=Paper=
{{Paper
|id=Vol-1324/paper_7
|storemode=property
|title=Blind User Requirements to Support Tactile Mobility
|pdfUrl=https://ceur-ws.org/Vol-1324/paper_7.pdf
|volume=Vol-1324
|dblpUrl=https://dblp.org/rec/conf/tabletop/ConradieMS14
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==Blind User Requirements to Support Tactile Mobility==
https://ceur-ws.org/Vol-1324/paper_7.pdf
Blind User Requirements to Support Tactile Mobility
Peter Conradie Tina Mioch Jelle Saldien
Department of Industrial System and TNO Department of Industrial System and
Product Design, Faculty of Kampweg 5, Product Design, Faculty of
Engineering and Architecture, Ghent Engineering and Architecture, Ghent
University 3769 DE Soesterberg, The University
Graaf Karel de Goedelaan 5 Netherlands Graaf Karel de Goedelaan 5
8500, Kortrijk, Belgium Tina.Mioch@tno.nl 8500, Kortrijk, Belgium
Peter.Conradie@UGent.be Jelle.Saldien@UGent.be
ABSTRACT Tactile and haptic information is an important source for blind
Various innovations have been identified in assistive technology persons to improve orientation and mobility [6]. Technological
for the visually impaired. One of these innovations are systems improvements, both non-visual communication targeted for non-
that present feedback and information in a tactile format. These disabled persons [2][3], and applications specifically introduced to
tactile systems have the potential to help the visually impaired, support blind mobility using non-visual tactile displays [23], can
but there is little attention to how it can be combined with other offer assistance to blind persons.
assistive technology. In this research, we present a set of user Yet, the adoption of assistive devices is not always optimal, and
requirements for tactile systems, focusing on the needs of the abandonment rates can be up to 29% [12]. For example Bateni
visually impaired. This is done by telephone, personal, and group and Maki [1] note that while devices to assist mobility and
interviews. As a result, we identify three themes related to the use balance (walkers and canes) benefit their users, persons often have
of non-visual tactile assistive devices for blind persons: 1) context problems using them. Lack of end-customer involvement has been
of use, 2) trust issues, and 3) user interaction. Our identified as contributing factor to high abandonment [13] of such
recommendations include focusing on a devices that solve very assistive devices.
specific mobility problems, being transparent with users about
This suggests that, while innovations such as tactile feedback on
system status such as battery life and accuracy, and limiting
tablet interfaces can provide valuable improvements to the
output to prevent overload.
personal wellbeing of blind persons, we also need to take into
account the user experience of these devices. In addition, it is
Categories and Subject Descriptors important to better understand the user needs and concerns in the
K.4.2 [Social Issues]: Assistive technologies for persons with design and development of tactile mobility devices.
disabilities.
To do this, we propose a user centred design approach for the
conceptualization and design of these devices. This attitude to
General Terms design is based on the active involvement of users to improve the
Human Factors understanding of user and task requirements, and the iteration of
design and evaluation [9]. Moreover, the context of use is also an
Keywords important factor in understanding the end user [19].
Blind mobility, assistive devices, user requirements, tactile In this paper, we identify relevant user requirements for the
feedback development of non-visual tactile assistive devices for blind
persons. Finally, we focus specifically on the wishes for the
design of a tactile feedback device, emphasizing tactile
1. INTRODUCTION interaction.
Mobility is an important contributing factor to wellbeing [15]. For
various persons with disabilities, having support (both social and The remainder of the paper is structured as follows: Section 2 will
technological) to increase their mobility can contribute to quality review related efforts to understand mobility needs of blind
of life. persons, in addition to providing a brief overview of systems that
improve blind mobility. Section 3 will briefly introduce the
process of developing a system to improve the mobility of the
Permission to make digital or hard copies of part or all of this work for blind. Section 4 will present the method used during this study,
personal or classroom use is granted without fee provided that copies are while Section 5 will introduce the themes encountered during
not made or distributed for profit or commercial advantage and that interviews. In Section 6 we will discuss the implications of these
copies bear this notice and the full citation on the first page. Copyrights results, while in Section 7 we conclude and suggest future
for third-party components of this work must be honored. For all other research.
uses, contact the Owner/Author.
Copyright is held by the owner/author(s). 2. RELATED WORK
Not being able to see can be a significant barrier to mobility [15]
TacTT '14, Nov 16 2014, Dresden, Germany and for blind persons, contextual information provided as audio or
tactile information can be beneficial [6][24]. As a result, systems
User Requirements System Requirements Functional Requirements
User wants to be notified of System Interaction System shall notify user of Camera must detect certain
obstacles in collision path obstacles obstacles
User Input
User wants to locate certain System shall assist user in Tactile feedback must alert users
places finding locations of obstacles
User wants to reposition System feedback System shall identify important Tactile feedback must allow user
themselves objects re-orientation
etc... etc... etc..
Environment
Figure 1. Depiction of the process from user requirements to system and functional requirements. For illustration purposes,
some examples are included in the figure
that provide blind persons with information about their of obstacles. Particularly notable is the distrust of technology by
surroundings to support mobility make use of either auditory or respondents. Finally, Williams et al. [21] interviewed 30 blind
tactile substitution [24]. These systems may receive input from persons regarding their mobility, focusing on assistive devices in
one or many sensors, such as GPS [8], stereo vision cameras [22], general but also including elements such as mobility training.
external RFID tags [16], or online map sources [14]. The ability These examples highlight some related work on understanding
for touch-based tablet interfaces to provide tactile feedback thus blind mobility from a user perspective. Our aim in this paper is to
presents the chance to contribute to user wellbeing, by providing expand on this research to include user research on blind mobility
users with information about geographical landmarks, or especially in the context of tactile devices,. We also taking
obstacles, without the need for sight. emphasise the contextual use of current assistive devices and how
MoBIC, is an example of such a system. Introduced by Strothotte comfortable people are using the system, presented as system
et al. [18], it uses a touch enabled tablet that helps blind persons to trust.
explore a map. The system gives audio feedback about locations.
KnowWhere [5] similarly projects a 2D image, while a camera 3. USER CENTERED DESIGN APPROACH
translates visual map features to sounds when the blind person This research is being performed within an EU project to develop
touches particular geographic features on the projected image. a standalone prototype that detects close range obstacles and can
Likewise, the Talking Tactile Tablet [7] presents blind persons recognize objects such as doors or stairs. Based on individual
with audio information about visual maps. needs and with respect to context, presentation of information will
While these systems uses tablet-like displays to translate map be in tactile and/or audio modality. The system consists, in part, of
environments to audio, Zeng and Weber [23] introduces a system a 3D, time-of-flight DepthSense camera by SoftKinetic, combined
that translates geo-data to an audio haptic map that blind persons with a wearable tactile display developed by Elitac.
can use to find their way. The Talking TMAP [10] takes a similar The current exploratory study is part of a general system
approach, also offering tactile information in the form of Braille, requirements analysis that is being done to ensure a system that
including scale indications and street names. will be not only technically feasible, but also optimally adjusted to
Among these, we also identify solutions intended for mobile use, the users’ needs. When developing personalized support systems,
such as TANIA [4], which provides blind and visually impaired an iterative development process is necessary. After each cycle,
persons with surrounding information, using a wearable tablet that the requirements the system needs to fulfil are revisited, leading to
can be connected to a mobile braille display. The system relies on validations and refinements.
GPS and maps to guide the user, while the tablet display provides In Figure 1, the process that we will use to develop the system is
information about the location. depicted. Operational demands, human factor knowledge, and
These examples show the variation of assistive devices, spanning envisioned technology are taken into account to explicitly derive
tactile and audio feedback and relying on various input sensors to use-cases, requirements, and give a rationale for the requirements.
capture data. Several authors have also studied blind persons in The use cases put the requirements into context. Through
order to understand mobility and needs associated with mobility, interviews, where scenarios are presented and used as a basis for
with the goal of user requirements for assistive devices, or to discussion, user requirements are determined, which are
increase understanding of mobility. consequently translated into functional requirements and technical
requirements. The user requirements form the basis of the
For example, Strelow [17] looked at how blind people walk to development of the system, and deriving them should be of
develop a theory of mobility. The author notes specific skills such utmost importance and focus in the initials phase, but also during
as a sense for the location of obstacles, the use of canes to aid the development of the system.
mobility, or echo localization.
In the following, it is described how the user requirements have
Völkel et al. [20] describe requirements for geographical data been derived, and an overview is given over the most relevant
annotation for blind persons, with map based navigation as focus. user requirements for the proposed system.
They stress the issues of low thresholds such as curbs but also the
heterogeneity of the target group. Paredes et al. [11] similarly
interviewed visually impaired persons in the context of a system
that provides audio based feedback to blind persons to alert them
4. METHOD For our respondents the guide dog also plays a prominent role.
Our method consists of interviews, conducted during several Not only does the dog help to navigate around obstacles, but it
sessions with blind persons. First, 6 interviews were held by also plays an important social function, with passers-by
phone (4 female, 2 male). Telephone interviews ranged from 32 approaching the dog, or striking up a conversation. For some
minutes to 104 minutes. Interviews on location were limited to 60 persons, the dog also acts as driving force to leave the house and
minutes, while group interviews were 2 hours. Data was recorded go for a walk.
and statements cards were made using the audio recording. These Participants make the distinction between primary or secondary
were subsequently analysed to finally arrive at the presented assistance, which can change depending on the current situation,
themes. destination and route. For example, the white cane may be the
A loose script was followed, structured in four parts. First, general primary assistive device in certain situations where the surface is
demographic data were collected such as sex, age, location, uneven, while the dog may take over the primary role in indoor
degree, and duration of blindness. Subsequently, we had a general environments. Additionally, when accompanied by a caregiver,
discussion of issues related to blind mobility, using the identified both the cane and the dog (if applicable) may be used only
scenarios as basis. Concluding this, we focused on the use of secondarily, if at all.
current and previous assistive devices, including dogs, but also the Devices are also used and interchanged on a contextual basis. For
role of caregivers. example, when a partner or caregiver takes the role of primary
The use of a hypothetical tactile systems was introduced and assistance, the cane (or dog) plays a less important role.
discussed, where participants were asked to reflect on its use in A participant’s destination and route may further impact the
contexts earlier described, such as going shopping or traveling by combination of devices used. For example, one respondent always
train. Sample questions include: “Do you often travel around?”, takes a digital compass when traveling to a particular metro
“Do you travel with, or without assistance?”, “How far should station where it is hard to discern direction, but leaves the
detection [of unknown obstacles] be necessary?”, and “How compass at home when traveling somewhere else.
would you like to feel the information about obstacles?”.
External factors such as rain or snow also impacts assistive device
These interviews were followed with 2 focus group discussions selection, such as a specific type of cane that is longer and can be
with blind persons. Group 1 contained 9 participants, while group used to feel the street surface through the snow. Additionally, rain
2 contained 12. Interviews were chosen because they allow for may effect how accurate echo localization may be, while snow
rich data to be collected, while also allowing researchers to may have the same effect. An outdoor system should be usable in
follow-up with relevant questions. different (weather) conditions, not being affected by temperature
Finally, 4 follow-up interviews were conducted with persons at or humidity.
home, also examining the home environment. Participants were Significantly, needs differ when discussing mobility indoors vs.
recruited through local organisations for blind persons, digital and outdoors. In an indoor situation, points of interest such as the
analogue communication platforms, and word of mouth. The ages location of a lift, its destination and the location of service
of respondents varied, with the youngest 33 and the oldest 78, all counters are important. Information such as the length of a queue,
living in Belgium. Participants were all over 18 years old and or the current number displayed when queuing at official
included congenital blind persons in addition to people who lost buildings is also of importance.
their sight as a result of illness.
5.1.2 Recommendations
The goal of the interviews described above is to gain a first idea
As illustrated, users rely on a variety of assistive devices that can
and overview of the user requirements for the intended system.
change depending on the context. As a consequence of the above-
During further, the user requirements will be regularly evaluated
mentioned aspects, we present some recommendations.
and re-assessed to be sure that the system will be not only be
acceptable by the users, but be in line of the users’ wishes. Due to the context-based interchange-ability of devices, systems
could focus on solving a very specific problem, while universal
5. THEMES solutions may prove too complex. An example may be the ability
to retrace steps to a previously specified location, or indications of
The following themes have been identified that are of importance
where building exits are.
for the end users about mobility, and which need to be taken into
account when specifying user requirements (and consecutively, The presence of existing assistance also influences the types of
functional and technical requirements): (1) context of use, (2) trust goals and functionalities desired by participants. For example,
issues and (3) interaction with the user. persons with dogs may be less in need of large obstacle detection
and notification, but may rather desire notification of uneven
Below we discuss these themes, focusing on the most important
aspects and several themes that emerged from the interviews. surfaces. In the case of devices that - through tactile feedback –
provide blind persons with contextual information about their
5.1 Context of Use surroundings, the most important information that needs to be
communicated is information that cannot be detected by the
5.1.1 Summary of findings current accompanying assistive devices. For example, for
Currently, the most important assistive devices are the white cane participants with a cane and a dog, there was a strong need to be
and the dog. The white cane is an important device for notified of uneven floor surfaces such as loose street tiles, puddles
participants, both when used actively to assist mobility, but also as or other small holes, or the location of objects that cannot be
a visual and auditory signifier for blind persons, with people detected accurately by a dog.
tapping the cane to alert passers-by of their presence. When
traveling by car with someone, a different cane might be used than Designers of new assistive systems should be aware of the various
when traveling alone. weather conditions in which devices could be used. For example,
for tactile feedback outdoor, cold conditions may prevent proper
feedback. Simultaneously, it is important to provide functions for hearing for echo localization and ambient sounds. None of the
the various goals that may not be met by current devices. participants wears earphones on both ears while traveling (even
The current assistive devices assume that a person has at least one incidentally) with the only exception being earphones that hang
hand available for using the white cane or controlling the dog. down from the ear and still allow ambient sounds to be heard. As
This excludes (or at least makes it more difficult for) people with a consequence, a system to support them should not rely on
a walking impairment, e.g., when sitting in a wheelchair. communicating important or vital information via audio only.
A large emphasis is placed on giving tactile feedback about
5.2 Trust Issues unexpected obstacles. Given that participants worried about
5.2.1 Summary of findings impulse overload, the tactile actuators need to be positioned in a
A recurring theme during the interviews when electronic assistive way that it is not burdensome to experience, not irritating, and not
devices were discussed relates broadly to issues of trust. One in a sensitive place. In addition, the signals should not be
participant insisted on waiting for a device to become popular continuous to prevent overload. Also, it was mentioned that not all
before using it to ensure sufficient training and support. information should be presented: a filter is needed.
Lack of training for devices was also noted as a reason why some As a result, the desired distance detection remained short.
assistive devices did not get used extensively. While training However, in certain cases, longer distances might be preferred,
might be given initially, the use of the particular device is too such as being able to scan a new, unknown path. While memory
complicated and users stated that due to the complexity, they have of a station might be good, having an unexpected new obstacle is
forgotten how to use it and do not want to rely on using the troublesome. This is especially possible in locations such as
system in critical situations. public transport halls, i.e.: before or after taking the train. This
also applies to situations where the stairs are slightly higher, or
These issues are augmented with general fears about the failing of stop abruptly. Given this, the distance might not be as relevant,
technology. Anxiety about power running out at unfortunate but rather the ability to reveal only unexpected obstacles. A
locations, or the accurateness of the system, impacts buying significant concern for some participants was the presence of
decisions. For a blind person, attempting something as potentially cyclists. While cars can be heard, when crossing a road, cyclists
life threatening as crossing the street while relying solely on a are not easily detected.
technological device may seem daunting.
A focus on the interaction with any tactile feedback device that is
One of the participants biggest stated fears were feeling lost in a intended for use outside the home is also important, given that the
new environment. While aides such as GPS systems might offer users hands may already be occupied with the white cane, or
help in such contexts, participants were afraid to rely on them, possibly the dog. Additionally, the cane might go from the left to
stating that they are often made without consideration for blind the right hand, depending on the current situation. In this case,
persons. input devices must be useable and accessible with both hands.
This fear is heightened in situations where there are no bystanders Despite their hands being already occupied, participants
that can assist blind persons to find their way again. While dogs nonetheless stated a preference for a physical input device that can
might be trained in mobility around familiar locations, when be operated by hand. Voice commands were mentioned by some,
arriving in an entirely new situation, they are not always capable but were accompanied by reservations about inference of
of assistance. Subsequent failure of devices in such unknown background noise. A notable preference was also given to cabled
environments impacts the willingness to try them. solutions: this prevents losing the input device.
Given that participants rely heavily on backpacks to carry
5.2.2 Recommendations personal belongings, any mobile system must take into account
As illustrated, safety and trust in the system is a very important
that persons are already carrying something on their back. Any
aspect. The following user requirement can be identified:
newly introduced system should not interfere with the interaction
Systems should reliably provide relevant information when with other assistive devices or necessary resources.
needed, while also considering information accuracy. Designers
Additionally, there was a stated need for two-dimensional
should also consider providing critical features such as re-location
information, in the sense that participants wanted to be able to
or re-positioning, to allow users to find their way back.
discern between obstacles that are higher, such as at chest level, or
Furthermore, users should be provided with system status those on floor.
information that is critical to use. This may include battery status
Directional information is also importance. For example, when
or current system accuracy. Additionally, devices that are used
actively searching for a particular object or location, such as a lift,
outdoor may need easy ways of recharging batteries, or make use
doors, or stairs, being given information about their location
of external batteries.
relative to the direction that the blind person is facing is valuable.
System complexity should also be avoided, to prevent long
In a system where the sensor device such as a camera or infrared
training times. This is especially important because devices may
sensor must be place on the body, initial insights illustrate that
only be used incidentally to solve a specific problem. Finally, it
some adjustability of the wearing location is deemed valuable. For
should not interfere with other safety relevant interaction
example, the wearing location for a sensing device on top of
mechanisms.
summer clothing might be different to a winter coat. While the
5.3 Interaction with User head as sensor location may arguably provide good results due to
its height, is a reluctance to wear any sensing device on the head.
5.3.1 Summary of findings
However, as one respondent suggested, applications such as
While audio based feedback devices are interesting for blind
Google Glass may be interesting in this context, as the relative
persons, participants remained reluctant to rely heavily on audio
size of the device is small and the attention it might attract is less,
feedback outdoor because of the current strong dependence on
than when a large device is worn on the head.
5.3.2 Recommendations As next step, the user requirements will be translated into
From the interviews various requirements are identified related to functional and technical requirements. Based on these, a prototype
user input. First, audio should not be the main mode of feedback, will be built and evaluated with visually impaired participants.
especially in situations where users rely heavily on sound to locate The exploratory study of this paper will be the basis on which the
and orientate themselves. Alternatives to in-ear earphones may be practicability and usefulness of the prototype will be evaluated.
considered, but critical system information is best communicated
via alternative means. 8. Acknowledgements
This research was supported by the EU FP7 SME Program,
The types of obstacles that are communicated to the user should Project 605998 (Range-IT). We would like to thank all interview
be restricted to those that are unexpected. This is especially participants for their effort.
important to limit information overload and reduce system
complexity.
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