ISO 15622:2002

INTERNATIONAL ISO
STANDARD 15622
First edition
2002-10-15


Transport information and control
systems — Adaptive Cruise Control
systems — Performance requirements and
test procedures
Systèmes de commande et d'information des transports — Systèmes
stabilisateurs de vitesse adaptés — Exigences de performance et modes
opératoires




Reference number
ISO 15622:2002(E)
©
 ISO 2002

---------------------- Page: 1 ----------------------
ISO 15622:2002(E)
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but shall not
be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In downloading this
file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat accepts no liability in this
area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation parameters
were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In the unlikely event
that a problem relating to it is found, please inform the Central Secretariat at the address given below.


©  ISO 2002
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic
or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISO's member body
in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.ch
Web www.iso.ch
Printed in Switzerland

ii © ISO 2002 – All rights reserved

---------------------- Page: 2 ----------------------
ISO 15622:2002(E)
Contents Page
Foreword . iv
Introduction. v
1 Scope. 1
2 Normative references. 1
3 Terms and definitions. 1
4 Symbols. 3
5 Classification . 5
5.1 Type of ACC systems . 5
5.2 Classification of curve capabilities . 5
6 Requirements . 5
6.1 Basic control strategy. 5
6.2 Functionality . 6
6.3 Basic driver interface and intervention capabilities. 8
6.4 Operational limits . 9
6.5 Activation of brake lights (ACC Type 2 only). 10
6.6 Failure reactions. 10
7 Performance evaluation test methods. 11
7.1 Environmental conditions . 11
7.2 Test target specification. 11
7.3 Detection range test — Test procedure for d , d , d and d (see 6.2.5.2). 12
0 1 2 max
7.4 Target discrimination test (see 6.2.5.3). 13
7.5 Curve capability test (see 6.2.5.4). 14
Annex A (normative) Technical information.17
Bibliography. 25

© ISO 2002 – All rights reserved iii

---------------------- Page: 3 ----------------------
ISO 15622:2002(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 15622 was prepared by Technical Committee ISO/TC 204, Transport information and control systems.
Annex A forms a normative part of this International Standard.
iv © ISO 2002 – All rights reserved

---------------------- Page: 4 ----------------------
ISO 15622:2002(E)
Introduction
The main system function of Adaptive Cruise Control is to control vehicle speed adaptively to a forward vehicle by
using information about: (1) ranging to forward vehicles, (2) the motion of the subject (ACC equipped) vehicle and
(3) driver commands (see Figure 1). Based upon the information acquired, the controller (identified as “ACC control
strategy” in Figure 1) sends commands to actuators for carrying out its longitudinal control strategy and it also
sends status information to the driver.

Figure 1 — Functional ACC elements

The goal of ACC is a partial automation of the longitudinal vehicle control and the reduction of the workload of the
driver with the aim to support and relieve the driver in a convenient manner.
This International Standard may be used as a system level standard by other standards, which extend the ACC to
a more detailed standard, e.g. for specific detection and ranging sensor concepts or higher level of functionality.
So, issues like specific requirements for the detection and ranging sensor function and performance or
communication links for co-operative solutions will not be considered here.
© ISO 2002 – All rights reserved v

---------------------- Page: 5 ----------------------
INTERNATIONAL STANDARD ISO 15622:2002(E)

Transport information and control systems — Adaptive Cruise
Control systems — Performance requirements and test
procedures
1 Scope
This International Standard specifies the basic control strategy, minimum functionality requirements, basic driver
interface elements, minimum requirements for diagnostics and reaction to failure, and performance test procedures
for Adaptive Cruise Control (ACC) systems. ACC is fundamentally intended to provide longitudinal control of
equipped vehicles while travelling on highways under free-flowing traffic conditions. ACC may be augmented with
other capabilities, such as forward obstacle warning.
2 Normative references
The following normative documents contain 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 editions of the normative documents 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.
ISO 2575, Road vehicles — Symbols for controls, indicators and tell-tales
UN ECE Regulation No.13-H, Uniform provisions concerning the approval of passenger cars with regard to braking
1) 2)
3 Terms and definitions
For the purpose of this International Standard, the following terms and definitions apply.
3.1
active brake control
function which causes application of the brake(s), not applied by the driver, in this case controlled by the ACC
system
3.2
Adaptive Cruise Control
ACC
enhancement to conventional cruise control systems (see conventional cruise control), which allows the subject
vehicle to follow a forward vehicle at an appropriate distance by controlling the engine and/or power train and
potentially the brake

1) Tell-tales (on board symbols) for ACC and ACC malfunctions will be specified in a future edition of ISO 2575.
2) Definitions are in accordance with Glossary of ISO/TC 204/WG14.
© ISO 2002 – All rights reserved 1

---------------------- Page: 6 ----------------------
ISO 15622:2002(E)
3.3
brake
part in which the forces opposing the movement of the vehicle develop. It may be a friction brake (when the forces
are generated by friction between two parts of the vehicle moving relatively to one another); an electrical brake
(when the forces are generated by electro-magnetic action between two parts of the vehicle moving relatively but
not in contact with one another); a fluid brake (when the forces are generated by the action of a fluid situated
between two parts of the vehicle moving relatively to one another); or an engine brake (when the forces are derived
from an artificial increase in the braking action, transmitted to the wheels, of the engine)
[UN ECE Regulation 13-H:1998, 2.6]
NOTE For the purposes of this International Standard, transmission control devices are not considered as brakes.
3.4
clearance
c
distance from the forward vehicle's trailing surface to the subject vehicle's leading surface
3.5
conventional cruise control
system capable of controlling the speed of a vehicle as set by the driver
3.6
forward vehicle
vehicle in front of and moving in the same direction and travelling on the same roadway as the subject vehicle
3.7
free-flowing traffic
smooth flowing and heavy traffic, excluding stop-and-go and emergency braking situations
3.8
time gap
τ
time interval for travelling the clearance between consecutive vehicles
NOTE The time gap is related to vehicle speed v and clearance c by: τ = c/ v. See Figure 2.

Figure 2 — Time gap
3.9
set speed
desired travel speed, set by either the driver or by some control system that is external to the ACC system,
corresponding to the maximum desired speed of the vehicle while under ACC control
3.10
steady state
condition whereby the value of the described parameter does not change with respect to time, distance, etc.
NOTE A circle can be described as a curve with a steady state radius. Similarly, a vehicle travelling at constant speed can
be described as travelling at steady state speed.
3.11
subject vehicle
vehicle equipped with the ACC system in question and related to the topic of discussion
2 © ISO 2002 – All rights reserved

---------------------- Page: 7 ----------------------
ISO 15622:2002(E)
3.12
System states
For the purposes of this International Standard, three system states are distinguished (see 3.12.1, 3.12.2, 3.12.3
and Figure 3).
3.12.1
ACC off state
state in which direct access for activation of the ACC active state is disabled
3.12.2
ACC stand-by state
state in which no longitudinal control by the ACC system and the system is ready for activation by the driver
3.12.3
ACC active state
state in which the system controls speed and/or time gap

a
Manually and/or automatically after self test. Manual transition describes a switch to enable/disable ACC function.
Automatic switch off can be forced by failure reaction.
Figure 3 — ACC states and transitions
4 Symbols
A Utilized area, general for area
A Illuminated surface
t
a Maximum allowed lateral acceleration in curves
lateral_max
a Minimum allowed longitudinal acceleration = Maximum allowed longitudinal deceleration
min
a Maximum allowed longitudinal acceleration
max
a Maximum allowed acceleration during curve test
test
a Maximum possible deceleration capability during manual driving
vehicle_max
CTT Coefficient for Test Target for infrared reflectors
c Clearance, inter vehicle distance
d Distance, between object and sensor, general for distance
d Distance, below which there is no need for detection of a target vehicle
0
d Distance, below which no distance measurement or determination of relative speed is required
1
d Distance for measurement purpose
2
d Distance between source and projected plane A
A
© ISO 2002 – All rights reserved 3

---------------------- Page: 8 ----------------------
ISO 15622:2002(E)
d Maximum detection range on straight roads
max
d Maximum detection range on curves
max_curve
E Intensity of irradiation, out of transmitter
t
FOV Field of View
HDA Horizontal detection area
I Radiated intensity
0
I Radiated intensity in a given direction
ref
L Length of a side of a radar test reflector
R Circle radius, curve radius
RCS RADAR Cross Section
R Actual radius of curve
circle
R Minimum curve radius
min
T Minimum time to achieve maximum deceleration
brake_max
t Time, start test
0
t Time, start manœuvre
1
t Time, end manœuvre
2
t Time, end test
3
v True subject vehicle speed over ground
v Maximum speed on a curve for a given lateral acceleration a
circle lateral_max
v Vehicle speed as it enters a curve of radius R
circle_start
v Minimum speed at which automatic acceleration is allowed
low
v Vehicle set speed
set
v Maximum selectable set speed
set_max
v Minimum selectable set speed
set_min
v Vehicle speed at the end of a test
vehicle_end
v Maximum vehicle speed
vehicle_max
v Vehicle speed at the start of a test
vehicle_start
y Width of FOV measured from the centre line at d
max max_curve
α Half angle of field of view
λ Wavelength of radar wave
τ Gap, time gap between vehicles
τ (v) Maximum possible steady-state time gap at a given speed v
max
τ Maximum selectable time gap
max
τ (v) Minimum steady-state time gap at speed v
min
τ Minimum selectable time gap
min
Φ Radiated power
Ω Solid angle
Ω Solid angle (of the source)
0
Ω Illuminated solid angle
1
4 © ISO 2002 – All rights reserved

---------------------- Page: 9 ----------------------
ISO 15622:2002(E)
5 Classification
5.1 Type of ACC systems
Different configurations of actuators for longitudinal control result in very different system behaviour. Therefore four
types of ACC systems are addressed in this International Standard:
Table 1 — Classification of ACC system types
Manual clutch
Type Active brake control
operation required
1a yes no
1b no no
2a yes yes
2b no yes

The deceleration capability of the ACC system shall be clearly stated in the vehicle owner’s manual.
In case of active brake intervention in vehicles with a clutch pedal (Type 2a) the driver shall be informed clearly and
early about a potential conflict between brake and engine idle control, if the clutch cannot be disengaged
automatically. A practicable and unambiguous handing-over procedure shall be provided for the driver (see 6.3.1)
5.2 Classification of curve capabilities
This International Standard is applicable to ACC systems of different curve capabilities as specified in Table 2.
Table 2 — ACC performance classifications
Dimensions in metres
Performance class Curve radius capability
I no performance capability claimed
II
W 500
III W 250
IV W 125

6 Requirements
6.1 Basic control strategy
ACC systems shall as a minimum, provide the following control strategy and state transitions. The following
constitutes the fundamental behaviour of ACC systems.
 When the ACC is active, the vehicle speed shall be controlled automatically either to maintain a time gap to a
forward vehicle, or to maintain the set speed, whichever speed is lower. The change between these two
control modes is made automatically by the ACC system.
 The steady-state time gap may be either self adjusting by the system or adjustable by the driver (see 6.3.1).
© ISO 2002 – All rights reserved 5

---------------------- Page: 10 ----------------------
ISO 15622:2002(E)
 The transition from “ACC-stand-by” to “ACC-active” shall be inhibited if the subject vehicle's speed is below a
minimum operational speed, v . Additionally, if the vehicle's speed drops below v while the system is in
low low
the “ACC-active” state, automatic acceleration shall be inhibited. Optionally, the ACC system may drop from
“ACC-active” to “ACC-stand-by” (see 6.3.2).
 If there are more than one forward vehicle the one to be followed shall be selected automatically (see 6.2.5.3).
6.2 Functionality
6.2.1 Control modes
The transition between the control modes (time gap controlled or speed controlled) shall be made automatically.
6.2.2 Clearance capabilities
τ shall be the minimum selectable time gap for following control mode under steady-state conditions for all
min
speeds v. τ (v) shall be greater than or equal to τ = 1 s.
min min
At least one time gap τ in the range of 1,5 s to 2,2 s shall be provided.
6.2.3 Speed of subject vehicle
The ACC system shall be able to determine the speed of the subject vehicle.
6.2.4 Stationary targets
It is not a requirement that an ACC system be designed to respond to the presence of stationary targets. If the
system is designed not to respond to stationary targets the driver shall be informed at least by a statement in the
vehicle owner’s manual.
6.2.5 Following capability
6.2.5.1 General
Under steady-state conditions, ACC systems shall comply with the minimum time gap limit as specified in 6.2.2.
During transient conditions the time gap may temporarily fall below the limit. If such a situation occurs, the system
shall adjust the time gap to attain the limit within an appropriate time.
The ACC shall have detection range, target discrimination and curve capabilities as specified in 6.2.5.2 to 6.2.5.4.
6.2.5.2 Detection range on straight roads (performance class I ++++ II ++++ III ++++ IV)

Figure 4 — Zones of detection
6 © ISO 2002 – All rights reserved

---------------------- Page: 11 ----------------------
ISO 15622:2002(E)
If a forward vehicle is present within the distance range d to d , the ACC system shall measure the range
1 max
between the forward and subject vehicles (see Figure 4).
d = τ (v ) × v
max max set_max set_max
If a forward vehicle is present within the distance range d to d , the ACC system shall detect the presence of the
0 1
vehicle but is not required to measure the range to the vehicle nor the relative speed between the forward and
subject vehicles. If a forward vehicle is detected within this range, the system shall increase the clearance and/or
inhibit automatic acceleration.
d = τ (v ) × v
1 min low low
If a forward vehicle is present within the distance of d , the ACC system is not required to detect the presence of
0
the vehicle.
d = MAX[2, (0,25 × v )]
0 low
6.2.5.3 Target discrimination
If there are more than one forward vehicle on straight roads and for performance class II + III + IV also in steady
state curves, the forward vehicle (see Figure 5) in the subject vehicle's lane shall be selected for ACC control in
typical ACC situations as represented by the test scenario (see 7.4).

Figure 5 — Target discrimination

6.2.5.4 Curve capability (performance class II ++++ III ++++ IV)
The ACC system shall enable steady state vehicle following with a time gap of τ (v ), on straight roads (class
max circle
I + II + II + IV) and curves with a radius down to R = 500 m (class II + III + IV) and R = 250 m (class III + IV)
min,II min,III
and R = 125 m (class IV). Therefore the system shall be capable to follow a forward vehicle with the steady
min,IV
state time gap τ (v ), if the forward vehicle cruises on a constant curve radius R with a constant speed
max circle min
v .
circle
va=×R
circle lateral_max min
where
τ (v) is the maximum possible steady state time gap while driving with a speed v.
max
a is the design lateral acceleration for curves on highways.
lateral_max
© ISO 2002 – All rights reserved 7

---------------------- Page: 12 ----------------------
ISO 15622:2002(E)
The values to use are
2
a = 2,0 m/s and
lateral_max,II
2
a = 2,3 m/s and
lateral_max,III
2
a = 2,3 m/s .
lateral_max,IV
The values for a are adopted to the driver behaviour in curves (95 %-drivers); see Figure 6.
lateral,max

Figure 6 — Lateral acceleration of the average driver [B.3]

6.3 Basic driver interface and intervention capabilities
The system shall provide the following controls and intervention capabilities:
6.3.1 Operation elements and system reactions
6.3.1.1 ACC systems shall provide a means for the driver to select a desired set speed.
6.3.1.2 Braking by the driver shall deactivate ACC function at least if the driver initiated brake force demand is
higher than the ACC initiated brake force (leading to ACC standby state; see Figure 3). The ACC-system shall not
lead to a significant transient reduction of braking response to the driver's braking input (refer to ECE-R 13-H).
There shall not be a significant reduction of braking response to the driver's intervention on the brake pedal even
when the ACC-system has been braking automatically.
6.3.1.3 Type 1a and 2a ACC systems shall either temporarily suspend operation but remain in the ACC-active
state or transition to ACC-stand-by if the driver depresses the clutch pedal. For type 2a systems, the Automatic
brake manœuvre can be continued during the use of the clutch pedal. After the system releases the brakes, the
system may either resume ACC control or transition to ACC-stand-by in response to the driver depressing the
clutch.
6.3.1.4 The larger of the power demands from either the driver or the ACC system will be used to drive the
engine power actuator (e.g. throttle actuator). This always gives the driver authority to override the ACC system
engine power control.
If the power demand of the driver is greater than that of the ACC system automatic braking shall be disengaged
with an immediate brake force release. A driver intervention on the accelerator pedal shall not lead to a significant
delay of response to driver’s input.
8 © ISO 2002 – All rights reserved

---------------------- Page: 13 ----------------------
ISO 15622:2002(E)
6.3.1.5 Automatic brake activation (ACC type 2 only) shall not lead to locked wheels for periods longer than
anti lock devices (ABS) would allow. This need not require an anti lock device (ABS) system.
6.3.1.6 Automatic power control by ACC shall not lead to excessive positive wheel slip for periods longer than
traction control would allow. This need not require a traction control system.
6.3.1.7 ACC systems may automatically adjust the time gap without action by the driver in order to respond to
the driving environment (i.e. poor weather). However, the adjusted time gap shall not be less than the minimum
time gap selected by the driver.
6.3.1.8 If the system allows the driver to select a desired time gap, the selection method shall conform to
either one of the following:
a) If the system retains the last selected time gap after it is switched to ACC OFF, as shown in Figure 3, the time
gap shall be clearly presented to the driver at least upon system activation.
b) If the system does not retain the last selected time gap after it is switched to ACC OFF, as shown in Figure 3,
the time gap shall be set to a predefined default value of 1,5 s or greater.
6.3.1.9 If there is a conventional cruise control function in addition to ACC there shall be no automatic
switching between the ACC and conventional cruise control.
6.3.2 Display elements
 A minimum feed back information for the driver contains activation state (ACC system is active or not active)
and the set speed. This can be done by a combined output, e.g. displaying of set speed information only when
ACC is active.
 If the ACC system shuts down or is not available due to a failure, the driver shall be informed. If a symbol is
used to notify the driver, a standard symbol shall be employed (refer to ISO 2575).
 If the vehicle is equipped with both ACC and conventional cruise control systems, the driver should be made
aware of which system is operating.
 A “Vehicle-detected” signal, with the meaning that the ACC system has detected a forward vehicle, which will
be used for the adaptation of the control, is recommended, but is not mandatory.
6.3.3 Symbols
If symbols are used to identify ACC function or malfunction, standardized symbols in accordance with ISO 2575
shall be used.
6.4 Operational limits
3)
Automatic positive acceleration of ACC requires a vehicle speed v of at least 5 m/s.
low
There shall not be a sudden brake force release in the case of an automatic deactivation of the ACC system below
v .
low
The minimum set speed shall be v W 7 m/s and v W v .
set_min set_min low
2
The average automatic deceleration of ACC systems shall not exceed 3,0 m/s (average over 2 s).
3
The average rate of change of automatic deceleration (negative jerk) shall not exceed 2,5 m/s (average over 1 s).

3) The lowest existing Conventional Cruise Control system limit is 5 m/s.
© ISO 2002 – All rights reserved 9

---------------------- Page: 14 ----------------------
ISO 15622:2002(E)
2
Automatic acceleration of ACC systems shall not exceed a u 2,0 m/s .
max
6.5 Activation of brake lights (ACC Type 2 only)
If automatic service braking is applied, the brake light shall be illuminated. When the ACC system applies other
deceleration devices the system may illuminate the brake lights. The brake lights shall be illuminated within 100 ms
after ACC system initiated the service brake. To prevent irritating brake light flickering, the brake light may remain
on for a reasonable time after the ACC initiated braking has ended.
6.6 Failure reactions
Table 3 and Table 4 show the required reactions to failures depending on which subsystem fails (see Figure 7).
The failures described in Table 3 and Table 4 shall result in immediate notification to the driver (except in the case
of a gearbox failure with Type 2 systems). The notification shall remain active until the system is switched off.
The reactivation of the ACC system shall be prohibited until a successful self-test, initiated by either ignition off/on
or ACC-off/on, is accomplished.

a
Type 2 systems only.
Figure 7 — Actuators for longitudinal control
Table 3 — Failure reactions for ACC type 1
Required reactions
Failed
ACC operating mode during failure
subsystem
Deceleration control mode Engine control mode
Engine ACC engine control mode shall be ACC engine control mode shall be
relinquished relinquished
Gearbox ACC control mode shall be relinquished ACC engine control mode shall be
relinquished
Detecting and Shall maintain same strategy as the time ACC engine control mode shall be
ranging sensor before fault at least as long as v > v relinquished
low
The system shall be switched off
immediately after driver intervention by
brake or accelerator pedal or ACC off
switch
ACC controller ACC control mode shall be relinquished ACC control mode shall be relinquished
10 © ISO 2002 – All rights reserved

---------------------- Page: 15 ----------------------
ISO 15622:2002(E)
Table 4 — Failure reactions for ACC type 2
Required reaction
...