1、BRITISH STANDARD AUTOMOBILE SERIES BS AU228-2: 1989 ISO8721:1987 Impact tests on road vehicles Part2: Specification for measurement techniques using optical instrumentation ISO title: Road vehicles Measurement techniques in impact tests Optical instrumentation UDC 629.11:620.1/.111.1BSAU228-2:1989 T
2、his BritishStandard, having been prepared under the directionof the Automobile Standards Committee, was published under the authority ofthe Board of BSI and comesintoeffect on 31 March 1989 BSI 01-2000 The following BSI references relate to the work on this standard: Committee reference AUE/7 Draft
3、for comment86/77884DC ISBN 0 580 16859 X Committees responsible for this BritishStandard The preparation of this BritishStandard was entrusted by the Automobile Standards Committee (AUE/-) to Technical Committee AUE/7 upon which the following bodies were represented: Association for Consumer Researc
4、h Automobile Association Child Accident Prevention Trust Consumer Policy Committee of BSI Department of Transport (Highways) Department of Transport (Transport and Road Research Laboratory) Institute for Consumer Ergonomics Ltd. Man-made Fibres Producers Committee Medical Research Council Ministry o
5、f Defence Motor Industry Research Association National Automobile Safety Belt Association Royal Automobile Club Royal Society for the Prevention of Accidents Society of Motor Manufacturers and Traders Ltd. University of Birmingham Amendments issued since publication Amd. No. Date of issue CommentsBS
6、AU228-2:1989 BSI 01-2000 i Contents Page Committees responsible Inside front cover National foreword ii 1 Scope and field of application 1 2 Reference 1 3 Definitions 1 4 Performance 1 Annex Distortion index measurement methods 2 FigureTarget for distortion index determination 3 Publications referre
7、d to Inside back coverBSAU228-2:1989 ii BSI 01-2000 National foreword This Part of BS AU228 has been prepared under the direction of the Automobile Standards Committee and is identical with ISO8721:1987 “Road vehicles Measurement techniques in impact tests Optical instrumentation”, published by the
8、International Organization for Standardization (ISO). Terminology and conventions. The text of the International Standard has been approved as suitable for publication as a BritishStandard without deviation. Some terminology and certain conventions are not identical with those used in BritishStandar
9、ds; attention is drawn especially to the following. The comma has been used as a decimal marker. In BritishStandards it is current practice to use a full point on the baseline as the decimal marker. Wherever the words “International Standard” appear, referring to this standard, they should be read a
10、s “Part of BS AU228”. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Cross-reference Int
11、ernational Standard Corresponding BritishStandard ISO6487:1987 BS AU228 Impact tests on road vehicles Part1:1988 Specification for measurement techniques and general instrumentation (Identical) Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 to4, a
12、n inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BSAU228-2:1989 BSI 01-2000 1 1 Scope and field of application This International Standard define
13、s performance criteria for an optical data channel used in impact tests on road vehicles, when numerical time and space data are taken from the images to analyse impact test results. The requirements are to facilitate comparison between results obtained by different laboratories. The annex gives a m
14、ethod of measuring the distortion index as a quality parameter of the optical data channel using a standard target, and, as an alternative, an indirect method. This International Standard complements ISO6487 which covers non-optical instrumentation used in impact tests on road vehicles. 2 Reference
15、ISO6487, Road vehicles Techniques of measurement in impact tests Instrumentation. 3 Definitions For the purposes of this International Standard, the following definitions apply. 3.1 optical data channel 1) system composed of an image-taking device (e.g.acamera), a recording medium for these images (
16、film, disc, magnetic tape, etc.) and a system for analysing the images, including any analysis procedure and data correction that modify the content of the data 3.2 distortion index quality parameter of the optical data channel 3.3 analysis system system to measure and collect the coordinates of tar
17、get points as a function of time 3.4 time-base system device allowing determination of the time interval elapsing between any two recorded events 3.5 time origin identification device device to identify the instant chosen as the time origin, usually the beginning of the impact 3.6 imaging rate frequ
18、ency of renewal of information for a given point expressed in renewals per second or in images per second when all the points of the image are renewed simultaneously 4 Performance The performance of the optical data channel shall be evaluated initially to establish performance levels; this evaluatio
19、n shall be repeated whenever the system is modified to an extent which could cause a change in accuracy. 4.1 Distortion index The distortion index shall be assessed using the photographic target and procedure described respectively inA.1.1 andA.1.2 of the Annex. It shall be evaluated as indicated in
20、A.1.3. The distortion index shall not exceed1%. 4.2 Time base A time base is required. It shall permit determination of the time between recorded events to an accuracy of the reciprocal of the imaging rate or1% of the actual time, whichever is greater. 4.3 Time origin identification device The accur
21、acy of the device shall be equal to the reciprocal of the imaging rate. 4.4 Imaging rate The imaging rate shall be left to the users discretion, taking account of all factors including: the goal to be attained; the limitations due to the equipment (e.g.blur); the need to combine data from several im
22、age-taking devices and from electronic recordings of the impact test. The users choice shall be guided by the distance the recorded point moves between two images analysed. This distance shall not exceed any accuracy requirement there may be on determination of position. 4.5 Reference length A lengt
23、h calibration shall be carried out which permits determination of lengths within any requirements there may be on accuracy. In the absence of such requirements, it is recommended that determinations of length to within 1% of the diagonal of the picture should be possible. 1) The influence of the ope
24、rator on accuracy has not been taken into account during the development of this International Standard.BSAU228-2:1989 2 BSI 01-2000 Annex Distortion index measurement methods (This annex forms an integral part of the Standard.) A.1 Standard target method A.1.1 Test target A rectangular target of ty
25、pe and dimensions in conformity with the figure shall be used. This target shall be divided into four parts by joining the centre points of the two opposite sides. In each quadrant thus obtained, and at the target centre, circles400 1mm in diameter shall be drawn. The five circles shall be marked on
26、 their circumferences with16 reference marks, this defining eight diameters for each, and hence40diameters for the whole target. A.1.2 Test method The target shall be recorded full-frame by the image-taking device which forms one element of the optical data channel to be tested. The image-recording
27、medium to be used for calibration shall be of the same type and quality as those used for impact testing. It shall be analysed using the analysis system. The coordinates of the marks of each diameter d ishall be measured on the same frame while the coordinates of the marks of different diameters sha
28、ll be measured on consecutive analysed images. A.1.3 Calculation of results The40diameters d ishall be calculated between two points, P and Q, from the equation d i =(x P x Q ) 2 +(y P y Q ) 2 0,5 The diameter, , and the standard deviation, s, respectively shall be calculated taking the40diameter va
29、lues d iinto account from the following equations: where N=40 where N1=39 The distortion index is equal to the ratio of the standard deviation, s, to the mean diameter, , i.e. A.2 Alternative (indirect) method Other targets with different sizes or patterns of reference marks may be used, in which ca
30、se the user shall determine the distortion index indirectly. There is then also a need to show that the indirect method gives results equivalent to those using the target specified inA.1.1. This may be of advantage when for instance a target with a rectangular pattern of reference marks is used for
31、the determination of lens corrections, which are needed in case of some wide-angle lenses. d d s d -BSAU228-2:1989 BSI 01-2000 3 Figure Target for distortion index determination4 blankBSAU228-2:1989 BSI 01-2000 Publications referred to Seenational foreword.BS AU228-2: 1989 ISO8721:1987 BSI 389 Chisw
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