ISO 20901:2020
(Main)Intelligent transport systems — Emergency electronic brake light systems (EEBL) — Performance requirements and test procedures
Intelligent transport systems — Emergency electronic brake light systems (EEBL) — Performance requirements and test procedures
This document contains the basic alert strategy, minimum functionality requirements, basic driver interface elements, minimum requirements for diagnostics and reaction to failure, and performance test procedures for Emergency Electronic Brake Light systems (EEBL). EEBL alerts the driver against danger caused by the emergency braking of an FV on the upcoming road, so that the driver may reduce the speed. The system does not include the means to control the vehicle to meet the desired speed. The responsibility for safe operation of the vehicle always remains with the driver. The scope of this document does not include performance requirements and test procedures of the wireless communication device used for EEBL. The requirements of communication devices are defined in other standards, e.g. the IEEE series listed in the Bibliography[6][7][8]. The test procedure in this document is designed for third party testing of the product while the test procedure can also be used for other stakeholders such as manufacturers or consumer unions. The document applies to light duty vehicles and heavy vehicles. These systems are not intended for off-road use.
Systèmes de transport intelligents — Systèmes de diffusion de l’information d'un freinage d'urgence (EEBL) — Exigences de performance et procédures d'essai
General Information
Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 20901
First edition
2020-04
Intelligent transport systems —
Emergency electronic brake light
systems (EEBL) — Performance
requirements and test procedures
Systèmes de transport intelligents — Systèmes de diffusion de
l’information d'un freinage d'urgence (EEBL) — Exigences de
performance et procédures d'essai
Reference number
ISO 20901:2020(E)
©
ISO 2020
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ISO 20901:2020(E)
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© ISO 2020
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ISO 20901:2020(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviated terms . 3
5 Specifications and requirements. 3
5.1 Basic functions . 3
5.2 Necessary functions . 4
5.3 Basic operation principle . 4
5.3.1 State functional descriptions. 5
5.3.2 Operational limits . 6
5.4 Alert functionality . 6
5.4.1 General. 6
5.4.2 Generating the message including emergency braking flag for broadcasting . 6
5.4.3 Judging to issue the alert . 6
5.5 Alerting element requirements . 7
5.5.1 EEBL-R output . 7
5.5.2 Alert modality. 7
5.5.3 Optional functions of EEBL-R . 7
5.6 Performance requirement of EEBL . 8
5.6.1 Minimum communication range . 8
5.6.2 System delay requirement between FV and SV . 8
5.7 Driver interface requirements . 8
5.7.1 Alert output specification. 8
5.7.2 Fault indication . 8
6 Performance evaluation test methods . 8
6.1 Environmental conditions for test . 8
6.2 Test course conditions . 9
6.3 Test system installation and configuration . 9
6.4 Parameters recoverable from data record . 9
6.5 Test cases . 9
6.6 Test procedure .10
6.6.1 Test case 1 — FV transmission test and delay measurement .10
6.6.2 Test case 2 — False positive test .12
6.6.3 Test case 3 — True positive test .13
6.6.4 Test case 4 — Test when there is interfering vehicle (IV) .14
6.6.5 Test case 5 — Basic communication function test .16
Bibliography .18
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ISO 20901:2020(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
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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).
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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.
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ISO 20901:2020(E)
Introduction
Emergency Electronic Brake Light systems (EEBL) alert the driver against the danger caused by the
emergency braking of a forward vehicle (FV) on the upcoming road. EEBL generates an emergency
brake message based on vehicle emergency brake and transmit. The system periodically broadcasts
the message to nearby vehicles through vehicle to vehicle (V2V) wireless communication. If the
system equipped on an FV detects the emergency braking of its own vehicle, the system generates the
emergency braking flag, and sends the message including emergency braking flag. When the system
equipped on the subject vehicle (SV) receives the message containing the emergency braking flag,
the system judges whether an alert needs to be issued. If the location of the FV is within the specified
region of interest (ROI) of the SV, the system provides an alert to the driver to prompt appropriate
deceleration for driver safety. The scope of EEBL does not include automated intervention features or
means for controlling the vehicle to match a desired speed.
A significant benefit of cooperative safety systems such as EEBL is the significant reduction of the
potential risk of collision when a driver cannot see the brake light of an FV that is braking hard. For
example, when there is an interfering vehicle between the emergency braking vehicle (FV) and the SV,
the driver in the SV can still be alerted through vehicle to vehicle (V2V) wireless communication while
on-board sensor-based systems cannot even detect the existence of the FV.
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INTERNATIONAL STANDARD ISO 20901:2020(E)
Intelligent transport systems — Emergency electronic
brake light systems (EEBL) — Performance requirements
and test procedures
1 Scope
This document contains the basic alert strategy, minimum functionality requirements, basic driver
interface elements, minimum requirements for diagnostics and reaction to failure, and performance
test procedures for Emergency Electronic Brake Light systems (EEBL).
EEBL alerts the driver against danger caused by the emergency braking of an FV on the upcoming
road, so that the driver may reduce the speed. The system does not include the means to control the
vehicle to meet the desired speed. The responsibility for safe operation of the vehicle always remains
with the driver.
The scope of this document does not include performance requirements and test procedures of the
wireless communication device used for EEBL. The requirements of communication devices are defined
[6][7][8]
in other standards, e.g. the IEEE series listed in the Bibliography . The test procedure in this
document is designed for third party testing of the product while the test procedure can also be used
for other stakeholders such as manufacturers or consumer unions.
The document applies to light duty vehicles and heavy vehicles. These systems are not intended for off-
road use.
2 Normative references
There are no normative references in this document.
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:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
Emergency Electronic Brake Light system
EEBL
system consisting of EEBL-T (3.1.1) and EEBL-R (3.1.2)
3.1.1
Emergency Electronic Brake Light – Transmitting system
EEBL-T
system capable of detecting the emergency braking of the vehicle where the system is equipped, and
capable of transmitting a message including emergency brake flag and other information, e.g. location,
speed, to nearby vehicles
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ISO 20901:2020(E)
3.1.2
Emergency Electronic Brake Light – Receiving system
EEBL-R
system capable of receiving a message including emergency brake flag from forward vehicles (FVs) (3.3),
and capable of alerting the driver of emergency braking of an FV on the same road and traveling in the
same direction as the SV (3.2)
3.2
subject vehicle
SV
receiving vehicle
vehicle equipped with the EEBL-R (3.1.2) system
Note 1 to entry: The subject vehicle is located behind and traveling in the same direction as the forward vehicle
(FV) (3.3).
3.3
forward vehicle
FV
transmitting vehicle
vehicle equipped with the EEBL-T (3.1.1) system
Note 1 to entry: The forward vehicle (FV) (3.3) is located ahead of the subject vehicle (SV) (3.2) within the region of
interest (ROI) (3.9) of the SV.
3.4
interfering vehicle
IV
vehicle which is located in between the subject vehicle (SV) (3.2) and forward vehicle (FV) (3.3) to
interfere with the line-of-sight between the SV and FV
Note 1 to entry: During the test, the IV does not generate a message including emergency brake flag nor issue an
emergency brake alert to the driver, so the IV will not influence the EEBL (3.1) operation of the FV (3.3) and SV.
3.5
subject vehicle speed
longitudinal component of the subject vehicle (SV) (3.2) velocity
3.6
visibility
distance at which the illuminance of a non-diffusive beam of white light with the colour temperature of
2700K is decreased to 5 % of its original light source illuminance
3.7
host lane
lane in which the subject vehicle (SV) (3.2) is located
3.8
adjacent lane
lane of travel sharing one lane boundary with the host lane and having the same direction of travel as
the host lane
3.9
region of interest
ROI
area in which a subject vehicle (SV) (3.2) receives the emergency brake flag from the forward vehicle
(FV) (3.3)
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ISO 20901:2020(E)
4 Symbols and abbreviated terms
a The deceleration of the FV
d
a Absolute value of the deceleration of the FV
d_Current
a Threshold amount of deceleration of the FV to judge the emergency braking
d_Threshold
EEBL Emergency Electronic Brake Light system
EEBL-T Emergency Electronic Brake Light -Transmitting system
EEBL-R Emergency Electronic Brake Light - Receiving system
FSRA Full Speed Range ACC
FV Forward Vehicle
FVCWS Forward Vehicle Collision Warning System
GNSS Global Navigation Satellite System
HMI Human Machine Interface
IV Interfering Vehicle
PER Packet Error Rate
ROI Region of Interest
RSE Road Side Equipment
SV Subject Vehicle
V A pre-set speed of vehicle for test
1
V2I Vehicle to Infrastructure communication
V2V Vehicle to Vehicle communication
V Maximum operational speed value
max
5 Specifications and requirements
5.1 Basic functions
The purpose of the EEBL is to provide alerts that will assist drivers in avoiding or reducing the severity
of rear end crashes caused by emergency braking of an FV.
EEBL has following functions.
— EEBL-T detects and judges the emergency braking of an FV, and broadcasts a message including
the emergency braking flag. For better understanding, the vehicle that broadcasts the emergency
braking flag is denoted as FV in this document.
— EEBL-R receives the message including the emergency braking flag, judges whether the alert shall
be issued, and provides the alert to the driver. For better understanding, the vehicle whose driver is
alerted is denoted as SV in this document.
— The EEBL requires both of these functions, EEBL-T and EEBL-R, on separate vehicles. The
implementations can be different for different manufacturers on their respective vehicles.
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ISO 20901:2020(E)
The alert should be issued as soon as the SV receives the emergency braking message flag from an FV
within its ROI and has evaluated it to be relevant. EEBL provides an alert only and does not perform
vehicle control to mitigate the crash.
EEBL may suppress or delay the alert when the SV is applying an automatic braking or alert(s)
commanded by another system in the vehicle, e.g. FVCWS or FSRA.
The basic components of EEBL can include radio communication transmitter/receiver and antenna,
GNSS receiver and antenna, processing device and HMI device. The processing device can be a separate
control unit or it can be combined with another control unit.
5.2 Necessary functions
Vehicles equipped with EEBL-T shall be equipped to fulfil the following functions:
— monitor vehicle deceleration, vehicle position, vehicle speed and vehicle heading direction;
— detect emergency braking in accordance with deceleration threshold value;
— broadcast the message including emergency braking flag to nearby vehicles.
Vehicles equipped with EEBL-R shall be equipped to fulfil the following functions:
— receive the message including emergency braking flag;
— judge the position and heading of the FV with respect to the SV;
— provide alerts to driver in accordance with the EEBL function and requirements.
5.3 Basic operation principle
Figure 1 — EEBL states and transitions
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ISO 20901:2020(E)
5.3.1 State functional descriptions
5.3.1.1 State transition conditions
Conditions for EEBL transitions from system Off state to system On state:
a) For EEBL vehicles equipped with on/off control, both the vehicle ignition and the on/off control are
on.
b) For EEBL vehicles not equipped with on/off control, the vehicle ignition is on.
c) The transition from EEBL Off to EEBL On may be performed by the driver or automatically.
d) The transition from EEBL Off to EEBL On shall only occur if no EEBL system failures have been
detected.
Conditions for EEBL transitions from system On state to system Off state:
a) For EEBL vehicles equipped with on/off control, either the vehicle ignition or the on/off control
are off.
b) For EEBL vehicles not equipped with on/off control, the vehicle ignition is off.
c) If the system is in on state, and a system failure occurs.
The system may be fitted with an on/off control that can be operated by the driver at all times.
EEBL shall as a minimum, provide the following operations and state transitions. The following
constitutes the fundamental behaviour of EEBL. The alert criteria are described in 5.4.
— The EEBL-T system of an FV generates the message including the emergency braking flag as long as
the vehicle braking exceeds the threshold value ( a ), and returns back to the stand-by
d_Threshold
state after the vehicle braking no longer exceeds the threshold value. The system broadcasts the
message including the emergency braking flag to nearby vehicles through V2V wireless
communication within 100 ms of detecting the emergency brake.
— When the EEBL-R system of an SV is in the stand-by state, the system monitors messages from
external wireless communication sources. If a message including the emergency braking flag is
received, the system judges the alert criteria to determine whether the alert should be issued. If
the system judges to alert, the system transitions to the alert state, and the EEBL-R starts alert(s)
immediately.
— When the EEBL-R system of an SV is in the alert state, the system provides alert(s) to the driver for
a minimum 2 s, and maximum of the duration that the FV emergency braking flag is received, and
then returns back to the stand-by state.
One of several stages or phases of system operation.
— EEBL off state: The state that EEBL is off. This state has one of the following three causes: the driver
has selected the off condition, the ignition is off, or the EEBL is in failure. The failure of EEBL means
that the system cannot function as it is described in the user manual due to the failure of the system
or the failure of the sub-component of the EEBL. The cause of failure can be, e.g. system malfunction,
communication fail, failure during self- diagnosis process.
— EEBL system on state: For EEBL-T equipped on a FV, this state is either stand-by or broadcast state.
For EEBL-R equipped on an SV, this state is either stand-by or alert state. Vehicles equipped with
EEBL-T periodically broadcast and the vehicles equipped with the EEBL-R receive status messages.
— EEBL system stand-by state: For EEBL-T equipped on a FV, the system monitors the vehicle
deceleration. For EEBL-R equipped on an SV, the system is ready to receive the message including
the emergency braking flag.
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ISO 20901:2020(E)
— EEBL-T transmission of emergency braking state: The system generates the emergency braking
flag, and sends the message including emergency braking flag to nearby vehicles using wireless
communication module. The EEBL-T starts broadcasting the message including emergency braking
flag if the amount of deceleration of the vehicle exceeds the threshold value.
— EEBL-R alert state: The system starts alert(s) or is operating the alert(s). The EEBL-R starts alert(s)
if the message including emergency brake flag is received, and the system judged that the alert
criteria are all met.
5.3.2 Operational limits
The maximum operational speed value (for SV) of Vmax shall be greater than or equal to 27,8 m/s.
The system shall not operate when the speed of SV or FV is less than 2,8 m/s.
The operational limits of EEBL shall be indicated in an owner’s manual and/or caution label.
5.4 Alert functionality
5.4.1 General
EEBL shall provide an alert for emergency braking of an FV in the forward path of the SV. The EEBL
alert is provided in accordance with the following functions.
5.4.2 Generating the message including emergency braking flag for broadcasting
EEBL-T monitors the deceleration of the vehicle. If the deceleration, a is greater than or equal
d_Current
to the absolute value of the threshold value, the EEBL-T generates the message including emergency
braking flag. The message is broadcast through the wireless communication module of EEBL-T to
2
nearby vehicles. The threshold value, a , is 4,0 m/s .
d_Threshold
If aa≥ , FV broadcasts the message including emergency braking flag.
d_Current d_Threshold
5.4.3 Judging to issue the alert
When the EEBL-R in an SV receives the message including emergency braking flag, and the FV is within
the ROI, the EEBL-R starts the alert. The judgement whether the location of the FV is inside of the ROI of
the SV’s EEBL-R is based on the GNSS location of the SV and FV.
Dimensions in metres
Figure 2 — Minimum region of interest (ROI) for EEBL
The minimum area of the ROI is described in Figure 2. The ROI in the longitudinal direction shall be
greater than or equal to 150 m measured from the tip of the front bumper of the SV. The ROI in the
lateral direction shall be greater than or equal to 6 m to both left and right sides, measured from the
center of the SV
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ISO 20901:2020(E)
Longitudinal distance of ROI ≥ 150 m
Lateral distance of ROI ≥ 6 m (each left and right)
If the following criteria are all met, the alert shall be issued.
— The location of the FV is inside of the ROI of the SV.
— Both the FV and SV are traveling in the same direction on the same roadway.
— The EEBL-R is in System On state, and the gear selection is in forward or neutral position (all gear
positions except reverse and park).
It is permitted to have a larger ROI but the minimum value in both longitudinal and lateral directions
shall be at least 150 m and 12 m, respectively. If the road is curved, the longitudinal distance is measured
along the centerline of the road.
The method to judge whether the FV is in the location to cause a possible danger to SV depends upon
the manufacturer of EEBL-R.
If the manufacturer of EEBL-R can judge that the emergency brake of FV in ROI will not result in danger
for the SV (e.g. FV in adjacent lane), the EEBL-R is allowed not to provide an alert to the driver.
5.5 Alerting element requirements
5.5.1 EEBL-R output
When the alert criteria mentioned in 5.4.3 are all met, EEBL-R of the SV shall provide an emergency
brake alert to the driver.
5.5.2 Alert modality
When the system transitions to the EEBL-R alert state, the driver shall be alerted by an audible, haptic
or visual element.
While the alert is designed and provided, the following related standards may be used for reference.
— ISO/TR 12204:2012
— ISO/TS 16951:2004
Drivers shall be informed of the conditions that result in EEBL-R activation and deactivation and of the
limitations of the system performance by the vehicle owner’s manual.
If EEBL-R is not available due to a failure, the driver shall be informed, and the description of the notice
shall be stated in the vehicle owner’s manual.
An alert should be selected such that it can easily be distinguished from warnings unrelated to forward
direction threats (e.g. lateral threat warnings).
5.5.3 Optional functions of EEBL-R
The required deceleration threshold for collision may be adapted based on the detected road condition,
environmental conditions, driver conditions or driver behaviour.
The system may suppress additional alerts to avoid repetitive alerts.
The system may suppress alerts when the driver is applying the brake.
The EEBL-R alert may be suppressed or delayed if the SV is detected to be performing a lane change or
high dynamic manoeuvring.
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ISO 20901:2020(E)
The EEBL-R alert may be suppressed or delayed if an automatic warning braking or braking is already
activated. The automatic warning braking or braking can be issued by ACC, FVCMS or other automatic
braking systems.
It is optional to use V2I communication for EEBL-R. For example, the message including emergency
braking flag of the FV can be transferred to an RSE on road infrastructure and redirected to the SV.
If any of these optional functions is included, it shall be described in the vehicle owner’s manual.
5.6 Performance requirement of EEBL
5.6.1 Minimum communication range
The minimum communication range between the FV and SV shall be 300 m of roadway.
5.6.2 System delay requirement between FV and SV
Within the communication range required in 5.6.1, the SV shall be able to receive the message including
emergency braking flag within 0,3 s for test cases specified in 6.6. This system delay is from the time
that the EEBL-T of the FV starts generating emergency braking flag to the time that the EEBL-R of the
SV starts the alert.
Figure 3 — Definition of system delay
5.7 Driver interface requirements
5.7.1 Alert output specification
All visual, audible, and haptic alerts shall be perceptible by the driver. It is recommended that the visual
and audible alert satisfy appropriate human factors. The alert modality requirements for collision
alerts are shown in 5.5.2.
5.7.2 Fault indication
If the EEBL is in fault condition, fault indication shall be provided to driver. The indication modality can
be visual.
6 Performance evaluation test methods
6.1 Environmental conditions for test
a) The test location shall be on a flat
...
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