ISO 15623:2002

INTERNATIONAL ISO
STANDARD 15623
First edition
2002-10-01


Transport information and control
systems — Forward vehicle collision
warning systems — Performance
requirements and test procedures
Systèmes de commande et d'information des transports — Systèmes
d'avertissement de collision frontale — Exigences de performance et
modes opératoires




Reference number
ISO 15623:2002(E)
©
 ISO 2002

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ISO 15623:2002(E)
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ISO 15623:2002(E)
Contents Page
Foreword . iv
Introduction. v
1 Scope. 1
2 Normative reference. 1
3 Terms and definitions. 1
4 Symbols. 2
5 Specifications and requirements. 3
5.1 Warnings . 3
5.2 System classification. 4
5.3 Obstacle vehicle detection area and performance . 4
5.4 User safety requirements . 6
5.5 Human interface requirements . 6
5.6 Awareness of system limitations . 7
6 Evaluation test method for measuring detection performance. 8
6.1 Test target specification. 8
6.2 Environmental conditions . 8
6.3 Test method for detection zone. 8
6.4 Test method for warning distance accuracy. 10
6.5 Test method for target discrimination ability. 10
Annex A (normative) Basic consideration of collision warning . 14
A.1 Basic equation. 14
A.2 Scenarios where warning is issued . 14
A.3 Evaluation results of T and a . 15
A.4 Calculation examples of the warning distance . 16
A.5 Design parameter . 18
Annex B (normative) Obstacle detection along curves. 19
Annex C (normative) Laser radar — Coefficient of test target. 21
C.1 Solid angle, ΩΩΩΩ . 21
C.2 Radiated intensity, I. 21
C.3 Intensity of irradiation, E . 22
C.4 Coefficient of Test Target, CTT. 22
Annex D (normative) Radio wave radar test target geometry. 24
Bibliography. 25

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ISO 15623:2002(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 3.
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 International Standard may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 15623 was prepared by Technical Committee ISO/TC 204, Transport information and control systems.
Annexes A, B, C, and D form a normative part of this International Standard.
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ISO 15623:2002(E)
Introduction
The main system function of a Forward Vehicle Collision Warning System (FVCWS) is to warn the driver when the
subject vehicle encounters the situation when a forward vehicle in the subject vehicle’s trajectory becomes a
potential hazard. This is done by using information about: (1) the range to forward vehicles, (2) the time to a
potential collision and (3) the grade of warnings provided to the driver (see Figure 1). Based upon the information
acquired, the controller identified as “FVCWS warning strategy” in Figure 1 produces the warning to the driver.

Figure 1 — Functional forward vehicle collision warning system’s elements
Automobile manufacturers and component suppliers throughout the world have been vigorously pursuing the
development and commercialization of these FVCWS systems. Systems of this type have already been introduced
onto the market in some countries. Thus the standardization efforts began in 1994 amongst interested countries.
This International Standard is composed to address only the basic performance requirements and test procedures
for the FVCWS type systems. This International Standard may be used as a basis by other advanced standards for
systems which have more advanced features and may extend beyond this International Standard.

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INTERNATIONAL STANDARD ISO 15623:2002(E)

Transport information and control systems — Forward vehicle
collision warning systems — Performance requirements and test
procedures
1 Scope
This International Standard specifies performance requirements and test procedures for systems capable of
warning the driver of short inter-vehicle distance and closing speed which may cause a rear-end collision with other
vehicles, including motor cycles, ahead of the subject vehicle while it is operating at ordinary speed.
This International Standard is applicable to operations on roads with curve radii over 125 m as well as higher radius
curves.
2 Normative reference
The following normative document contains provisions which, through reference in this text, constitute provisions of
this International Standard. For dated references, subsequent amendments to, or revisions of, any of these
publications do not apply. However, parties to agreements based on this International Standard are encouraged to
investigate the possibility of applying the most recent edition of the normative document indicated below. For
undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC
maintain registers of currently valid International Standards.
IEC 60825-1:2001, Safety of laser products — Part 1: Equipment classification, requirements and user's guide
(consolidated edition)
3 Terms and definitions
For the purposes of this International Standard, the following terms and definitions apply.
3.1
collision warning
information that the system gives to the driver indicating the need for urgent action to avoid a collision
NOTE This warning is issued in the advanced stages of a dangerous situation to warn the driver of the need to perform
emergency braking, lane changing or other emergency manoeuvres in order to avoid a collision.
3.2
coefficient of test target
CTT
coefficient representing the optical radar reflectivity of the target which is defined as the coefficient of radiated
intensity, measured in front of the receiver surface, divided by the intensity of irradiation out of the transmitter
NOTE See clause C.4.
3.3
forward vehicle
vehicle in front of and moving in the same direction and travelling on the same roadway as the subject vehicle
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ISO 15623:2002(E)
3.4
forward vehicle collision warning system
system capable of warning the driver of a potential collision with another vehicle in the forward path of the subject
vehicle, but excluding intersections
3.5
obstacle vehicles
vehicles, both moving and stationary, considered potential hazards that can be detected by this system
NOTE Vehicles include motor vehicles only, that is cars, trucks, buses, and motorcycles.
3.6
preliminary collision warning
information that the system gives to the driver indicating the presence of a forward obstacle vehicle
NOTE This warning is issued in the early stages of a potentially dangerous situation, caused by such circumstances as
driver’s inattention/daydreaming, or the sudden change in movement of a preceding vehicle, which may result in a collision.
3.7
radar cross section
RCS
measure of the reflective strength of a radar target expressed in square meters, and defined as 4π times the ratio of
the power per unit solid angle scattered in a specified direction to the power per unit area in a radio wave incident
on the scatterer from a specified direction
3.8
visibility
distance which the illuminance of a non-diffusive beam of white light with the colour temperature of 2 700 K is
decreased to 5 % of its original light source illuminance
4 Symbols
a Maximum allowed lateral acceleration in curves

lateral_max
a Minimum deceleration of the subject vehicle’s emergency braking
min
CTT Coefficient for Test Target for infrared reflector
d Minimum detectable distance without distance measuring capability

0
d Minimum detectable distance with distance measuring capability

1
d Minimum detection distance for a cut-in vehicle

2
d Maximum detectable distance
max
h Upper detection height from ground
h Lower detection height from ground
1
T Maximum driver’s brake reaction time after the warning
max
T Minimum driver’s brake reaction time after the warning
min
RCS Radar Cross Section
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ISO 15623:2002(E)
V Speed of the test vehicles at the start of the test

circle_start
V Maximum vehicle speed at which the system is capable of operating
max
V Minimum vehicle speed at which the system is capable of operating
min
W Lane width

L
W Subject vehicle width

V
5 Specifications and requirements
5.1 Warnings
5.1.1 General
Forward vehicle collision warning systems shall provide warnings in accordance with the following functions.
5.1.2 Monitoring distance and relative speed between obstacle vehicle and subject vehicle
A forward obstacle vehicle is sensed by obstacle detecting devices such as optical radar, radio wave radar, and
image processing systems.
5.1.3 Judging the timing of collision
The timing of a potential collision is judged by the results of evaluating the subject vehicle speed, the distance to
the obstacle vehicle, and the relative speed between the subject vehicle and the obstacle vehicle. When the
system detects multiple obstacle vehicles at the same time, the one in the subject vehicle’s expected trajectory that
1)
the subject vehicle will reach the soonest shall be selected.
5.1.4 Preliminary collision warning and collision warning (see annex A)
Forward vehicle collision warning systems shall provide at least two separate warnings: a preliminary collision
warning and a collision warning. The purpose of the preliminary collision warning is to inform the driver of the
presence of a forward obstacle vehicle. In this case the driver should prepare to take the necessary action to avoid
a collision. The purpose of the collision warning is to inform the driver of the need to take action in order to avoid a
collision.
Warnings consist of independent or combined use of visual, audible and/or tactile senses. However in the case of a
collision warning, audible and/or tactile means of warning shall be used and visual means may be used in addition
to the aforementioned means.
Warnings are issued depending on the relative speed between the subject vehicle and the obstacle vehicle, the
subject vehicle speed, the inter-vehicle distance, the free running (driver's brake reaction) time and the
deceleration.
When the subject vehicle is approaching an obstacle vehicle, the warning distance should be decided according to
criteria with respect to time to collision threshold values.
5.1.5 Fault indicator
If a fault is detected during system start up or during system operation, the driver shall be informed.

1) “Soonest” means the smallest time to collision.
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ISO 15623:2002(E)
5.2 System classification
Systems are classified according to curve radius capability as shown in Table 1.
Table 1 — System classifications
Class Horizontal curve radius capability
I curve radius W 500 m
II curve radius W 250 m
III curve radius W 125 m

 Class I systems shall have the capability to detect forward obstacle vehicles in the subject vehicle’s trajectory
along curves of radii down to 500 m.
 Class II systems shall have the capability to detect forward obstacle vehicles in the subject vehicle’s trajectory
along curves of radii down to 250 m.
 Class III systems shall have the capability to detect forward obstacle vehicles in the subject vehicle’s trajectory
along curves of radii down to 125 m.
5.3 Obstacle vehicle detection area and performance
5.3.1 Obstacle vehicle detection area
5.3.1.1 Minimum detection area (Class I, II and III)
The minimum detection area is illustrated in Figure 2.

Figure 2 — Detection area
5.3.1.1.1 Detection range
Detection range requirements are specified in Table 2.
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ISO 15623:2002(E)
Table 2 — Detection range requirements
Distance Formula or value Meaning
2
d
V × T + V / 2a The maximum detectable distance.
max
max max max min
d
Less than or equal to 10 m for Class I The minimum detection distance for a cut-in vehicle (which
2
crosses the line of the subject vehicle’s trajectory by the
Less than or equal to 7,5 m for Class II
width of the subject vehicle and is thus possible to disturb
the subject vehicle’s ordinary driving).
Less than or equal to 5 m for Class III
d T × V The system’s minimum distance with distance measuring
1 min min
capability.
d
Less than or equal to 2 m The minimum detectable distance without distance
0
measuring capability.

where
V is the maximum vehicle speed at which the system is capable of operating, in metres per second
max

(m/s);
V is the minimum vehicle speed at which the system is capable of operating, in metres per second
min
(m/s);
T is the maximum driver’s brake reaction time after the warning, in seconds (s);
max

T is the minimum driver’s brake reaction time after the warning, in seconds (s);
min
a is the minimum deceleration of the subject vehicle’s emergency braking, in metres per square second
min
2
(m/s ).
V and V are the design parameters for actual systems, which will be decided by the vehicle manufacturer,
max
min
while T , T and a are the design parameters (see Annex A) and following values should be used to
max
min min
calculate the d and d .
max
1
T = 1,5 s
max
T = 0,4 s
min

2
a = 3,6 m/s
min
5.3.1.1.2 Detection width and detection height
Table 3 — Detection width and detection height requirements
Distance Minimum detection width Minimum detection height
d W , metres
h = 0,2 m and h = 1,1 m
max L
1
d W , metres
h = 0,2 m and h = 1,1 m
2 V
1
d
not specified not specified
1
d not specified not specified
0

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ISO 15623:2002(E)
5.3.1.2 Detection range for horizontal curve radius
The width of the detection range for horizontal curve radius shall be extended in relation to the curve’s radius (see
Annex B).
5.3.2 Warning distance accuracy
Warning distance accuracy, which is defined as the difference between the warning distance where the system
produces the warning at the test and the system design warning distance, shall be the maximum system design
warning distance, with a relative tolerance of ± 1 m or ± 5 %. Both distances are calculated by evaluating the inter-
vehicle distance, the relative speed, the time to collision, the subject vehicle speed and so on.
5.3.3 Target discrimination ability
5.3.3.1 Longitudinal discrimination
If there are two or more obstacle vehicles in the detection range from a distance d to d from the subject
1 max
vehicle's front end, the system shall be capable of clearly selecting the soonest one in the subject vehicle’s
trajectory and shall give appropriate warnings.
5.3.3.2 Lateral discrimination
If there are two or more obstacle vehicles in the subject vehicle’s trajectory or in an adjacent position, the system
shall be capable of clearly selecting the vehicle in the subject vehicle’s trajectory and shall give appropriate
warnings.
5.3.3.3 Overhead discrimination
If there are obstacles at overhead of the road
...