ISO 26022:2010
(Main)Road vehicles — Ergonomic aspects of transport information and control systems — Simulated lane change test to assess in-vehicle secondary task demand
Road vehicles — Ergonomic aspects of transport information and control systems — Simulated lane change test to assess in-vehicle secondary task demand
ISO 26022:2010 describes a dynamic dual-task method that quantitatively measures human performance degradation on a primary driving-like task while a secondary task is being performed. The result is an estimate of secondary task demand. The method is laboratory based, and ISO 26022:2010 defines the method, the minimum requirements for equipment to support the method, and procedures for collecting and analyzing data derived from the method. The method is applicable to all types of interactions with in-vehicle information, communication, entertainment and control systems; manual, visual, haptic and auditory, and combinations thereof. Secondary tasks requiring speed variations to be performed cannot be tested with this method. It applies to both Original Equipment Manufacturer (OEM) and aftermarket in-vehicle systems. It also applies to systems either portable or integrated into the vehicle. The driver behaviour principles, the specific task procedures and driving task correspond only to the operation of a passenger car.
Véhicules routiers — Aspects ergonomiques des systèmes de commande et d'information du transport — Essai du changement de voie simulé pour évaluer la demande de tâche secondaire à bord du véhiculex
General Information
Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 26022
First edition
2010-09-01
Road vehicles — Ergonomic aspects of
transport information and control
systems — Simulated lane change test to
assess in-vehicle secondary task demand
Véhicules routiers — Aspects ergonomiques des systèmes de
commande et d'information du transport — Essai du changement de
voie simulé pour évaluer la demande de tâche secondaire à bord du
véhicule
Reference number
ISO 26022:2010(E)
©
ISO 2010
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ISO 26022:2010(E)
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ISO 26022:2010(E)
Contents Page
Foreword .iv
Introduction.v
1 Scope.1
2 Terms and definitions .1
3 Lane change test (LCT).3
3.1 Principle and overview.3
3.2 Participants .4
3.3 Equipment .4
3.4 Scenario design.5
3.5 Experimental design .8
3.6 Procedure.9
3.7 Performance measures and data analysis.11
3.8 Validation .14
Annex A (normative) Instructions to participants .15
Annex B (informative) Experimental plan.18
Annex C (informative) Background and rationale .20
Annex D (informative) Adapting LCT to a real vehicle .23
Annex E (normative) Calculation of LCT metric using an adapted path trajectory for each
participant .24
Annex F (informative) Interpretation of LCT measures.32
Annex G (informative) Initial validation of LCT.38
Bibliography.40
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ISO 26022:2010(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 26022 was prepared by Technical Committee ISO/TC 22, Road Vehicles, Subcommittee SC 13,
Ergonomics applicable to road vehicles.
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ISO 26022:2010(E)
Introduction
Many advances are being made in introducing a wide range of information, communication, entertainment and
driver assistance systems in motor vehicles. Navigation aids, emergency messaging systems and wireless
communication, including e-mail and internet access, are all possible. Since many of these features require
the driver's attention it is important to recognise that, on one hand, these systems provide information and
assistance but, on the other hand, have the potential to distract the driver as well.
The lane change test (LCT) described in this International Standard, is a dual-task method that is intended to
estimate secondary task demand on the driver resulting from the operation of an in-vehicle device in a
laboratory setting. The method is simple and inexpensive so that it can be used by vehicle manufacturers,
in-vehicle device manufacturers, and other organizations.
The driver behaviour and attentional demand principles embodied in the LCT only apply to the operation of a
typical passenger car, as the vehicle dynamics model, driver eye height, and lane change dimensions and
geometries are scaled for such vehicles.
The test procedure specified in this International Standard uses software to set up the LCT task on a
computer, and to calculate the primary task performance measures. Appropriate software is available from the
ISO Central Secretariat.
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INTERNATIONAL STANDARD ISO 26022:2010(E)
Road vehicles — Ergonomic aspects of transport information
and control systems — Simulated lane change test to assess
in-vehicle secondary task demand
1 Scope
This International Standard describes a dynamic dual-task method that quantitatively measures human
performance degradation on a primary driving-like task while a secondary task is being performed. The result
is an estimate of secondary task demand.
The method is laboratory based, and this International Standard defines the method, the minimum
requirements for equipment to support the method, and procedures for collecting and analyzing data derived
from the method.
The method is applicable to all types of interactions with in-vehicle information, communication, entertainment
and control systems; manual, visual, haptic and auditory, and combinations thereof. Secondary tasks requiring
speed variations to be performed cannot be tested with this method. It applies to both Original Equipment
Manufacturer (OEM) and aftermarket in-vehicle systems. It also applies to systems either portable or
integrated into the vehicle. The driver behaviour principles, the specific task procedures and driving task
correspond only to the operation of a passenger car.
2 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
2.1
adaptive model
reference path trajectory adapted to each participant
2.2
baseline
test condition with the primary task only
2.3
basic model
nominal reference path trajectory is the same for all participants
2.4
calibration task
type of reference task used for the purpose of comparing different tests or test results between sites, or over
time at a given site
2.5
course
path along which the simulated vehicle actually travels
2.6
dual task
two tasks concurrently performed, primary task plus a secondary task
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ISO 26022:2010(E)
2.7
environment
physical surroundings in which data are captured
2.8
goal
system end state sought by the driver and which is meaningful in the context of a driver's use of an in-vehicle
system
EXAMPLE Obtaining guidance to a particular destination; magnification of a map display; or cancelling route
guidance.
2.9
integrated system
two or more in-vehicle devices, which provide information to, or receive output from, the driver of a motor
vehicle, whose input and/or output have been combined or harmonized
EXAMPLE 1 An in-vehicle entertainment system and route guidance system which use the same visual, manual and
auditory interface.
EXAMPLE 2 An in-vehicle entertainment system whose auditory output mutes when a mobile phone call is made or
received.
2.10
lane change
lateral displacement of a vehicle from current lane to another lane, including crossing one or two lanes
2.11
lane change task
series of prescribed lane change manoeuvres that are the main component of the primary task in the lane
change test
2.12
outlier
an observation that lies outside the overall pattern of a distribution
2.13
manufacturer
organisation or person designing, developing, producing, integrating and/or supplying in-vehicle equipment
2.14
path deviation measure
mdev
difference between a reference path trajectory and an actual driven course
2.15
portable system
nomadic device
device which provides information to, or receives output from the driver of a motor vehicle, that can be used
within the vehicle without installation or can be rapidly and easily installed in and removed from the vehicle
2.16
primary task
course following and manoeuvring control activity which a participant performs throughout the duration of a
test (simulated substitute for driving)
2.17
reference task
a standardized secondary task which can be used to compare different levels of performance degradation
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ISO 26022:2010(E)
2.18
run
driving used to collect LCT data, typically consisting of 18 lane changes accomplished over a 3 minute period
in either single task or dual task conditions
2.19
secondary task
interaction with an in-vehicle information, communication, entertainment, or control system, carried out
concurrently with the primary task
2.20
secondary task demand
sum of perceptual, cognitive and motoric activity required by a secondary task
2.21
single task
one task (primary or secondary task) without additional activity (as opposed to dual task)
2.22
task
process of achieving a specific and measurable goal using a prescribed method
NOTE Ultimately, it is for the users of this International Standard to determine tasks that are meaningful in the
context of a driver's use of an in-vehicle device.
EXAMPLE 1 Obtaining guidance by entering a street address using the scrolling list method, continuing until route
guidance is initiated (visual-manual task).
EXAMPLE 2 Determining where to turn based on a turn-by-turn guidance screen (visual task).
2.23
track
three-lane, straight, simulated roadway
2.24
trial
investigation of one participant undertaking one repetition of one secondary task
3 Lane change test (LCT)
3.1 Principle and overview
The lane change test (LCT) is a simple laboratory dynamic dual task method that quantitatively measures
performance degradation in a primary driving task while a secondary task is being performed. The primary
task in the LCT is a simulated driving task which resembles the visual, cognitive and motor demands of
driving.
In the LCT, a test participant is required to do a primary task consisting of driving at a constant, system-limited
speed of 60 km/h along a simulated straight three-lane road containing a series of lane changes defined by
signs displayed on a screen. Simulated vehicle position is controlled by means of a steering wheel.
Participants are instructed in which of the lanes to drive by signs that appear at approximately regular intervals
on both sides of the track. The LCT is performed by participants according to pre-test instructions contained in
this International Standard (see Annex A). The method may be implemented in a laboratory, in a driving
simulator, in a mock-up or in a real vehicle.
There is no limitation to the definition of a secondary task according to this International Standard as long as
the secondary task is compatible with the LCT procedure.
EXAMPLE Secondary tasks requiring speed variations to be performed are not accommodated.
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ISO 26022:2010(E)
3.1.1 Application of the LCT
In a typical application of the LCT, the primary task performance degradation resulting from a certain
secondary task can be compared to the performance degradation resulting from a reference task
(see Annex B). A reference task is a standardized secondary task which can be used to compare different
levels of performance degradation. Such standardized reference task can also be employed to compare
different test sites or to verify consistency in repeated testing.
For product development purposes, the LCT can also be used to compare alternative HMI candidates or
solutions rather than comparing each of these solutions to a reference task (see Annex C).
3.2 Participants
Participants shall be licensed drivers having a similar level of familiarity with the secondary task under
investigation. Other relevant characteristics of the participants shall be recorded (gender, age, driving
experience and previous experience with the LCT). At least 16 participants shall take part in the evaluation of
a single secondary task or in the comparison of two or more secondary tasks for a within-subject design.
3.3 Equipment
3.3.1 Display of visual driving scene
The LCT visual driving scene shall be realised with a monitor or projector with a net refresh rate of at least
50 Hz. A minimum resolution of 1024 × 768 pixels with a colour depth of 24 bit (also called True Color) is
required. The size of the display device must meet the requirements defined in 3.4.3.
3.3.2 Testing environment
The illumination level in the testing environment shall be appropriate to the secondary task. Simulated engine
sound is optional and, if used, shall be adjusted to a low level.
Participants shall be comfortably seated directly in front of the primary task visual display while performing
each test. The seat shall not swivel or rock. A seat belt shall be used if it is assumed that the use of a seat belt
might influence the test results (e.g. restrictions in posture and reach).
3.3.3 Steering wheel and simulation characteristics
For the lateral control of the simulated vehicle, a computer game steering wheel can be used for a
laboratory/monitor setup. For seating buck or real vehicle testing, movement of the steering wheel shall
provide signals to replicate movements of the game steering wheel. The steering wheel force displacement
characteristics shall be approximately linear, and the tangential force at the rim to turn the steering wheel shall
be no more than 20 N. A centering (breakout) force, which is optional, shall be no more than 12 N. Adapting
LCT to a real vehicle is discussed in Annex D.
The overall transport delay between an initial steering input and a visual display response shall be < 120 ms
(not including the simulated vehicle model delay).
The steering wheel sensor shall have a resolution less than 1,5 degrees.
With the steering wheel turned 90 degrees from the straight ahead position, the simulated vehicle shall, at a
constant speed of 60 km/h, complete a 360 degree turn in between 13 s and 17 s, corresponding to a turning
circle of 70 m to 90 m in diameter.
3.3.4 Vehicle dynamics
The simulated vehicle shall be programmed to respond approximately like a typical passenger car in terms of
its size and inertial properties. Yaw rate to steer angle characteristics shall be represented by a first order lag
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ISO 26022:2010(E)
with an equivalent time constant of approximately 0,15 s (±0,03 s), including vehicle mathematical model
response and other simulation transport delays (see 3.3.3).
3.3.5 Measurement recording
All vehicle parameters (i.e. position on track, steer angle, heading angle, heading (yaw) rate, etc.) are
recorded at a sampling rate of at least 10 Hz. Additional parameters and information such as a unique time
stamp, track number and markers for tasks (typically set manually by the experimenter) shall also be
recorded. The LCT simulation shall have a minimum update rate of 100 Hz. In addition, secondary task
performance shall be recorded (see 3.7.3). These data are needed to ensure the participant's compliance with
the instructions (see Annex A).
3.4 Scenario design
3.4.1 Simulated roadway and surroundings
The simulated roadway (see Figure 1) consists of a straight, three-lane track. A series of lane changes are
defined by roadside signs placed at approximately regular intervals. The road is located on a plain green field.
Figure 2 shows the dimensions of the lanes and the markers (delineators). The road surface is grey (like a
typical paved road). Lane markings are white.
The simulated roadway shall be displayed as if viewed from an eye point 120 cm ± 10 cm over the road
surface. This is consistent with that of a typical passenger car.
NOTE 1 The roadway and lane change geometries and the vehicle dynamics are not scaled to correspond to a truck or
other large commercial vehicle.
Minimum track length shall be 3 000 m corresponding to 3 min of driving at 60 km/h. This is sufficient in length
to collect 2 min of LCT data.
NOTE 2 According to the signs in Figure 1, the participant has to change from the current (middle lane) to the right
lane.
Figure 1 — Simulated roadway
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ISO 26022:2010(E)
Dimensions in metres
1
3,85
0,14
3,85
1,50
3,85
11,20
1
Key
1 road edge line
Figure 2 — Dimensions of the road markers (not to scale)
3.4.2 Signs
Both “START” signs and “Lane Change” signs appear in pairs on both sides of the simulated roadway
(see Figure 1 for example of sign positions). “Lane Change” signs are rectangular and have a thin black
border and black symbols on a white background (see Figure 4). The signs are 2,0 m wide and 1,0 m high
and the lower border is 1,0 m above the ground. The downwards arrow on the “Lane Change” sign indicates
the target lane. In Figure 4, (a), (b), and (c) show the left, middle and right lanes, respectively. Dimensions of
the “Start” sign can be the same as the “Lane Change” sign, but the colours shall be different from those of
the “Lane Change” signs (see Figure 3). The “START” sign shall appear approximately 150 m before the first
“Lane Change” sign.
Figure 3 — “Start” sign
Figure 4 — “Lane Change” signs
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ISO 26022:2010(E)
3.4.3 Experimental and measurement setup
3.4.3.1 Participant's view of display
The horizontal viewing angle to the display for the road scenery (monitor or screen) shall be between 20° and
55°. The eye-to-display distance shall be no less than 60 cm. The horizon of the visual scene shall be
between −5° and +5° from the participant's eye point height.
3.4.3.2 Steering wheel location
The steering wheel shall be located where it does not interfere with the visual scene of the LCT. It shall be
capable of being handled comfortably.
3.4.3.3 Standard scenario
The standard scenario for a 3 000 m test track is as follows:
⎯ only the scripted instructions are given to the participants (see Annex A),
⎯ speed is specified and limited to 60 km/h, resulting in a duration of about 180 s per track,
⎯ there are 18 pairs of “Lane Change” signs along a track.
3.4.3.4 Lane change sign spacing
The lane change signs are always visible but blank until the lane indications on the signs appear (i.e. pop-up)
at a distance of 40 m before the signs. The mean distance from sign to sign is 150 m (a minimum of 140 m
plus an exponentially distributed random variable with a mean of 10 m), so that the mean duration between
two lane changes is about 9 s (at a speed of 60 km/h).
3.4.3.5 Ordering the lane change directions
The number of the six possible lane changes (from left lane to middle lane, from left lane to right lane, etc.)
shall be balanced within 18 pairs of signs. This balancing also applies if tracks longer than 3 000 m are used.
If the total number of pairs of signs on a track is not a multiple of 18, balancing shall be done to the extent
possible. The presentation order of lane change signs in tracks used for different runs shall be randomised to
avoid learning effects. At least five different orders shall be used randomly for different runs.
3.4.3.6 Secondary task equipment
The equipment for evaluating the secondary task shall be positioned where the participants can properly
interact with it. The position depends on the purpose of the test, e.g. systems intended for vehicle use shall be
positioned in their intended locations in the vehicle relative to the participant.
3.4.3.7 Document the setup
Because experimental setting effect may have an impact on the results, description of the setup, viewing
distance and angle to road scene and type of road scene presentation, testing environment (personal
computer, buck or complete car), and type of seat shall be reported.
It has been shown that better lane change trajectories have resulted when using a driving simulator instead of
a personal computer [12], presumably due to the increased visual realism in a driving simulator. This
emphasises the need to describe precisely each equipment setup before comparing the results of different
experimental contexts.
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ISO 26022:2010(E)
3.5 Experimental design
3.5.1 General
A within-subject design shall be used (see Clause B.1). This allows for each participant to experience both the
single and dual task conditions and facilitates statistical comparison between the two conditions. Furthermore,
the experimental design shall be designed to minimize carry over or training effects between the two
conditions (for an example see Figure 5).
The secondary task(s) is (are) conducted in the dual task runs. The secondary task can either be performed
block wise (the same secondary task repeated within one track is a blocked run) or in a mixed design
(different secondary tasks given within one track is a mixed run). See Annex B.2 for rationale. Dual task runs
[primary task plus secondary task(s)] are conducted between baseline runs.
Each participant performs identical secondary tasks of equal difficulty but with different presentation order.
The order of secondary tasks, the track parts used and the combinations between secondary task and track
parts used shall be counterbalanced or randomised.
Start and end points of each secondary task operation are recorded, as well as driving performance during
single and dual task conditions for later data analysis. Start point is typically as soon as the verbal instructions
have been given. End point is the last operation made by the participant on the secondary task (e.g. a button
press) which leads to a predefined final state.
Total time on task for each secondary task shall be no less than 2 min. This means that at least 12 lane
changes during which the secondary task is being performed shall be taken into account.
During the LCT in dual task conditions, the experimenter shall monitor participant behaviour to ensure that the
participant is following the instructions and engaging in both tasks as instructed.
If the participant does not follow the experimental instructions (as described in Annex A) this part of the data
shall be excluded from data analysis. Furthermore, if the participant does not perform the secondary task, this
shall be recorded and considered in the evaluation of the interface design.
3.5.2 Baseline runs
In the experimental design, and once training is completed, baseline run data are collected at the beginning, in
the middle and at the end of the experimental phases. If only 2 baseline runs are carried out to avoid overly
long experimentation time, these runs shall be at the beginning and at the end of the experimental phases.
Mean deviation values (mdev) in the baseline runs can later be compared to check for learning effects. The
participant is free to use both hands for steering. One track with 18 signs (about 3 min) shall be used for each
baseline run.
A participant shall accomplish at least one baseline run at the beginning of the experimental phase without a
lane change error (wrong lane or missed lane change). This will ensure an adequate level of skill and training
(see Annex A). It will also provide at least one baseline suitable for calculating the participant's adaptive model
(see Annex E). To establish baseline performance for comparison with dual task performance, the mdev
values from several error-free baseline runs can be averaged.
3.5.3 Blocked runs
Given a blocked design, either the same secondary task with different parameters or a new task of the same
type is repeated within a single run for a duration of at least 2 min (see Figure 5).
With a blocked design a driving distance of 3 km (corresponding to 3 min) should be sufficient to collect data
for at least 2 min, with time for instructions for each secondary task item considered.
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3.5.3.1 Mixed runs
In a mixed design, different secondary tasks (ST) are repeated within a single run (see Figure 5). With a
mixed design, each secondary task shall be repeated enough times to record 2 min of data for each
secondary task. This will require more than one run if there is more than one secondary task.
For analysis, the combination of all of the results of a given secondary task are used to calculate a single
mean deviation.
3.6 Procedure
3.6.1 Participant instructions and training
All participants shall receive identical instructions. These shall be read to the participant. As described in
Annex A, the participant shall receive:
⎯ information on the general purpose of the test, and in particular instructions on the lane change task,
⎯ training on the primary task only,
⎯ training on the secondary tasks only,
⎯ training on the dual task situations,
⎯ instructions before first baseline run,
⎯ instructions before dual task testing, and
⎯ if required, instructions during dual task testing.
Baseline run (3)
Baseline run (3)
Dual Task Run 4 Dual Task Run 4
ST#4, ST#4, ST#4, . ST#1, ST#3, ST#4, .
Instruction ST#4
Dual Task Run 3
ST#2, ST#4, ST#2, .
Dual Task Run 3
ST#3, ST#3, ST#3, .
Baseline run (2)
Instruction ST#3
Dual Task Run 2
Baseline run (2)
ST#3, ST#1, ST#2, .
Dual Task Run 1
Dual Task Run 2
ST#4, ST#1, ST#3, .
...
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