Visually impaired people often have to take the help of escorts or a passer-by while travelling, but all that may change. A new navigational device Tormes System has been developed, which promises unprecedented travel autonomy to visually impaired people.

The Tormes System consists of a small Sonobraille computer (with a Braille keyboard and voice synthesiser) teamed with several navigation technologies to give a high degree of positioning accuracy. It is easy to carry as it weighs less then a kilogram.

The system can also be used to indicate where a person is, as they walk around. It can be queried and responds with verbal directions, like any Global Positioning System (G.P.S.) device.

At present, satellite navigation based on G.P.S. is not accurate enough to guide pedestrians, especially around cities. This is where Tormes system has an edge. It incorporates the European Space Agency's (E.S.A.), European Geostationary Navigation Overlay Service (Egnos) system. This improves the accuracy of G.P.S. 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 G.P.S. signals.

A pedestrian in a city with high-rise buildings, however, is even less likely to be in direct line of sight of an Egnos satellite than a G.P.S. satellite. So E.S.A. has also developed a complementary technology, Sisnet (or Signal in Space through the Internet), which relays the Egnos signal in real time over the internet.

Tormes System has been developed by the Spanish National Organisation of the Blind (O.N.C.E.) and Spanish company G.M.V. Sistemas. O.N.C.E. and E.S.A. are already working on how to improve Tormes.