Navigation system offers travel autonomy for the blind
By Mike Hanlon
January 20, 2004
A new device which enables blind people to navigate without other assistance promises unprecedented autonomy for the sight impaired.
The Tormes system is a small computer using the Sonobraille platform, which includes a Braille keyboard and voice synthesiser, plus several navigation technologies to give a high degree of positioning accuracy.
The system can be queried and responds with verbal directions, like any GPS device in a car, but weighing less than one kilo it can be carried over the shoulder.
It can be used in two ways: to guide the user to their destination or to tell them where they are as they walk around. The device has been developed by ONCE, the National Organisation of Spanish Blind people and Spanish company GMV Sistemas and was recently presented to the media in Madrid.
At present, satellite navigation based on GPS is not accurate enough to guide pedestrians, especially around cities. When few GPS satellites are in view because of tall buildings, positioning accuracy can drop to 30 to 40 metres, hardly accurate enough to guide a blind person through a city.
Where Tormes becomes very clever in its design is in the use of the European Space Agency's EGNOS system, which improves the accuracy of GPS positions to a few metres, making it sensitive enough to locate obstacles in the street. EGNOS does this by broadcasting information from geostationary satellites which enables receivers on the ground to correct for errors in GPS signals. A pedestrian in a city of tall buildings, however, is even less likely to be in direct line of sight of an EGNOS satellite than a GPS satellite. So ESA has also developed a complementary technology, SISNET, which relays the EGNOS signal in real time over the internet.
ONCE and ESA are already working on how to improve Tormes.