To: Internet:nfb-rd@nfbcal.org
Greetings:
Remember the discussion about navigational aids for the blind
that I forwarded to this list in late February? Here is Mr.
Kallewaard's summary of the results he received from the BLIND-L
list. I observe that the conclusions he has reached are not much
different from those he originally seemed to have had in the
first place. Note that no specific devices are recommended.
Happy reading.
Cordially, Curtis Chong
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Date: 12-Apr-94 10:57 CDT
From: Patrick Kallewaard >INTERNET:93701420@vax1.dcu.ie
Subj: Summary of points raised on Blind-l re navigation aid
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Date: Tue, 12 Apr 1994 16:54:46 +0000 (GMT)
From: Patrick Kallewaard <93701420@vax1.dcu.ie>
Subject: Summary of points raised on Blind-l re navigation aid
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Dear Curtis,
Firstly let me thank you again for your contribution to the discussion,
you raised many valid points. I have summarised all the main points
raised in the discussion below. I'd appreciate your opinion on what I
have written and any suggestion you may have as to alterations or
inclusions I could make. At the moment I'm drawing up yet another
possible solution to the problem which I hope is more acceptable and
versatile than my last proposal. I look forward to hearing from you.
This report is based on the feedback obtained from many blind and visually
disabled people when asked their opinions and expectations of a navigation
aid. It must be pointed out at this stage that this survey was conducted
over the Internet, which means that the average participant was not the
statistically average visually disabled person in terms of age and income.
Responses varied greatly, from very negative to very positive. The
responses are split up into four main categories. The first category is
arguments which do not favour the development of a navigation aid, the
second is arguments in favour of the development of a navigational aid.
The remaining two categories deal with design considerations of navigational
aids.
Arguments which do not favour
the development of a navigational aid
A common assumption made by many sighted people is that cane and guide
dog users cannot travel independently without a great deal of difficulty and
stress. Given proper training in the use of a primary mobility aid, the
blind can travel wherever they choose to go without a great deal of
difficulty without the benefit of a navigation aid. Learning new areas
should not take a great deal of time, information may easily be acquired
from other people and/or maps. Obtaining information from other people is
a very reliable method of navigation in the sense that is almost always
available. Tactile and braille maps are inexpensive to produce and are
adequate for many areas. Navigation systems can enforce the popularly held
opinion that travel for blind people is an ordeal by implying that they are
helpless without such a system. Negative images of the blind may also lead
to reduced employment prospects since employers may envisage blind
employees as being dependent and hence not as productive.People who use
navigation systems may foster dependency and hence avoid areas not fitted
with navigation systems, which is contradictory to the intended purpose of
a navigation system, namely to increase the overall mobility of people with
a visual disability. The motivation to learn how to correctly use primary
mobility aids may be eroded if navigation systems reduce the need for
having these skills.
Arguments in favour of the development of a navigation aid
While canes and guide dogs are adequate mobility aids in most
everyday situations, they offer a limited amount of information about the
environment. Canes are mobility aids, essential for travel, but they do
not provide information about the layout of an area other than the
immediate area within reach of the cane. Getting information about ones
position within an area and the location of objects in relation to each
other can be done by consulting maps, human guides or navigational aids.
Tactile and braille maps are good at relating fine details but are less
adequate when relating an overall view of an area, a knowledge of braille
may also be required if explicit information is needed. Both human guides
and navigational aids are superior in this respect. In large, complicated
environments, a navigation aid would allow a person to immediately access
information without the need for tactile maps and without constantly having
to ask for directions. Asking for directions in itself is not an ordeal,
but offering an alternative to having to ask them would make life a little
easier, especially if one suffers from speech problems.Navigation aids
would be especially useful in complicated, unfamiliar environments not
likely to be frequented which would make familiarisation with the area
impractical, such as airports, railway stations and so on. They could also
be beneficial on familiar routes as best described below by a respondent;
..anything that could augment the reception of stimuli garnered by the
cane should be welcomed. I disagree that a familiar route presents no
problem to the traveller. The fact is that conditions change--wind
currents, snow, rain, personal attentiveness--and a navigation aid could
surely supplement the meagre information which one can get from the
cane alone. In my travels, I have to deal with rounded corners, and
how many times have I gone too far, and had to retrace...
Snow especially can lead to problems even on familiar routes, covering
familiar landmarks and surface details that would usually be used to
ascertain orientation and position.
Large environments can benefit from navigation systems not just for people
unfamiliar with the area, but as an optional aid that can be consulted if
desired, for instance if one visiting a less well known section of say, a
university campus a navigation device can help in locating such sections as
well as relating information about them in relation to other, well known
sections. An added benefit is that people who use a navigation aid can
easily acquaint themselves with all the services and facilities available
in a particular area and which of these services and facilities located
conveniently.
Audio versus tactile interfaces
What would be the best method of relating navigational information to
a person using a navigation aid? The most common interface types are audio
and tactile. Both have their advantages and disadvantages.
Auditory perception can be very versatile and used for identifying and
locating objects at considerable distances, in contrast to tactile
perception which can only be used to detect and locate objects within the
immediate vicinity. Relating navigational information through tactile
interfaces has the advantage that it leaves ones auditory senses free to
concentrate on gathering the information required for basic mobility as
well as listening to announcements, conversations and so on. Other
advantages that tactile interfaces have over audio interfaces is that audio
interfaces usually consist of loudspeakers or headphones, both of which are
not as discreet as tactile sensors. Up to 30% of people with a visual
disability also suffer from light to severe hearing loss, for whom tactile
interfaces are a better option.Interpreting tactile information other than
locating and identifying objects may require training, whereas audio
information tends to be more self explanatory. Many people cannot read
braille and as such braille tactile information should be avoided. Some
diabetics may also suffer from reduced tactual perception. This would
favour the use of audio interfaces, especially if the information presented
is not continuous but no more than an occasional signal to indicate correct
or incorrect directions of travel. Based on the above advantages and
disadvantages of audio and tactile interfaces, offering a choice of
interface types would seem essential in order to make the device practical
for as wide as possible a range of people. It may be possible to allow a
person to select the degree of information coming from the tactile and
audio information sources to suit his or her needs according to their
environments. The user can thus not only choose his/her preferred
interface type, but also select the degree of information being relayed by
the device, for instance, the device may be consulted if required or set so
as to give continuous navigation signals.Complex information related to a
person through the sense of touch can best be done through braille or moon,
and not only requires knowledge of one or more of these alphabets, but
requires concentration. Verbally communicating complex information is very
effective but also requires concentration. In short, very detailed
information should be avoided unless explicitly requested by the user.
Considerations
Electronic navigation aids must be used in conjunction with existing
travelling techniques if they are to provide a good service. They must in
no way interfere with the travel techniques employed by blind travellers
and must in no way limit the options available to them. In other words, a
navigation aid must complement existing travel techniques and should not
attempt to replace them.A navigation system must not limit the traveller in
any way. Systems which limit the traveller to fixed, pre-defined routes
curtail the independence of the user in the sense that they exert a certain
amount of control over the route options available to him/her. Individual
preferences vary dramatically, what may be suitable for one may be less
than adequate for another, fixed routed do not allow for this. For
example, guide dog users and cane dog users may rely on different aspects
of the environment and may therefore choose different routes. Having to
adhere to rigid routes may also demands concentration and effect ones
ability to give sufficient attention to the various audio and tactile
queues needed for basic mobility.
The position of the user interface is a very important factor. Hand held
electronic devices may be useful but have the disadvantage that any user
will have both hands in use. Fitting a navigation aids to a cane has the
advantage that the aid need not be carried by the free hand as well as
providing a good position for a tactual interface, i.e. on the handle of
the cane. However, integrating a navigation aid with a cane excludes guide
dog users as using both a cane and a guide dog is impractical. It is also
important not to interfere with the information obtained from the cane.
Fitting a navigation aid may affect the canes weight, rigidity and may also
reduce its collapsibility. From a design point of view, mounting sensors
on a helmet can have many potential benefits. However, head mounted
systems are conspicuous and, referring back to the point made earlier
about spreading the image of helplessness and dependency associated with
blind people, are not desirable.
Expense is a major consideration. Developing a system that is costly,
keeping in mind the large percentage of unemployment among the blind, will
limit the amount of people that will benefit from the device. Consider
that only about 10% of the legally blind people in the U.S. use canes,
which are primary mobility aids and cost about $35. While there are many
factors involved in the reasons for this low percentage One of the
main reasons is that despite being legally blind (many (+/- 75%) have
enough vision to allow unaided mobility), it puts into perspective the
value placed on navigation and mobility aids by many blind people. The
finished product must therefore be inexpensive or subsidised.
Alternatively, locally managed areas such as airports and railway stations
could provide a navigational system as a service. This would require that
potential users be alerted as to the availability of the system when
entering the area.
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Patrick L. Kallewaard E-Mail: 93701420@vax1.dcu.ie
Dept. of Electronic Engineering, Phone : +353 +1 7045872
Dublin City Universtiy, Fax : +353 +1 7045508
Glasnevin,
Dublind 9,
Ireland
______________________________________________________________________
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Cordially, Curtis Chong
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