SIST EN 894-4:2010

SLOVENSKI STANDARD
01-december-2010
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Safety of machinery - Ergonomics requirements for the design of displays and control
actuators - Part 4: Location and arrangement of displays and control actuators
Sicherheit von Maschinen - Ergonomische Anforderungen an die Gestaltung von
Anzeigen und Stellteilen - Teil 4: Lage und Anordnung von Anzeigen und Stellteilen
Sécurité des machines - Spécifications ergonomiques pour la conception des dispositifs
de signalisation et organes de service - Partie 4: Agencement et arrangement des
dispositifs de signalisation et organes de service
Ta slovenski standard je istoveten z: EN 894-4:2010
ICS:
13.110 Varnost strojev Safety of machinery
13.180 Ergonomija Ergonomics
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN 894-4
NORME EUROPÉENNE
EUROPÄISCHE NORM
June 2010
ICS 13.110; 13.180
English Version
Safety of machinery - Ergonomics requirements for the design of
displays and control actuators - Part 4: Location and
arrangement of displays and control actuators
Sécurité des machines - Spécifications ergonomiques pour Sicherheit von Maschinen - Ergonomische Anforderungen
la conception des dispositifs de signalisation et organes de an die Gestaltung von Anzeigen und Stellteilen - Teil 4:
service - Partie 4: Agencement et arrangement des Lage und Anordnung von Anzeigen und Stellteilen
dispositifs de signalisation et organes de service
This European Standard was approved by CEN on 6 May 2010.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the CEN Management Centre or to any CEN member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as the
official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland,
Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2010 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 894-4:2010: E
worldwide for CEN national Members.

Contents Page
Foreword .3
Introduction .4
1 Scope .5
2 Normative references .5
3 Terms and definitions .5
4 Principles for location and arrangement of displays and control actuators .6
5 Phases and steps for location and arrangement of displays and control actuators .8
5.1 Phase 1 – Evaluation of task/activities and information collection .8
5.1.1 Step 1.1 – Define tasks and functions .8
5.1.2 Step 1.2 – Determine the operators' relevant physical and cognitive characteristics .8
5.2 Phase 2 – Evaluation of task requirements and constraints .8
5.2.1 Step 2.1 – List of displays and control actuators .8
5.2.2 Step 2.2 – Determine general priorities .8
5.2.3 Step 2.3 – Define operators' work postures .9
5.2.4 Step 2.4 – Define space constraints .9
5.2.5 Step 2.5 – Define and analyse information flows . 10
5.3 Phase 3 – Location of displays and control actuators . 10
5.3.1 Step 3.1 – Identify location of zones within fields of vision and actuation areas for primary
and secondary elements . 10
5.3.2 Step 3.2 – Specify location of consoles and panels . 13
5.3.3 Step 3.3 – Locate displays and control actuators on consoles and panels according to
priorities and constraints . 14
5.4 Phase 4 – Arrangement of displays and control actuators − principles and applications . 17
5.4.1 General . 17
5.4.2 Step 4.1 – Arrange displays and control actuators among themselves – Grouping . 18
5.4.3 Step 4.2 − Ensuring Compatibility . 26
5.4.4 Step 4.3 − Ensuring integration of the system . 32
5.5 Phase 5 – Implementation and evaluation . 33
5.5.1 General . 33
5.5.2 Steps for carrying out an evaluation . 33
Annex A (informative) Dimensions for sitting and standing consoles . 35
Annex B (informative) Coding Methods . 39
Annex C (informative) Suitability of Colour Combinations . 42
Annex ZA (informative) Relationship between this European Standard and the Essential
Requirements of EU Directive 2006/42/EC . 43
Bibliography . 44

Foreword
This document (EN 894-4:2010) has been prepared by Technical Committee CEN/TC 122 “Ergonomics”, the
secretariat of which is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an identical
text or by endorsement, at the latest by December 2010, and conflicting national standards shall be withdrawn
at the latest by December 2010.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
This document has been prepared under a mandate given to CEN by the European Commission and the
European Free Trade Association, and supports essential requirements of EU Directive(s).
For relationship with EU Directive(s), see informative Annex ZA, which is an integral part of this document.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.
Introduction
This European Standard has been prepared to be a harmonized standard in the sense of the Machinery
Directive and the associated EFTA regulations.
This document is a type B standard as stated in EN ISO 12100.
The provisions of this document can be supplemented or modified by a type C standard.
NOTE For machines which are covered by the scope of a type C standard and which have been designed and built
according to the provisions of that standard, the provisions of that type C standard take precedence over the provisions of
this type B standard.
1 Scope
This European Standard contains ergonomic requirements for the location and arrangement of displays and
control actuators in order to avoid hazards associated with their use.
This European Standard applies to displays and control actuators for machinery and other interactive
equipment (e.g. devices and installations, instrument panels, control and monitoring consoles).
This European Standard is not applicable to the location and arrangement of displays and control actuators
which are manufactured before the date of its publication as EN.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
EN 614-1, Safety of machinery — Ergonomic design principles — Part 1: Terminology and general principles
EN 894-1:1997+A1:2008, Safety of machinery — Ergonomics requirements for the design of displays and
control actuators — Part 1: General principles for human interactions with displays and control actuators
EN 894-2:1997+A1:2008, Safety of machinery — Ergonomics requirements for the design of displays and
control actuators — Part 2: Displays
EN 894-3, Safety of machinery — Ergonomics requirements for the design of displays and control
actuators — Part 3: Control actuators
EN ISO 9241-11, Ergonomic requirements for office work with visual display terminals (VDTs) — Part 11:
Guidance on usability (ISO 9241-11:1998)
EN ISO 9241-110, Ergonomics of the human-system interaction — Part 110: Dialogue principles
(ISO 9241-110:2006)
EN ISO 12100-1:2003 Safety of machinery — Basic concepts, general principles for design — Part 1: Basic
terminology, methodology (ISO 12100-1:2003)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN ISO 12100-1:2003 and the following
apply.
3.1
control/display ratio
C/D ratio
ratio of the movement of a control actuator to that of an associated element, display or controlled object
3.2
elements
generic term for displays and control actuators on consoles and panels
3.3
primary element
element frequently used for direct operation and monitoring of the system which includes safety and
emergency related elements
3.4
secondary element
element not frequently used for the direct operation of a system
EXAMPLE The time and duration of use can be freely selected.
3.5
grouping
arrangement of several elements of a system in such a way that they appear to be associated functionally
3.6
coding
procedure within the design process by which categories of information (e.g. form, colour, etc.) are allocated
to elements for the purpose of reliable identification
3.7
arrangement
way of combining or separating displays and control actuators relative to their function, task and/or location
3.8
surface
surface on which elements are positioned and arranged, considering task priorities, information flows, and
space constraints
4 Principles for location and arrangement of displays and control actuators
The location and arrangement of displays and control actuators are intended to ensure the general reliability,
safety and efficiency of the human-machine system. The most important tasks of the operator are to monitor,
control and ensure continuous availability of the technical system and the interaction of its elements. This shall
place the operator in a position to fulfil the following functions correctly and on time without becoming
overtaxed:
 to perceive the current tasks;
 to control the operation;
 to select and/or develop suitable action strategies.
Basic principles for human machine interaction are given in EN 894-1.
The following describes a design procedure that will assist designers and manufacturers in complying with the
requirements in this standard. It consists of six main phases, each of which contains several more detailed
steps. These steps should be carried out iteratively until the requirements are met. The procedure is illustrated
in Figure 1. In Phase 0 the initial information about the overall purpose, design goals and roles of the
operators (see EN 894-1) is assembled.
Key
Possible iteration
Figure 1 — Design procedure for location and arrangement
NOTE For details of each step see Clause 5 (e.g. step 1.1 is in 5.1.1; step 3.1 in 5.3.1).
5 Phases and steps for location and arrangement of displays and control actuators
5.1 Phase 1 – Evaluation of task/activities and information collection
5.1.1 Step 1.1 – Define tasks and functions
Typical operator tasks are e.g. monitoring, error detection, diagnosis of faults and performing control actions;
the following operating situations should be considered: start up, normal operation, troubleshooting, shutdown,
emergency stop, etc., see EN 894-1, -2 and -3.
Task sequence and relevant information flows shall be recorded for each relevant operating situation.
If two or more operators may work at the same workplace the interactions between their tasks, control actions
and information flows shall be specified to help avoid possible conflicts and improve overall safety.
5.1.2 Step 1.2 – Determine the operators' relevant physical and cognitive characteristics
The general principle as defined in EN 614-1, e.g. strength, body size, visual acuity, skills, experience and
disabilities, shall be considered. Specific information on relevant physical characteristics for displays and
control actuators is given in EN 894-2 and -3.
5.2 Phase 2 – Evaluation of task requirements and constraints
5.2.1 Step 2.1 – List of displays and control actuators
Types of displays and control actuators which comply with the relevant requirements of EN 894-2 and
EN 894-3 should be compiled in a list.
Technological features and/or constraints such as for multifunctional elements, e.g. touch screens, scroll balls,
remote or handheld controllers need to be assessed.
5.2.2 Step 2.2 – Determine general priorities
The task requirements for each operational situation shall be specified and prioritized taking into account
safety, performance and usability goals. Task requirements include accuracy, speed, force, frequency,
importance, duration of use, sensitivity to error and sequence of use, etc.
Tasks should be assigned a level of priority, i.e. primary or secondary elements as defined in 3.3 and 3.4.
These priorities are used in Phase 3 to help locate displays and control actuators, and to exclude unnecessary
elements.
The activities that make up the tasks should be identified, this helps to choose the most appropriate physical
arrangements, e.g. which parts of the task can be done seated, which parts of the task require communication
with other operators, which parts of the task require problem solving activities. There also needs to be
consideration of the operator's action strategy in each operating situation.
The following constraints on activities shall be considered where appropriate:
a) need for direct vision over the top of a console e.g. when monitoring supplementary information;
b) need for continuous direct vision while controlling e.g. during a driving task, using a mobile machine;
c) need for indirect vision (by e.g. camera systems) while controlling;
d) need for direct vision and interaction with other people, e.g. crane operation;
e) need to use horizontal surfaces e.g. for writing, placing written material, work material, etc.
5.2.3 Step 2.3 – Define operators' work postures
5.2.3.1 General
The postures that have to be adopted when using displays and control actuators need to be specified as they
strongly influence where the elements can be placed. Natural (not awkward) body postures should be
selected which allow a balance between avoiding excessive movement and encouraging sufficient movement
to allow a range of muscles to be used. Arrangements which allow changing of posture and do not
continuously stress one part of the body should be selected. EN ISO 14738 provides additional information on
how to select the main working postures.
5.2.3.2 Activities in seated position
The sitting position shall be selected particularly if the following demands are made:
 a high degree of body stability;
 high accuracy requirements.
For prolonged work periods it is important to allow for changes of posture and rest periods.
5.2.3.3 Activities in standing position
The standing position shall be selected for carrying out activities if:
 high mobility is required;
 extensive control movements are to be carried out;
 body weight is used in application of the force; and
 a large workplace is to be serviced.
5.2.3.4 Combination of activities in the sitting and standing positions
Control consoles where both standing and sitting is possible shall be set up when:
a) a firm sitting support has to be assured for precise work;
b) wide panels with displays and control actuators have to be monitored and actuation activities have to be
carried out on them;
c) there is an anticipated temporary increase in task demands where another operator has to help out.
Wherever possible, the operator should be able to sit and stand in order to have the benefits of both work
postures. This helps to avoid the build up of musculoskeletal problems which can occur, particularly under
conditions of psychological stress, when using one posture for a prolonged period of time.
5.2.4 Step 2.4 – Define space constraints
Any restrictions on the dimensions of the space available for positioning and moving displays and control
actuators shall be fully recorded. This should include restrictions for direct vision of the process or objects
where this is relevant to the performance of the tasks. Restrictions can arise from technological,
environmental or task limitations.
5.2.5 Step 2.5 – Define and analyse information flows
Collate information on the sequence of use of elements, their frequency of use and their relative importance.
Identify any pre-existing stereotypes for the use of these elements.
Identify those elements which are used in combination, e.g. controls with their associated displays.
5.3 Phase 3 – Location of displays and control actuators
5.3.1 Step 3.1 – Identify location of zones within fields of vision and actuation areas for primary and
secondary elements
5.3.1.1 General
Displays and control actuators should be located in the appropriate zones taking account of requirements for
frequency, importance, accuracy and order of operation, as well as operator's work postures and physical
dimensions. Surfaces on which elements are positioned and arranged should then be determined within these
zones considering task priorities, information flows and space constraints.
The field of vision (monitoring area) A, B, C is defined in EN 894-2:1997+A1:2008, Figure 2.
NOTE The information in EN 894-2:1997+A1:2008, Figure 2 applies to activities when sitting or standing.
In the same way, as shown in the following Figure 2, the actuation area A', B', C' are classified in three
different zones, each with a different level of suitability.
The field of vision and the actuation area are classified as follows:
 A, A' : recommended;
 B, B' : acceptable;
 C, C' : not recommended.
Thus for the various task priorities the following applies:
Elements used in primary tasks are located in recommended zones A and A’. They are used for the following:
a) maximum priority for safe operation;
b) quick and accurate reading (or actuation);
c) important indicators (or control actuators) for operating the system;
d) lengthy observation (and/or frequent actuation);
e) elements for secondary and less important tasks, if space is left.
Elements used in secondary tasks are located in acceptable zones B and B’. They are used for the following:
f) displays (or control actuators) of secondary importance that only have to be observed (or actuated)
intermittently.
Elements used in less important tasks are located in the not recommended zones C and C’. They are used for
the following:
g) only suitable for displays (or control actuators) that are seldom used and are of low priority or importance
such as for temperature regulation in a room.
5.3.1.2 Zones within fields of vision − seated
Figure 2 illustrates the display zones A, B, C. The eye height of the operators should be taken into account
when calculating the position of displays using these angles. Annex A gives an example of console
dimensions based on an average European sitting eye height of 1 250 mm. Further information on sight lines
in different seated postures for control centre workstations can be found in EN ISO 11064-4, and for mobile
machinery in EN ISO 6682. Typical distances for comfortably viewing displays such as video screens are
400 mm to 700 mm.
NOTE 1 A distinction should be made between leaning forwards, keeping vertical and leaning backwards in the sitting
postures. When the posture is changed, the field of vision (or actuation) moves. For design purposes it is helpful to use the
vertical (upright) position as a reference when calculating constraints on postures, for details see EN ISO 3411. Good
design permits the adoption of other postures and easy accessibility.
The line of sight is located at 15° to the horizontal from the eye point. Zones (A, B, C) within the field of vision
are derived from those given in EN 894-2.
It is important to ensure that discrimination of colours is not required towards the extremes of the field of vision.
Figures 2 and 3 give some information about colour discrimination.
NOTE 2 The information about colour discrimination does not take account of head movement.

Key
1 Optimum control zone between elbow and shoulder height 7 Horizontal
2 Lower visual limit 70° 8 Primary display & secondary control
3 Upper visual limit 9 Primary display & control
4 Limit for colour vision 10 Primary control, secondary display
5 Low priority display, control A, B, C Display zones (see 5.3.1.1)
6 Secondary display, control A', B', C' Control zones (see 5.3.1.1)
Figure 2 — Location of Display Zones A, B, C and Control Zones A', B', C' (Vertical)
Key
1 Line of Sight-0°
2 Limit for colour vision
A, B, C Display zones (see 5.3.1.1)
NOTE 1 Vision to both sides needs to be considered.
NOTE 2 For the field of vision it is good practise to move the head 45° to left and right.
Figure 3 — Location of display zones A, B and C (horizontal)
5.3.1.3 Zones within actuation areas − seated
The zones within actuation areas are shown in Figure 2 as A', B', C' and partially overlap with the zones for
field of vision A, B, C. The actuation areas should be readily reached by an operator, this means that they
should be no more than 450 mm in front of the body for frequently used or important controls. The actuation
area for primary elements in the horizontal plane is within a sector of about 60° in front of the operator. This
sector of 60° is defined by the lateral rotation of both left and right arms in a horizontal plane. For further
dimensions of actuation areas see Annex A and EN ISO 14738 and for mobile machinery see EN ISO 6682.
If all the control actuators cannot be housed in actuation zone A', they shall be as close as possible to it.
EN ISO 14738 gives further information on reach zones.
It is important to consider the angles of the shoulder, elbow and wrist that will be required in order to operate a
control actuator, EN 1005-4 gives some advice on suitable angles for maintaining comfort. The degree of
accuracy, the frequency and duration of use will all affect the overall comfort of using a control actuator in a
particular posture (EN 894-3).
5.3.1.4 Zones within field of vision and actuation areas − Standing
The zones within field of vision and actuation areas for a standing operator need not be as precisely defined
as those for a seated operator because a standing operator can easily face in any direction or can walk from
one position to another. Information on working heights with different visual demands are given in
EN ISO 14738:2008, Clause 9:
th
 the 50 percentile shall be used as the basis for specifying the fields of vision and actuation areas in the
standing position;
 the recommended zone within the field of vision should be between 1 370 mm and 1 680 mm above the
horizontal reference surface (floor);
 in most cases lateral dimensions need not be taken into account because the operator can freely change
position when standing. However, if groups of control actuators are to be operated quickly and
simultaneously, their sideways separation should be within 760 mm;
 the recommended zone within the actuation area should be between 1 040 mm and 1 370 mm above the
horizontal reference surface;
 actuation area positions more than 1 830 mm above the horizontal reference surface are not suitable;
 actuation area positions less than 920 mm above the horizontal reference surface are not suitable.
Annex A provides further information on dimensions of a standing console that is based on average European
body measurements.
5.3.1.5 Zones for combined sitting and standing positions
Special attention should be paid to specifying a similar eye height for both the sitting and standing positions by
using an adjustable raised seat and adjustable foot support. EN ISO 14738 contains information on suitable
dimensions for raised sitting. An installation angle for surfaces with displays of 50° to 70° from the horizontal is
suggested. (See Annex A, Figure A.2.)
5.3.2 Step 3.2 – Specify location of consoles and panels
5.3.2.1 External shape and inclination of surfaces of consoles and panels
The following points shall be taken into account when specifying the shape and inclination of the surfaces:
 the displays for the particular visual tasks such as observation, screen or scale reading and activities that
are to be carried out;
 the avoidance of parallaxes of displays by correct design of the shapes and inclination of the surfaces;
 prevention of unintentional actuation;
 location and direction of movement of the controls so that they are easy to handle;
 adequate space for the body of the operator in the selected work postures and for the activities of
operators in a team;
 task constraints (e.g. need for direct vision in control room or vehicle, need for direct vision and personal
interaction, need for using horizontal work surface);
 technological constraints (e.g. touch screens, scroll bars, remote controls, handheld controls).
Work surfaces of consoles and panels can be used for various purposes, e.g. as writing surfaces or for
accommodating certain control actuators, e.g. joysticks.
The working surfaces should preferably be horizontal or nearly horizontal (no more than 15°).
Information on the space required beneath a console (leg room) can be found in EN ISO 14738 and for mobile
machinery in EN ISO 6682.
5.3.2.2 Surfaces for locating primary and secondary elements
A distinction shall be made between surfaces for locating primary and secondary elements. As far as possible
primary elements should be located in the A zone for field of vision and the A' zone for actuation. The overlap
of the A zone for displays and the A' zone for control actuators is comparatively small, it should be used for
those elements which require quick and accurate identification and rapid actuation. Secondary elements can
be located in the appropriate zone B or where necessary, for occasional use, in zone C.
Surfaces are located taking account of the imposed space constraints. It is important that sequential use of
primary or secondary elements should not cause a conflict, e.g. hiding high priority elements. Information from
the primary visual elements shall be visible at all times and in a fixed position.
The following requirements apply:
 control actuators forming a functional unit with displays shall be located directly beneath the displays;
 control actuators with a higher priority should be located in the actuation zone A'.
Where there are limitations on the surfaces available, multifunctional elements shall be preferred.
5.3.3 Step 3.3 – Locate displays and control actuators on consoles and panels according to priorities
and constraints
5.3.3.1 Requirements relating to accommodating elements
When accommodating displays and control actuators on consoles and panels, the priorities relate to fields of
vision and actuation zones. The following requirements apply:
a) primary elements shall be located in display zone A or control zone A';
b) secondary elements should be located within display zone B or control zone B' so that they are easily
accessible if required;
c) elements of little importance to the system should be located at points that warrant the lowest priority
(display zone C or control zone C'), e.g. elements not used during continuous operation;
d) where two operators use certain elements simultaneously:
1) elements that are primary for both operators shall be duplicated or, for displays, positioned so that
they are clearly visible to both operators;
2) secondary elements should be positioned closer to the operator who uses them most;
3) special arrangements may need to be put in place to ensure that conflicts cannot occur.
5.3.3.2 Location of displays – Requirements
The information from step 2.2 on the activities shall be used to help locate the displays. Then, after locating
displays in the appropriate zone corresponding to their importance (see 5.3.1), the following needs to be
considered:
 take account of the sequence of readings;
 to ensure situational awareness for more than one operator, relevant elements shall be located so that
they can be seen and interpreted similarly by these operators;
 provide the same displays for the same functions and/or units;
 displays should clearly indicate the operating function;
 ensure that displays for different functions have clearly different appearances;
 locate similar displays in the same way;
 locate the surfaces orthogonally to the line of sight, as far as possible;
 avoid/minimize parallaxes, reflection, glare, specular reflection, heavy shadows.
5.3.3.3 Location of control actuators – Requirements
The information from step 2.2 on the activities shall be used to help locate the control actuators. Then the
following needs to be considered:
 locate important and frequently operated control actuators in zone A' (the recommended actuation area);
 take account of the sequence of operation of the control actuators (from top to bottom and from left to
right – following the stereotype employed in Western countries);
 provide the same control actuators for the same functions;
 ensure that control actuators for different functions have clearly different appearances (coding);
 locate similar control actuators with the same function in the same way;
 ensure that separation distances are no less than the minima in Tables 2 and 3. For handheld
microelectronic devices smaller dimensions may be appropriate however safety critical functions will need
to be carefully designed to avoid unintentional activation;
 use the recommended separation distances in Table 2 for high priority tasks.
Table 1 — Separation distances for control actuators on consoles or similar surfaces
Separation distances (mm)
Control
Type of use Illustration
Type
Minimum Recommended
Push Button One finger – randomly 13 50
and sliders
One finger – sequentially 6 25

Different fingers 6 13
Toggle One finger – randomly 19 50
switch
One finger – sequentially 13 25
Different fingers 16 19
Cranks One hand – randomly 50 100
Two hands – simultaneously 75 125

Levers
(forward/
One hand – randomly 50 100
a
backward)
Two hands – simultaneously 75 125

Levers
a
(left/right)
One hand – randomly 50 75
Two hands – simultaneously 75 100

Knobs
One hand – randomly 25 50
(turnable)
Two hands – simultaneously 75 125
Pedals
One foot – randomly 100 150
One foot – sequentially 50 100

a See [1] in bibliography.
Table 2 — Minimum separation distances between different types of control actuator
Dimensions in millimetres
Continuous Rotary
Push Toggle Discrete
rotary selector
buttons switches thumbwheels
controls switches
Push buttons – 13 13 13 13
Toggle switches 13 – 19 19 13
Continuous rotary controls 13 19 – 25 19
Rotary selector switches 13 19 25 – 19
Discrete thumbwheels 13 13 19 19 –

The shape of the control actuator shall be adapted to the part(s) of the body that is intended to operate it. The
ratio of the size of the control actuator to the size of the surface it is mounted on should be considered. The
purpose, action and frequency of use will determine the suitability of the position and mounting surface of the
control actuator (see EN 894-3 for information on selecting suitable control actuators).
5.4 Phase 4 – Arrangement of displays and control actuators − principles and applications
5.4.1 General
Ergonomic design measures shall ensure that the operator is able to carry out the following functions without
being overloaded:
a) to perceive and perform emergency related tasks quickly and positively;
b) to perceive the current tasks such as function-related monitoring of the system, diagnosing or correcting
faults, maintenance or ensuring availability of the system, etc.;
c) to understand the operating situation, i.e.:
1) always to have an "internal overall picture" of the operating conditions and phases, circuits, duties,
etc.;
2) to observe, accurately detect, identify and follow the information flows;
3) to interpret them with the relevant aids;
d) to select, develop and perform adequate, i.e. timely, action strategies suited to the situation.
To do this, the relevant displays and control actuators shall be arranged, i.e. grouped or divided up, in a
suitable way. The following aspects shall be noted in particular:
e) the arrangement should help to identify operational situations and to interpret them quickly;
f) the groupings and sub-assemblies shall be aligned with specific tasks. The arrangement shall reflect in an
easily comprehensible way the design and functional structures of each human-machine system;
g) the arrangements should reflect the process, causes and/or consequences of the operating situations;
h) the order and clarity of the groupings shall be optimized to avoid clutter;
i) the movement of the actuators and the indicated functions should correspond to the intended effect;
j) the location of groups of elements should take account of the shape and construction of the machine and
operators' expectations of their placement.
Large numbers of elements shall be arranged to reduce the information an operator has to monitor and control.
Applying the principles of grouping and dividing helps to achieve this. Such arrangements form the basis for
perceptual organisation and of the resulting cognitive processes (see also EN 894-1:1997+A1:2008, A.3.3)
such as formation of an internal picture by identification and interpretation. This includes:
k) the contrast between the background (e.g. colour of the consoles and panels) and the elements located in
each particular operational situation;
l) forming a pattern;
m) enclosing an assembly of elements in a frame;
n) marking the relationship of elements by proximity or space;
o) generating an impression of relationship through homogeneity of colour, shape, size, grouping structure,
layout in the room, flashing frequency, etc.;
p) common behaviour through the same direction of movement, frequency of occurrence , speed, etc.
NOTE Uniform grouping and patterns are quicker to spot than others, are seen more accurately, assessed more
reliably, retained in the memory better and deviations from the norm are noticed more quickly and larger numbers of
elements are seen more clearly.
5.4.2 Step 4.1 – Arrange displays and control actuators among themselves – Grouping
5.4.2.1 General
When arranging elements, the requirements for the basic structures of the groupings are designed to optimize
order, simplicity, clarity, uniformity (homogeneity), etc.
Overall, this is used to reduce information and increase redundancy.
Arrangements should try to minimize the cognitive requirements on the operator during human-machine
dialogue relative to perception, processing, or questions of capacity.
Some examples of ways of achieving this are:
a) grouping in rows and columns. Regular arrangements provide order and can help operators to locate
elements. Irregular arrangements are more difficult to use but are able to highlight particular elements.
Subgrouping shall be used with large regular arrangements (Figure 4);

a) Regular
b) Irregular arrangement
arrangement
Figure 4 — Grouping
b) using quadrant divisions for marking conditions and types of duty such as Off = 9 o'clock, Normal =
12 o'clock and Maximum = 3 o'clock on displays and control actuators (Figure 5).
a) Off b) Normal c) Maximum
Figure 5 — Use of quadrant divisions to improve clarity
Where a control actuator is linked to a particular display, it shall be located so that the operator's hand does
not cover the display.
The following sections describe ergonomics principles which provide a basis for grouping displays and control
actuators including coding methods and means for ensuring compatibility.
5.4.2.2 Principle of proximity (distance)
Minimum distances (proximity) amongst otherwise large ones between elements in an assembly give the
impression of operational association in a group. Larger distances between smaller ones separate assemblies
and split groups up as shown in Figure 6.

Figure 6 — Related elements grouped by proximity
Proximity as a grouping and dividing principle is easy to use for large assemblies that are to be combined.
a) Proximity can be easily combined with others.
b) Many different shapes of elements can be grouped with proximity.
The distances between elements in groupings or divisions depend to a large extent on the shapes.
th
c) Minimum distance between rectangular shaped displays within a group is approximately 1/20 of the
height of displays. For numerical displays minimum dimension is about three times the width of the stroke.
All framing is part of the display, not separation.
d) For groupings of elements of a mixture of shapes such as circles, rectangles, etc. larger distances should
generally be used. Usability testing may be required to check the arrangement is satisfactory (see for
example EN ISO 9241-11).
e) The distances between groups should be increased in a relevant ratio to the above (for instance
geometric or logarithmic, not arithmetic).
f) Sub-groups formed by distance only have 70 % to 100 % of the distance to elements in other sub-groups.
g) All elements in the group should lie within the appropriate field of vision.
If points f) and g) cannot be fulfilled simultaneously, other grouping principles should be used.
5.4.2.3 Principle of symmetry
The principle of symmetry is used when combining several components with the same function in a system.
Vertical or horizontal directions of observation are possible depending on the sequence of use and the
functional structure. For two groups mirror imaging of the blocks is preferred. For more than two groups of
blocks similar parallel combinations improve perception and interpretation.
Criteria for arranging blocks of elements result from the hierarchy of the tasks, the way that operators use the
elements and their stereotypes.
Blocks of elements can be combined in parallel as shown in Figure 7.

a) Two groups b) More than two groups
Figure 7 — Combination of blocks with the same elements
5.4.2.4 Principle of similarity
Elements more or less similar as regards colour, shape, size, spatial layout or behaviour are perceptually
organized into groups by the principle of similarity. This effect persists even over large intermediate spaces
containing other elements or groups.
This makes it possible to group or split up adjacent elements and also easier to find more distant but
operationally associated elements.
The principle of similarity is most frequently used for grouping or splitting up and it is the most important and
versatile of the principles that can be used.
The resistance of a grouping to deliberate reorganization depends on the following conditions:
 the greater the number of similar elements, the stronger their association appears;
 the more that similar features are united on elements in the same way, then the stronger the grouping;
 s
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