ISO 19638:2018

INTERNATIONAL ISO
STANDARD 19638
First edition
2018-09
Intelligent transport systems — Road
boundary departure prevention
systems (RBDPS) — Performance
requirements and test procedures
Systèmes intelligents de transport — Systèmes de prévention de
sortie de route (RBDPS) — Exigences de performance et modes
opératoires d'essai
Reference number
©
ISO 2018
© ISO 2018
All rights reserved. Unless otherwise specified, or required in the context of its implementation, 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
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2018 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols . 4
5 Specifications and requirements. 4
5.1 System function . 4
5.2 Requirements . 5
5.2.1 Functionality . 5
5.2.2 State transition . 5
5.2.3 Driver interface and system reaction . 6
5.2.4 Minimum functionality . 7
5.2.5 Failure reactions . .10
6 Performance evaluation test methods .10
6.1 General .10
6.2 Environmental conditions .10
6.3 Test course conditions .10
6.4 Test vehicle conditions .10
6.5 Test system installation and configuration .11
6.6 Parameters recoverable from data record .11
6.7 Test track .11
6.8 Test procedure .11
6.8.1 Test 1: RBDPS basic performance test .12
6.8.2 Test 2: RBDPS deceleration performance test .13
Annex A (normative) Road boundaries by road type .14
Annex B (informative) Example curved track for the test procedure .15
Annex C (informative) Relationship between LDWS, LKAS, and RBDPS .17
Annex D (informative) Speed reduction performance summary .18
Bibliography .19
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 of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso
.org/iso/foreword .html.
This document was prepared by Technical Committee ISO/TC 204, Intelligent transport systems.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/members .html.
iv © ISO 2018 – All rights reserved

Introduction
Road boundary departure means a vehicle goes off the road unintentionally (not done intentionally
by the driver). Such a departure can cause a crash by colliding with an oncoming vehicle, surrounding
structures, or roll-over and the mortality rate in case of such accidents is high. To address this situation,
systems which are effective in lane keeping assistance have been developed. Some representative
systems are lane departure warning systems (LDWS) (presented in ISO 17361) and lane keeping
assistance systems (LKAS) (presented in ISO 11270). LDWS informs the driver of danger by a warning
in case of a departure but doesn’t have a function to control said departure. On the other hand, the
main functionality of LKAS is to support driver operations to keep the vehicle within the lane while
the vehicle is in the normal driving operation, not to avoid such accidents by actively preventing road
departure. This document specifies road boundary departure prevention systems (RBDPS) which aim
to prevent accidents caused by road departure.
RBDPS is a driving safety support system aimed at both the prevention of road departure accidents
by causes such as driver negligence and the mitigation of damages when accidents actually occur.
RBDPS detects or predicts road departure and activates the actuator(s) to prevent such a departure.
The actuator(s) controls yaw moment and deceleration of a vehicle such that the vehicle is effectively
controlled so as to remain within the road boundaries. By this mechanism, RBDPS effectively assists in
the prevention of accidents and mitigates damages when accidents actually occur. This system allows
driver operations to take priority over RBDPS when RBDPS is controlling the vehicle. Also, the driver is
adequately informed of the operational state of RBDPS support.
In this document, a road boundary is defined as a boundary of vehicle driving lanes delimited by solid
lane markers. Therefore, a dashed line, which a vehicle can cross in order to change lanes, is not a road
boundary. Also, this document does not define the means used to detect road boundaries.
INTERNATIONAL STANDARD ISO 19638:2018(E)
Intelligent transport systems — Road boundary departure
prevention systems (RBDPS) — Performance requirements
and test procedures
1 Scope
This document contains the basic control strategy, minimum functionality requirements, basic driver
interface elements, minimum requirements for diagnostics and reaction to failure, and performance
test procedures for road boundary departure prevention systems (RBDPS). RBDPS is a driving safety
support system which acts on vehicles to prevent road departures. RBDPS is designed to reduce damage
and accidents arising from road boundary departures.
This document is intended to be applied to systems that predict road boundary departures and
maintain the vehicle within the road boundaries by both lateral acceleration control and longitudinal
deceleration control. RBDPS is intended to operate on roads (well-developed and standardized freeways
or highways) having solid lane markers. Roadwork zones or roads without visible road boundary
markers are not within the scope of this document. RBDPS is intended for light duty passenger vehicles
and heavy vehicles. RBDPS is not designed to operate continuously, but to operate automatically only
when possible road boundary departures are detected or predicted. However, the driver’s decision and
operation takes priority at all times.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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, Road vehicles — Masses — Vocabulary and codes
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at https: //www .electropedia .org/
— ISO Online browsing platform: available at https: //www .iso .org/obp
3.1
control threshold
control trigger point set in the system where RBDPS control is issued
Note 1 to entry: In the case of TTLC (3.20) the control threshold shifts depending on the rate of departure.
Note 2 to entry: The control threshold is placed within the control threshold placement zone (see Figure 3).
3.2
control threshold placement zone
zone between the control threshold line and the latest control lines within which the control threshold
is placed
Note 1 to entry: There is one control threshold placement zone at the inner side of the lane marking and one at
the outer side of the lane marking (see Figure 3).
3.3
failure
inability of a system or system component to perform a required function within specified limits, which
is caused by mechanical or electronic malfunction
Note 1 to entry: Temporary performance reductions, for example, due to bad weather conditions, bad lane
markings, or temporary sensor blindness, are not considered a failure.
3.4
heavy vehicle
any single vehicle or combination of vehicles defined as Category M3, M2, N3, N2 in the United Nations
Economic and Social Council World Forum for Harmonization of Vehicle Regulations (WP.29) ECE/
TRANS/WP.29/78/Rev.2
3.5
lane
area of roadway delimited by visible lane markers between which, in the absence of any obstruction or
intention on the part of the driver to change direction, a vehicle would be expected to travel
3.6
lane departure warning
warning given to the driver in accordance with the lane departure warning condition in the absence of
suppression requests
3.7
latest control line
outermost limit of the control threshold
3.8
light duty passenger vehicle
vehicle defined as category M1 and N1 in the United Nations Economic and Social Council World Forum
for Harmonization of Vehicle Regulations (WP.29) ECE/TRANS/WP.29/78/Rev.2
3.9
rate of departure
subject vehicle’s lateral component of the approach velocity to the road boundary at the control issue point
3.10
RBDPS action
action which the system performs to influence the lateral movement of the subject vehicle with the
intention of assisting the driver to prevent departing the road boundaries
3.11
road
area for vehicular travel delineated by road boundaries
3.12
road boundary
innermost edge of visible, solid, markers between which a vehicle shall travel
Note 1 to entry: Refer to Table A.1 for a detailed definition.
3.13
road departure
situation in which the outermost edge of one of the front wheels with tyres of a vehicle or of the leading
part of an articulated vehicle, or, in the case of a three-wheeled vehicle, the outside of one of the wheels
on the axle with the widest track, is crossing a road boundary
Note 1 to entry: See Figure 3.
2 © ISO 2018 – All rights reserved

3.14
straight road
segment of road for which the curve radius is larger than 5 000 [m]
3.15
subject vehicle
vehicle equipped with RBDPS as defined herein
3.16
system states
one of several stages or phases of system operation
Note 1 to entry: See Figure 2.
3.17.1
RBDPS off state
state in which the system is switched off
3.17.2
RBDPS on state
state in which the system is switched on
3.17.3
RBDPS stand-by state
state in which the system is switched on but the activation criteria to issue intervention are not all met
3.17.4
RBDPS active state
state in which the system is switched on and the activation criteria to issue intervention are met
3.18
threshold for start timing of system support
maximum time threshold which may be set by the user for the start time of RBDPS support after the
road boundary departure has started
3.19
threshold for support level of the system
maximum level of system support which may be set by the user
3.20
time to line crossing
TTLC
calculated time to the crossing of the solid line, leading to road departure
Note 1 to entry: For example, the most simple calculation method of this time (TTLC) is to divide lateral distance
(D) between the predetermined part of the vehicle and the road boundary by rate of departure (Vdepart) of the
vehicle relative to the lane (TTLC = D/Vdepart).
3.21
visibility
distance at which the illuminance of a non-diffusive beam of white light with a colour temperature of
2 700 K is decreased to 5 % of its original light source illuminance
4 Symbols
Table 1 — Symbols and definitions
Symbol Definition
RBDPS_Lat_Accel_min [m/s ] minimum lateral acceleration which RBDPS shall be capable to achieve
RBDPS_Lat_Accel_max [m/s ] maximum lateral acceleration which shall be induced by a RBDPS action
RBDPS_Long_Decel_min [m/s ] minimum longitudinal deceleration which RBDPS shall be capable to achieve
RBDPS_Long_Decel_max [m/s ] maximum longitudinal deceleration which shall be induced by RBDPS action
RBDPS_Offset_max [m] maximum allowable road departure
RBDPS_Curvature_rate_max [1/m ] maximum rate of change of curvature which is allowed for the curve
test track
RBDPS_Lat_Jerk_max [m/s ] maximum lateral jerk which shall be induced by a RBDPS action
RBDPS_Active_Duration_max [s] maximum time duration of RBDPS control
Vdepart [m/s] rate of departure
Vmax [m/s] maximum velocity for RBDPS operation
Vmin [m/s] minimum velocity for RBDPS operation
SV_speed [m/s] speed of subject vehicle
5 Specifications and requirements
5.1 System function
RBDPS shall be designed taking into consideration the functional elements shown in Figure 1. However,
as regards the control methods, a manufacturer is allowed to decide which control methods are used.
As examples of the control methods, generation of vehicle yaw moment for RBDPS functionality is
achieved through the use of steering or four-wheel brake distribution, and reduction of vehicle velocity
is achieved through braking or braking by engine.
Figure 1 — RBDPS functional elements
4 © ISO 2018 – All rights reserved

The relationship with ISO 11270 (lane keeping assistance systems) and ISO 17361 (lane departure
warning systems) is described in Annexes C and D.
5.2 Requirements
5.2.1 Functionality
RBDPS is intended to attempt to prevent road departure crashes and minimize crash damages. The
system provides driving support for prevention of road departure and does not perform automatic
driving to support drivers. RBDPS shall, as a minimum, provide the following operations and state
transitions. The following constitutes the fundamental behaviour of RBDPS.
As a basic functionality of RBDPS, it shall operate automatically when a road departure is predicted or
detected by the system, and generate yaw moment and longitudinal deceleration to keep the vehicle
within the road boundaries. Road boundaries within which RBDPS shall operate are illustrated in
Table A.1. RBDPS shall react to road boundaries marked with solid lines. RBDPS may also react to other
road boundaries represented by dashed lines, tar/turf transition, discrete protruding lane markings, etc.
As Table A.1 shows, for the centreline of a two-way road and the solid lane markers between the lanes
in the case of a multi-lane road, RBDPS may operate.
5.2.2 State transition
RBDPS state transition is described in Figure 2. Specific implementation beyond what is illustrated
below is left to the manufacturer.
Key
1 ignition ON 2 system fail
and no system fail or ignition off
and RBDPS switch on or RBDPS switch off
3 solid lane marker is detected 4 SV_speed < Vmin
and road departure is predicted or SV_speed > Vmax
and Vmin ≤ SV_speed ≤ Vmax or road departure is not predicted
and no driver’s corrective action detected or solid lane marker is not detected
and other criteria specified by manufacturer or tu
...