Road vehicles -- Test method for the quantification of on-centre handling

ISO 13674-2:2016 specifies a test schedule that addresses a particular aspect of the transition test, the on-centre handling characteristics of a vehicle. It is applicable to passenger cars in accordance with ISO 3833 and to light trucks, N1 category. NOTE The manoeuvre specified in this test method is not representative of real driving conditions, but is useful for obtaining measures of vehicle on-centre handling behaviour in response to a specific type of steering input under closely controlled test conditions. Other aspects of on-centre handling are addressed in the companion ISO 13674‑1.

Véhicules routiers -- Méthode d'essai pour la quantification du centrage

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Published
Publication Date
03-Apr-2016
Current Stage
9020 - International Standard under periodical review
Start Date
15-Apr-2021
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INTERNATIONAL ISO
STANDARD 13674-2
Second edition
2016-04-01
Road vehicles — Test method for
the quantification of on-centre
handling —
Part 2:
Transition test
Véhicules routiers — Méthode d’essai pour la quantification du
centrage —
Partie 2: Essai de la transition
Reference number
ISO 13674-2:2016(E)
ISO 2016
---------------------- Page: 1 ----------------------
ISO 13674-2:2016(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2016, Published in Switzerland

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form

or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior

written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of

the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2016 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 13674-2:2016(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms, definitions and symbols ............................................................................................................................................................ 1

4 Principle ........................................................................................................................................................................................................................ 2

5 Variables ....................................................................................................................................................................................................................... 2

5.1 Reference system .................................................................................................................................................................................. 2

5.2 Variables to be measured ............................................................................................................................................................... 2

6 Measuring equipment ..................................................................................................................................................................................... 3

6.1 Description ................................................................................................................................................................................................. 3

6.2 Transducer installations ................................................................................................................................................................. 3

6.3 Data processing ...................................................................................................................................................................................... 3

7 Test conditions ....................................................................................................................................................................................................... 3

7.1 General ........................................................................................................................................................................................................... 3

7.2 Test track ...................................................................................................................................................................................................... 4

7.3 Wind velocity ............................................................................................................................................................................................ 4

7.4 Test vehicle ................................................................................................................................................................................................. 4

7.4.1 General data ......................................................................................................................................................................... 4

7.4.2 Tyres ........................................................................................................................................................................................... 4

7.4.3 Operating components ............................................................................................................................................... 4

7.4.4 Loading conditions of the vehicle ...................................................................................................................... 5

8 Test procedure ........................................................................................................................................................................................................ 5

8.1 Warm-up....................................................................................................................................................................................................... 5

8.2 Initial driving condition .................................................................................................................................................................. 5

8.3 Transition test procedure .............................................................................................................................................................. 5

9 Data evaluation and presentation of results ........................................................................................................................... 6

9.1 General ........................................................................................................................................................................................................... 6

9.2 Time histories .......................................................................................................................................................................................... 6

9.3 Characteristic values .......................................................................................................................................................................... 6

9.3.1 Presentation of results ................................................................................................................................................ 6

9.3.2 Steering-wheel torque versus steering-wheel angle (M vs. δ ) ........................................... 9

H H

9.3.3 Yaw velocity versus steering-wheel angle (dψ / dt vs. δ ) .......................................................... 9

9.3.4 Yaw velocity versus steering-wheel torque (dψ / dt vs. M ) ..................................................... 9

9.3.5 Lateral acceleration versus steering-wheel angle (a vs. δ ) .................................................... 9

y H

9.3.6 Lateral acceleration versus steering-wheel torque (a vs. M ) ............................................... 9

y H

Annex A (informative) Characteristic values ............................................................................................................................................10

Bibliography .............................................................................................................................................................................................................................15

© ISO 2016 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO 13674-2:2016(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national 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. International

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 intended 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.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 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 expressions related to conformity

assessment, as well as information about ISO’s 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 33, Vehicle

dynamics and chassis components.

This second edition cancels and replaces the first edition (ISO 13674-2:2006), which has been

technically revised.

ISO 13674 consists of the following parts, under the general title Road vehicles — Test method for the

quantification of on-centre handling:
— Part 1: Weave test
— Part 2: Transition test
iv © ISO 2016 – All rights reserved
---------------------- Page: 4 ----------------------
ISO 13674-2:2016(E)
Introduction

The main purpose of this part of ISO 13674 is to provide repeatable and discriminatory test results.

The dynamic behaviour of a road vehicle is a very important aspect of active vehicle safety. Any given

vehicle, together with its driver and the prevailing environment, constitutes a closed-loop system that

is unique. The task of evaluating the dynamic behaviour is therefore very difficult since the significant

interaction of these driver-vehicle-environment elements are each complex in themselves. A complete

and accurate description of the behaviour of the road vehicle must necessarily involve information

obtained from a number of different tests.

Since this test method quantifies only one small part of the complete vehicle handling characteristics,

the results of these tests can only be considered significant for a correspondingly small part of the

overall dynamic behaviour.

Moreover, insufficient knowledge is available concerning the relationship between overall vehicle

dynamic properties and accident avoidance. A substantial amount of work is necessary to acquire

sufficient and reliable data on the correlation between accident avoidance and vehicle dynamic

properties in general and the results of these tests in particular. Consequently, any application of this

test method for regulation purposes will require proven correlation between test results and accident

statistics.
© ISO 2016 – All rights reserved v
---------------------- Page: 5 ----------------------
INTERNATIONAL STANDARD ISO 13674-2:2016(E)
Road vehicles — Test method for the quantification of on-
centre handling —
Part 2:
Transition test
1 Scope

This part of ISO 13674 specifies a test schedule that addresses a particular aspect of the transition test,

the on-centre handling characteristics of a vehicle. It is applicable to passenger cars in accordance with

ISO 3833 and to light trucks, N1 category.

NOTE The manoeuvre specified in this test method is not representative of real driving conditions,

but is useful for obtaining measures of vehicle on-centre handling behaviour in response to a specific type of

steering input under closely controlled test conditions. Other aspects of on-centre handling are addressed in the

companion ISO 13674-1.
2 Normative references

The following documents, in whole or in part, are normatively referenced in this document and are

indispensable 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 1176, Road vehicles — Masses — Vocabulary and codes
ISO 2416, Passenger cars — Mass distribution
ISO 3833, Road vehicles — Types — Terms and definitions
ISO 8855, Road vehicles — Vehicle dynamics and road-holding ability — Vocabulary

ISO 15037-1:2006, Road vehicles — Vehicle dynamics test methods — Part 1: General conditions for

passenger cars
3 Terms, definitions and symbols

For the purposes of this document, the terms, definitions and symbols given in ISO 1176, ISO 2416,

ISO 3833, ISO 8855 and the following apply.
3.1
on-centre handling

description of the steering “feel” and steering precision of a vehicle during nominally straight-line

driving and in negotiating large radius bends at high speeds but low lateral accelerations

3.2
ordinate threshold

value of a parameter plotted as the ordinate on a graph and defined as the minimum threshold of human

perception
3.3
abscissa deadband

horizontal separation between the pair of straight-line fits at ordinate threshold values

© ISO 2016 – All rights reserved 1
---------------------- Page: 6 ----------------------
ISO 13674-2:2016(E)
3.4
gradient

ratio of change in the ordinate with respect to a unit change in the abscissa, for a straight-line fit to a

pair of recorded variables plotted one against the other on Cartesian coordinates

4 Principle

On-centre handling represents that part of the straight-line directional stability characteristics of the

vehicle existing at low lateral acceleration levels, typically no greater than 1 m/s . On-centre handling

is concerned primarily with features that directly influence the driver’s steering input, such as steering

system and tyre characteristics. Thus, test schedules for the evaluation of on-centre handling behaviour

seek to minimize other factors that influence the wider aspects of straight-line directional stability,

such as disturbance inputs due to ambient winds and road irregularities.

This part of ISO 13674 defines test schedules that involve driving the vehicle in a nominally straight line

at a constant forward speed. During the tests, driver inputs and vehicle responses are measured and

recorded. From the recorded signals, characteristic values are calculated.
5 Variables
5.1 Reference system

The variables of motion used to describe vehicle behaviour in a test-specific driving situation shall be

related to the intermediate axis system (X, Y, Z) (see ISO 8855).

The location of the origin of the vehicle axis system (X , Y , Z ) is the reference point and therefore

V V V

should be independent of the loading condition. The origin is therefore fixed in the longitudinal plane of

symmetry at half-wheelbase and at the same height above ground as the centre of gravity of the vehicle

at complete vehicle kerb mass (see ISO 1176).
5.2 Variables to be measured
When using this test method, the following variables shall be measured:
— steering-wheel angle, δ ;
— steering-wheel torque, M ;
— yaw velocity, dψ / dt;
— longitudinal velocity, v ;
— lateral acceleration, a (see the NOTE to 6.2).
The following variables should be measured:
— steering-wheel angular velocity, dδ / dt;
— roll angle, ψ.
The variables are defined in ISO 8855.

In order to acquire a deeper understanding of the vehicle behaviour, it may be desirable to determine

motions of various components within the steering system, especially for vehicles with more than one

steering axle.
2 © ISO 2016 – All rights reserved
---------------------- Page: 7 ----------------------
ISO 13674-2:2016(E)
6 Measuring equipment
6.1 Description
The measuring equipment shall be in accordance with ISO 15037-1.

Typical operating ranges and recommended maximum errors of the combined transducer and recording

system are shown in Table 1.

NOTE It is advisable that care be taken to ensure that friction or inertia added to the system by steering

robot or steering transducers does not improperly influence the measurement of steering-wheel torque.

Table 1 — Variables, typical operating ranges and recommended maximum errors
Recommended maximum error of the
Variable Typical operating range combined transducer and recorder
system
Steering-wheel angle ±50° ±0,1°
Steering-wheel torque ±10 Nm ±0,1 Nm
Yaw velocity ±10 °/s ±0,1 °/s
Longitudinal velocity 0 – 50 m/s ±0,5 m/s
2 2
Lateral acceleration ±5 m/s ±0,1 m/s
Steering-wheel angular velocity ±100 °/s ±1 °/s
Roll angle ±5° ±0,05°

Transducers for measuring some of the listed variables are not widely available and are not in general use. Many such

instruments are developed by users. If any system error exceeds the recommended maximum value, this and the actual

maximum error shall be stated in the test report (ISO 15037-1:2006, Annex A).

These transducer ranges are appropriate for the standard test conditions and may not be suitable for non-standard

test conditions.

The values for maximum errors are provisional until more experience and data are available.

6.2 Transducer installations

The transducers shall be installed according to the manufacturers’ instructions, where such instructions

exist, so that the variables corresponding to the terms and definitions of ISO 8855 can be determined.

If a transducer does not measure a variable directly, appropriate transformations into the specified

reference system shall be carried out.

NOTE Lateral acceleration, as defined, is measured in the intermediate XY plane. However, for the purpose

of this test procedure, measurement of “sideways” acceleration in the vehicle X Y plane (i.e. corrupted by vehicle

v v

roll) is typically adequate, provided that the roll angle versus lateral acceleration characteristic for the vehicle is

known and an appropriate correction in respect of roll angle can be made to the “sideways” acceleration.

6.3 Data processing
See ISO 15037-1:2006, 4.3.
7 Test conditions
7.1 General

General comments relating to test conditions are given in ISO 15037-1:2006, Clause 5.

© ISO 2016 – All rights reserved 3
---------------------- Page: 8 ----------------------
ISO 13674-2:2016(E)
7.2 Test track

The test track requirements shall be in accordance with those of ISO 15037-1:2006, 5.2. In addition, the

lateral gradient of the test surface should not exceed 1 %.
7.3 Wind velocity

During a test, the ambient wind velocity shall not exceed 5 m/s when measured at a height above

ground of not less than 1 m. Ideally, the maximum ambient wind velocity should not exceed 1,5 m/s. If

this cannot be achieved, then conditions of significant “gusting” should be avoided, i.e. testing should be

avoided in conditions where changes in wind velocity exceed a range of 1,5 m/s. In the event that the

ambient velocity exceeds 1,5 m/s or the range of “gusting” exceeds 1,5 m/s, or both, the vehicle should

be tested in a direction such that the ambient wind is a tail wind. For each test, the climatic conditions

shall be recorded in the test report (see ISO 15037-1:2006, Annex B).

Where measurement of wind velocity is not possible, estimation by use of the Beaufort scale is suggested

(see Table 2).

Table 2 — Estimation scale for wind intensity for observer without measuring instrument

(Beaufort scale)
Wind intensity
0 1 2 3 4
(Beaufort scale)
Name calm light air light breeze gentle breeze moderate breeze
Velocity in m/s 0 – 0,2 0,3 – 1,5 1,6 – 3,3 3,4 – 5,4 5,5 – 7,9
smoke rises wind direction leaves rustle, wind felt leaves and moves twigs and
Identification
vertically in a i
...

DRAFT INTERNATIONAL STANDARD ISO/DIS 13674-2
ISO/TC 22/SC 9 Secretariat: DIN
Voting begins on Voting terminates on
2013-03-08 2013-06-08

INTERNATIONAL ORGANIZATION FOR STANDARDIZATION • МЕЖДУНАРОДНАЯ ОРГАНИЗАЦИЯ ПО СТАНДАРТИЗАЦИИ • ORGANISATION INTERNATIONALE DE NORMALISATION

Road vehicles — Test method for the quantification of on-centre
handling —
Part 2:
Transition test
Véhicules routiers — Méthode d'essai pour la quantification du centrage —
Partie 2: Essai de la transition
[Revision of first edition (ISO 13674-2:2006)]
ICS 43.020

To expedite distribution, this document is circulated as received from the committee

secretariat. ISO Central Secretariat work of editing and text composition will be undertaken at

publication stage.

Pour accélérer la distribution, le présent document est distribué tel qu'il est parvenu du

secrétariat du comité. Le travail de rédaction et de composition de texte sera effectué au

Secrétariat central de l'ISO au stade de publication.

THIS DOCUMENT IS A DRAFT CIRCULATED FOR COMMENT AND APPROVAL. IT IS THEREFORE SUBJECT TO CHANGE AND MAY NOT BE

REFERRED TO AS AN INTERNATIONAL STANDARD UNTIL PUBLISHED AS SUCH.

IN ADDITION TO THEIR EVALUATION AS BEING ACCEPTABLE FOR INDUSTRIAL, TECHNOLOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT

INTERNATIONAL STANDARDS MAY ON OCCASION HAVE TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL TO BECOME STANDARDS TO

WHICH REFERENCE MAY BE MADE IN NATIONAL REGULATIONS.

RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT, WITH THEIR COMMENTS, NOTIFICATION OF ANY RELEVANT PATENT RIGHTS OF WHICH

THEY ARE AWARE AND TO PROVIDE SUPPORTING DOCUMENTATION.
© International Organization for Standardization, 2013
---------------------- Page: 1 ----------------------
ISO/DIS 13674-2
Copyright notice

This ISO document is a Draft International Standard and is copyright-protected by ISO. Except as permitted

under the applicable laws of the user’s country, neither this ISO draft nor any extract from it may be

reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic,

photocopying, recording or otherwise, without prior written permission being secured.

Requests for permission to reproduce should be addressed to either ISO at the address below or ISO’s

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 copyright@iso.org
Web www.iso.org
Reproduction may be subject to royalty payments or a licensing agreement.
Violators may be prosecuted.
ii © ISO 2013 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/DIS 13674-2
Contents Page

Foreword ............................................................................................................................................................ iv

Introduction ......................................................................................................................................................... v

1 Scope ...................................................................................................................................................... 1

2 Normative references ............................................................................................................................ 1

3 Terms, definitions and symbols .......................................................................................................... 1

4 Principle.................................................................................................................................................. 2

5 Variables ................................................................................................................................................. 2

5.1 Reference system .................................................................................................................................. 2

5.2 Variables to be measured ..................................................................................................................... 2

6 Measuring equipment ........................................................................................................................... 3

6.1 Description ............................................................................................................................................. 3

6.2 Transducer installations ....................................................................................................................... 3

6.3 Data processing ..................................................................................................................................... 3

7 Test conditions ...................................................................................................................................... 3

7.1 General ................................................................................................................................................... 3

7.2 Test track ................................................................................................................................................ 4

7.3 Wind velocity ......................................................................................................................................... 4

7.4 Test vehicle ............................................................................................................................................ 4

8 Test procedure ....................................................................................................................................... 5

8.1 Warm-up ................................................................................................................................................. 5

8.2 Initial driving condition ......................................................................................................................... 5

8.3 Transition test procedure ..................................................................................................................... 5

9 Data evaluation and presentation of results ....................................................................................... 6

9.1 General ................................................................................................................................................... 6

9.2 Time histories ........................................................................................................................................ 6

9.3 Characteristic values ............................................................................................................................ 6

Bibliography ...................................................................................................................................................... 12

© ISO 2012 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO/DIS 13674-2
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national 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. International 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.

International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.

The main task of technical committees is to prepare International Standards. Draft International Standards

adopted by the technical committees are circulated to the member bodies for voting. Publication as an

International Standard requires approval by at least 75 % of the member bodies casting a vote.

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.

ISO 13674-2 was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 9, Vehicle

dynamics and road-holding ability.

This second edition cancels and replaces the first edition (ISO 13674-2:2006), which has been technically

revised.

ISO 13674 consists of the following parts, under the general title Road vehicles — Test method for the

quantification of on-centre handling:
 Part 1: Weave test
 Part 2: Transition test
iv © ISO 2012 – All rights reserved
---------------------- Page: 4 ----------------------
ISO/DIS 13674-2
Introduction

The main purpose of this Standard is to provide repeatable and discriminatory test results.

The dynamic behaviour of a road vehicle is a very important aspect of active vehicle safety. Any given vehicle,

together with its driver and the prevailing environment, constitutes a closed-loop system that is unique. The

task of evaluating the dynamic behaviour is therefore very difficult since the significant interaction of these

driver-vehicle-environment elements are each complex in themselves. A complete and accurate description of

the behaviour of the road vehicle must necessarily involve information obtained from a number of different

tests.

Since this test method quantifies only one small part of the complete vehicle handling characteristics, the

results of these tests can only be considered significant for a correspondingly small part of the overall dynamic

behaviour.

Moreover, insufficient knowledge is available concerning the relationship between overall vehicle dynamic

properties and accident avoidance. A substantial amount of work is necessary to acquire sufficient and

reliable data on the correlation between accident avoidance and vehicle dynamic properties in general and the

results of these tests in particular. Consequently, any application of this test method for regulation purposes

will require proven correlation between test results and accident statistics.
© ISO 2012 – All rights reserved v
---------------------- Page: 5 ----------------------
DRAFT INTERNATIONAL STANDARD ISO/DIS 13674-2
Road vehicles — Test method for the quantification of on-
centre handling — Part 2: Transition test
1 Scope

This part of ISO 13674 specifies a test schedule that addresses a particular aspect of the transition test, the

on-centre handling characteristics of a vehicle. It is applicable to passenger cars in accordance with ISO 3833,

and to light trucks.

NOTE The manoeuvre specified in this test method is not representative of real driving conditions, but is useful for

obtaining measures of vehicle on-centre handling behaviour in response to a specific type of steering input under closely

controlled test conditions. Other aspects of on-centre handling are addressed in the companion ISO 13674-1 and

ISO/TS 20119.
2 Normative references

The following documents, in whole or in part, are normatively referenced in this document and are

indispensable 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 1176, Road vehicles — Masses — Vocabulary and codes
ISO 2416, Passenger cars — Mass distribution
ISO 3833, Road vehicles — Types — Terms and definitions
ISO 8855, Road vehicles — Vehicle dynamics and road-holding ability — Vocabulary

ISO 15037-1, Road vehicles — Vehicle dynamics test methods — Part 1: General conditions for passenger

cars
3 Terms, definitions and symbols

For the purposes of this document, the terms, definitions and symbols of ISO 1176, ISO 2416, ISO 3833,

ISO 8855 and the following apply.
3.1
on-centre handling

description of the steering “feel” and steering precision of a vehicle during nominally straight-line driving and in

negotiating large radius bends at high speeds but low lateral accelerations
3.2
ordinate threshold

value of a parameter plotted as the ordinate on a graph and defined as the minimum threshold of human

perception
3.3
abscissa deadband

horizontal separation between the pair of straight-line fits at ordinate threshold values

© ISO 2012 – All rights reserved
---------------------- Page: 6 ----------------------
ISO/DIS 13674-2
3.4
gradient

ratio of change in the ordinate with respect to a unit change in the abscissa, for a straight-line fit to a pair of

recorded variables plotted one against the other on Cartesian coordinates
4 Principle

On-centre handling represents that part of the straight-line directional stability characteristics of the vehicle

existing at low lateral acceleration levels, typically no greater than 1 m/s . On-centre handling is concerned

primarily with features that directly influence the driver’s steering input, such as steering system and tyre

characteristics. Thus, test schedules for the evaluation of on-centre handling behaviour seek to minimize other

factors that influence the wider aspects of straight line directional stability, such as disturbance inputs due to

ambient winds and road irregularities.

This part of ISO 13674 defines test schedules that involve driving the vehicle in a nominally straight line at a

constant forward speed. During the tests, driver inputs and vehicle responses are measured and recorded.

From the recorded signals, characteristic values are calculated.
5 Variables
5.1 Reference system

The variables of motion used to describe vehicle behaviour in a test-specific driving situation shall be related

to the intermediate axis system (X, Y, Z) (see ISO 8855).

The location of the origin of the vehicle axis system (X , Y , Z ) is the reference point and therefore should be

V V V

independent of the loading condition. The origin is therefore fixed in the longitudinal plane of symmetry at

half-wheelbase and at the same height above ground as the centre of gravity of the vehicle at complete

vehicle kerb mass (see ISO 1176).
5.2 Variables to be measured
When using this test method, the following variables shall be measured:
 steering-wheel angle,  ;
 steering-wheel torque, M ;
 yaw velocity, d/dt;
 longitudinal velocity, v ;
 lateral acceleration, a (see the NOTE to 6.2).
The following variables should be measured:
 steering-wheel angular velocity, d /dt.
The variables are defined in ISO 8855.

In order to acquire a deeper understanding of the vehicle behaviour, it may be desirable to determine motions

of various components within the steering system, especially for vehicles with more than one steering axle.

© ISO 2012 – All rights reserved
---------------------- Page: 7 ----------------------
ISO/DIS 13674-2
6 Measuring equipment
6.1 Description
The measuring equipment shall be in accordance with ISO 15037-1:2006.

Typical operating ranges and recommended maximum errors of the combined transducer and recording

system are shown in Table 1.

NOTE It is advisable that care be taken to ensure that friction or inertia added to the system by steering

robot or steering transducers does not improperly influence the measurement of steering-wheel torque.

Table 1 — Variables, typical operating ranges and recommended maximum errors
Recommended maximum error of the
Variable Typical operating range
combined transducer and recorder system
Steering-wheel angle  50°  0,1°
Steering-wheel torque  10 Nm  0,1 Nm
Yaw velocity  10 °/s  0,1 °/s
Longitudinal velocity 0 - 50 m/s  0,5 m/s
2 2
Lateral acceleration  5 m/s  0,1 m/s
Steering-wheel angular velocity  100 °/s  1 °/s

Transducers for measuring some of the listed variables are not widely available and are not in general use. Many such

instruments are developed by users. If any system error exceeds the recommended maximum value, this and the actual

maximum error shall be stated in the test report (ISO 15037-1:2006, Annex A).

These transducer ranges are appropriate for the standard test conditions and may not be suitable for non-standard test conditions.

The values for maximum errors are provisional until more experience and data are available.

6.2 Transducer installations

The transducers shall be installed according to the manufacturers’ instructions where such instructions exist,

so that the variables corresponding to the terms and definitions of ISO 8855 can be determined.

If a transducer does not measure a variable directly, appropriate transformations into the specified reference

system shall be carried out.

NOTE Lateral acceleration, as defined, is measured in the intermediate XY plane. H

...

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