Bsi bs au 228 2 1989 (2000) iso 8721 1987

BRITISH STANDARD AUTOMOBILE SERIES BS AU 228 2 1989 ISO 8721 1987 Impact tests on road vehicles — Part 2 Specification for measurement techniques using optical instrumentation [ISO title Road vehicles[.]

ISO 8721:1987

[ISO title: Road vehicles — Measurem ent techniques in im pact

tests — Optical instrum entation]

U C 6 9.1 :6 0.1 1 1.1

This Bri shStan ard, ha ing

b en pre ared u der the

directonof the Automo ile

Stan ards Commi e ,was

published u der the authoriy

ofthe Bo rd of BSI an

comesinto fect on

3 Mar h 1 8

© BSI 0 -2 0

The folowing BSI references

relate to the work on this

stan ard:

Commi e reference AUE/7

Draft for comment8 /77 8 DC

The prep ration of this BritishStand rd was entrusted b the Automobi e

Stand rd s Commit e ( AUE/-) to Tech ical Commit e AUE/ 7 upon which the

fol owing bodies were represented:

Association for Consumer Resear h

Automobi e Association

Chid Accident Prev ention Trust

Consumer Pol cy Commit e of BSI

Dep rtment of Transport ( Hig hway s)

Dep rtment of Transport ( Transport and Roa Resear h La oratory )

Institute for Consumer Erg onomic Ltd

Man-mad e Fibres Producer ’ Commit e

Med ical Resear h Cou ci

Ministry of Defence

Motor Ind ustry Resear h Association

National Automobi e Safety Belt Association

Roy al Automobie Club

Roy al Society for the Prev ention of Accidents

Society of Motor Man facturer and Tra er Ltd

Univ er ity of Birming ham

Am endm ents is ued sinc publ cation

Amd No Date of is ue Comments

Pag e

National foreword

This Part of BS AU2 8 has be n prep red u d er the d irection of the Automobie

Stand ards Commit e and is id entical with ISO8 2 :19 7 “R oa d vehicle —

Mea sur ement te hnique in impa ct te ts — O ptca l instr umenta tion”, publshed

b the International Org anization for Stand ardization ( ISO)

Term inolog y and conventions The text of the International Stand rd has

be n a prov ed as suita le for publcation as a BritishStand rd without

d ev iation Some terminolog y and certain conv entions are not identical with those

used in BritishStand rds; at ention is d rawn especial y to the fol owing

The comma has be n used as a decimal marker In BritishStand ards it is cur ent

practice to use a ful point on the b selne as the decimal marker

W herev er the words “ International Stand rd” a pear,refer ing to this stand rd ,

they should be read as “ Part of BS AU2 8”

A British Stand ard d oes not purport to includ e al the neces ary prov isions of a

contract User of British Stand rd s are responsible for their cor ect a plcation

Com pl anc with a British Standard does not ofitself confer im m unity

f om leg al o l g ations

Cros - referenc

Inte national Stand rd Cor esp nding BritishStand rd

ISO6 8 :19 7 BS AU2 8 Impa ct te ts on r oa d vehicle

Par t1:19 8 Spe ifica tion f r mea sur ement te h ique

a nd gener a l instr umenta tion

( Id entical

Sum mary of pag es

This document comprises a f ont cov er, an insid e font cov er, p g esi andi ,

p g es1 to4, an inside b ck cov er and a b ck cov er

This stand rd has be n up ated ( se copy rig ht d ate) an ma hav e ha

amendments incorporated This wi l be indicated in the amendment ta le on the

inside f ont cov er

1 Scope and field ofappl cation

This International Stand rd d efines per ormance

c iteria for an optical d ta chan el used in imp ct

tests on roa v ehicles, when numerical time and

sp ce d ta are taken f om the imag es to analy se

imp ct test results

The req uirements are to faci itate comp rison

betwe n results obtained b diferent la oratories

The an ex g iv es a method of measuring the

d istortion index as a qual ty p rameter of the

optical d ta chan el using a stand ard targ et, and ,

as an alternativ e, an ind irect method

This International Stand rd complements ISO6 8

which cov er non-optical instrumentation used in

imp ct tests on roa v ehicles

2 Ref r nce

ISO6 8 , R oa d vehicle — Te h ique o

mea sur ement in impa ct te ts — Instr umenta tion

3 Definitions

For the purposes of this International Stand rd , the

fol owing d efinitions a ply

3.1

o tical data channel

1)

sy stem composed of an imag e-taking dev ice

( e.g acamera), a recording medium for these

imag es ( fi m, d is ,mag netic ta e, etc.) and a sy stem

for analy sing the imag es, including any analy sis

proced ure and d ta cor ection that modify the

content of the d ata

3.2

distortion index

q ualty p rameter of the optical d ta channel

3.3

analysis system

sy stem to measure an col ect the co rd inates of

targ et points as a fu ction of time

3.4

tim e- base system

d ev ice al owing determination of the time interv al

ela sing betwe n any two recorded ev ents

3.5

tim e orig in identification devic

d ev ice to id entify the instant chosen as the time

orig in, usualy the beg in ing ofthe imp ct

3.6

im ag ing rate

f equency of renewal of information for a g iv en point

ex res ed in renewals per second or in imag es per

second when al the points of the imag e are renewed

simultane usly

4 Per ormance

The per ormance of the optical d ta chan el shal be

ev aluated initialy to esta lsh perormance lev els;

this ev aluation shal be repeated whenev er the

sy stem is modified to an extent which could cause a

chang e in ac uracy

4.1 Distortion index

The d istortion ind ex shal be as es ed using the

photog ra hic targ et and proced ure des ribed

respectiv ely inA.1.1andA.1.2 of the Annex It shal

be ev aluated as ind icated inA.1.3 The distortion

index shal not exce d1 %

4.2 Time b se

A time b se is req uired It shal permit

d etermination of the time betwe n recorded ev ents

to an ac uracy ofthe reciprocal of the imag ing rate

or1 % of the actual time, whichev er is g reater

4.3 Tim e orig in identification devic

The ac uracy of the dev ice shal be eq ual to the

reciprocal of the imag ing rate

4.4 Imag ing rate

The imag ing rate shal be left to the user’s

d is retion, taking ac ou t of al factor including :

— the g oal to be at ained ;

— the lmitations due to the eq uipment

( e.g blur);

— the ne d to combine d ata f om sev eral

imag e-taking d ev ices an fom electronic

recording s of the imp ct test

The user’s choice shal be g uid ed b the distance the

recorded point mov es betwe n two imag es analy sed

This distance shal not exce d any ac uracy

req uirement there ma be on determination of

position

4.5 Referenc leng th

A leng th calbration shal be car ied out which

permits determination of leng ths within any

requirements there ma be on ac uracy

In the a sence of such req uirements, it is

recommended that d eterminations of leng th to

within±1 % of the diag onal of the picture should be

pos ible

1)

The influence of the o erator on ac uracy has not b en taken into acou t d ring the dev elo ment of this Internatonal

Stan ard

Annex Distortion index m easur ment

methods

( This an ex forms an integ ral p rt of the Stand rd.)

A.1 Standard targ et m ethod

A.1.1 Te t target

A rectang ular targ et of ty pe and dimensions in

conformity with the fig ure shal be used

This targ et shal be div ided into four p rts b

joining the centre points of the two op osite sid es In

each qua rant th s obtained, and at the targ et

centre, cir les4 0±1mm in diameter shal be

drawn

The fiv e cir les shal be marked on their

cir umferences with16 reference marks, this

defining eig ht diameter for each, and

hence4 d iameter for the whole targ et

A.1.2 Te t met hod

The targ et shal be record ed ful f ame b the

imag e-taking dev ice which forms one element of the

optical d ta channel to be tested

The imag e-recording medium to be used for

cal bration shal be of the same ty pe an q ualty as

those used for imp ct testing It shal be analy sed

using the analy sis sy stem

The co rdinates of the marks of each d iameter d

i

shal be measured on the same fame whi e the

co rdinates of the marks of diferent diameter shal

be measured on consecutiv e analy sed imag es

A.1.3 Calculation o re ult s

The4 diameter d

i shal be calculated betwe n two

points, P and Q, f om the equation

d

i

=[( x

P

–x

Q

) 2

+(y

P –y ) 2

] 0,5

The diameter, , and the stand rd d ev iation, s,

respectiv ely shal be calculated taking

the4 diameter v alues d

i into ac ou t f om the

fol owing eq uations:

where N=4

where N–1 =3

The distortion index is eq ual to the ratio of the

stand rd dev iation, s, to the mean diameter, , i.e

A.2 Alternative ( ndire t) m etho

Other targ ets with d iferent siz s or p t erns of

reference marks ma be used,in which case the user

shal determine the d istor tion ind ex indirectly

There is then also a ne d to show that the ind irect

method g iv es results eq uiv alent to those using the

targ et specified inA.1.1

This ma be of a v antag e when for instance a targ et

with a rectang ular p t er n of reference marks is

used for the determination of lens cor ections, which

are ne ded in case of some wide-ang le lenses

d

d

s

d

-Fig ure — Targ et for distortion index determ ination

Publica tions referred to

Se national foreword

ISO 8721:1987

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