ISO 14793:2011

INTERNATIONAL ISO
STANDARD 14793
Second edition
2011-02-15
Road vehicles — Heavy commercial
vehicles and buses — Lateral transient
response test methods
Véhicules routiers — Véhicules utilitaires lourds et autobus —
Méthodes d'essai de réponse transitoire latérale

Reference number
©
ISO 2011
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ii © ISO 2011 – All rights reserved

Contents Page
Foreword .iv
Introduction.v
1 Scope.1
2 Normative references.1
3 Terms and definitions .1
4 Principle .2
5 Reference system.2
6 Variables.3
7 Measuring equipment .3
7.1 Description.3
7.2 Transducer installation.3
7.3 Data processing.3
8 Test conditions .7
8.1 General .7
8.2 Test track.7
8.3 Weather conditions .7
8.4 Test vehicle .8
8.5 Warm-up .9
8.6 Test speed.9
8.7 Lateral acceleration.9
8.8 Average longitudinal acceleration.10
9 Step input .10
9.1 Test procedure.10
9.2 Data analysis.10
9.3 Data presentation .11
10 Sinusoidal input — One period (see ISO/TR 8725) .12
10.1 Test procedure.12
10.2 Data analysis.12
10.3 Data presentation .13
11 Random input (see ISO/TR 8726) .13
11.1 Test procedure.13
11.2 Data analysis.14
11.3 Data presentation .14
12 Pulse input .15
12.1 Test procedure.15
12.2 Data analysis.15
12.3 Data presentation .15
13 Continuous sinusoidal input.16
13.1 Test procedure.16
13.2 Data analysis.16
13.3 Data presentation .17
Annex A (normative) Test report — General data .18
Annex B (normative) Test report — Presentation of results.24
Bibliography.29

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 14793 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 14793:2003), which has been technically
revised.
iv © ISO 2011 – All rights reserved

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 is each complex in itself. 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.

INTERNATIONAL STANDARD ISO 14793:2011(E)

Road vehicles — Heavy commercial vehicles and buses —
Lateral transient response test methods
1 Scope
This International Standard specifies test methods for determining the transient response behaviour of heavy
commercial vehicles, heavy commercial vehicle combinations, buses and articulated buses, as defined in
ISO 3833 for trucks and trailers above 3,5 t and buses above 5 t maximum weight, and in UNECE (United
Nations Economic Commission for Europe) and EC vehicle classification, categories M3, N2, N3, O3 and O4.
NOTE The open-loop manoeuvres specified in this International Standard are not representative of real driving
conditions, but are nevertheless useful for obtaining measures of vehicle transient behaviour — particularly with respect to
that which the driver experiences — in response to several specific types of steering input under closely controlled test
conditions. For combinations where the response of the last vehicle unit is of importance, see ISO 14791.
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 3833:1977, Road vehicles — Types — Terms and definitions
ISO/TR 8725:1988, Road vehicles — Transient open-loop response test method with one period of sinusoidal
input
ISO/TR 8726:1988, Road vehicles — Transient open-loop response test method with pseudo-random steering
input
ISO 8855:1991, Road vehicles — Vehicle dynamics and road-holding ability — Vocabulary
ECE Regulation No. 30, Uniform provisions concerning the approval of pneumatic tyres for motor vehicles and
their trailers
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 8855 and the following apply.
3.1
vehicle unit
unit of a vehicle combination which is connected with a yaw-articulation joint
EXAMPLE Tractor, semitrailer, dolly.
NOTE The number of vehicle units is one more than the number of articulation joints.
4 Principle
IMPORTANT — The method of data analysis in the frequency domain is based on the assumption that
the vehicle has a linear response. Over the whole range of lateral acceleration this is unlikely to be the
case, the standard method of dealing with such a situation being to restrict the range of the input so
that linear behaviour can be assumed and, if necessary, to perform more than one test at different
ranges of inputs which, together, cover the total range of interest.
The objective of these tests is to determine the transient response of a vehicle. Characteristic values and
fu
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