1、 ISO 2014 Quasi-static calibration procedure for belt force transducers Procdure dtalonnage quasi-statique pour capteurs defforts pour ceintures TECHNICAL SPECIFICATION ISO/TS 17242 First edition 2014-05-01 Reference number ISO/TS 17242:2014(E) ISO/TS 17242:2014(E)ii ISO 2014 All rights reserved COP
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3、ission. Permission can be requested from either ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ISO/TS 17
4、242:2014(E) ISO 2014 All rights reserved iii Contents Page Foreword iv 1 Scope . 1 2 Normative references 1 3 Gener al specifications . 2 3.1 General . 2 3.2 Limitations or the application of the test belt strap . 2 4 Test conditions . 3 4.1 Test method . 3 4.2 Clamping length . 3 4.3 Test velocity
5、. 3 4.4 Belt strap 3 4.5 Load relieving 3 4.6 Data acquisition . 3 4.7 Data evaluation . 3 4.8 Sensor excitation . 4 4.9 Environmental conditions . 4 5 Calibration procedure . 4 5.1 Conditioning 4 5.2 Test preparation . 4 5.3 Calibration test 4 5.4 Data storage . 4 5.5 Data evaluation . 4 5.6 Docume
6、ntation . 5 Annex A (normative) Test setup 6 Annex B (normative) Evaluation method 7 Annex C (informative) Belt strap characteristics .10 Annex D (informative) Applications notes 12 ISO/TS 17242:2014(E) Foreword ISO (the International Organization for Standardization) is a worldwide federation of na
7、tional standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. Intern
8、ational organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. The procedures used to develop this document and those inte
9、nded for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www
10、.iso.org/directives). Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any patent rights identified during the development of the document
11、will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents). Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement. For an explanation on the meaning of ISO specific terms and exp
12、ressions related to conformity assessment, as well as information about ISOs adherence to the WTO principles in the Technical Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information The committee responsible for this document is ISO/TC 22, Road vehicles, Subcommittee SC 1
13、2, Passive safety crash protection systems.iv ISO 2014 All rights reserved TECHNICAL SPECIFICATION ISO/TS 17242:2014(E) Quasi-static calibration procedure for belt force transducers 1 Scope The objective of this Technical Specification is to provide a procedure to calibrate seat belt force transduce
14、rs with loading capacities up to 25 kN and consistent test specifications and sequences in order to improve comparability of measurement results between testing laboratories. 2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indi
15、spensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 376, Metallic materials Calibration of force-proving instruments used for the verification of uniaxial te
16、sting machines ISO 5084, Textiles Determination of thickness of textiles and textile products ISO 6487, Road vehicles Measurement techniques in impact tests Instrumentation ISO 13499, Road vehicles Multimedia data exchange format for impact tests ECE-R16, Safety-belts, restraint systems, child restr
17、aint systems and ISOFIX child restraint systems for occupants of power-driven vehicles SAE-J2517, Hybrid III Family Chest Potentiometer Calibration Procedure ISO 2014 All rights reserved 1 ISO/TS 17242:2014(E) 3 Gener al specificati ons 3.1 General The described measurement procedure refers to belt
18、force transducers with the specifications according to Table 1 and a loading capacity of up to 25 kN. Table 1 Design categorization of belt force transducers Type Description Belt Orientation 1 Baffle (test belt strap according to Annex 3) 2 Loop (test belt strap according to customer requirement) 3
19、 Clamping (test belt strap according to customer requirement) 4 3-Bolt (test belt strap according to customer requirement) 3.2 Limitations or the application of the test belt strap In general, the standardized calibration belt strap (see C.1) is only recommended for the calibration of belt force tra
20、nsducers which are to be utilized in tests that focuses on comparability between different laboratories (such as during development efforts). In case absolute values have to be obtained, the seat belt webbing designated for subsequent testing purposes is to be used for calibration. 1) Calibration us
21、ing the standardized calibration belt strap shall be done for highly dynamically loaded transducers as shown in Type 1 (baffle). Consequently Types 2, 3, 4, and Type 1 transducers for quasi- static loads and measurement ranges up to 500 N (i.e. comfort measurements) are to be excluded. NOTE If requi
22、red (e.g. by the user or the test protocol), Type 1 transducers with measurement ranges beyond 500 N should be calibrated with a specimen of the seat belt webbing which is designated for subsequent testing purposes. For the calibration of Types 2, 3, 4, and Type 1 transducers for quasi-static loads
23、and measurement ranges below 500 N, a specimen of the seat belt webbing which is designated for subsequent testing purposes will be necessary. 1) Measurement of absolute values shows significant variation for type 1 transducers. A different measurement principle is recommended.2 ISO 2014 All rights
24、reserved ISO/TS 17242:2014(E) The belt strap type used for calibration as well as the straps average thickness (see Annex C) shall be identified in the calibration report. If a non-standardized belt strap is supplied, it is also recommended to perform a calibration using the standardized belt strap
25、for traceability. 4 Test conditions The calibration test shall be performed under the conditions identified below. 4.1 Test method A continuous loading up to the transducers full scale range 2)shall be applied. 4.2 Clamping length As shown in Annex A, the belt force transducer is tested on a belt st
26、rap specimen clamped into the universal tension machine. The free clamping length shall be within 375 mm 75 mm. 4.3 Test velocity The speed of displacement of the tension machine for the continuous loading shall be within 170 mm/min 30 mm/min. 4.4 Belt strap A standardized belt strap specimen as def
27、ined in Annex C should be utilized. 3) 4.5 Load relieving The hysteresis is not verified. 4.6 Data acquisition In case of polynomial regression, the zero offset shall not be corrected prior to the test. So the amplifier offset should be considered for the error of measurement of the whole measuremen
28、t channel. The filter settings shall comply with the ISO 6487 specifications. 4.7 Data evaluation For the evaluation, the first loading sequence 4)recorded with a minimum sampling rate of 100 Hz 5)shall be considered in a range from 2 % to 100 % of the transducers calibration range (e.g. 0,32 kN 16
29、kN 16 kN sensor range) 6) . The nonlinearity is displayed as a percentage in % of the calibration range. 2) See transducer data sheet. 3) Other belt strap types have to be identified in the calibration report. 4) No preloading procedures. 5) To reach appropriate accuracy. 6) Ensure the comparison st
30、andard is traceable (e.g. ISO 376). ISO 2014 All rights reserved 3 ISO/TS 17242:2014(E) 4.8 Sensor excitation The sensor excitation voltage, as well as the sensor connection, shall be in accordance to the customer requirements and shall be recorded. 7) 4.9 Environmental conditions The calibration te
31、st shall be performed under monitored environmental conditions within a temperature range of 19 C to 23 C and a Relative Humidity of 10 % to 70 %. For acclimatization purposes, the transducers as well as the belt strap specimen should be kept in this environment for a period of 8 h prior to the cali
32、bration. 5 Calibration procedure Proceed with the following steps to perform the calibration test. 5.1 Conditioning An adequate warm-up time for the data acquisition system, test and reference transducer should be allowed to reach thermal equilibrium. 5.2 Test preparation The sensor offset should be
33、 measured under no load condition. A new belt strap shall be inserted and centred in the fixations 8) . The test transducer shall be mounted centred and perpendicular in accordance to the sensor users manual. The belt strap preload shall not exceed 0,2 % of the calibration range (while holding the t
34、ransducer in place). 5.3 Calibration test In case of linear regression, prior to the test the sensors zero offset shall be corrected. In case of polynomial regression, the zero offset shall not be corrected prior to the test 9) . Only one loading sequence with one belt strap per test transducer up t
35、o a force level of 101 % of the transducers calibration range shall be performed within the given velocity range. The calibration data shall be acquired continuously. There are no requirements for the load relieving sequence. 5.4 Data storage The data storage format is optional 10) . 5.5 Data evalua
36、tion A Linear Equation following B.1 or a Third Degree Polynomial without any offset correction as defined in B.2 11)should be determined from the recorded data points. 7) Excitation voltage as well as pin assignment and if excitation sensing was utilized shall be stated in calibration report. 8) Fi
37、xation by clamp or loop (ECE-R16 conform). 9) Use of the calibration coefficient as defined in SAE-J2517: Prior to a crash test, the original zero offset level should be preserved by either not zeroing the transducer or the amount that was zeroed should be added during post-processing. 10) ISO 13499
38、 recommends: incl. time channel, output test sensor, output reference sensor, and travel distance. 11) If the calibrated transducer is used in tests, the hardware offset shall not be corrected.4 ISO 2014 All rights reserved ISO/TS 17242:2014(E) 5.6 Documentation The test report shall include the fol
39、lowing: temperature; humidity; belt strap type; strap thickness; 12) sensitivity in kN/mV/V and mV/kN/V (for linear regression) or a third degree polynomial equation in the form F = AS3+BS2+CS+M; 13) the polynomial coefficients in kN/mV/V (polynomial coefficients significant digits: 3rd degree: 9 (e
40、.g. 0,001 234 567 89), 2nd degree: 6 (e.g. 1,234 56), 1st degree: 3 (e.g. 12,3); measured sensor offset in unloaded condition in mV/V; 14) nonlinearity as a percentage in % of the transducers calibration range. 12) See page 13 “Measurement of Test Belt Strap Thickness”. 13) See page 11 ”Polynomial R
41、egression”. 14) To check the offset magnitude of the data acquisition system. ISO 2014 All rights reserved 5 ISO/TS 17242:2014(E) Annex A (normative) Test setup Figure A.1 Schematic calibration test setup6 ISO 2014 All rights reserved ISO/TS 17242:2014(E) Annex B (normative) Evaluation method B.1 Li
42、near regression For the software linearization a least-squares fit method applied through the point of origin is used: The starting point of the linearized line is identical with the starting point of the measurement. This point is set to zero (point of origin). This measurement is independent of th
43、e defined evaluation interval (see 4.7). The resulting linear equation is F i= b (S i S 0 ) + D (B.1) where S 0 = 0; D = 0. For the linearization, the square sum of the difference between measured value and linearized value must be minimal: (B.2) The differentiation is equated to zero: S i , F i= me
44、asured From this will follow: (B.3) 1Key F is the actual force in kN S is the sensor output reading in mV/V D is the calculated offset in kN (linear regression) a is the sensitivity in mV/kN/V b is the inverse sensitivity in kN/mV/V is the deviation ISO 2014 All rights reserved 7 ISO/TS 17242:2014(E
45、) B.2 Polynomial regression For the polynomial approximation, a least-squares fit method shall be utilized to determine the polynomial coefficients A, B, C, and M. With mesh points (S i ; F i ) the third degree polynomial will acquire the general form: F i= AS i a+ BS i 2+ CS i+ M (B.4) The function
46、 values F iare complemented by residues r i(corrections) F i+ r i= AS i a+ BS i 2+ CS i+ M (B.5) Applied on the mesh points the observation formulae follow: r 1= AS 1 a+ BS 1 2+ CS 1+ M F 1(B.6) r 1= AS i a+ BS i 2+ CS i+ M F iThe observation equations are squared and then pooled. T o determine the
47、minimum of the residues r i , the observation formulas sum of squares are differentiated and equated to zero. A linear system of equations results from putting in the mesh points (x i ; y i ). Coefficients A, B, C, and M and therefore the equalization polynomial through the point of origin can be calculated.8 ISO 2014 All rights reserved ISO/TS 17242:2014(E) Key F is the actual force in kN S is the sensor output reading in mV/V M is the physical offset prior to the test
