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Handheld GPS device helps blind
steer safely through the metropolitan jungle
Dermot
McGrath
in Dublin
A
HIGH-tech handheld navigation tool is set to revolutionise travel
for the blind and partially sighted by helping them find their way
around the urban jungle.
The device, which uses advanced European Space Agency (ESA) satellite
technology to locate and guide pedestrians in real time over a wireless
internet connection, is being put through its paces is on European
streets by volunteers from ONCE, Spain's national organisation for
the blind.
The application enables access to precise locations, directions
and routing, detailed descriptions of surroundings such as points
of interest, and other co-ordinates. It promises, in time, to reinvent
travel for visually impaired people, offering them unprecedented
levels of independence and confidence in navigating the most complex
urban environments.
Current satellite navigation based on the global positioning system
(GPS) works well for many location-based services, but lacks the
precision blind people require for detailed navigation along city
streets.
This is mainly because tall buildings in urban areas — as
well as other obstacles like trees — impede the ability of
receivers on the ground to track GPS satellites, resulting in a
positioning accuracy that is often little better than 30 to 40 metres.
To improve the accuracy of GPS positioning to a few metres, Europe
is developing the European Geostationary Navigation Overlay Service
(EGNOS), which broadcasts augmentation signals through geostationary
satellites, enabling receivers on the ground to correct errors in
GPS signals.
To surmount the problem of buildings obscuring the EGNOS signal,
the European Space Agency created a complementary technology known
as SISNeT (Signal-In-Space through the internet) to relay the signal
in real time over the internet using wireless networks.
The new handheld system, developed by Spanish company GMV Sistemas,
makes use of this technology to improve the accuracy of GPS positions
to a few metres, making it sensitive enough to locate obstacles
in the street.
GMV Sistemas' personal navigator for the blind, known as TORMES
(developed for ONCE), includes a Braille keyboard, a voice synthesiser
and a GPS receiver. The latest version comes packed with an ‘always-on’
GPRS wireless internet connection, providing access to the SISNeT
services.
All this high-tech gadgetry gives users constant updates about their
location and tells them which street they are walking on, which
buildings are near them and when they are approaching a junction.
“We think the addition of Sisnet to Tormes is very interesting.
It should allow the blind user to navigate using a map, just as
a sighted person can,” said Alfredo Catalina, who is overseeing
the project at GMV.
The addition of an Internet connection also has the potential to
enhance the function of personal navigators in other ways.
“When you are connected to the Internet you can also send
messages back. You can ask for directions to a particular place
or say that you are lost or have had an accident. By connecting
the Internet to the world of navigation with, we are opening up
many new possibilities,” said the ESA’s Javier Ventura-Traveset.
Tests on the Tormes system began in early February and will continue
for several months.
“We plan to do two tests, one with and one without the EGNOS/SISNeT
technology so that we can compare them. Members of ONCE will be
helping to define the tests and assess the performance of the technology,”
Felix Toran-Marti from the ESA said.
EGNOS is the first element of the European satellite navigation
strategy and a major stepping-stone towards Galileo, Europe’s
global satellite navigation system for the future.
Consisting of 30 satellites in medium-Earth orbit, plus an associated
network of ground stations, Galileo is expected to deliver an independent,
civilian-controlled positioning service worldwide with metre-scale
accuracy.
The introduction of Tormes follows the United Kingdom launch in
late 2002 of another PDA-type device for people with visual difficulties.
The Victor Trekker, designed and manufactured by Canada-based company
VisuAid, in association with the Royal National Institute for the
Blind (RNIB), also uses a GPS system hooked up to an electronic
voice box, which tells users where they are as well as giving them
precise directions to their destination.
The developers stress, however, that the device was not intended
to replace completely the white cane or guide dog because it cannot
detect small obstacles 0.6 to 0.9 metres (2ft to 3ft) in front of
people as they walked.
The Victor Trekker is also prone to the problem of erratic GPS coverage
in narrow streets with tall buildings, which Tormes is currently
trying to overcome.
Javier
Ventura-Traveset PhD
EGNOS Principal System Engineer
Email: Javier.Ventura-Traveset@esa.int
Felix Toran-Marti
EGNOS System and Analysis Engineer
Email: Felix.Toran@esa.int
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