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T/ITS 0002-2014: Intelligent Transportation Systems -- Full speed range adaptive-cruise control systems -- Performance requirements and test-procedures
T/ITS 0002-2014
T/ITS
INTELLIGENT TRANSPORTATION INDUSTRY ALLIANCE
STANDARD OF THE PEOPLE’S REPUBLIC OF CHINA
ICS 43.020
T 06
Intelligent Transportation Systems - Full speed range
adaptive cruise control systems - Performance
requirements and test procedures
ISSUED ON: NOVEMBER 24, 2014
IMPLEMENTED ON: JANUARY 01, 2015
Issued by: China Intelligent Transportation Industry Alliance
Table of Contents
Foreword ... 3 
Introduction ... 4 
1 Scope ... 5 
2 Normative references ... 5 
3 Terms and definitions ... 6 
4 Classification ... 8 
5 Performance requirements ... 9 
6 Test methods for performance evaluation ... 17 
Annex A (normative) Related technical description ... 24 
Intelligent Transportation Systems - Full speed range
adaptive cruise control systems - Performance
requirements and test procedures
1 Scope
This Standard specifies the basic control strategy, minimum functional
requirements, basic interaction methods, minimum requirements for diagnosis
and response to faults, and system performance test methods for full speed
range adaptive cruise control system (hereinafter referred to as FSRA) of the
vehicle.
The FSRA system is suitable for unobstructed and congested road conditions
on expressways (that is, roads that prohibit non-motorized vehicles and
pedestrians from passing). It provides longitudinal control for subject vehicle in
driving. The working speed range is from zero to the highest speed limit that
can be set by the system. The system can park the subject vehicle behind the
tracked forward vehicle with the deceleration capability within its limit. And it can
start again after the driver inputs the command to the system to continue driving.
The system does not respond to stationary or low-speed moving targets
(consistent with the adaptive cruise control system standard in GB/T 20608-
2006).
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.
GB/T 20608-2006, Intelligent transportation systems - Adaptive cruise
control systems - Performance requirements and test procedures
JTG B01-2003, Technical Standard of Highway Engineering
ISO 15623:2013, Transport information and control systems - Forward
vehicle collision warning systems - Performance requirements and test
procedures
ISO 22179:2009, Intelligent transport systems - Full speed range adaptive
3.6 forward vehicle
the vehicle that is located in front of the road where the subject vehicle is
traveling and is traveling in the same direction
3.7 free-flowing traffic
including start-stop and emergency braking conditions, smooth flow and heavy
traffic
3.8 time headway, THW
use time to represent the distance between two vehicles traveling on the same
path, and calculate by dividing the distance between the two vehicles by the
speed of the subject vehicle
3.9 set speed
the desired driving speed set by the driver or by other control systems other
than the FSRA system
NOTE: This speed is the highest expected speed of the vehicle under the control of the
FSRA system.
3.10 steady state
the state of the vehicle in which the relevant parameters do not change with
time and distance
3.11 subject vehicle
the vehicle that is equipped with the full speed range adaptive cruise control
system defined in this Standard
3.12 system state
a certain stage or state of the system's work
1) FSRA off
No direct action can trigger the FSRA system.
2) FSRA stand-by
The FSRA system does not participate in the longitudinal control of the
vehicle, but it can be triggered by the driver to enter the working state at
any time.
3) FSRA active
5) In the hold state, the automatic parking control will be used to keep the
subject vehicle stationary (to take over the electronic braking function of
the ESP).
5.2 Functions
5.2.1 Control mode
The switching between the distance control state and the speed control state
shall be automatically completed by the system.
5.2.2 Stationary or slow moving targets
The system attempts to stop the subject vehicle behind the target vehicle within
its deceleration capacity. Whether the system responds to stationary or slow
moving targets, this Standard does not make mandatory design requirements.
If the system does not respond to stationary or slow moving targets, it shall be
declared in the vehicle's user manual.
5.2.3 Vehicle following ability
When the vehicle is running in a steady state, the minimum clearance between
vehicles shall be set to MAX(cmin, τmin×v). When operating under transient
conditions, the clearance can be temporarily lower than the minimum clearance.
At this time, the system shall have the function of automatic adjustment to adjust
the clearance to the desired value.
When the vehicle speed is higher than 8m/s, the setting range of headway is:
1.5s≤τ≤2.2s. [GB/T 20608-2006, definition 5.2.2].
Minimum requirement: When the target vehicle starts to stop with deceleration
as astopping and driving speed as vstopping, the system can control the subject
vehicle to stop behind the target vehicle.
Where, cmin is the minimum steady state headway when the system is operating
in the following control mode within the full speed range (including the hold
state), and cmin≥2m;
τmin is the minimum steady-state time headway available for selection, which
can be used for FSRA control in the full speed range, τmin≥1s;
v is the speed of the subject vehicle;
τ is the time headway;
astopping =2.5m/s2;
vstopping =10m/s.
When the driver and the FSRA system both have engine power control (throttle
input) requests, whichever is greater shall prevail. This will enable the driver to
always give priority to engine power control over the FSRA system. If the
driver's braking demand is higher than that of the FSRA system, the automatic
braking force of the FSRA system shall be released immediately. There shall
be no significant response delay for the driver to control the accelerator pedal.
The locking time of the wheels in the automatic braking state shall not exceed
the allowable value of ABS. The FSRA system does not interfere with the ABS
system.
The wheel slip time caused by the engine power control effect of the FSRA
system shall not exceed the allowable value of the traction control system. The
FSRA system does not interfere with the traction control system.
The FSRA system can appropriately adjust the time headway to adapt to
changes in the driving environment (such as inclement weather). But the
adjusted time headway shall not be lower than the driver's set-value.
If the FSRA system allows the driver to select the desired time headway, one of
the following methods shall be adopted:
a) If the FSRA system still stores the last selected headway value after
shutting down, then when the system is activated again, the time headway
value shall be displayed to the driver;
b) If the FSRA system does not store the recently-selected time headway
value after shutting down, then the time headway shall be set to the default
value (≥1.5s).
If the vehicle is equipped with both the FSRA system and the conventional
cruise control system, there shall not be automatic switching between the two.
The system can be activated by the driver at any time, even if the vehicle is
stationary or the driver is stepping on the brake pedal.
5.3.2 Display
a) Provide the driver with the most basic feedback information, including
FSRA system state and set speed, and they can be combined together to
show the output. For example, the set speed information is displayed only
when the FSRA system is activated, and the display shall not affect driving
behavior;
b) If the FSRA system fails to work normally, the driver shall be notified in
time. The prompt symbol shall comply with the regulations (see 0);
c) If the FSRA system is automatically deactivated, the driver shall be notified
in time. The prompt symbol shall comply with the regulations (see 0);
d) If the vehicle is equipped with both the FSRA system and the conventional
cruise control system, the driver shall be notified of the system that is
currently working;
e) If the forward vehicle is locked as the target vehicle, the prompt message
"Detection Vehicle" shall be used to indicate that the FSRA system is
detecting the vehicle in front.
5.3.3 Symbols
If symbols are used to identify the function and failure state of the FSRA system,
it shall comply with the requirements of ISO 2575.
5.4 Operational restrictions
To ensure comfort, when the vehicle speed is lower than 5m/s, no sudden
braking force release is allowed, such as the releases caused by:
a) The target vehicle is lost;
b) System failure (not the failure of the brake itself) causes the system to
automatically deactivate;
The lowest set speed should be: vset_min ≥7m/s.
When the vehicle speed is higher than 20m/s, the average deceleration of the
FSRA system shall not be greater than 3.0m/s2 (it is averaged according to the
sampled value with a length of 2s), [GB/T 20608-2006, definition 5.4]. When
the vehicle speed is lower than 5m/s, the average deceleration of the FSRA
system shall not be greater than 4.1m/s2 (average the sampled value with a
length of 2s).
When the vehicle speed is higher than 20m/s, the average rate of change of
the deceleration of the FSRA system shall not be greater than 2.5m/s3 (it is
averaged according to the sampled value with a length of 1s), [GB/T 20608-
2006, definition 5.4]. When the vehicle speed is lower than 5m/s, the average
rate of change of the deceleration of the FSRA system shall not be greater than
3m/s3 (average the sampled value with a length of 2s).
When the vehicle speed is higher than 20m/s, the average acceleration of the
FSRA system shall not be greater than 2m/s2 (average according to the
sampled value with a length of 2s), [GB/T 20608-2006, definition 5.4]. When
the vehicle speed is lower than 5m/s, the average acceleration of the FSRA
system shall not be greater than 3.1m/s2 (average the sampled value with a
length of 2s).
The minimum reflection cross section of test targets A and B is 20cm2.
- Test target A is a diffuse reflector with CTT = 2m2/sr±10% (see Annex A);
- Test target B is a diffuse reflector, and its CTT = 1m2/sr±10%.
NOTE: The test target is defined by the parameters of the reflector.
Target A shall represent at least 95% of vehicles driving on highways.
Target B represents the reflectivity of a vehicle with a dirty surface and no retro-
reflector.
6.2.2 Millimeter wave radar
The test target is defined by the scattering cross section RCS of the radar signal.
The frequency range is 20GHz~95GHz.
- The RCS of test target A shall be 10m2;
- The RCS of test target B shall be 3m2.
For obviously different frequency ranges, RCS shall be redetermined and
defined (see Annex A).
6.3 Automatic stopping ability test
6.3.1 Test target vehicle
Install the test target A as described in 0 at the rear of the target vehicle. The
remaining uncovered surfaces are hidden according to the following principles:
After removing test target A, make the radar cross section RCS at the rear of
the vehicle not greater than 2m2 or make its reflectivity not greater than 20% of
the test target.
6.3.2 Initial conditions
The driving speed of the target vehicle is vstopping;
The width range of the target vehicle is: 1.4m~2.2m;
The subject vehicle runs in the following control mode and follows the target
vehicle steadily;
In the whole test process, the expected headway value is τmin;
The lateral deviation between the longitudinal centerline of the subject vehicle
and the longitudinal centerline of the target vehicle is less than 0.5m (see Figure
6).