ISO 22139:2022

INTERNATIONAL ISO
STANDARD 22139
First edition
2022-05
Heavy commercial vehicles and
buses — Test method for steering
effort measurement when
manoeuvring at low speed or with
stationary vehicle
Véhicule utilitaires lourds et autobus — Méthode d’essai pour la
mesure des efforts de direction lors de braquage à basse vitesse ou sur
place
Reference number
ISO 22139:2022(E)
© ISO 2022

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ISO 22139:2022(E)
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© ISO 2022
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Published in Switzerland
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ISO 22139:2022(E)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 4
5 Variables . 4
6 Measuring equipment . 5
6.1 Description . 5
6.2 Transducer installations . 5
6.3 Data processing. 5
7 Test conditions .6
7.1 General . 6
7.2 Test track when manoeuvring at low speed . 6
7.3 Test track with stationary vehicle. 6
7.4 Test vehicle . 6
7.4.1 General data . . . 6
7.4.2 Operating components . 6
7.4.3 Tyres and rims . 6
7.4.4 Vehicle loading conditions . 6
8 Test procedure .7
8.1 Preparation of test vehicle . 7
8.2 Warm-up . 7
8.3 Measurement with a stationary vehicle . 7
8.4 Measurement when manoeuvring at low speed . 8
9 Data evaluation and presentation of results . 9
9.1 Time histories . 9
9.2 Maximum steering-wheel torque vs. steering-wheel speed . 10
9.3 Catch up steering-wheel speed . 11
9.4 Cartesian coordinates . 11
9.5 Maximum steering-wheel torque (M and M ) . 11
HmaxL HmaxR
9.6 Steering-wheel work when steering OUT (W and W ) .12
H OutL H OutR
9.7 Steering-wheel torque when steering IN (M and M ) .13
H 0L H 0R
9.8 Steering work when steering IN (W and W ) . 14
H InL H InR
9.9 Steering return ability . 15
9.9.1 Remaining steering-wheel angle (δ and δ ) .15
H remL H remR
9.9.2 Steering-wheel speed when returning to steering-wheel straight forward
position . 16
9.10 Steering-wheel torque variation ∆M / M . 16
Hmax Hmax (%)
Annex A (normative) Test report — General data .18
Annex B (normative) Test report — Test conditions .21
Bibliography .23
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ISO 22139:2022(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
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on the ISO list of patent declarations received (see www.iso.org/patents).
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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.
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INTERNATIONAL STANDARD ISO 22139:2022(E)
Heavy commercial vehicles and buses — Test method for
steering effort measurement when manoeuvring at low
speed or with stationary vehicle
1 Scope
This document specifies a test method for steering effort measurement when manoeuvring a vehicle
at low speed or with the vehicle stationary. It is mainly applicable to trucks having a mass exceeding
3,5 tonnes and buses and articulated buses having a mass exceeding 5 tonnes, according to ECE and EC
vehicle classification, i.e. categories M3, N2, N3.
This document can also be applicable to trucks having a mass not exceeding 3,5 tonnes and buses and
articulated buses having a mass not exceeding 5 tonnes, i.e. categories M2, N1.
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 15037-2, Road vehicles — Vehicle dynamics test methods — Part 2: General conditions for heavy
vehicles and buses
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 8855 and the following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
rim offset
distance of a rim from its hub mounting surface to the centreline of the wheel
Note 1 to entry: A positive rim offset is when the hub mounting surface is more toward the outside of the
centreline of the wheel.
3.2
catch up
point when the steering-wheel torque abruptly increases while increasing the steering-wheel speed
Note 1 to entry: (See Figure 3).
Note 2 to entry: On a hydraulic or an electric-hydraulic system this is usually the point when the steering servo
fluid pump reaches the limit when the fluid flow is no longer sufficient to give the required output torque to turn
the steering wheel.
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ISO 22139:2022(E)
3.3
catch up steering-wheel torque limit
predetermined level of steering-wheel torque limit for the specific application
Note 1 to entry: The catch-up steering-wheel torque limit level corresponds to the torque when a driver
depending on application is no longer able to apply or is no longer comfortable with the torque needed to turn the
steering-wheel. (See Figure 3).
3.4
steering-wheel straight forward position
δ
H0
steering-wheel angle resulting in vehicle zero course angle
Note 1 to entry: See Figure 1.
3.5
maximum steering-wheel angles
δ
HmaxL
δ
HmaxR
steering-wheel angles (left and right) that due to mechanically limitations are the maximum that can
be reached in the steering system
Note 1 to entry: In order not to overload the steering components when reaching the maximum steering wheel
angles, vehicles with power steering system are equipped with a mechanism for lowering the boost torque before
reaching the maximum steering wheel angles e.g. a hydraulic relief pressure valve. (See Figure 1 and 8.1).
3.6
maximum steering-wheel angles range of interest
δ
H maxroiL
δ
H maxroiR
range of steering wheel angles (left and right) of interest for the test and that are used while collecting
data
Note 1 to entry: See Figure 1 and 8.1.
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ISO 22139:2022(E)
Key
X steering-wheel angle δ (°)
H
Y steering-wheel torque M (Nm)
H
δ steering-wheel straight forward position (°)
H0
δ maximum steering-wheel angles in right direction (°)
HmaxR
δ maximum steering-wheel angles range of interest in right direction (°)
H maxroiR
δ maximum steering-wheel angles in left direction (°)
HmaxL
δ maximum steering-wheel angles range of interest in left direction (°)
H maxroiL
Figure 1 — Maximum steering wheel angles and
maximum steering wheel angles range of interest
3.7
remaining steering wheel angles
δ
H remL
δ
H remR
left and right steering-wheel angles when steering-wheel torque changes sign and is passing zero after
reversing the steering-wheel inwards towards the steering-wheel straight forward position (3.4)
Note 1 to entry: See Figure 8.
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ISO 22139:2022(E)
3.8
steering-wheel work
W
H
work needed to turn the steering-wheel between two defined steering-wheel angles
Note 1 to entry: See Figures 5 and 7.
3.9
steering-wheel return ability
ability of the steering-wheel to return towards the steering-wheel straight forward position (3.4) without
applying any torque to the steering-wheel
Note 1 to entry: See 9.9.
3.10
steering-wheel torque variation
∆M
Hmax
M
Hmax
variation in steering-wheel torque
Note 1 to entry: The variation can result, e.g. from non-optimum phasing of steering column intermediate shaft
universal joints.
Note 2 to entry: See 9.10.
4 Principle
The purpose of the test method is to objectively evaluate and quantify the driver’s perception of the
steering feel and effort while manoeuvring a vehicle at low speed or with the vehicle stationary.
The method is not intended to specify how to measure and evaluate mechanical or electrical properties
in a steering system, e.g. pressure, flow, temperature, electrical current.
The driver’s perception is quantified by calculating and evaluating characteristics parameters from the
measured variables.
The main characteristic parameters are:
— steering-wheel torque;
— steering-wheel work;
— steering-wheel return ability;
— steering-wheel torque variation.
See Clause 9 for detailed characteristic parameters.
5 Variables
The following variables shall be determined:
— steering-wheel angle δ (°);
H
— steering-wheel torque M (Nm);
H
— steering-wheel speed dδ /dt (°/s).
H
If not directly available, the steering-wheel speed may be calculated from the time signal of steering
wheel angle, i.e. dδ /dt.
H
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ISO 22139:2022(E)
6 Measuring equipment
6.1 Description
The measuring equipment shall be in accordance with ISO 15037-2.
The variables listed in Clause 5 shall be monitored using appropriate transducers and the data shall
be recorded on a multi-channel recorder with time base. Typical operating ranges and recommended
maximum errors of the combined transducer and recording system are shown in Table 1.
A steering machine including driver emergency override functionality is preferred to be used to turn
the steering wheel while collecting data.
The steering machine shall be able to perform triangular wave steering angle input with a steering-
wheel torque, steering-wheel speed and maximum steering wheel angles corresponding to the test
needs.
Care shall be taken to ensure that friction and inertia added to the system by steering machine or
steering transducers does not improperly influence the measurement of steering-wheel torque. For
example, any friction added by the steering-wheel torque sensor shall be estimated and compensated
for if this is not done in the measuring equipment.
The steering input may be done manually without the help of a steering machine but with a risk of loss
of accuracy in the results as it can be hard to maintain a constant steering-wheel speed during the
manoeuvres. See 8.3 and 8.4.
Table 1 — Variables, typical operating ranges and recommended maximum errors. Not listed in
or changed from ISO 15037-2
Recommended maximum error of
a
Variable Typical operating range the combined transducer and re-
corder system
Vehicle, axle or track mass: Up to 40 000 kg ±0,2 %
Steering-wheel angle ±1 000° ±1°
Steering-wheel torque ±30 Nm ±0,3 Nm
b
Steering-wheel speed ±600°/s ±2°/s
Transducers for measuring some of the listed variables are not widely available and are not in general use. Some such
instruments are developed by users. If any system error exceeds the recommended maximum value, this and the actual
maximum error shall be stated in the test report as shown in Annex B.
a
These transducer ranges are appropriate for the standard test conditions and may not be suitable for non-standard
test conditions.
b
Steering-wheel speeds above ±600°/s are usually not of interest for a normal driver.
6.2 Transducer installations
The transducers shall be installed according to the manufacturers’ instructions, where such
instructions exist, so that the variables in Clause 5 corresponding to the terms and definitions in
Clause 3 and ISO 8855 can be determined.
If a transducer does not measure a variable directly, appropriate transformations into the specified
reference system shall be carried out. For example, if not directly available the steering-wheel speed
should be calculated from the time signal of steering wheel angle, i.e. dδ /dt.
H
6.3 Data processing
See Clause 9.
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ISO 22139:2022(E)
7 Test conditions
7.1 General
For each test the surface characteristics, paving material and ground (or ambient) temperature shall be
recorded and documented in the test report. See Annex B.
If possible, the coefficient of friction should be estimated and documented. See Annex B.
7.2 Test track when manoeuvring at low speed
For measurements when manoeuvring the vehicle at low speed a large, smooth, flat and hard asphalt or
concrete area of minimum size of 50 m × 150 m is preferred. Then a complete test while increasing the
steering-wheel speed can be performed without interruption.
However, if this area is not available the test should be adapted and divided into smaller parts.
The lateral gradient of the test surface shall not exceed 2 %.
7.3 Test track with stationary vehicle
For measurements with stationary vehicle the steering effort is quite dependant on the tyre to road
surface friction. It is recommended to perform the test on a surface with a stable coefficient of friction
during the test.
On some surfaces the coefficient of friction can vary with the ground temperature and on some surfaces
the coefficient of friction can change due to, e.g. polishing when steering multiple times at the same
spot.
Due to this the vehicle may have to be moved a little bit between each set of measurements not to
change the coefficient of friction or to damage the tyres and /or the surface.
In stationary tests with vehicles with more than one steerable axle, all steerable axles shall be on the
same type of surface.
7.4 Test vehicle
7.4.1 General data
General data of the test vehicle shall be presented in the test report shown in Annex A.
7.4.2 Operating components
For the standard test conditions, all operating components likely to influence the test results shall
be according to specification. Any deviations from specification shall be noted in the presentation of
general data. See Annex A.
7.4.3 Tyres and rims
For general information regarding tyres used for test purposes, see ISO 15037-1:2019, 6.4.2.
Rim offset can have a significant influence and shall be reported in the test report-general data. See
Annex A.
7.4.4 Vehicle loading conditions
See ISO 15037-1:2019, 6.4.4.
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ISO 22139:2022(E)
Depending on the purpose of the test it may be performed in any load condition of the vehicle even if a
test at maximum design total mass for the vehicle is usually included.
The axle loads shall be documented in the test report-general data. See Annex A.
8 Test procedure
8.1 Preparation of test vehicle
Load the vehicle to the desired axle loads.
Check and adjust tyre pressure to the load.
Find the maximum steering-wheel angles and if applicable choose the maximum steering-wheel angles
range of interest to be used in the measurement.
In many test cases measuring the steering-wheel torque all the way out to maximum steering-wheel
angles is not necessary or even desirable. The reason being that the level of rise in torque when getting
close to maximum steering wheel angles usually is irrelevant for the driver as there is no practical use
to try to steer close to or beyond this point. Also, if using a steering machine to perform the manoeuvre
going all the way out to maximum steering wheel angles can cause unwanted terminations of the
measurements due to the sudden rise in torque exceeding the physical or pre-set torque limit for the
machine.
In many cases the absolute values of the maximum steering-wheel angles range of interest left and right
will be equal. For example, ±600 (°) as in examples in 9.5 to 9.10.
If there is a special interest in the behaviour of the system close to maximum steering-wheel angles, the
measurement could be extended to these angles.
If available, activate the steering machine steering-wheel torque limit. This is the limit when the
machine automatically stops the tests. It is recommended to set the value to a maximum of (30 to
40) Nm not to get too high forces in the machine attachment and also to have an automatic stop of the
test when torque values become too high to be of any interest to measure, i.e. too high of a torque for a
driver to handle.
Higher steering-wheel torque limit values can be used for special test cases.
As the servo fluid temperature in a hydraulic steering system can have a significant influence on the
performance of the steering system it is recommended to have control of the temperature and report it
together with the corresponding test results.
8.2 Warm-up
All relevant vehicle components shall be warmed up prior to the test in order to achieve a temperature
representative for the purpose of the test.
8.3 Measurement with a stationary vehicle
The engine should normally be at idle speed, but the engine speed may be increased to check any change
in performance.
The parking brake shall be released, and no foot brake applied.
Use the steering machine to give input on the steering-wheel starting at steering-wheel straight
forward position and then performing complete cycles of triangular waves at constant steering-wheel
speed going to maximum steering-wheel angles range of interest right, then to the maximum left and
back to the maximum right again at a constant turning speed starting at 30 (°/s).
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ISO 22139:2022(E)
In this position increase steering-wheel speed to 60 (°/s) and going to the maximum left and back to
maximum right again.
Continue in the same way while increasing the steering-wheel speed in 30 (°/s) increments until
reaching the catch-up steering-wheel torque limit or when reaching the pre-set steering machine
torque limit or when reaching a decided maximum steering-wheel speed, e.g. 120 (°/s).
Depending on the specific test and test object other ranges and increments of turning speeds may be
used.
The tests can be repeated with either parking or foot brake, or both, applied.
Make sure not to exceed maximum temperatures specified by the manufacturer as this can damage the
system.
If the steering input is done by hand, it is very important to keep a constant steering-wheel speed
throughout the test and a minimum of five consistent test runs shall be made where the time histories
are checked.
The test runs for which the control criteria steering-wheel speed are best met shall be selected for data
analysis.
8.4 Measurement when manoeuvring at low speed
This test can be done at any chosen engine r/min but will typically start with engine at idle, e.g. 600 r/
min and then the test should be repeated with increased engine speeds e.g. (800, 1 000, 1 200 and
1 400) r/min. Other engine speeds can be used depending on vehicle and test purpose.
Choose a gear to keep the vehicle speed between 5 km/h and 10 km/h at the chosen engine r/min.
The exact vehicle speed is not very critical for the result as long as the speed is between 5 km/h and
10 km/h which is for making sure that when performing the manoeuvres, no significant dynamic side
forces are acting on the tyres and that the vehicle dynamic yaw behaviour is not influencing the result
in a significant way.
With the vehicle placed at the end of the test surface area, start driving at steering-wheel straight
forward position while keeping the engine speed constant at the chosen r/min.
Use the steering machine to give input on the steering-wheel starting at steering-wheel straight forward
position and then perform complete cycles of triangular waves with constant steering-wheel speed
going to the maximum steering-wheel angles range of interest right, then to the maximum left and back
to maximum right again at a constant turning speed starting at 120 (°/s). In this position increase to
180 (°/s) going to the maximum left and back to maximum right again. Continue in the same way while
increasing the steering-wheel speed in 60 (°/s) increments until reaching the catch-up steering-wheel
torque limit or when reaching the pre-set steering machine torque limit or when reaching a decided
maximum steering-wheel speed, e.g. 600 (°/s).
Depending on the specific test and test object other ranges and increments of turning speeds may be
used.
The test can be repeated while reversing the vehicle at low speed.
If the steering input is done by hand, it is very important to keep a constant steering-wheel speed.
A minimum of five consistent test runs at each steering-wheel speed shall be made where the time
histories are checked. The test runs for which the control criteria steering-wheel speed is best met
shall be selected for data analysis.
Performing the test at higher vehicle speeds (>10 km/h) may be done if for some reason this is of
interest, but it has to be taken into consideration that with increasing vehicle speeds the dynamic yaw
behaviour of the vehicle, for example, under/over steering and the corresponding time delays between
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ISO 22139:2022(E)
time signals will have increasingly influence on the test results, e.g. between steering-wheel speed and
steering-wheel torque time signals.
Especially when comparing steering characteristics between vehicles with different specifications
or when changing the load case on a specific vehicle it is important to understand if any
...