Heavy commercial vehicles and buses -- Test method for roll stability -- Closing-curve test

ISO 11026:2010 specifies an open-loop test method for determining the roll stability of a vehicle negotiating a curve on dry surface. It applies to heavy vehicles, that is commercial vehicles, commercial vehicle combinations, buses and articulated buses as defined in ISO 3833 (trucks and trailers with maximum weight above 3,5 t and buses and articulated buses with maximum weight above 5 t, according to ECE and EC vehicle classification, categories M3, N2, N3, O3 and O4). The method is intended for vehicles equipped with electronic roll stability control systems.

Véhicules utilitaires lourds et autobus -- Méthode d'essai de stabilité au renversement -- Essai en courbe se fermant

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Status
Published
Publication Date
23-Jun-2010
Current Stage
9093 - International Standard confirmed
Start Date
17-Jun-2021
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ISO 11026:2010 - Heavy commercial vehicles and buses -- Test method for roll stability -- Closing-curve test
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INTERNATIONAL ISO
STANDARD 11026
First edition
2010-07-01
Heavy commercial vehicles and buses —
Test method for roll stability —
Closing-curve test
Véhicules utilitaires lourds et autobus — Méthode d'essai de stabilité
au renversement — Essai en courbe se fermant
Reference number
ISO 11026:2010(E)
ISO 2010
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ISO 11026:2010(E)
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ii © ISO 2010 – All rights reserved
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ISO 11026:2010(E)
Contents Page

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

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

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

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

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

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

5 Measuring equipment ...........................................................................................................................2

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

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

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

7.2 Test vehicle ............................................................................................................................................3

8 Test method ...........................................................................................................................................4

8.1 Initial driving condition.........................................................................................................................4

8.2 Performance of the steering procedure..............................................................................................4

9 Data evaluation ......................................................................................................................................5

9.1 General ...................................................................................................................................................5

9.2 Average jerk ...........................................................................................................................................5

9.3 Validity criteria.......................................................................................................................................5

9.4 Characteristic values ............................................................................................................................5

9.5 Other values of interest ........................................................................................................................5

Annex A (normative) Test report — General data and test conditions .........................................................6

Annex B (informative) Example of calculating a test path..............................................................................7

Annex C (informative) Examples of sequencing closing-curve tests ...........................................................9

© ISO 2010 – All rights reserved iii
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ISO 11026:2010(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 11026 was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 9, Vehicle

dynamics and road-holding ability.
iv © ISO 2010 – All rights reserved
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ISO 11026:2010(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 11026:2010(E)
Heavy commercial vehicles and buses — Test method for roll
stability — Closing-curve test
1 Scope

This International Standard specifies an open-loop test method for determining the roll stability of a vehicle

negotiating a curve on dry surface.

It applies to heavy vehicles, that is commercial vehicles, commercial vehicle combinations, buses and

articulated buses as defined in ISO 3833 (trucks and trailers with maximum weight above 3,5 t and buses and

articulated buses with maximum weight above 5 t, according to ECE and EC vehicle classification, categories

M3, N2, N3, O3 and O4).

The method is intended for vehicles equipped with electronic roll stability control systems.

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 3833, Road vehicles — Types — Terms and definitions
ISO 8855, Road vehicles — Vehicle dynamics and road-holding ability — Vocabulary

ISO 15037-2:2002, Road vehicles — Vehicle dynamics test methods — Part 2: General conditions for heavy

vehicles and buses
3 Terms, definitions and symbols

For the purposes of this document, the terms, definitions and symbols given in ISO 15037-2, ISO 8855 and

the following apply.
3.1
jerk
rate of change of lateral acceleration
3.2
steady-state rollover threshold

maximum magnitude of lateral acceleration that a vehicle can sustain during steady-state cornering on a flat

and level surface without rolling over
4 Principle

The objective of this test method is to determine the effect of roll stability control on the roll stability of a

vehicle travelling at constant longitudinal velocity on a path with a constantly increasing curvature, a closing

curve. Also, effects on the yaw stability will be considered. The initial state for the test is driving in a straight

line at constant longitudinal velocity.
© ISO 2010 – All rights reserved 1
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ISO 11026:2010(E)

The path is defined by the curvature rate, k , which gives the curvature, κ, along the path:

κ=⋅ks
where s is the distance along the path.
At constant longitudinal velocity, V , the jerk, k , is constant.
X a
kk=⋅V
ac X

The path can be expressed in Cartesian coordinates in the earth-fixed system as follows:

Xs = cos ν ds
() ( )
Ys = sin ν ds
() ( )
where ν is the course angle, calculated as follows:
a 2
νκ=⋅ ds= ⋅ s
2 ⋅V

The severity of the test depends both on the jerk and on the longitudinal velocity. Higher velocity on a path

with a certain jerk is more demanding than a lower velocity on another path with the same jerk. Thus, varying

the jerk by changing the velocity on a given path is not identical to changing the path while maintaining the

velocity.
5 Measuring equipment

The measuring equipment, transducer installation and data processing shall be in accordance with

ISO 15037-2.
6 Variables

The variables of motion used to describe the behaviour of the vehicle shall be related to the intermediate axis

system (X, Y, Z) of the first vehicle unit (see ISO 8855). For the purpose of this International Standard, the

location of the reference point is at ground level in the plane of symmetry and at the longitudinal position of the

first axle of the first vehicle unit.

The following variables shall be determined for compliance with this International Standard:

⎯ longitudinal velocity, V ;
⎯ lateral acceleration, a ;
⎯ indication of intervention of the electronic stability control system;

⎯ indication of roll instability, which may be indicated by the outriggers touching the ground if they are

mounted at a height that corresponds to roll instability;

⎯ indication of yaw instability of vehicle combinations, which may be indicated by the engagement of the

anti-jackknife device if it is mounted in such a way that it allows an articulation angle of at least 45°.

2 © ISO 2010 – All rights reserved
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ISO 11026:2010(E)

NOTE Determination of lateral acceleration is most important prior to intervention of the stability co

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