dina e ans o ma ion). In he case o he conical disc, he geome y pa ame e 𝐶
and 𝑣 a e de i ed om he da um cone axis. The assigned coo dina e sys em is ske ched in Figu e 20.
Figu e 20 Wo kpiece coo dina e sys em o he conical disc
Fo he conical disc, special measu emen poin amoun s a e a ailable
𝑃(1)={𝑃1(1),…,𝑃𝑚1
(1)},
𝑃(2)={𝑃1(2),…,𝑃𝑚2
(2)},
𝑃(3)={𝑃1(3),…,𝑃𝑚3
(3)},
𝑃(4)={𝑃1(4),…,𝑃𝑚4
(4)},
𝑃(5)={𝑃1(5),…,𝑃𝑚5
(5)}
o he i e holes. Fu he mo e, 𝑃(6)={𝑃1(6),…,𝑃𝑚6
(6)}
and 𝑃(7)={𝑃1(7),…,𝑃𝑚7
(7)}
s and o he la e al su aces si ua ed opposi e o he slo . When de ining 𝑃(𝑘), 𝑚𝑘 is he
espec i e numbe o poin s pe da a se . The ans o ma ion o he measu emen poin s in o he
wo kpiece coo dina e sys em is o mally calcula ed by 𝑃𝑖(𝑘)=𝑅(𝑃𝑖(𝑘)−𝐶). In he ollowing, he
designa ion 𝑃𝑖(𝑘) is used o he poin s in he wo kpiece coo dina e sys em o simpli y he no a ion.
Speci ica ion o he i ual gauge
The i ual gauge consis s o i e cylinde s and a pai o pa allel planes wi h an ideal geome ical
o m. All cylinde axes a e pa allel o he common di ec ion ec o 𝑣=(0,0,1)𝑇. Likewise, e e y

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cylinde has he adius 𝑟=3.9 mm (diame e 7.8 mm). Howe e , he posi ions o he indi idual
cylinde axes a e di e en : 𝐶1,…,𝐶5
They a e also e e ed o as 𝐶𝑘 (𝑘=1,…,5). The calcula ion o he nominal posi ion is ca ied ou
by means o he speci ied bol ci cle wi h he adius 𝑟𝐿=22 mm,𝜏0=−30°0 and he angula
dis ance 𝜏=60°
𝐶𝑘=(𝐶𝑘𝑥
𝐶𝑘𝑦
𝐶𝑘𝑧)=(𝑟𝐿cos(𝜏0+𝑘𝜏)
𝑟𝐿sin(𝜏0+𝑘𝜏)
0).
The pai o pa allel planes o he slo is ini ially de ined by he no mal ec o 𝑛=(1,0,0)𝑇 in i s
o ien a ion. Thus, he planes a e pa allel o he conical axis and symme ical o he i e gauge
cylinde s. Fo each plane, he sign o he no mal is selec ed in such a way ha i poin s away om he
heo e ical ma e ial side in he echnical d awing and/o a he eal p oduc . Fu he mo e, he
posi ion is de ined by a poin which is si ua ed cen ally be ween he wo planes. Fo 𝑘=6 and 𝑘=
7 his poin is
𝐶𝑘=(𝐶𝑘𝑥
𝐶𝑘𝑦
𝐶𝑘𝑧)=( 0
−22
0).
This is exac ly he in e sec ion poin o he heo e ically exac bol ci cle and he y axis o he
gauge coo dina e sys em which is si ua ed cen ally in he slo . The o hogonal dis ance o he la e al
planes o he median plane ia poin 𝐶𝑘 wi h he no mal ec o 𝑛 is 𝑑=7.925 mm. The ma ix
o mula ion o he s o ing o he gauge geome y pa ame e s is
𝑀=
(
𝐶1𝑥 𝐶1𝑦 𝐶1𝑧 𝑣𝑥𝑣𝑦𝑣𝑧 0 0 0 𝑟
𝐶2𝑥 𝐶2𝑦 𝐶2𝑧 𝑣𝑥𝑣𝑦𝑣𝑧 0 0 0 𝑟
𝐶3𝑥 𝐶3𝑦 𝐶3𝑧 𝑣𝑥𝑣𝑦𝑣𝑧 0 0 0 𝑟
𝐶4𝑥 𝐶4𝑦 𝐶4𝑧 𝑣𝑥𝑣𝑦𝑣𝑧 0 0 0 𝑟
𝐶5𝑥 𝐶5𝑦 𝐶5𝑧 𝑣𝑥𝑣𝑦𝑣𝑧 0 0 0 𝑟
𝐶6𝑥 𝐶6𝑦 𝐶6𝑧 0 0 0 −𝑛𝑥−𝑛𝑦−𝑛𝑧𝑑
𝐶7𝑥 𝐶7𝑦 𝐶7𝑧 0 0 0 𝑛𝑥 𝑛𝑦 𝑛𝑧𝑑
)
. (17)
The i s i e lines a e he pa ame e s o he gauge bol s o he holes. The wo emaining lines
p o ide he pa ame e s o he pai o planes o he i ing o he slo .
4.2.3. Calcula ion o he ini ial alue and he 3D hole pa e n i
The s a ing poin o he modelling o he 3D hole pa e n i o he conical disc a e he
measu emen poin s ans o med in o he wo kpiece coo dina e sys em o he holes 𝑃(1),…,𝑃(7)
and he ma ix wi h he pa ame e s o he gauge geome y 𝑀.
The ee pa ame e o he i ing is he angle 𝜑 which o a es he gauge in he coo dina e o igin
a ound he z axis o he wo kpiece coo dina e sys em. The angle de e mines a special o a y ma ix
𝐻 which helps o calcula e he pa ame e s o he o a ed gauge ia
𝑀(𝜑)=𝑀∙𝐻(𝜑).
He eby,
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𝐻(𝜑)=
(
𝑐𝑜
−𝑠𝑖
00000000
𝑠𝑖
𝑐𝑜
00000000
0010000000
0001000000
0000100000
0000010000
000000
𝑐𝑜
−𝑠𝑖
00
000000
𝑠𝑖
𝑐𝑜
00
0000000010
0000000001
)
(18)
wi h he alues 𝑠𝑖=sin(𝜑) and 𝑐𝑜=cos(𝜑). In 𝑀(𝜑), only he posi ion en ies ( he x and y
coo dina es o he gauge bol s, plane cen e) and he no mal ec o s o he pai o planes change.
Fo a simpli ied no a ion, hese en ies a e hus also e e ed o as
𝐶𝑘(𝜑)=(𝐶𝑘𝑥,𝐶𝑘𝑦,𝐶𝑘𝑧)(𝑐𝑜 𝑠𝑖 0
−𝑠𝑖 𝑐𝑜 0
0 0 1)
and
𝑛𝑘(𝜑)=(𝑛𝑘𝑥,𝑛𝑘𝑦,𝑛𝑘𝑧)(𝑐𝑜 𝑠𝑖 0
−𝑠𝑖 𝑐𝑜 0
0 0 1).
4.2.3 Ini ial alue and 3D hole pa e n i o he conical disc
In his subsec ion, he ma hema ical models a e desc ibed o he 3D hole pa e n i . In u n, a
coa se i ing s a s acco ding o a sui able Gaussian c i e ion. Subsequen ly, he 3 D hole pa e n i
is implemen ed acco ding o he Chebyshe c i e ion.
S a ing solu ion wi h a Gaussian i ing
As in he case o he lange, he calcula ion o a coa se i ing conside ed he e is o ien ed owa ds he
cen es o he ideal gauge geome ies and he measu emen poin s. In a i s s ep, he cen oid is
calcula ed o each ex ac ed hole 𝑃(𝑘) wi h 𝑘=1,…,5. The z componen o he cen oid is se o 0,
as i mus no in luence he i ing esul . The o he componen s a e
𝑞𝑘𝑥=1
𝑚𝑘∑𝑥𝑘𝑖
𝑚𝑘
𝑖=1
and
𝑞𝑘𝑦=1
𝑚𝑘∑𝑦𝑘𝑖
𝑚𝑘
𝑖=1 .
The calcula ion is e icien o la ge da a olumes. Likewise, a cen oid is calcula ed o he
ex ac ed pai o pa allel planes o he slo . This cen oid is 𝑄6=(𝑞6𝑥,𝑞6𝑦,0)𝑇 wi h
𝑞6𝑥=1
𝑚6+𝑚7(∑𝑥6𝑖
𝑚6
𝑖=1 +∑𝑥7𝑖
𝑚7
𝑖=1 )
and
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𝑞6𝑦=1
𝑚6+𝑚7(∑𝑦6𝑖
𝑚6
𝑖=1 +∑𝑦7𝑖
𝑚7
𝑖=1 ).
In o de o de e mine he s a ing posi ion o he gauge, he angle 𝜑0 is calcula ed in a second s ep
which sol es he minimiza ion ask
min
φ0 12∑ ‖𝐶𝑘(𝜑0)−𝑄𝑘‖2.
6𝑘=1 (19)
P oblem (19) is a Gaussian i ing. I minimizes he sum o he dis ance squa es be ween he
cen oids o he poin clouds and he a i hme ically ideal cen es o he gauge elemen s. The
dis ances a e only calcula ed in he x-y-plane o he wo kpiece coo dina e sys em. The si ua ion is
shown in Figu e 21 o a be e unde s anding.
Figu e 21 Ini ial alue o he conical disc i ing.
In he op iew, he gauge geome y is shown in he di ec ion o he median axis (conical axis).
The gauge geome y comp ises he cylind ical bol s ma ked in blue and he slo a ea ma ked in
g een. The ex ac ed geome y o he holes and slo la e al su aces is ske ched using black poin s.
The gauge geome y and he ex ac ed geome y a e wis ed owa ds each o he p io o he i ing.
This is shown in he le side o he igu e. The ideal cen es o he gauge 𝐶𝑘 and he cen oids o he
ex ac ed geome y 𝑄𝑘 de ined o he Gaussian i ing a e clea ly isible. A e he o a ion o he
gauge by he calcula ed angle 𝜑0, he ini ial i is a ailable which is shown on he igh side o he
igu e.
Calcula ion o he 3D hole pa e n i
The solu ion angle 𝜑0 om he ini ial alue (19) is no ye he angle wi h he smalles possible
o e lapping and/o la ges possible emp y space be ween he gauge geome y and he measu emen
poin s. In o de o apply he gene al Chebyshe i ing (2) om chap e 2.4, sui able dis ance
unc ions o he gauge cylinde s and he slo mus be de ined. As in case o he lange, he ollowing
de ini ion is alid o he gauge cylinde wi h 𝑘=1,…,5
𝑓𝑘𝑖(𝑀(𝜑))=𝑟−‖(𝑃𝑖(𝑘)−𝐶𝑘(𝜑))×𝑣‖.
𝜑0
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In case o he slo , a dis inc ion is made be ween he le and he igh la e al su ace. This is
ealized by a espec i e assignmen o he poin se s o he planes o he gauge geome y and he
opposi e de e mina ion o he no mal di ec ion. In his applica ion example, 𝑃(6) is he ex ac ed
geome y o he le la e al su ace and 𝑃(7) is he ex ac ed geome y o he igh la e al su ace. Fo
his, he ollowing is alid: 𝑓𝑘𝑖(𝑀(𝜑))=𝑑−〈𝑃𝑖(𝑘)−𝐶𝑘(𝜑),𝑛𝑘(𝜑)〉.
The ollowing i ing p ocedu e is se up.
min
φ∈ℝ,𝑠∈ℝ𝑠 𝑠.𝑡. 𝑓𝑘𝑖(𝜑)≤𝑠 ∀ 𝑘=1,..,7 𝑎𝑛𝑑 ∀ 𝑖=1,…,𝑚𝑘 (20)
By means o he o a ion angle 𝜑 calcula ed om his i ing p og am and he maximum dis ance
𝑠 he de e mina ion o he desi ed quan i y o a minimum o e lap o a maximum emp y space is
easy o ealize. The ollowing s a emen s a e alid:
 I 𝑠>0, he e is an o e lap be ween he gauge and he measu emen poin s. I has he alue
𝑠.
 I 𝑠<0, he e is emp y space be ween he gauge and he measu emen poin s. I has he
alue 𝑠.
 I 𝑠=0, he gauge is adjacen o he measu emen poin s. The e is nei he emp y space no
o e lap.
To be able o e alua e o which o he gauge geome y elemen s he e is an o e lap whe e 𝑠>
0, he dis ances o he locally assigned measu emen poin s can be inspec ed o each indi idual
elemen . These a e as ollows: 𝑠𝑘≔ max
i=1,.,,,mk𝑓𝑘𝑖(𝑀(𝜑))
o all 𝑘=1,…,7. I 𝑠𝑘>0, he e is an o e lapping wi h he p oduc .
5. Applica ion example 3: cubes
In he case o he applica ion examples o langes and conical discs conside ed abo e, he gauge
elemen s a e pa allel. The inspec ion using a physical gauge is possible by means o a one-sided
plugging o he gauge wi h he es specimen. In con as o his, he applica ion example o cubes
conside s he assembly o p oduc s on op o holes o bol s ha a e wis ed owa d each o he . I.e.,
he geome y elemen s o he gauge a e no longe pa allel. As a esul , he inspec ion by means o
physical gauges ha a e made o only one pa a e no longe possible. Speci ically in his case, i ual
gauging by means o CMM and 3D hole pa e n i is a sui able means o es ing wi h ega d o
easibili y. Fo he applica ion, he cube ske ched in Figu e 22 is conside ed.
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Figu e 22 Applica ion example o a cube
Figu e 23 ISO 1101 complian inspec ion ask o he cube.
The cube has an edge leng h o 40.0 mm. In wo o he six la e al su aces, h ee holes
espec i ely, ha e been in eg a ed. The dep h o all holes is 20.0 mm each. The diame e s a e 6.0
mm. All hole axes a e e ical o he espec i e la e al su aces. In o de o be e iden i y he
posi ion o he holes, he ex e nal su ace o he cube was d awn as anspa en (Fig. 22).
La e al su aces
Uppe hole
Side hole

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5.1. Inspec ion acco ding o he s anda d
No speci ic unc ion is a ibu ed o he inspec ion o he cube. The e o e, a common inspec ion ask
is desc ibed he e. This ask is shown in Figu e 23.
When selec ing he inspec ion ask, a da um o da um sys em was o ally dispensed wi h. Only
he posi ion o he six holes is ole a ed. This leads o a gauging o 3D hole pa e n i wi h a
maximum numbe o six deg ees o eedom. A he same ime, i places he highes demands on
nume ical s abili y and e iciency o ma hema ical p ocedu es o an a i hme ical i .
5.2. Ma hema ical model o he 3D hole pa e n i
The a i hme ical 3D hole pa e n i is ca ied ou by he ou s eps shown in Figu e 24.
Figu e 24 Flowcha on he 3D hole pa e n i o he cube.
A he beginning, he wo kpiece coo dina e sys em and he gauge pa ame e s we e assigned.
Subsequen ly, he discussion o a sui able ini ial alue ook place. The p ocedu e is much mo e ime-
consuming han o he p e ious applica ions. Fu he mo e, a gene al 3D ans o ma ion o he
gauge geome y mus be de ined. Finally, he o mal speci ica ion o he Chebyshe 3D hole pa e n
i is ca ied ou .
Wo kpiece coo dina e sys em and gauge pa ame e s
As we ha e he case o a gene al i o he cube (no cons ain s due o da um elemen s), basically
e e y Ca esian coo dina e sys em can be used as a wo kpiece coo dina e sys em. In he example,
he Ca esian measu emen poin coo dina e sys em is selec ed o he wo kpiece, he e o e, we do
no need o con e he poin coo dina es in his case.
Figu e 25 Coo dina e sys em and model o he i ual gauge o he cube.
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The gauge consis s o six ideal cylinde s. These cylinde s a e assigned o each hole o he cube.
They ha e a adius o 𝑟=2.94 mm (co esponding o a diame e o MMVS = 5.88 mm). The posi ion
and di ec ion o he gauge cylinde s is p esen ed in Figu e 25.
On he le side o he igu e, he gauge coo dina e sys em o he cube is shown. Fu he mo e, he
holes a e clea ly numbe ed by he indices o 𝑘=1,..,6. In he igu e on he igh , he gauge
geome y ( he coun e pa o he i ing) is shown. The cen es 𝐶1,…,𝐶6 o he geome ically ideal
cylinde s ha e been plo ed. Each o hese cylinde s is loca ed on he axis o he gauge cylinde . The
posi ion is he cen e be ween he ends o each hole in he echnical d awing o he p oduc . In he
ollowing, he pa ame e alues a e p o ided.
𝐶1=(𝐶1𝑥,𝐶1𝑦,𝐶1𝑧)𝑇=(−10,−30,−10)𝑇, 𝐶4=(𝐶4𝑥,𝐶4𝑦,𝐶4𝑧)𝑇=(−30,−10,−10)𝑇
𝐶2=(𝐶2𝑥,𝐶2𝑦,𝐶2𝑧)𝑇=(−30,−25,−10)𝑇, 𝐶5=(𝐶5𝑥,𝐶5𝑦,𝐶5𝑧)𝑇=(−10,−10,−25)𝑇
𝐶3=(𝐶3𝑥,𝐶3𝑦,𝐶3𝑧)𝑇=(−10,−10,−10)𝑇, 𝐶6=(𝐶6𝑥,𝐶6𝑦,𝐶6𝑧)𝑇=(−30,−10,−30)𝑇
The di ec ion ec o o he cylinde s 1 o 3 is
𝑣1=(𝑣1𝑥,𝑣1𝑦,𝑣1𝑧)𝑇=(0,0,1)𝑇.
The cylinde s 4 o 6 ha e he di ec ion ec o
𝑣2=(𝑣2𝑥,𝑣2𝑦,𝑣2𝑧)𝑇=(0,1,0)𝑇.
He e, he pa ame e alues a e also summa ized in a join ma ix 𝑀.
𝑀=
(
𝐶1𝑥 𝐶1𝑦 𝐶1𝑧 1𝑣1𝑥 𝑣1𝑦 𝑣1𝑧 𝑟
𝐶2𝑥 𝐶2𝑦 𝐶2𝑧 1𝑣1𝑥 𝑣1𝑦 𝑣1𝑧 𝑟
𝐶3𝑥 𝐶3𝑦 𝐶3𝑧 1𝑣1𝑥 𝑣1𝑦 𝑣1𝑧 𝑟
𝐶4𝑥 𝐶4𝑦 𝐶4𝑧 1𝑣2𝑥 𝑣2𝑦 𝑣2𝑧 𝑟
𝐶5𝑥 𝐶5𝑦 𝐶5𝑧 1𝑣2𝑥 𝑣2𝑦 𝑣2𝑧 𝑟
𝐶6𝑥 𝐶6𝑦 𝐶6𝑧 1𝑣2𝑥 𝑣2𝑦 𝑣2𝑧 𝑟
)
(21)
The column wi h he nume ical alues o "1" is o special impo ance o he ans o ma ion o he
pa ame e ma ix. This will be explained in he ollowing.
Speci ica ion o he ans o ma ion ope a o o he i ing
The ans o ma ion comp ises six di e en pa ame e s. Ini ially, h ee ansla ions o he gauge along
he wo kpiece coo dina e sys em a e possible. These ansla ions a e deno ed by he pa ame e .
𝑇=(𝑡𝑥,𝑡𝑦,𝑡𝑧)𝑇
The componen s indica e he espec i e ac ion o he ansla ion owa ds he coo dina e axis
wi h an iden ical index. Fu he mo e, h ee o a ions a ound he wo kpiece coo dina e axes a e
possible. This is ealized he e wi h he aid o he Eule o a ion angle.
𝜑=(𝜑𝑥,𝜑𝑦,𝜑𝑧)𝑇
Each componen de ines a o a ion ma ix. These a e
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𝑅𝑥=( 1 0 0
0 cos(𝜑𝑥)−sin(𝜑𝑥)
0 sin(𝜑𝑥) cos(𝜑𝑥))𝑇,
𝑅𝑦=( cos(𝜑𝑦) 0 sin(𝜑𝑦)
0 1 0
−sin(𝜑𝑦)0 cos(𝜑𝑦))𝑇
and
𝑅𝑧=(cos(𝜑𝑧)−sin(𝜑𝑧) 0
sin(𝜑𝑧) cos(𝜑𝑧)0
0 0 1)𝑇.
F om he indi idual o a ion ma ices, he ollowing ma ix is o med by means o mul iplica ion:
𝑅=𝑅𝑥𝑅𝑦𝑅𝑧=(𝑟11 𝑟12 𝑟13
𝑟21 𝑟22 𝑟23
𝑟31 𝑟32 𝑟33)
The eby, he ma ix 𝐻(𝑇,𝜑) o he ans o ma ion o he gauge geome y 𝑀 in (21) is
𝐻(𝑇,𝜑)=
(
𝑟11 𝑟21 𝑟31 0 0 0 0 0
𝑟12 𝑟22 𝑟32 0 0 0 0 0
𝑟13 𝑟23 𝑟33 0 0 0 0 0
𝑡𝑥 𝑡𝑦 𝑡𝑧 1 0 0 0 0
0 0 0 0 𝑟11 𝑟21 𝑟31 0
0 0 0 0 𝑟12 𝑟22 𝑟32 0
0 0 0 0 𝑟13 𝑟23 𝑟33 0
0 0 0 0 0 0 0 1
)
. (22)
The ans o med pa ame e ma ix is 𝑀(𝑇,𝜑)≔𝑀∙𝐻(𝑇,𝜑).
Du ing he calcula ion, he poin s indica ing he posi ion o he gauge cylinde s a e o a ed and
subsequen ly shi ed. The calcula ion o mula is 𝐶𝑘(𝑇,𝜑)=𝐶𝑘𝑅+𝑇. The di ec ion ec o s o he
gauge cylinde s a e exclusi ely wis ed. The o a ed ec o s a e designa ed wi h 𝑣𝑙(𝜑)=𝑣𝑙𝑅. These
ans o ma ion p o isions o he gauge pa ame e s a e used o he speci ica ion o he i ing ask
la e on.
Fo mula ion o an ini ial alue acco ding o he Gaussian c i e ion
Again, a a ou able ini ial o ien a ion o he gauge is being sough o ia a sui able Gaussian i ing.
Ini ially, 𝑃(𝑘)={𝑃1(𝑘),…,𝑃𝑚𝑘
(𝑘)}
wi h 𝑘=1,…,6 shall be he poin clouds o he measu ed holes o he cube. The indica ion
co esponds o he speci ica ion om Figu e 25. The a i hme ical cen oid is assigned o each poin
cloud:
𝑄𝑘=1
𝑚𝑘∑ 𝑃𝑖(𝑘)
𝑚𝑘
𝑖=1
The ini ial alue is hen he solu ion o he Gaussian p og am
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min
T0,φ0 12 ∑ ‖𝐶𝑘(𝑇0,𝜑0)−𝑄𝑘‖
6𝑘=1 2. (23)
In Figu e 26, he ini ial alue is illus a ed once again. The uppe pa shows he gauge and he
ex ac ed holes in he s a ing posi ion. The measu ed holes a e shown in simpli ied manne by
means o black do ed con ou s. The ans o ma ion ope a o s a e illus a ed a he axes o he
coo dina e sys em. By means o he Gaussian i ing, he median gauge poin s 𝐶𝑘 a e shi ed as nea
as possible o he cen oids o he poin clouds. This is shown by he lowe hal o he igu e.
Figu e 26 Ini ial alue o he cube i ing
De ini ion o he 3D hole pa e n i o he cube
Also in his applica ion example, cylind ical gauge elemen s a e a ailable. The e o e, he local
o hogonal dis ances be ween gauge and he measu ed poin s nea he elemen s 𝑘=1,…,3 a e
de ined by
𝑓𝑘𝑖(𝑀(𝑇,𝜑))=𝑟−‖(𝑃𝑖(𝑘)−𝐶𝑘(𝑇,𝜑))×𝑣1(𝜑)‖
and o 𝑘=4,…,6 by
Gaussian