ISO 15622:2010

INTERNATIONAL ISO
STANDARD 15622
Second edition
2010-04-15

Intelligent transport systems — Adaptive
Cruise Control systems — Performance
requirements and test procedures
Systèmes intelligents de transports — Systèmes stabilisateurs de
vitesse adaptés — Exigences de performance et modes opératoires




Reference number
ISO 15622:2010(E)
©
ISO 2010

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ISO 15622:2010(E)
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ISO 15622:2010(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
4.1 Symbols.3
4.2 Abbreviated terms .4
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 .9
6.4 Operational limits .10
6.5 Activation of brake lights (ACC type 2 only).11
6.6 Failure reactions.11
7 Performance evaluation test methods .12
7.1 Environmental conditions .12
7.2 Test target specification .12
7.3 Target acquisition range test (see 6.2.4.2).13
7.4 Target discrimination test (see 6.2.4.3) .14
7.5 Curve capability test (see 6.2.4.4) .16
Annex A (normative) Technical information .19
Bibliography.25

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ISO 15622:2010(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 2.
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 document 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, Intelligent transport systems.
This second edition cancels and replaces the first edition (ISO 15622:2002) which has been technically
revised.
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ISO 15622:2010(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.

Subject vehicle
Acquisition of
motion determination
driver commands
ACC
Detection and ranging

of forward vehicles
control strategy
Actuators for
Driver information
longitudinal control
Environment Vehic le Dr iver

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 of supporting and relieving the driver in a convenient manner.
This International Standard can 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. Therefore, 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.

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INTERNATIONAL STANDARD ISO 15622:2010(E)

Intelligent transport systems — Adaptive Cruise Control
systems — Performance requirements and test procedures
1 Scope
This International Standard 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 Adaptive Cruise Control (ACC) systems. Adaptive cruise control is fundamentally intended to
provide longitudinal control of equipped vehicles while travelling on highways (roads where non-motorized
vehicles and pedestrians are prohibited) under free-flowing traffic conditions. ACC can be augmented with
other capabilities, such as forward obstacle warning.
2 Normative references
The following referenced documents are indispensable for the application 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 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
3 Terms and definitions
For the purpose of this document, the following terms and definitions apply.
3.1
active brake control
function that causes application of the brake(s), not applied by the driver, in this case controlled by the ACC
system
3.2
Adaptive Cruise Control
enhancement to conventional cruise control systems [see Conventional Cruise Control (3.5)], 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
3.3
brake
part in which the forces opposing the movement of the vehicle develop
NOTE 1 It can 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); an engine brake (when the
forces are derived from an artificial increase in the braking action, transmitted to the wheels, of the engine).
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ISO 15622:2010(E)
NOTE 2 Adapted from UN ECE Regulation No. 13-H:1998, definition 2.6.
NOTE 3 For the purposes of this International Standard, transmission control devices are not considered as brakes.
3.4
clearance
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
(3.11)
3.7
free-flowing traffic
smooth-flowing and heavy traffic excluding stop and go and emergency braking situations
3.8
time gap
τ
value calculated from vehicle speed v and clearance c by: τ = c/v
c

v

3.9
set speed
desired travel speed, set either by the driver or by some control system that is external to the ACC system
NOTE The set speed is 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.
3.11
subject vehicle
vehicle equipped with the system in question and related to the topic of discussion
3.12
ACC system states
For the purposes of this International Standard, three system states are distinguished (see Figure 2)
3.12.1
ACC off state
state in which direct access for activation of “ACC active state” is disabled
3.12.2
ACC stand-by state
state in which there is no longitudinal control by ACC system and the system is ready for activation by the
driver
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ISO 15622:2010(E)
3.12.3
ACC active state
state in which the system controls speed and/or clearance
3.12.3.1
ACC speed control sub-state
state in which the system controls the speed according to the set speed
3.12.3.2
ACC following control sub-state
state in which the system controls the clearance to the target vehicle according to the selected time gap
3.13
target vehicle
vehicle that the subject vehicle follows
3.14
stationary object
object in front of the subject vehicle which is stationary
4 Symbols and abbreviated terms
4.1 Symbols
See Table 1.
Table 1 — Symbols and meanings
Symbol Meaning
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
c Clearance, inter-vehicle distance
d Distance between object and sensor, general for distance
d Distance below which detection of a target vehicle is not required

0
d Distance below which neither distance measurement nor determination of relative speed is required

1
d Distance for measurement purpose
2
d Distance between source and projected plane A

A
d Maximum detection range on straight roads

max
d Maximum detection range on curves

max_curve
E Intensity of irradiation out of transmitter
t
I Radiated intensity

0
I Radiated intensity in a given direction

ref
L Length of a side of a radar test reflector
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ISO 15622:2010(E)
Table 1 (continued)
Symbol Meaning
R Circle radius, curve radius
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 manoeuvre
1
t Time, end manoeuvre
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 centreline at d

max max_curve
α Half angle of field of view
λ Wavelength of radar wave
τ 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
4.2 Abbreviated terms
⎯ CTT coefficient for test target for infrared reflectors
⎯ FOV field of view
⎯ HDA horizontal detection area
⎯ RCS radar cross-section
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ISO 15622:2010(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. See Table 2.
Table 2 — 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 3.
Table 3 — 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
NOTE Manual transition describes a switch to enable/disable ACC function. Automatic switch-off can be forced by
failure reaction.
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 clearance
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.
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ISO 15622:2010(E)
⎯ The steady-state clearance may be either self-adjusting by the system or adjustable by the driver
(see 6.3.1).
⎯ 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
low low
system is in 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 and 6.4).
⎯ If there is more than one forward vehicle, the one to be followed shall be selected automatically
(see 6.2.4.2).

Key
a
Manual and/or automatically after self-test.
Figure 2 — ACC states and transitions
6.2 Functionality
6.2.1 Control modes
The transition between the control modes (following controlled or speed controlled) shall be made
automatically.
6.2.2 Speed of subject vehicle
The ACC system shall be able to determine the speed of the subject vehicle.
6.2.3 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.
6.2.4 Following capability
6.2.4.1 General
τ shall be the minimum selectable time gap for following control mode under steady-state conditions for all
min
speeds v. τ shall be W 0,8 s.
min
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ISO 15622:2010(E)
At least one time gap setting τ in the range of 1,5 s to 2,2 s shall be provided.
Under steady-state conditions the minimum clearance shall be τ × v.
min
Under transient conditions, the clearance may temporarily fall below the minimum clearance. If such a
situation occurs, the system shall adjust the clearance to attain the desired clearance.
The ACC shall have detection range, target discrimination and curve capabilities as specified in 6.2.4.2 to
6.2.4.4.
6.2.4.2 Detection range on straight roads (performance class I + II + III + IV)
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 3.
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
0 1
the vehicle but is not required to measure the range to the vehicle nor the relative speed between the forward
and subject vehicles.
d = τ (v ) × v
1 min low low
If a forward vehicle is present at a distance less than d , the ACC system is not required to detect the
0
presence of the vehicle.
d = max.[2 (0,25 × v )]
0 low
1
2
d d d
0 1 max
bc
a

Key
1 subject vehicle
2 forward vehicle
a
Detection not required.
b
Detection of vehicles required.
c
Determination of range required.
Figure 3 — Zones of detection
6.2.4.3 Target discrimination
If there is 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 4) in the subject vehicle's path shall be selected for ACC
control in typical ACC situations as represented by the test scenario. See 7.4.
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ISO 15622:2010(E)


Figure 4 — Target discrimination
6.2.4.4 Curve capability (performance class II + III + IV)
The ACC system shall enable a steady-state vehicle following with a time gap of τ (v ), on straight roads
max circle
(class I + III + IIII + IIV) and curves with a radius down to R = 500 m (class II + IIII + IIV) and
min,II
R = 250 m (class III + IIV) and R = 125 m (class IV). Therefore the system shall be capable of
min,III min,IV
following a forward vehicle with the steady-state time gap τ (v ), if the forward vehicle cruises on a
max circle
constant curve radius R with a constant speed v .
min circle
va=×R
circle lateral _max min
where
τ (v) is the maximum possible steady-state time gap while driving with a speed v on a straight;
max
a is the design lateral acceleration for curves on highways.
lateral_max
The values to use are
2
a = 2,0 m/s ;
lateral_max,II
2
a = 2,3 m/s ;
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 5.
lateral_max
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ISO 15622:2010(E)

Key
X subject vehicle speed, in kilometres per hour
Y lateral acceleration, in metres per second squared
1 maximum value
2 95 % zone
a
Class IV.
b
Class III.
c
Class II.
Figure 5 — Lateral acceleration of the average driver
6.3 Basic driver interface 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 the ACC function, at least if the driver-initiated brake force
demand is higher than the ACC initiated brake force (leading to ACC stand-by state, see Figure 2). The
ACC system shall not lead to a significant transient reduction of braking response to the driver's braking input
(see UN/ECE Regulation No. 13-H) 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 manoeuvre 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.
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ISO 15622:2010(E)
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.
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 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 (e.g. 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:
1) if the system retains the last selected time gap after it is switched to ACC OFF, as shown in Figure 2,
the time gap shall be clearly presented to the driver at least upon system activation;
2) if the system does not retain the last selected time gap after it is switched to ACC OFF, as shown in
Figure 2, the time gap shall be set to a predefined default value equal 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 feedback information for the driver contains activation state (whether the 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 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. See ISO 2575.
If the ACC system deactivates automatically, the driver shall be informed. If a symbol is used to notify the
driver, a standard symbol shall be employed.
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 active ACC system is detecting a forward vehicle which
is used for adaptation of the control, is recommended but 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
1)
Automatic positive acceleration of ACC requires a vehicle speed v of at least 5 m/s.

low

1) The lowest existing conventional cruise control system limit = 5 m/s.
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ISO 15622:2010(E)
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 3,5 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).
2
Automatic acceleration of ACC systems shall not exceed a u 2,0 m/s .
max
If a forward vehicle is detected within the distance range d to d and the distance cannot be determined, the
0 1
system shall inhibit automatic acceleration.
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 350 ms of the ACC system initiating 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 4 and Table 5 show the required reactions to failures depending on which subsystem fails. See Figure 6.
The failures described in Table 4 and Table 5 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.

ACC
control strategy
Actuators for
longitudinal
  control
Engine
Transmission
Brake
a
control control
control

Key
a
Type 2 systems only.
Figure 6 — Actuators for longitudinal control
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ISO 15622:2010(E)
Table 4 — Failure reactions for ACC type 1
Failure occurs whilst ACC is applying:
Failure in subsystem
Deceleration control Engine control
ACC
...