Heavy commercial vehicles and buses -- Stopping distance in straight-line braking with ABS -- Open loop and closed loop test methods

ISO 16552:2014 describes test methods for determining the stopping distance during a straight-line braking manoeuvre with the braking system fully operational. It applies to heavy vehicles equipped with an anti-lock braking system (ABS), including commercial vehicles, commercial vehicle combinations, buses and articulated buses as defined in ISO 3833 (trucks and trailers with maximum weight above 3,5 tonnes and buses and articulated buses with maximum weight above 5 tonnes, according to ECE and EC vehicle classification, categories M3, N2, N3, O3, and O4).

Véhicules utilitaires lourds -- Distance d'arrêt de freinage en ligne droite avec ABS -- Méthodes d'essai en boucle ouverte et boucle fermée

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Status
Published
Publication Date
16-Jul-2014
Current Stage
9093 - International Standard confirmed
Start Date
23-Sep-2020
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ISO 16552:2014 - Heavy commercial vehicles and buses -- Stopping distance in straight-line braking with ABS -- Open loop and closed loop test methods
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INTERNATIONAL ISO
STANDARD 16552
First edition
2014-07-15
Heavy commercial vehicles and
buses — Stopping distance in straight-
line braking with ABS — Open loop
and closed loop test methods
Véhicules utilitaires lourds — Distance d’arrêt de freinage en ligne
droite avec ABS — Méthodes d’essai en boucle ouverte et boucle
fermée
Reference number
ISO 16552:2014(E)
ISO 2014
---------------------- Page: 1 ----------------------
ISO 16552:2014(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2014

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.
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Published in Switzerland
ii © ISO 2014 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 16552:2014(E)
Contents Page

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

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

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

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

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

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

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

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

5.2 Variables to be measured ............................................................................................................................................................... 3

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

7 Test conditions ....................................................................................................................................................................................................... 4

7.1 General ........................................................................................................................................................................................................... 4

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

7.3 Ambient conditions ............................................................................................................................................................................. 4

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

8 Test method ............................................................................................................................................................................................................... 5

8.1 General ........................................................................................................................................................................................................... 5

8.2 Performance of the braking procedure .............................................................................................................................. 5

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

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

9.2 Stopping distance ................................................................................................................................................................................. 7

9.3 Deceleration at full braking (optional)............................................................................................................................... 7

9.4 Braking distance (optional) ......................................................................................................................................................... 8

9.5 Build-up distance (optional) ....................................................................................................................................................... 8

9.6 Lateral deviation, Y (optional, for open-loop tests).............................................................................................. 8

9.7 Yaw angle deviation, ψ (optional, for open-loop tests) ........................................................................................ 8

9.8 Steering-wheel angle, δ (optional, for closed-loop test) .................................................................................. 9

Annex A (normative) Test report — General data and test conditions..........................................................................10

Annex B (informative) Test report — Results ..........................................................................................................................................11

Annex C (informative) Brake burnishing and calibrations ........................................................................................................14

Annex D (informative) Principle graphs ........................................................................................................................................................15

© ISO 2014 – All rights reserved iii
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ISO 16552:2014(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 9, Vehicle

dynamics and road-holding ability.
iv © ISO 2014 – All rights reserved
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ISO 16552:2014(E)
Introduction

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

The stopping distance and the dynamic behaviour of a road vehicle is a most important aspect of active

vehicle safety. Any given vehicle, together with its driver and the prevailing environment, constitutes

a closed-loop system which is unique. The task of evaluating the dynamic behaviour is therefore very

difficult, since the significant interaction of these driver-vehicle-road elements are each complex in

themselves. A complete and accurate description of the behaviour of the road vehicle shall inevitably

involve information obtained from a number of different tests.

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

results of this test can only be considered significant for a correspondingly small part of the overall

dynamic behaviour.

Moreover, insufficient knowledge is available to correlate overall vehicle dynamic properties with

accident prevention. A substantial amount of work is necessary to acquire sufficient and reliable data on

the correlation between accident prevention and vehicle dynamic properties in general and the results

of this test in particular. Consequently, any application of this test method for regulation purposes will

require proven correlation between test results and accident statistics.

Test conditions and tyres have a strong influence on test results. Therefore, only results obtained under

comparable test and tyre conditions are comparable.
© ISO 2014 – All rights reserved v
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INTERNATIONAL STANDARD ISO 16552:2014(E)
Heavy commercial vehicles and buses — Stopping distance
in straight-line braking with ABS — Open loop and closed
loop test methods
1 Scope

This International Standard describes test methods for determining the stopping distance during a

straight-line braking manoeuvre with the braking system fully operational. It applies to heavy vehicles

equipped with an anti-lock braking system (ABS), including commercial vehicles, commercial vehicle

combinations, buses and articulated buses as defined in ISO 3833 (trucks and trailers with maximum

weight above 3,5 tonnes and buses and articulated buses with maximum weight above 5 tonnes,

according to ECE and EC vehicle classification, categories M3, N2, N3, O3, and O4).

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 3833, Road vehicles — Types — Terms and definitions
ISO 8349, Road vehicles — Measurement of road surface friction
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

commercial vehicles and buses
3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 8855, ISO 15037-2:2002 and

the following apply.
3.1
actuation time

time interval from the first pedal contact until the speed of the vehicle is reduced 20 % from its initial

value
3.2
stopping distance

distance travelled by the vehicle from the first pedal contact until it comes to a standstill

3.3
build-up distance
distance travelled by the vehicle during the actuation time
3.4
braking distance

distance travelled by the vehicle during the time between two specified velocities

© ISO 2014 – All rights reserved 1
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ISO 16552:2014(E)
4 Principle

This International Standard specifies a method to determine the stopping distance and other braking

distances during full braking at certain nominal initial velocities. The driving situation represents an

emergency or panic brake application during straight-ahead driving on an even road surface with a

uniform coefficient of friction.

The evaluation range is ideally from the actuation of the brakes to standstill of the vehicle. As it might

be difficult to measure accurately at low velocities, the evaluation range may be ended at a certain low

velocity. From the initial velocity and the velocity at the end of the evaluation range, and the distance

between these two velocities, the mean longitudinal deceleration is determined.
2 2
vv−
0 2
a = (1)
where
a is the calculated deceleration;
v is the initial velocity;
v is the velocity at the end of the evaluation range;
s is the measured distance between v and v .
x 0 2
The stopping distance from the nominal initial velocity is calculated from
nom
s = (2)
ref
where

s is the stopping distance for a single test run referenced to the nominal velocity;

ref
v is the nominal initial velocity for the test series.
nom

Test results can only be compared if measurements took place under identical conditions, on the same

test surface and under very similar ambient conditions. Therefore, comparison of results should only be

made for tests done on a given surface within a short time period. Apart from the technical equipment

and especially the braking characteristics of the vehicle, the distance travelled after the first pedal

contact very strongly depends on the specific character of brake-pedal actuation. To minimize this

influence, this International Standard specifies rules for brake pedal actuation.

For vehicle combinations, test results depend on the performance of each vehicle unit. Therefore, the

performance of first vehicle units can only be compared when the following units are identical in

the vehicle combination. When measuring the performance of vehicle combinations, weight transfer

between the units has significant influence on the results. Furthermore, electronic braking systems can

include settings for the compatibility between the vehicle units, which can also influence the results.

5 Variables
5.1 Reference system
The reference system specified in ISO 15037-2 shall apply.
2 © ISO 2014 – All rights reserved
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ISO 16552:2014(E)
5.2 Variables to be measured

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). The variables that shall be determined for

compliance with this International Standard are the following:
— longitudinal velocity, v ;
— time of brake pedal actuation (t );
— longitudinal distance (s);
— brake pedal position (s ) or actuation force (F ).
B P
It is recommended that the following variables also be determined:
— longitudinal acceleration, a ;

— lateral deviation, Y , of the reference point of the first vehicle unit from the axis X of the initial

straight-ahead vehicle velocity, v ;
— steering-wheel angle, δ ;
— yaw angle, ψ;
— brake temperature for each axle.
6 Measuring equipment

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

ISO 15037-2:2002.

Typical operating ranges of the variables to be determined for this International Standard are shown in

Table 1 and in ISO 15037-2:2002. It shall be ensured that changes in vehicle pitch angle during braking

do not affect the measurement of the velocity and distance variables.

To monitor the running in of tyres and burnishing of brakes, and to monitor test conditions, brake

temperature sensors and a device for measuring and displaying vehicle deceleration are required.

Table 1 — Variables, typical operating ranges and recommended maximum errors of variables

not listed in ISO 15037-2
Recommended maximum
Variable Typical operating range errors of the combined trans-
ducer and recorder system
Longitudinal velocity 0 km/h to 100 km/h ±0,5 km/h
Longitudinal distance 0 m to 100 m ±0,05 m
Lateral deviation 0 m to 5 m ±0,05 m
Brake pedal position, if rotational 0° to 45° ±0,5°
Brake pedal position, if translational 0 mm to 100 mm ±1 mm
Brake pedal actuation force 0 N to 1000 N ±10 N
Yaw angle ±20° ±1°

NOTE The accuracy of the measured longitudinal distance depends not only on the resolution of the recorded

signals, but also on the on the sampling frequency. For instance, at 90 km/h, a sampling rate of 100 Hz gives

0,25 m travelled distance per sample.
© ISO 2014 – All rights reserved 3
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ISO 16552:2014(E)
7 Test conditions
7.1 General

The test conditions described in ISO 15037-2:2002, along with the following additions, shall apply to this

International Standard. General data of the test vehicle shall be recorded as specified in Annex A.

7.2 Test track

All tests shall be carried out on an even road surface with a uniform coefficient of friction. The gradient

of the test surface shall not exceed 0,5 % longitudinal inclination when measured over any distance

interval greater than or equal to the vehicle
...

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