ISO 22735:2021

Road vehicles — Test method to evaluate the performance of lane-keeping assistance systems

This document specifies test methods and performance metrics to evaluate the behaviour of a vehicle equipped with lane keeping assistance system (LKAS, see 3.2). For this purpose, variables relevant to vehicle dynamics as well as controllability of a vehicle with LKAS and their measurement methods are defined. A system requiring a driver intervention is excluded from the scope. This document applies to the vehicles of M1 category.

Véhicules routiers — Méthode d'essai pour évaluer la performance des systèmes d'aide au maintien de la trajectoire

General Information

• Status: Published
• Publication Date: 20-May-2021
• ICS: 43.020 - Road vehicles in general
• Technical Committee: ISO/TC 22/SC 33 - Vehicle dynamics and chassis components
• Drafting Committee: ISO/TC 22/SC 33/WG 3 - Driver assistance and active safety functions
• Current Stage: 6060 - International Standard published
• Start Date: 21-May-2021
• Due Date: 19-Jul-2021
• Completion Date: 21-May-2021

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 22735
First edition
2021-05
Road vehicles — Test method to
evaluate the performance of lane-
keeping assistance systems
Véhicules routiers — Méthode d'essai pour évaluer la performance
des systèmes d'aide au maintien de la trajectoire
Reference number
ISO 22735:2021(E)
©
ISO 2021

---------------------- Page: 1 ----------------------
ISO 22735:2021(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved

---------------------- Page: 2 ----------------------
ISO 22735:2021(E)

Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Variables . 2
4.1 Coordinate systems . 2
4.2 Lateral deviation from path (Y error) . 2
VUT
4.3 Variables to be measured . 3
5 Measuring equipment . 3
5.1 General . 3
5.2 Transducer installation. 3
5.3 Calibration . 3
5.4 Data processing . 4
6 Test conditions . 4
6.1 General . 4
6.2 Test data . 4
6.3 Test track . 4
6.3.1 General. 4
6.3.2 Lane marking . 4
6.4 Environmental conditions . 5
6.5 Test vehicle . 5
6.5.1 General condition . 5
6.5.2 LKAS settings . 5
6.5.3 Tyres . 5
6.5.4 Wheel alignment measurement . 6
6.5.5 Loading conditions . . 6
6.6 Vehicle preparation . 6
7 Test procedure . 7
7.1 Pre-test conditioning . 7
7.1.1 General. 7
7.1.2 Brakes conditioning . 7
7.1.3 Tyres conditioning . 8
7.1.4 System check . 8
7.2 Test scenarios . 8
7.3 Test execution .10
8 Performance metrics .11
8.1 General .11
8.2 Lateral speed of VUT during a test run (V ) and last lateral speed of VUT
latVUT
before line crossing (V ) .11
latVUT blc
8.3 Lane departure warning activation time during a test run (T ) and last lane
LDW
departure warning activation time before line crossing (T ) .11
LDW blc
8.4 LKAS activation time during a test run (T ) and last LKAS activation time before
LKAS
line crossing (T ) .11
LKAS blc
8.5 Time to line crossing during a test run (T ) and last T before line crossing
TLC TLC
(T ) .11
TLC blc
during a test run and last before crossing
8.6 Distance to line crossing (D ) D line (D ) .11
TLC TLC TLC blc
8.7 Maximum yaw velocity during a test run (Ψ̇ ) and last (Ψ̇ ) before line
VUT max VUT max
crossing (Ψ̇ ) .11
VUT max,blc
8.8 Maximum lateral acceleration during a test run (A ) and last (A )
latVUT max latVUT max
before line crossing (A ) .11
latVUT max,blc
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ISO 22735:2021(E)

8.9 Maximum steering torque during a test run (M ) and last (M ) before
VUT max VUT max
line crossing (M ) .12
VUT max,blc
Annex A (informative) Road markings .13
Annex B (informative) Test report .21
Bibliography .23
iv © ISO 2021 – All rights reserved

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ISO 22735:2021(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.
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).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 33,
Vehicle dynamics and chassis components.
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.
© ISO 2021 – All rights reserved v

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ISO 22735:2021(E)

Introduction
The main function of a lane keeping assistance system (LKAS) is to support the driver in keeping the
vehicle within the current lane. LKAS acquires information on the position of the vehicle within the
lane and, when required, sends commands to actuators to influence the lateral movement of the vehicle,
and in turn provides status information to the driver.
This document is intended to assess the complete performance of an LKAS fitted in a road vehicle:
— the capacity to keep the vehicle within the current lane during other situations not described in this
test method (more complex scenarios, other weather conditions);
— the capacity to avoid undesired lane change.
vi © ISO 2021 – All rights reserved

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INTERNATIONAL STANDARD ISO 22735:2021(E)
Road vehicles — Test method to evaluate the performance
of lane-keeping assistance systems
1 Scope
This document specifies test methods and performance metrics to evaluate the behaviour of a vehicle
equipped with lane keeping assistance system (LKAS, see 3.2).
For this purpose, variables relevant to vehicle dynamics as well as controllability of a vehicle with LKAS
and their measurement methods are defined.
A system requiring a driver intervention is excluded from the scope. This document applies to the
vehicles of M1 category.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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 8855, Road vehicles — Vehicle dynamics and road-holding ability — Vocabulary
ISO 15037-1:2019, Road vehicles — Vehicle dynamics test methods — Part 1: General conditions for
passenger cars
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 8855, ISO 15037-1 and the
following 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
distance to line crossing
DTLC
remaining lateral distance (perpendicular to the line) between the inner side of the lane marking and
most outer edge of the tyre, before the vehicle under test (VUT) (3.5) crosses the line, assuming that the
VUT would continue to travel with the same lateral velocity towards the lane marking
3.2
lane keeping assistance system
LKAS
heading correction system that is applied automatically by the vehicle in response to the detection of
the vehicle that is about to drift beyond a delineated edge line of the current travel lane
Note 1 to entry: There are two kinds of LKAS: lane centring LKAS where steering intervention is constantly
occurring to keep the vehicle running along the centreline of lane and lane departure prevention LKAS where
steering intervention only occurs when the vehicle is imminent to cross the lane boundary. Different performance
metrics can be applied for each system.
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ISO 22735:2021(E)

3.3
peak braking coefficient
PBC
measure of tyre to road surface friction based on the maximum deceleration of a rolling tyre
Note 1 to entry: Measured by using the American Society for Testing and Materials (ASTM) E1136–10 (2010)
standard reference test tyre, in accordance with ASTM Method E 1337–90 (1996), at a speed of 64,4 km/h,
without water delivery.
Note 2 to entry: Alternatively, the method as specified in UNECE R13-H.
3.4
time to line crossing
T
TLC
remaining time before the vehicle under test (VUT) (3.5) crosses the line, assuming that the VUT
continues to travel with the same lateral velocity towards the lane marking
3.5
vehicle under test
VUT
vehicle tested according to this document with a lane keeping assistance system
3.6
vehicle width
widest point of the vehicle ignoring the rear-view mirrors, side marker lamps, tyre pressure indicators,
direction indicator lamps, position lamps, flexible mudguards and the deflected part of the tyre
sidewalls immediately above the point of contact with the ground
4 Variables
4.1 Coordinate systems
The road fixed reference system X -Y -Z , as shown in Figure 1, is fixed to the lane, and the vehicle fixed
E E E
reference system X-Y-Z is fixed to the centre of gravity (CG) of VUT.
4.2 Lateral deviation from path (Y error)
VUT
The lateral deviation from path is determined as the lateral distance between the centre of the front
of the VUT when measured in parallel to the intended path as shown in Figure 1. This measure applies
during both the straight-line approach and the curve that establishes the lane departure.
Key
1 intended path
2 actual path
3 lateral deviation from path
Figure 1 — Definition of lateral deviation from path
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ISO 22735:2021(E)

4.3 Variables to be measured
Variables that shall be measured are listed in Table 1 along with notations.
Table 1 — Measured variables
Variable Symbol
T
Time when manoeuvre starts with 2 s of straight path
0
Time when LKAS activates T
LKAS
Time
Time when lane departure warning is issued T
LDW
Time when VUT crosses the line T
crossing
Position Position of the VUT during the entire test X , Y
VUT VUT
Longitudinal and lateral speed of the VUT during the entire test V , V
longVUT latVUT
Speed and angular
Speed when VUT crosses the line V
crossing
velocity
Yaw velocity of the VUT during the entire test Ψ̇
VUT
Steering wheel velocity of the VUT during the entire test Ω̇
Steering wheel VUT
a
motion
Steering wheel torque of the VUT during the entire test M
VUT
Lateral acceleration of the VUT during the entire test A
Lateral accelera-
latVUT
b
tion and jerk
Lateral jerk of the VUT during the entire test Ȧ
latVUT
a
Steering wheel torque characterizes the beginning of the intervention by LKAS and determines driver’s overriding
capability to LKAS function.
b
Lateral jerk is the measure of smoothness of lateral movement. Too high jerk prevents driver from correcting path
when needed.
Variables shall be sampled and recorded at a frequency of at least 100 Hz.
5 Measuring equipment
5.1 General
VUT shall be equipped with data measurement and acquisition system to sample and record data with
an accuracy of at least:
— longitudinal speed to 0,1 km/h;
— lateral and longitudinal position to 0,03 m;
— heading angle to 0,1°;
— yaw rate to 0,1°/s;
2
— longitudinal acceleration to 0,1 m/s ;
— steering wheel velocity to 1,0°/s.
5.2 Transducer installation
The requirements of ISO 15037-1:2019, 5.2 shall apply. In addition, it shall be ensured that transient
vehicle pitch changes do not adversely affect the measurement of the velocity and position variables for
the chosen transducer system.
5.3 Calibration
All transducers shall be calibrated according to the manufacturer instructions. In some cases,
calibration may be performed immediately before testing.
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ISO 22735:2021(E)

If parts of the measuring system used can be adjusted such calibration shall be performed immediately
before the beginning of the tests.
5.4 Data processing
Filter the measured data as follows:
— position and speed are not filtered and are used in their raw state;
— acceleration with a 12-pole phaseless Butterworth filter with a cut off frequency of 10 Hz;
— yaw rate with a 12-pole phaseless Butterworth filter with a cut off frequency of 10 Hz;
— force with a 12-pole phaseless Butterworth filter with a cut off frequency of 10 Hz.
6 Test conditions
6.1 General
The test conditions shall be in accordance with ISO 15037-1:2019, Clause 6, unless otherwise specified
below.
6.2 Test data
General data on the test vehicle and test conditions shall be recorded as specified in ISO 15037-1:2019,
6.4.1.
6.3 Test track
6.3.1 General
All tests shall be carried out on a smooth, clean, dry and uniform paved road surface.
Conduct tests on a dry (no visible moisture on the surface), uniform, solid-paved surface with a
consistent slope between level and 1 %. The test surface shall have a minimal peak braking coefficient
(PBC) of 0,9.
The surface shall be paved and should not contain any irregularities (e.g. large dips or cracks, manhole
covers or reflective studs) within a lateral distance of 3,0 m to either side of the test line(s) and with a
longitudinal distance of 30 m ahead of the VUT from the point after the test is complete.
6.3.2 Lane marking
The tests described in this document shall use two different types of lane markings conforming to the
individual lane markings (width, length of segment or void) to mark a lane with a width of 3,5 m to
3,7 m:
— dashed line with a width between 0,10 m and 0,25 m;
— solid line with a width between 0,10 m and 0,25 m.
The lane markings should be sufficiently long to ensure that there is at least 20 m of marking remaining
ahead of the vehicle after the test is complete.
Lane markings for different nations are listed in Annex A.
Some proving grounds have different lane markings. In that case, difficulties to recognizing the lane
should be equivalent to the lane marking.
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ISO 22735:2021(E)

Figure 2 — Lane marking
6.4 Environmental conditions
Conduct tests in dry conditions with ambient temperature above 5 °C and below 40 °C.
For some proving ground where the low limit of ambient temperature of 5 °C is difficult to achieve,
lower value can be adopted. However, in that case, the lower limit values shall be reported.
No precipitation shall be falling and horizontal visibility at ground level shall be greater than 1 km.
Wind speeds shall be below 10 m/s to minimize VUT disturbance.
Natural ambient illumination shall be homogenous in the test area and in excess of 2 000 lx for daylight
testing with no strong shadows cast across the test area other than those caused by the VUT. Ensure
testing is not performed driving towards, or away from the sun when there is direct sunlight.
Measure and record the following parameters preferably at the commencement of every single test or
at least every 30 min:
— ambient temperature in °C;
— wind speed and direction in m/s;
— ambient illumination in lx.
6.5 Test vehicle
6.5.1 General condition
The test vehicle condition shall be in accordance with the vehicle manufacturer specifications,
particularly with respect to the wheel alignments, power train (e.g. differentials and locks)
configuration and tyre fitment.
6.5.2 LKAS settings
If different settings are available, the chosen setting shall be kept during the complete test procedure.
The test procedure can be repeated for different settings if needed.
NOTE The aim of this document is to measure performance of a vehicle equipped with LKAS. It is not
intended to compare performance of different vehicles, such as Euro NCAP procedure.
6.5.3 Tyres
Generally, all measurements shall be conducted with original fitment tyres mounted. If several types of
tyres are available, the types of tyres shall be reported.
For a general tyre condition, new tyres shall be fitted on the test vehicle according to the manufacturer's
specifications. If not specified otherwise by the tyre manufacturer, they shall be run-in according to the
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ISO 22735:2021(E)

tyre conditioning procedure specified in 7.1.3. After running-in maintain the run-in tyres in the same
position on the vehicle for the duration of the testing
Tyres shall have a tread depth of at least 90 % of the original value across the whole breadth of the
tread and around the whole circumference of the tyre.
Tyres shall be manufactured not more than one year before the test. The date of manufacturing shall be
noted in the presentation of test conditions.
Tyres shall be inflated to the pressure as specified by the vehicle manufacturer for the test vehicle
configuration. The tolerance for setting the cold inflation pressure is ±5 kPa for pressures up to 250 kPa
and ±2 % for pressure above 250 kPa.
6.5.4 Wheel alignment measurement
The vehicle should be subject to a vehicle (in-line) geometry check to record the wheel alignment set by
the vehicle manufacturer. This should be done with "unladen kerb mass" specified in 6.5.5.
6.5.5 Loading conditions
The fuel tank shall be filled up and, in the course of the measurement sequence, the indicated fuel level
should not drop below "half-full".
Check the oil level and top up to its maximum level if necessary. Similarly, top up the levels of all other
fluids to their maximum levels if necessary.
Measure the front and rear axle masses and determine the total mass of the vehicle. Record this mass
in the test details.
Calculate the required ballast mass, by subtracting the mass of the test driver and test equipment so
that the test mass is the "unladen kerb mass" as specified by vehicle manufacturer plus 200 kg.
The weight distribution in a ready-for-measurement condition shall be adjusted according to the axle
load distribution specified by the vehicle manufacturer for a ready-to-drive (kerb) condition.
If the vehicle is to be tested in any other load condition (for example, GVM) then the additional payload
shall be evenly distributed such that cross-axle variations do not exceed 50 kg.
6.6 Vehicle preparation
Fit the on-board test equipment and instrumentation in the vehicle. Also fit any associated cables,
cabling boxes and power sources.
Place weights with a mass of the ballast mass. Any items added should be securely attached to the car.
With the driver in the vehicle, weigh the front and rear axle loads of the vehicle.
Compare these loads with the "unladen kerb mass".
The total vehicle mass shall be within ±1 % of the sum of the unladen kerb mass, plus 200 kg. The
front/rear axle load distribution needs to be within 5 % of the front/rear axle load distribution of the
original unladen kerb mass plus full fuel load. If the vehicle differs from the requirements given in this
paragraph, items may be removed or added to the vehicle which has no influence on its performance.
Any items added to increase the vehicle mass should be securely attached to the car.
Repeat weighing the front and rear axle load and comparison until the front and rear axle loads and
the total vehicle mass are within the limits set in the above paragraph. Care should to be taken when
adding or removing weight in order to approximate the original vehicle inertial properties as close as
possible. Record the final axle loads in the test details. Record the axle weights of the VUT in the "as
tested" condition.
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ISO 22735:2021(E)

Vehicle dimensional measurements shall be taken. For the purposes of this test procedure, vehicle
dimensions shall be represented by a two-dimensional polygon defined by the lateral and longitudinal
dimensions relative to the centroid of the vehicle. The corners of the polygon are defined by the lateral
and longitudinal locations where the plane of the outside edge of each tyre touches the road. This plane
is defined by running a perpendicular line from the outer most edge of the tyre to the ground at the
wheelbase, as illustrated in Figure 3.
The vehicle’s wheelbase and the lateral and longitudinal locations shall be measured and recorded.
Key
1 definition of lateral location
2 longitudinal
...

FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 22735
ISO/TC 22/SC 33
Road vehicles — Test method to
Secretariat: DIN
evaluate the performance of lane-
Voting begins on:
2021­02­15 keeping assistance systems
Voting terminates on:
Véhicules routiers — Méthode d'essai pour évaluer la performance
2021­04­12
des systèmes d'aide au maintien de la trajectoire
RECIPIENTS OF THIS DRAFT ARE INVITED TO
SUBMIT, WITH THEIR COMMENTS, NOTIFICATION
OF ANY RELEVANT PATENT RIGHTS OF WHICH
THEY ARE AWARE AND TO PROVIDE SUPPOR TING
DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
ISO/FDIS 22735:2021(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN­
DARDS TO WHICH REFERENCE MAY BE MADE IN
©
NATIONAL REGULATIONS. ISO 2021

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ISO/FDIS 22735:2021(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH­1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved

---------------------- Page: 2 ----------------------
ISO/FDIS 22735:2021(E)

Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Variables . 2
4.1 Coordinate systems . 2
4.2 Lateral deviation from path (Y error) . 2
VUT
4.3 Variables to be measured . 3
5 Measuring equipment . 3
5.1 General . 3
5.2 Transducer installation. 3
5.3 Calibration . 3
5.4 Data processing . 4
6 Test conditions . 4
6.1 General . 4
6.2 Test data . 4
6.3 Test track . 4
6.3.1 General. 4
6.3.2 Lane marking . 4
6.4 Environmental conditions . 5
6.5 Test vehicle . 5
6.5.1 General condition . 5
6.5.2 LKAS settings . 5
6.5.3 Tyres . 5
6.5.4 Wheel alignment measurement . 6
6.5.5 Loading conditions . . 6
6.6 Vehicle preparation . 6
7 Test procedure . 7
7.1 Pre­test conditioning . 7
7.1.1 General. 7
7.1.2 Brakes conditioning . 7
7.1.3 Tyres conditioning . 8
7.1.4 System check . 8
7.2 Test scenarios . 8
7.3 Test execution .10
8 Performance metrics .10
8.1 General .10
8.2 Lateral speed of VUT during a test run (V ) and last lateral speed of VUT
latVUT
before lane crossing (V ) .
latVUT blc 10
8.3 Lane departure warning activation time during a test run (T ) and last lane
LDW
departure warning activation time before lane crossing (T ) .
LDW blc 10
8.4 LKAS activation time during a test run (T ) and last LKAS activation time before
LKAS
lane crossing (T ) .
LKAS blc 10
8.5 Time to line crossing during a test run (T ) and last T before line crossing (T ) .
TLC TLC TLC blc 11
during a test run and last before crossing
8.6 Distance to line crossing (D ) D line (D ) .
TLC TLC TLC blc 11
8.7 Maximum yaw velocity during a test run (Ψ̇ ) and last (Ψ̇ ) before line
VUT max VUT max
crossing (Ψ̇ ) .
VUT max,blc 11
8.8 Maximum lateral acceleration during a test run (A ) and last (A )
latVUT max latVUT max
before line crossing (A ) .
latVUT max,blc 11
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ISO/FDIS 22735:2021(E)

8.9 Maximum steering torque during a test run (M ) and last (M ) before
VUT max VUT max
line crossing (M ) .
VUT max,blc 11
Annex A (informative) Road markings .12
Annex B (informative) Test report .20
Bibliography .22
iv © ISO 2021 – All rights reserved

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ISO/FDIS 22735:2021(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 non­governmental, 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.
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).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 33,
Vehicle dynamics and chassis components.
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.
© ISO 2021 – All rights reserved v

---------------------- Page: 5 ----------------------
ISO/FDIS 22735:2021(E)

Introduction
The main function of a lane keeping assistance system (LKAS) is to support the driver in keeping the
vehicle within the current lane. LKAS acquires information on the position of the vehicle within the
lane and, when required, sends commands to actuators to influence the lateral movement of the vehicle,
and in turn provides status information to the driver.
This document is intended to assess the complete performance of an LKAS fitted in a road vehicle:
— the capacity to keep the vehicle within the current lane during other situations not described in this
test method (more complex scenarios, other weather conditions);
— the capacity to avoid undesired lane change.
vi © ISO 2021 – All rights reserved

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FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 22735:2021(E)
Road vehicles — Test method to evaluate the performance
of lane-keeping assistance systems
1 Scope
This document specifies test methods and performance metrics to evaluate the behaviour of a vehicle
equipped with lane keeping assistance system (LKAS, see 3.2).
For this purpose, variables relevant to vehicle dynamics as well as controllability of a vehicle with LKAS
and their measurement methods are defined.
A system requiring a driver intervention is excluded from the scope. This document applies to the
vehicles of M1 category.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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 8855, Road vehicles — Vehicle dynamics and road-holding ability — Vocabulary
ISO 15037­1:2019, Road vehicles — Vehicle dynamics test methods — Part 1: General conditions for
passenger cars
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 8855, ISO 15037-1 and the
following 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
distance to line crossing
DTLC
remaining lateral distance (perpendicular to the line) between the inner side of the lane marking and
most outer edge of the tyre, before the vehicle under test (VUT) (3.5) crosses the line, assuming that the
VUT would continue to travel with the same lateral velocity towards the lane marking
3.2
lane keeping assistance system
LKAS
heading correction system that is applied automatically by the vehicle in response to the detection of
the vehicle that is about to drift beyond a delineated edge line of the current travel lane
Note 1 to entry: There are two kind of LKAS systems: lane centring LKAS where steering intervention is
constantly occurring to keep the vehicle running along the centreline of lane and lane departure prevention
LKAS where steering intervention only occurs when the vehicle is imminent to cross the lane boundary. Different
performance metrics can be applied for each system.
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3.3
peak braking coefficient
PBC
measure of tyre to road surface friction based on the maximum deceleration of a rolling tyre
Note 1 to entry: Measured by using the American Society for Testing and Materials (ASTM) E1136–10 (2010)
standard reference test tyre, in accordance with ASTM Method E 1337–90 (1996), at a speed of 64,4 km/h,
without water delivery.
Note 2 to entry: Alternatively, the method as specified in UNECE R13-H.
3.4
time to line crossing
T
TLC
remaining time before the vehicle under test (VUT) (3.5) crosses the line, assuming that the VUT
continues to travel with the same lateral velocity towards the lane marking
3.5
vehicle under test
VUT
vehicle tested according to this document with a lane keeping assistance system
3.6
vehicle width
widest point of the vehicle ignoring the rear-view mirrors, side marker lamps, tyre pressure indicators,
direction indicator lamps, position lamps, flexible mudguards and the deflected part of the tyre
sidewalls immediately above the point of contact with the ground
4 Variables
4.1 Coordinate systems
The road fixed reference system X ­Y ­Z , as shown in Figure 1, is fixed to the lane, and the vehicle fixed
E E E
reference system X-Y-Z 1 is fixed to the centre of gravity (CG) of VUT.
4.2 Lateral deviation from path (Y error)
VUT
The lateral deviation from path is determined as the lateral distance between the centre of the front
of the VUT when measured in parallel to the intended path as shown in Figure 1. This measure applies
during both the straight­line approach and the curve that establishes the lane departure.
Key
1 intended path
2 actual path
3 lateral deviation from path
Figure 1 — Definition of lateral deviation from path
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4.3 Variables to be measured
Variables that shall be measured are listed in Table 1 along with notations.
Table 1 — Measured variables
Variable Symbol
T
Time when manoeuvre starts with 2 s of straight path
0
Time when LKAS activates T
LKAS
Time
Time when lane departure warning is issued T
LDW
Time when VUT crosses the line T
crossing
Position Position of the VUT during the entire test X , Y
VUT VUT
Longitudinal and lateral speed of the VUT during the entire test V , V
longVUT latVUT
Speed and angular
Speed when VUT crosses the line V
crossing
velocity
Yaw velocity of the VUT during the entire test Ψ̇
VUT
Steering wheel velocity of the VUT during the entire test Ω̇
Steering wheel VUT
a
motion
Steering wheel torque of the VUT during the entire test M
VUT
Lateral acceleration of the VUT during the entire test A
Lateral accelera­
latVUT
b
tion and jerk
Lateral jerk of the VUT during the entire test Ȧ
latVUT
a
Steering wheel torque characterizes the beginning of the intervention by LKAS and determines driver’s overriding
capability to LKAS function.
b
Lateral jerk is the measure of smoothness of lateral movement. Too high jerk prevents driver from correcting path
when needed.
Variables shall be sampled and recorded at a frequency of at least 100 Hz.
5 Measuring equipment
5.1 General
VUT shall be equipped with data measurement and acquisition system to sample and record data with
an accuracy of at least:
— longitudinal speed to 0,1 km/h;
— lateral and longitudinal position to 0,03 m;
— heading angle to 0,1°;
— yaw rate to 0,1°/s;
2
— longitudinal acceleration to 0,1 m/s ;
— steering wheel velocity to 1,0°/s.
5.2 Transducer installation
The requirements of ISO 15037-1:2019, 5.2 shall apply. In addition, it shall be ensured that transient
vehicle pitch changes do not adversely affect the measurement of the velocity and distance variables for
the chosen transducer system.
5.3 Calibration
All transducers shall be calibrated according to the manufacturer instructions. In some cases,
calibration may be performed immediately before testing.
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If parts of the measuring system used can be adjusted such calibration shall be performed immediately
before the beginning of the tests.
5.4 Data processing
Filter the measured data as follows:
— position and speed are not filtered and are used in their raw state;
— acceleration with a 12-pole phaseless Butterworth filter with a cut off frequency of 10 Hz;
— yaw rate with a 12-pole phaseless Butterworth filter with a cut off frequency of 10 Hz;
— force with a 12-pole phaseless Butterworth filter with a cut off frequency of 10 Hz.
6 Test conditions
6.1 General
The test conditions shall be in accordance with ISO 15037­1:2019, Clause 6, unless otherwise
specified below.
6.2 Test data
General data on the test vehicle and test conditions shall be recorded as specified in
ISO 15037­1:2019, 6.4.1.
6.3 Test track
6.3.1 General
All tests shall be carried out on a smooth, clean, dry and uniform paved road surface.
Conduct tests on a dry (no visible moisture on the surface), uniform, solid-paved surface with a
consistent slope between level and 1 %. The test surface shall have a minimal peak braking coefficient
(PBC) of 0,9.
The surface shall be paved and should not contain any irregularities (e.g. large dips or cracks, manhole
covers or reflective studs) within a lateral distance of 3,0 m to either side of the test line(s) and with a
longitudinal distance of 30 m ahead of the VUT from the point after the test is complete.
6.3.2 Lane marking
The tests described in this document shall use two different types of lane markings conforming to the
individual lane markings (width, length of segment or void) to mark a lane with a width of 3,5 m to 3,7 m:
— dashed line with a width between 0,10 m and 0,25 m;
— solid line with a width between 0,10 m and 0,25 m.
The lane markings should be sufficiently long to ensure that there is at least 20 m of marking remaining
ahead of the vehicle after the test is complete.
Lane markings for different nations are listed in Annex A.
Some proving grounds have different lane markings. In that case, difficulties to recognizing the lane
should be equivalent to the lane marking.
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Figure 2 — Lane marking
6.4 Environmental conditions
Conduct tests in dry conditions with ambient temperature above 5 °C and below 40 °C.
For some proving ground where the low limit of ambient of 5 °C is difficult to achieve, lower value can
be adopted. However, in that case, the lower limit values shall be reported.
No precipitation shall be falling and horizontal visibility at ground level shall be greater than 1 km.
Wind speeds shall be below 10 m/s to minimize VUT disturbance.
Natural ambient illumination shall be homogenous in the test area and in excess of 2 000 lx for daylight
testing with no strong shadows cast across the test area other than those caused by the VUT. Ensure
testing is not performed driving towards, or away from the sun when there is direct sunlight.
Measure and record the following parameters preferably at the commencement of every single test or
at least every 30 min:
— ambient temperature in °C;
— wind speed and direction in m/s;
— ambient illumination in lx.
6.5 Test vehicle
6.5.1 General condition
The test vehicle condition shall be in accordance with the vehicle manufacturer specifications,
particularly with respect to the wheel alignments, power train (e.g. differentials and locks)
configuration and tyre fitment.
6.5.2 LKAS settings
If different settings are available, the chosen setting shall be kept during the complete test procedure.
The test procedure can be repeated for different settings if needed.
NOTE The aim of this document is to measure performance of a vehicle equipped with LKAS. It is not
intended to compare performance of different vehicles, such as Euro NCAP procedure.
6.5.3 Tyres
Generally, all measurements shall be conducted with original fitment tyres mounted. If several types of
tyres are available, the types of tyres shall be reported.
For a general tyre condition, new tyres shall be fitted on the test vehicle according to the manufacturer's
specifications. If not specified otherwise by the tyre manufacturer, they shall be run-in according to the
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tyre conditioning procedure specified in 7.1.3. After running-in maintain the run-in tyres in the same
position on the vehicle for the duration of the testing
Tyres shall have a tread depth of at least 90 % of the original value across the whole breadth of the
tread and around the whole circumference of the tyre.
Tyres shall be manufactured not more than one year before the test. The date of manufacturing shall be
noted in the presentation of test conditions.
Tyres shall be inflated to the pressure as specified by the vehicle manufacturer for the test vehicle
configuration. The tolerance for setting the cold inflation pressure is ±5 kPa for pressures up to 250 kPa
and ±2 % for pressure above 250 kPa.
6.5.4 Wheel alignment measurement
The vehicle should be subject to a vehicle (in-line) geometry check to record the wheel alignment set by
the vehicle manufacturer. This should be done with "unladen kerb mass" specified in 6.5.5.
6.5.5 Loading conditions
The fuel tank shall be filled up and, in the course of the measurement sequence, the indicated fuel level
should not drop below "half­full".
Check the oil level and top up to its maximum level if necessary. Similarly, top up the levels of all other
fluids to their maximum levels if necessary.
Measure the front and rear axle masses and determine the total mass of the vehicle. Record this mass
in the test details.
Calculate the required ballast mass, by subtracting the mass of the test driver and test equipment so
that the test mass is the "unladen kerb mass" as specified by vehicle manufacturer plus 200 kg.
The weight distribution in a ready-for-measurement condition shall be adjusted according to the axle
load distribution specified by the vehicle manufacturer for a ready-to-drive (kerb) condition.
If the vehicle is to be tested in any other load condition (for example, GVM) then the additional payload
shall be evenly distributed such that cross-axle variations do not exceed 50 kg.
6.6 Vehicle preparation
Fit the on-board test equipment and instrumentation in the vehicle. Also fit any associated cables,
cabling boxes and power sources.
Place weights with a mass of the ballast mass. Any items added should be securely attached to the car.
With the driver in the vehicle, weigh the front and rear axle loads of the vehicle.
Compare these loads with the "unladen kerb mass".
The total vehicle mass shall be within ±1 % of the sum of the unladen kerb mass, plus 200 kg. The
front/rear axle load distribution needs to be within 5 % of the front/rear axle load distribution of the
original unladen kerb mass plus full fuel load. If the vehicle differs from the requirements given in this
paragraph, items may be removed or added to the vehicle which has no influence on its performance.
Any items added to increase the vehicle mass should be securely attached to the car.
Repeat weighing the front and rear axle load and comparison until the front and rear axle loads and
the total vehicle mass are within the limits set in the above paragraph. Care should to be taken when
adding or removing weight in order to approximate the original vehicle inertial properties as close as
possible. Record the final axle loads in the test details. Record the axle weights of the VUT in the "as
tested" condition.
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Vehicle dimensional measurements shall be taken. For the purposes of this test procedure, vehicle
dimensions shall be represented by a two-dimensional polygon defined by the lateral and longitudinal
dimensions relative to the centroid
...