EN ISO 9241-910:2011
(Main)Ergonomics of human-system interaction - Part 910: Framework for tactile and haptic interaction (ISO 9241-910:2011)
Ergonomics of human-system interaction - Part 910: Framework for tactile and haptic interaction (ISO 9241-910:2011)
ISO 9241-910:2011 provides a framework for understanding and communicating various aspects of tactile/haptic interaction. It defines terms, describes structures and models, and gives explanations related to the other parts of the ISO 9241 "900" subseries. It also provides guidance on how various forms of interaction can be applied to a variety of user tasks.
It is applicable to all types of interactive systems making use of tactile/haptic devices and interactions.
It does not address purely kinaesthetic interactions, such as gestures, although it might be useful for understanding such interactions.
Ergonomie der Mensch-System-Interaktion - Teil 910: Rahmen für die taktile und haptische Interaktion (ISO 9241-910:2011)
Dieser Teil der ISO 9241 bietet ein Rahmenwerk für das Verständnis und den Austausch über die verschiedenen Aspekte der taktilen/haptischen Interaktion. Sie definiert Begriffe, beschreibt Strukturen und Modelle, und gibt Erläuterungen, die auf andere Teile der Normen¬reihe 9241 "900" Bezug nehmen. Sie bietet auch Anweisungen, wie verschiedene Formen der Interaktion auf unterschiedliche Anwenderaufgaben angewendet werden können.
Sie ist für alle Typen von Interaktionssystemen, die taktile/haptische Geräte und Interaktionen anwendbar.
Sie spricht keine rein kinästhetischen Interaktionen, wie Gesten an, auch wenn es für das Verständnis derartiger Interaktionen nützlich sein könnte.
Ergonomie de l'interaction homme-système - Partie 910: Cadre pour les interactions tactiles et haptiques (ISO 9241-910:2011)
L'ISO 9241-910:2011 fournit un cadre permettant de comprendre et d'échanger sur différents aspects de l'interaction tactile/haptique. Elle définit des termes, décrit des structures et des modèles, et donne des explications en rapport avec les autres parties de la série de normes «900» de l'ISO 9241. Elle donne également des lignes directrices sur la façon dont les différentes formes d'interaction peuvent être appliquées aux diverses tâches de l'utilisateur.
Elle est applicable à tous les types de systèmes interactifs utilisant des dispositifs et interactions tactiles/haptiques.
L'ISO 9241-910:2011 ne traite pas des interactions purement kinesthésiques, tels que les gestes, bien qu'elle puisse être utile pour de telles interactions.
Ergonomija medsebojnega vpliva človek-sistem - 910. del: Okvirna specifikacija za otipno in haptično medsebojno vplivanje (ISO 9241-910:2011)
Ta standard zagotavlja okvirno specifikacijo za razumevanje in komunikacijo o različnih vidikih otipnega in haptičnega medsebojnega vplivanja.
Vsebuje definicije, strukture, modele in razlage, ki so uporabljene v drugih delih serij 9241-9xx.
Prav tako zagotavlja splošne informacije o tem, kako se lahko uporabijo različne oblike medsebojnega vpliva za različne naloge uporabnika.
Velja za vse vrste sistemov medsebojnega vpliva, ki izrabljajo uporabo otipnih in haptičnih naprav in medsebojnih vplivanj.
OPOMBA: ta standard ne naslavlja čista kinestetična medsebojna vplivanja, kot so geste, čeprav je lahko koristen pri takih medsebojnih vplivanjih.
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-december-2011
(UJRQRPLMDPHGVHERMQHJDYSOLYDþORYHNVLVWHP GHO 2NYLUQDVSHFLILNDFLMD]D
RWLSQRLQKDSWLþQRPHGVHERMQRYSOLYDQMH ,62
Ergonomics of human-system interaction - Part 910: Framework for tactile and haptic
interaction (ISO 9241-910:2011)
Ergonomie der Mensch-System-Interaktion - Teil 910: Rahmen für die taktile und
haptische Interaktion (ISO 9241-910:2011)
Ergonomie de l'interaction homme-système - Partie 910: Cadre pour les interactions
tactiles et haptiques (ISO 9241-910:2011)
Ta slovenski standard je istoveten z: EN ISO 9241-910:2011
ICS:
13.180 Ergonomija Ergonomics
35.180 Terminalska in druga IT Terminal and other
periferna oprema IT peripheral equipment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EUROPEAN STANDARD
EN ISO 9241-910
NORME EUROPÉENNE
EUROPÄISCHE NORM
July 2011
ICS 13.180; 35.180
English Version
Ergonomics of human-system interaction - Part 910: Framework
for tactile and haptic interaction (ISO 9241-910:2011)
Ergonomie de l'interaction homme-système - Partie 910: Ergonomie der Mensch-System-Interaktion - Teil 910:
Cadre pour les interactions tactiles et haptiques (ISO 9241- Rahmen für die taktile und haptische Interaktion (ISO 9241-
910:2011) 910:2011)
This European Standard was approved by CEN on 8 July 2011.
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-CENELEC 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-CENELEC 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
© 2011 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 9241-910:2011: E
worldwide for CEN national Members.
Contents Page
Foreword .3
Foreword
This document (EN ISO 9241-910:2011) has been prepared by Technical Committee ISO/TC 159
“Ergonomics” in collaboration with 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 January 2012, and conflicting national standards shall be withdrawn at
the latest by January 2012.
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.
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.
Endorsement notice
The text of ISO 9241-910:2011 has been approved by CEN as a EN ISO 9241-910:2011 without any
modification.
INTERNATIONAL ISO
STANDARD 9241-910
First edition
2011-07-15
Ergonomics of human-system
interaction —
Part 910:
Framework for tactile and haptic
interaction
Ergonomie de l'interaction homme-système —
Partie 910: Cadre pour les interactions tactiles et haptiques
Reference number
ISO 9241-910:2011(E)
©
ISO 2011
ISO 9241-910:2011(E)
© ISO 2011
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
ISO's member body in the country of the requester.
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Published in Switzerland
ii © ISO 2011 – All rights reserved
ISO 9241-910:2011(E)
Contents Page
Foreword .v
Introduction.vii
1 Scope.1
2 Terms and definitions .1
3 Introduction to haptics.4
4 Human haptic exploration .5
4.1 Importance of the haptic sense .5
4.2 Haptics and vision.5
4.3 Manual exploration of objects.6
4.4 Training in exploratory procedures.6
4.5 The problem of getting an overview of a scene with haptics .7
4.6 Minimum physical stimulation: absolute thresholds .7
4.7 Minimum differences needed for perception.7
4.8 Perception of geometric properties of objects.7
4.9 Perception of weight .7
4.10 Perception of material properties .8
4.11 Number and size of contact surfaces in tactile/haptic devices.8
4.12 Summary .8
5 When to use tactile/haptic interactions.9
5.1 General .9
5.2 Accessibility.9
5.3 Desktop interactions .10
5.4 Mobile interactions.10
5.5 Robotics .10
5.6 Medical.11
5.7 Gaming .11
5.8 Art and creativity .12
5.9 Multimodal applications and simulators.12
6 Designing tactile/haptic interactions.13
6.1 Design guidelines for tactile/haptic interaction .13
6.2 Designing tactile/haptic space.14
6.3 Addressability and resolution in tactile/haptic interaction.15
7 User-initiated interactive task primitives .17
7.1 General .17
7.2 Searching .17
7.3 Overviewing .17
7.4 Navigating .18
7.5 Targeting .18
7.6 Selection.18
7.7 Manipulation .19
8 Tactile/haptic interaction elements .20
8.1 General .20
8.2 Tactile/haptic functional effects.20
8.3 Tactile/haptic properties of objects.21
8.4 Control elements .23
8.5 Using multi-point-contact interfaces.23
8.6 Combining elements and effects .24
8.7 Distinguishability.24
ISO 9241-910:2011(E)
9 The range of tactile/haptic interface devices.24
9.1 General.24
9.2 Selection criteria.24
Annex A (informative) Tactile devices.35
Annex B (informative) Tactile/haptic devices that provide force feedback.39
Annex C (informative) Physiology of haptics.44
Bibliography .50
iv © ISO 2011 – All rights reserved
ISO 9241-910:2011(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 9241-910 was prepared by Technical Committee ISO/TC 159, Ergonomics, Subcommittee SC 4,
Ergonomics of human-system interaction.
ISO 9241 consists of the following parts, under the general title Ergonomic requirements for office work with
visual display terminals (VDTs):
⎯ Part 1: General introduction
⎯ Part 2: Guidance on task requirements
⎯ Part 4: Keyboard requirements
⎯ Part 5: Workstation layout and postural requirements
⎯ Part 6: Guidance on the work environment
⎯ Part 9: Requirements for non-keyboard input devices
⎯ Part 11: Guidance on usability
⎯ Part 12: Presentation of information
⎯ Part 13: User guidance
⎯ Part 14: Menu dialogues
⎯ Part 15: Command dialogues
⎯ Part 16: Direct manipulation dialogues
⎯ Part 17: Form filling dialogues
ISO 9241 also consists of the following parts, under the general title Ergonomics of human-system interaction:
⎯ Part 20: Accessibility guidelines for information/communication technology (ICT) equipment and services
⎯ Part 100: Introduction to standards related to software ergonomics [Technical Report]
⎯ Part 110: Dialogue principles
ISO 9241-910:2011(E)
⎯ Part 129: Guidance on software individualization
⎯ Part 143: Forms
⎯ Part 151: Guidance on World Wide Web user interfaces
⎯ Part 171: Guidance on software accessibility
⎯ Part 210: Human-centred design for interactive systems
⎯ Part 300: Introduction to electronic visual display requirements
⎯ Part 302: Terminology for electronic visual displays
⎯ Part 303: Requirements for electronic visual displays
⎯ Part 304: User performance test methods for electronic visual displays
⎯ Part 305: Optical laboratory test methods for electronic visual displays
⎯ Part 306: Field assessment methods for electronic visual displays
⎯ Part 307: Analysis and compliance test methods for electronic visual displays
⎯ Part 308: Surface-conduction electron-emitter displays (SED) [Technical Report]
⎯ Part 309: Organic light-emitting diode (OLED) displays [Technical Report]
⎯ Part 310: Visibility, aesthetics and ergonomics of pixel defects [Technical Report]
⎯ Part 400: Principles and requirements for physical input devices
⎯ Part 410: Design criteria for physical input devices
⎯ Part 411: Evaluation methods for the design of physical input devices [Technical Specifiction]
⎯ Part 420: Selection of physical input devices
⎯ Part 910: Framework for tactile and haptic interaction
⎯ Part 920: Guidance on tactile and haptic interactions
The following parts are under preparation:
⎯ Part 154: Interactive voice response (IVR) applications
Human-centred design and evaluation methods, optical characteristics of autostereoscopic displays, and
requirements, analysis and compliance test methods for the reduction of photosensitive seizures are to form
the subjects of future parts 230, 331 and 391.
vi © ISO 2011 – All rights reserved
ISO 9241-910:2011(E)
Introduction
Tactile and haptic interactions are becoming increasingly important as candidate interaction modalities in
computer systems such as special-purpose computing environments (e.g. simulation) and assistive
technologies.
While considerable research exists, it involves a wide diversity of terms, meanings of terms, viewpoints,
software and hardware objects, attributes and interactions. This diversity can lead to serious ergonomic
difficulties for both developers and users of tactile/haptic interactions.
This part of ISO 9241 provides a common set of terms, definitions and descriptions for the various concepts
central to the design and use of tactile/haptic interactions. It includes basic guidance (including references to
related standards) in the design of tactile/haptic interactions. It also provides an overview of the range of
tactile/haptic applications, objects, attributes and interactions.
INTERNATIONAL STANDARD ISO 9241-910:2011(E)
Ergonomics of human-system interaction —
Part 910:
Framework for tactile and haptic interaction
1 Scope
This part of ISO 9241 provides a framework for understanding and communicating various aspects of
tactile/haptic interaction. It defines terms, describes structures and models, and gives explanations related to
the other parts of the ISO 9241 “900” subseries. It also provides guidance on how various forms of interaction
can be applied to a variety of user tasks.
It is applicable to all types of interactive systems making use of tactile/haptic devices and interactions.
It does not address purely kinaesthetic interactions, such as gestures, although it might be useful for
understanding such interactions.
2 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
2.1
haptics, noun
sensory and/or motor activity based in the skin, muscles, joints and tendons
NOTE Haptics consists of two parts: touch and kinaesthesis.
2.2
haptic, adj
appertaining to haptics
NOTE While there is no difference between haptic and tactile in most dictionary definitions, in the area of haptics,
researchers and developers use haptic to include all haptic sensations, while tactile is limited to mechanical stimulation of
the skin. In ISO 9241, the word haptic covers all touch sensations and tactile is used in a more specific manner. Also, both
terms can be used together to assist in searches.
2.3
touch
sense based on receptors in the skin
NOTE Cutaneous receptors are used for the perception of touch.
2.4
cutaneous
belonging to the skin
NOTE Cutaneous receptors respond to mechanical stimulation and temperature changes.
ISO 9241-910:2011(E)
2.5
tactile
appertaining to touch
2.6
vibrotactile
vibration-based stimulation of the skin
EXAMPLE A cellular phone uses vibrotactile stimulation to alert the user.
2.7
kinaesthesis, noun
sense and motor activity based in the muscles, joints and tendons
NOTE 1 Kinaesthesis includes both input and output.
NOTE 2 Receptors in the muscles, joints and tendons are used for the perception of kinaesthesis.
NOTE 3 Muscles, tendons and joints are used for motor activity.
2.8
kinaesthetic, adj
appertaining to kinaesthesis
NOTE 1 Types of kinaesthetic sensation arise from force, movement, position, displacement and joint angle.
NOTE 2 Types of kinaesthetic actions include movement, exertion of force and torque, and achievement of position,
displacement and joint angle.
NOTE 3 Proprioception refers to the sense of one's own body position and movement. This term is often used
interchangeably with kinaesthesis, although the latter is concerned more with motion. The sense of balance, for example,
might fall more under proprioception than kinaesthesis.
2.9
force feedback
force presented to and detected by a user
NOTE Although this does not necessarily involve feedback, the term “force feedback” is commonly used in this
context.
2.10
perceptual illusion
perception that does not correspond to a physical measurement of the stimulus source
2.11
sensory adaptation
change over time in the responsiveness of the sensory system to a constant stimulus
2.12
(tactile/haptic) spatial masking
effect that occurs when a distracter stimulus, which is close to the target stimulus, degrades the perception of
the target
2.13
(tactile/haptic) temporal masking
effect that occurs when a distracter stimulus, which is presented immediately preceding or following a target
stimulus, degrades the perception of the target
2 © ISO 2011 – All rights reserved
ISO 9241-910:2011(E)
2.14
tactile/haptic object
component of an interactive system that a user can interact with haptically
2.15
(tactile/haptic) user interface element
entity of a user interface that is presented in a tactile/haptic form
2.16
(tactile/haptic) task primitive
fundamental action of a user for carrying out the tasks for which the device is designed
2.17
tactile label
label of a user interface element that is presented in the tactile/haptic modality
2.18
tactile map
map that is presented in the tactile/haptic modality with input functions
NOTE 1 The input functions include finger touching, lifting off, or moving across the map for producing position and
selection.
NOTE 2 Tactile maps are often used to help blind people navigate.
2.19
stiffness
hardness
elasticity
haptic response to interactions involving force normal to a virtual object's surface
NOTE 1 “Stiffness” is often known as “hardness” when applied to rigid material.
NOTE 2 “Stiffness” is often known as “elasticity” when applied to soft material.
NOTE 3 Maximum stiffness is the highest equivalent spring constant of a virtual surface that can be provided by the
device without instability.
2.20
burst
intentionally short tactile/haptic stimulation
NOTE A burst typically lasts between 10 ms and 1 s.
2.21
probe
object in a virtual space that is under the control of a tactile/haptic device
2.22
spatial resolution
degree to which the physical output from a user can be utilized by the device
2.23
addressability
ability to address a specific point or set of points in a workspace
ISO 9241-910:2011(E)
3 Introduction to haptics
The science of haptics and the creation of tactile/haptic devices depend on knowledge of the human body,
especially on its capability to sense both touch to the skin and kinaesthetic activity in the limbs and body joints.
Figure 1 shows the relationship between the components that make up the field of haptics. The field is divided
between the study of touch and the study of kinaesthesis.
Figure 1 — The components of haptics
“Touch” includes such diverse stimuli as mechanical, thermal, chemical and electrical stimulation to the skin.
Specific nerves and sensing organs in the skin respond to these stimuli with different spatial and temporal
resolutions.
The kinaesthetic sense can be matched by kinaesthetic activity by which a user exerts force or torque on an
object external to the active body part. With the combination of kinaesthetic sensing and kinaesthetic activity,
the user can detect the force and torque with which the body resists the force and torque of a tactile/haptic
device. Likewise, by imposing a measured force and torque on an object, the user can determine macro
properties such as its inertia.
Kinaesthesis is thereby bi-directional, both sensing the environment and actively manipulating it in a two-way
exchange of information and action.
NOTE 1 Active touch involves kinaesthesis, passive touch does not. Active and passive touch are often very useful
concepts by which to distinguish interactions. In interactions, it is not always possible to identify the two concepts with
particular devices. Depending on the task, one form of touch might be superior to another.
NOTE 2 Interaction with tactile/haptic devices might use different combinations of these haptic components at multiple
points of contact.
NOTE 3 See Annex C for the details of the physiology of human haptics.
4 © ISO 2011 – All rights reserved
ISO 9241-910:2011(E)
4 Human haptic exploration
4.1 Importance of the haptic sense
Haptics is of great importance for human life, much more so than is generally recognized. For instance, when
you are searching for an object in your pocket or bag without the help of vision, haptics is engaged. When you
identify the object you wanted, grasp it with suitable force and take it out, your actions are based on haptics.
This sense can identify common objects quite efficiently, with near perfect discrimination within a few seconds,
especially when the observer has some expectation about the options.
By palpating the surface of a body, a physician can obtain information about the conditions of organs under
the skin and fat layers, conditions that cannot be perceived visually.
The haptic sense can also allow remote touching, as when a distant object is probed with a tool. For example,
a visually impaired person may use a cane to perceive the properties of the ground at the tip of the cane.
The hands, in particular, have had an enormous importance in the biological and cultural development of
human beings in their contact with the environment. They are at the same time useful for both perception and
action in a continuous interaction with the environment. A hand has an impressive ability to adapt to many
different kinds of manipulation tasks, from very small ones requiring high precision to large ones where large
forces are needed. The actions are at all times guided by haptic feedback.
However, haptics within computer applications is new compared to visual and auditory interactions and is still
relatively limited. Present-day tactile/haptic devices still need much development before they can fully utilize
the capacity of the haptic sense.
Touch is also often used to confirm information we gain about the reality of the world.
4.2 Haptics and vision
4.2.1 Similarities and differences between haptics and vision
Haptics has many properties in common with vision. It can be used to locate objects in relation to the observer
in near space (but only within arm's reach unless a tool is used), to find edges separating surfaces and to
perceive the size and form of objects (that are not too large to be explored by a person). In perceiving texture,
haptics not only matches vision but is, in many conditions, superior to it.
In some tasks, haptics lags considerably behind vision or cannot perform the task at all. For example, it is
unable to be used to get an overview of a scene, perceive 3D space beyond arm's reach, perceive colours, or
perceive edges in a 2D picture without embossment.
In other tasks, haptics is superior to vision. With haptics, we can directly judge the weight of objects, as well
as their hardness and temperature. Vision can to some extent perceive such object properties, but only by
observing another person's actions.
4.2.2 Co-location of visual and haptic space
In the real world, objects are usually perceived to occupy the same location visually and tactually but, in virtual
worlds, this is not necessarily the case. The visual object can be located on a screen, while the haptic object
has another location — presented on a tactile/haptic device by the side of the keyboard, for example.
Advantages of co-location have been shown for object targeting and for perception of form. Informally, it has
also been found that performing tasks such as finding knobs and regaining contact with lost virtual objects
was facilitated under co-location conditions.
Combining the visual and haptic modalities can enrich a user's perception of a scene. The visual sense might
dominate at first, allowing a quick overview of a scene and identification of objects in the scene. But a tactile
display can allow a more rapid judgment of the texture of an object. The relative distances of objects can be
ISO 9241-910:2011(E)
perceived haptically within personal space, reinforcing visual judgment of the distances. Then object
properties such as mass and deformability can be confirmed only through the haptic sense.
EXAMPLE A pianist, when sight-reading music, relies on haptics to locate the position of the notes on the keyboard,
but, while playing from memory, utilizes visual and haptic modalities together, making the performance more relaxed and
thus enriching it.
4.2.3 Implications for haptic displays
The differences between vision and haptics make it hazardous to simply render copies of visual objects in
order to present them haptically. Such copying might succeed in simple cases, but problems will often occur in
more complex ones. It is important that the creation of effective haptic scenes involves the haptic
consideration of their properties. An effective visual rendering of a scene is no guarantee that the same scene
can be successfully rendered in a haptic sense.
Advantage can be taken of the ability of the body to quickly coordinate cross-modal maps of its environment.
Both visual and tactile senses can work together to allow a more rapid location of a stimulus than is possible
with either modality alone.
Other prediction experiments have shown that dynamic tactile information can be used to reorient visual
attention, and that dynamic visual information can be used to accurately reorient tactile information.
4.3 Manual exploration of objects
The movements of an observer during haptic exploration of the environment are typically not random, but are
specifically directed to acquire desired information. These movement patterns, called exploratory procedures,
consist of a number of basic procedures such as
a) lateral motion for perceiving texture,
b) pressure for perceiving hardness,
c) unsupported holding for perceiving weight,
d) enclosure (enclosing an object in a hand or both hands) for perceiving global shape and volume, and
e) contour-following for perceiving global shape and exact shape.
Tactile/haptic devices might limit the exploratory procedures that are available to a user, significantly
decreasing exploratory performance. Special training in the movements useful for specific displays can
partially compensate for this lack.
4.4 Training in exploratory procedures
Texture is less of a problem for the perception of objects than is shape. This might be because the exploratory
procedure for texture is much simpler than that for shape. When exploring for texture, the user might make
arbitrary movements over the object's surface, while exploring for shape requires quite specific movements.
However, training in appropriate exploratory procedures for a given shape can result in much better
performance. This is important to consider when evaluating haptic displays, as there is a risk of under-
estimating the usefulness of a device if the users have insufficient experience with the device.
6 © ISO 2011 – All rights reserved
ISO 9241-910:2011(E)
4.5 The problem of getting an overview of a scene with haptics
One of the most difficult problems with haptics in many practical contexts is gaining an overview of a scene. In
vision, this overview is carried out almost instantaneously. There are situations where a “haptic glance” (short
contact with the object) can provide something of the same quality as vision, especially when the observer has
hypotheses about the object in question. However, it is usually a laborious and time-consuming task to identify
objects in more complex conditions using haptics alone. It is often useful to enhance haptics with auditory or
visual information. For instance, there could be verbal or textual information about the object, or instructions
about how to explore the scene.
4.6 Minimum physical stimulation: absolute thresholds
Haptic perception is based on many kinds of sensors in the skin, as well as in the muscles, tendons and joints.
A minimum of physical stimulation, called absolute threshold, is needed to get the sensors to react and send
messages providing experience for the observer. Many physical events can stimulate the skin, from a light
brush stroke to pressure from points, edges, corners and curvature. They might cause skin motion, skin
stretch or vibration, and require different amounts of energy to be perceived. The spatial acuity of the skin has
been found to be around 1 mm. In general, the hand is not as good in spatial discrimination as the eye but is
better than the ear. With regards to temporal discrimination, the hand is better than the eye, but poorer at it
than the ear.
The skin is a large sense organ and its different parts vary in sensitivity. The fingertips are among the most
sensitive parts and best suited to exploring the environment. The lips and the mouth are also very sensitive.
This particular sensitivity has recently been utilized by the development of a tactile/haptic device that is to be
placed in the mouth. Less sensitive parts of the body, such as the stomach and back, have also been used as
locations for tactile/haptic devices, but spatial resolution in these locations is much lower than in the hands
and mouth.
It is important to consider the age of potential users of tactile/haptic devices, since there is a considerable
decline in haptic sensitivity with age.
4.7 Minimum differences needed for perception
A minimum of physical difference between two stimulations is necessary for an observer to experience the
difference. This is called the difference threshold or “just noticeable difference” (JND).
EXAMPLE 1 In discerning the difference in the direction of two forces, the difference is at least 33° in order for the
difference to be detected.
EXAMPLE 2 In comparing objects by squeezing them, the resistance force in one is about 7 % larger than in the other
in order for the difference to be detected.
4.8 Perception of geometric properties of objects
Object properties can be divided into geometric and material properties. Size and shape are geometric
properties commonly used for the identification of objects. In the real world, the exploratory procedures of
enclosure and contour-following are used to gain this information. These procedures are not always possible
with current haptic displays. Perception of shape is possible with such displays but is less efficient and more
time-consuming than in the real world. One key reason for this is that most tactile/haptic devices offer a single
point of contact.
4.9 Perception of weight
Haptic perception of weight has been studied since the nineteenth century. Such studies recently took a new
direction in considering how people judge weight on the basis of wielding the object to be judged. The
stimulation in this case is the resistance to the rotational torque picked up by the haptic system. Properties
such as the length of a rod or the form of an object can be judged by wielding the rod or object. The amount of
liquid in an opaque container can be judged by haptics alone when the container is shaken.
ISO 9241-910:2011(E)
4.10 Perception of material properties
An object's surface can have many material properties. It can vary from hard to soft, as well as from smooth to
rough. The latter property is called texture, and depends on the microstructure of the surface — regular or
irregular deviations from complete evenness. Microstructure can be contrasted with macrostructure that gives
shape. Soft/hard and smooth/rough are the two main perceptual dimensions of haptically perceived objects.
Another is sticky/slippery, based on the degree of resistance a surface makes to movements along it. There
have been efforts to render thermal properties, but they have so far not been very successful.
In the real world there are complex interactions between the haptic, visual and auditory senses when texture
is perceived. Sometimes they complement each other, sometimes they are in conflict, and one can dominate
the others. The combined effects of all three aspects have to be taken into account when multisensory
rendering is being considered.
Texture is typically perceived when a textured surface is in direct contact with a rubbing finger. But texture can
also be perceived in other ways, such as by means of a hand tool — a rigid link between skin and surface.
This method can be useful in virtual environments for rendering texture.
In contrast to shape, virtual surface properties are relatively easy to judge by haptics in both real and virtual
worlds. In an experiment where the roughness of both real and virtual sandpaper was explored with a stylus,
the judgements were very similar. However, there are sometimes problems with rendering complex, realistic
haptic textures.
4.11 Number and size of contact surfaces in tactile/haptic devices
When a hand is functioning naturally, there are several contact surfaces, with the tips of several fingers
typically on a surface at one time. In many present-day haptic displays, the number of contacts is low and, in
most cases, it is just one. The virtual contact surface itself is also, except in a few devices, represented by
only a single point. This gives a contact analogue, but not a realistic simulation.
When only one contact area is used, it is not possible to get simultaneous information from several contact
areas; only successive information is available.
The use of only one finger means that enclosure cannot be used.
NOTE Enclosure is an important exploratory procedure for perceiving global shape in which several fingers grasp an
object.
Results from perceptual studies have shown that the lack of spatially-distributed information across the
contact points is more important than the actual number of contact points.
4.12 Summary
Even if the haptic sense cannot provide an immediate overview of a space and cannot cover distances out of
arm's reach, it has great efficiency in providing information about objects and events in near space. The hands
can very competently perform many tasks in real environments. They can judge geometric and material
surface properties by specific exploratory procedures. They can determine weight and form by wielding the
object and feeling its translational and rotational inertia (as in ascertaining the amount of fluid in a shaken
container).
When rendering objects and events for haptic perception, it is important to consider the special properties of
the haptic senses. Devices and software currently available provide good analogue clues that allow the partial
rendering of haptic scenes. On the other hand, they limit the ways in which the user can perceive a scene by
haptic means. Future devices might well make use of more of the haptic sensing modalities available to the
human operator.
8 © ISO 2011 – All rights reserved
ISO 9241-910:2011(E)
5 When to use tactile/haptic interactions
5.1 General
Tactile and haptic devices can be used in many different situations and for many different tasks. For some
tasks they are interchangeable, for some they can be used together and for others the nature of the particular
type of feedback means that one type is most effective.
Due to their compact size and power requirements, tactile displays offer a discrete, affordable means of
providing access to data via the sense of touch. Tactile displays are often small enough to be mounted on
other interaction devices such as a mouse, keyboard or games controller, or portable devices such as mobile
telephones and personal digital assistants (or even on tactile/haptic devices providing force feedback). Tactile
information is widely used within the video gaming community as an inexpensive means of providing touch
feedback in handheld games controllers. Tactile sensations are crucial to success in object manipulation,
edge detection and texture perception. They are also implicated in more expressive and qualitative contexts
such as non-visual communication (e.g. a tap on the shoulder or a caress on the hand), and perceptions of
product quality.
Tactile/haptic devices providing force feedback are typically much larger than purely tactile ones and require
more power to exert stronger forces. Therefore, they are not usually mobile. They are more commonly
focused on simulating real world tasks, e.g. work on surgery simulation and training. Their high fidelity and
accuracy means that they can be used to teach subtle touch-based skills, even when these require the
simulation of very heavy or dynamic objects.
In some respects it is easier to simulate the larger forces required to interact with objects kinaesthetically
rather than the smaller cutaneous ones for tactile feedback, so devices that provide force feedback can often
make more-realistic-feeling objects than tactile ones can. The following sections outline some of the major
areas of use of tactile and force feedback displays.
5.2 Accessibility
Haptic displays can offer an alternative channel through which to pre
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