Road vehicles -- Sensitivity to lateral wind -- Open-loop test method using wind generator input

ISO 12021:2011 specifies an open-loop test method to determine the sensitivity to lateral wind of a vehicle by means of a wind generator. It applies to passenger cars as defined in ISO 3833, passenger car-trailer combinations and light trucks. Its applicability to motorcycles is yet to be investigated. The test conditions specified in this test method are not representative of real driving conditions but are useful to obtain measures of vehicle dynamic response to lateral wind.

Véhicules routiers -- Sensibilité au vent latéral -- Méthode en boucle ouverte avec génération de vent

General Information

Status
Published
Publication Date
22-Nov-2010
Current Stage
6060 - International Standard published
Start Date
11-Nov-2010
Completion Date
23-Nov-2010
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INTERNATIONAL ISO
STANDARD 12021
First edition
2010-12-01
Road vehicles — Sensitivity to lateral
wind — Open-loop test method using
wind generator input
Véhicules routiers — Sensibilité au vent latéral — Méthode en boucle
ouverte avec génération de vent
Reference number
ISO 12021:2010(E)
ISO 2010
---------------------- Page: 1 ----------------------
ISO 12021:2010(E)
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ii © ISO 2010 – All rights reserved
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ISO 12021:2010(E)
Contents Page

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

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

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

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

3 Terms and definitions ...........................................................................................................................1

4 Principle .................................................................................................................................................1

5 Reference system..................................................................................................................................2

6 Variables.................................................................................................................................................2

7 Measuring equipment ...........................................................................................................................2

7.1 Description.............................................................................................................................................2

7.2 Transducer installation.........................................................................................................................3

7.3 Data processing.....................................................................................................................................3

8 Test conditions ......................................................................................................................................3

8.1 General ...................................................................................................................................................3

8.2 Test track................................................................................................................................................4

8.3 Weather conditions ...............................................................................................................................4

8.4 Test vehicle ............................................................................................................................................4

8.5 Vehicle loading conditions...................................................................................................................4

9 Wind generators ....................................................................................................................................5

10 Test procedure.......................................................................................................................................5

10.1 Warm-up .................................................................................................................................................5

10.2 Test speed..............................................................................................................................................5

10.3 Steering ..................................................................................................................................................5

10.4 Number of test runs ..............................................................................................................................5

10.5 Measuring points of lateral position using the dye-trail method .....................................................5

10.6 Data excluded from the computation method....................................................................................6

11 Data analysis..........................................................................................................................................6

11.1 General ...................................................................................................................................................6

11.2 Yaw velocity and lateral acceleration..................................................................................................7

11.3 Lateral deviation....................................................................................................................................8

12 Data presentation ..................................................................................................................................8

Annex A (informative) Test report — General data .........................................................................................9

Annex B (normative) Test report — Presentation of results........................................................................12

Bibliography......................................................................................................................................................14

© ISO 2010 – All rights reserved iii
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ISO 12021:2010(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.

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 12021 was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 9, Vehicle

dynamics and road-holding ability.

This first edition of ISO 12021 cancels and replaces ISO 12021-1:1996, which has been technically revised.

iv © ISO 2010 – All rights reserved
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ISO 12021:2010(E)
Introduction

The main purpose of this International 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 2010 – All rights reserved v
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INTERNATIONAL STANDARD ISO 12021:2010(E)
Road vehicles — Sensitivity to lateral wind — Open-loop test
method using wind generator input
1 Scope

This International Standard specifies an open-loop test method to determine the sensitivity to lateral wind of a

vehicle by means of a wind generator. It applies to passenger cars as defined in ISO 3833, passenger car-

trailer combinations and light trucks. Its applicability to motorcycles is yet to be investigated.

The test conditions specified in this test method are not representative of real driving conditions but are useful

to obtain measures of vehicle dynamic response to lateral wind.

NOTE The test conditions in this test method do not simulate natural wind conditions. However, the wind velocity

proposed here is representative of fairly severe wind conditions occurring naturally.

2 Normative references

The following referenced documents are indispensable for the application of this document. For dated

references, only the edition cited applies. For undated references, the latest edition of the referenced

document (including any amendments) applies.
ISO 1176:1990, Road vehicles — Masses — Vocabulary and codes
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 and definitions

For the purposes of this document, the terms and definitions given in ISO 8855 apply.

4 Principle

The purpose of this test method is to determine vehicle sensitivity to lateral wind by which the vehicle motion

is disturbed. This method requires the measurement of vehicle behaviour under a lateral wind condition. The

vehicle behaviour can be characterized by several measures.

In this test method the vehicle is initially driven along a straight path and its response to a crosswind input of a

wind generator is then measured. The steering-wheel is held fixed during most of the test.

Two methods for finding the lateral deviation are proposed:

⎯ a direct method by means of direct measurement or with a dye-trail left on the road surface, and

⎯ an indirect method by means of a computation from on-board-measured vehicle motions.

© ISO 2010 – All rights reserved 1
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ISO 12021:2010(E)
5 Reference system
The reference system specified in ISO 15037-1 shall apply.
6 Variables

The following variables corresponding to the terms and definitions of ISO 8855 shall be measured:

a) yaw velocity, ψ ;
b) lateral acceleration, a ;
c) steering-wheel angle, δ ;
d) longitudinal velocity, v .
Measuring the following additional variables is optional:
⎯ lateral deviation, γ;
⎯ roll angle, ϕ;
⎯ sideslip angle, β;
⎯ lateral velocity, v .

The variables listed in this clause are not intended to comprise a complete list.

7 Measuring equipment
7.1 Description

The variables selected from the list in Clause 6 shall be measured by means of appropriate transducers. Their

time histories shall be recorded on a multi-channel recorder having a time base. This is not obligatory for

lateral deviation, which can be measured directly after the test has been completed.

The typical operating ranges of the variables and recommended maximum errors of the combined transducers

and the recording system are shown in Table 1.
2 © ISO 2010 – All rights reserved
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ISO 12021:2010(E)

Table 1 — Typical operating ranges of the variables and recommended maximum errors of

transducers and recording system
Recommended maximum error of the combined
Variable Range of variable
transducers and recording system
Yaw velocity −10°/s to +10°/s ±0,1°/s
2 2 2
Lateral acceleration −5 m/s to +5 m/s ±0,05 m/s
Steering-wheel angle −30° to +30° ±1°, but resolution < 0,3°
Longitudinal velocity 0 m/s to 40 m/s ±0,4 m/s
Lateral deviation 5 m ±0,02 m
Roll angle −10° to +10° ±0,1°
Sideslip angle −5° to +5° ±0,2°
Lateral velocity −10 m/s to +10 m/s ±0,2 m/s

NOTE Transducers for 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 (see Annex A).
Assuming a conventional steering system.
7.2 Transducer installation
7.2.1 General
Subclause 4.2 of ISO 15037-1:2006 shall apply.
7.2.2 Lateral deviation

The lateral deviation may be measured either by direct measurement using appropriate instrumentation or by

means of a dye-trail, or by means of a computational method (see 11.3.3). The dye-trail shall be made on the

test track by means of a water jet. The water outlet should be 0,02 m above the track surface. An elastic tube

may be used to extend this outlet.

The water jet should be positioned as close as possible to the z-axis of the intermediate axis system. If this is

not the case, a correction can be applied to achieve values within the tolerance for lateral acceleration.

7.3 Data processing

The recording system and data processing requirements contained in 4.3 of ISO 15037-1:2006 shall apply.

8 Test conditions
8.1 General

The test conditions specified in 5.1 of ISO 15037-1:2006 and the conditions of 8.2 and 8.3 in this International

Standard shall apply. Any deviations shall be specified in the test report (see Annex A), including individual

diagrams for the presentation of results (see Annex B).
© ISO 2010 – All rights reserved 3
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ISO 12021:2010(E)
8.2 Test track

All tests shall be carried out on a uniform hard road surface which is free of contaminants. The gradient, as

measured over the full width of the track in the lateral direction and over a distance of at least 50 m in the

longitudinal direction, shall be <2,5 %.

It is recommended that the track have either a smooth surface (asphalt or concrete) or a high-friction surface.

The test surfa
...

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