Innovative students and professors at the University of Rochester have created a navigational assistant that can help inform a visually impaired person of his whereabouts, or even bring new dimensions to museum navigation or campus tours for sighted individuals. The system, nicknamed "NAVI" for Navigational Assistance for the Visually Impaired, uses radio signals to gauge when someone is near passive transponders that can be as small as a grain of rice and located on the outside of a building, on a specific door inside, or on a painting or object of interest. Biomedical engineering and electrical and computer engineering students in conjunction with professors created the device and have now applied for a patent on the technology.

"This is a wonderful example of our students taking theory from the classroom, knowledge of some of the difficulties faced by some groups of people, and combining that with existing devices to transform it into a real-world application that is of genuine usefulness to people," says Jack Mottley, associate professor of electrical and computer engineering and biomedical engineering.

The system works like the security tags that are frequently on items in retail stores, or those used by certain gasoline stations and fast-food chains that allow you to wave a tiny wand near a detector on a gas pump or cash register. In those circumstances, a radio signal is beamed from the detectors by the door, gas pump, or cash register and is picked up and returned by a tag within a certain range. The security tags simply set off an alarm, while other tags can encode information, allowing the reader to debit your account for the sale.

Mottley and his students decided to turn things around.

The engineering students decided to make the reader portable and affix the tags to stationary objects, like buildings. The system can then use the encoded information to make possible an assistance device for the blind. They built a piece of equipment that was essentially a portable detector coupled to an audio playback device.

The undergraduate students decided to connect a portable CD player to the device, programmed to play a particular track through an earphone whenever a certain tag was detected. It could be a simplistic message such as, "Mr. Smith's office door," to an elaborate discussion of a piece of art in a museum, or the history of a building on a self-guided campus tour. Using a CD player would allow a person to switch CDs for different purposes and locations; for instance, there may be a CD for getting around a city, complete with street names and structures of interest, or another to guide a user throughout an office building. Future incarnations of the device could store information in solid-state memory that could be updated automatically when entering a new building, or allow a person to lay out her own tags and record relevant information for each.

Built of off-the-shelf components, the NAVI device currently is a black box about half the size of a loaf of bread, with a portable CD player and an antenna that looks like a singer's microphone. A final version would probably be as small as a portable CD player, and if solid state memory like those in today's popular MP3 players were incorporated, the entire device may be no larger than a deck of cards.

"To prepare a building or site for use with this system will be relatively inexpensive," Mottley says. "The tags are inexpensive now and the prices are still dropping. The plan is to use only passive tags that do not require batteries or need to be plugged in, meaning once they are installed they can be ignored." Tags could even be painted over without losing their capabilities. An organization using the system would assemble an audio recording of the messages to be played when in proximity of each tag, and then burn compact discs with these messages. When a user comes into a new area or onto a new campus, they would be given a CD that they would put into their own reader. Updates and upgrades will be handled by facility managers by recording new CD's.

In the far future, a NAVI system may find uses well beyond helping the visually impaired navigate their surroundings. Such a personal identifier might be built into cell phones or wristwatches, allowing someone to gain information on almost anything around them, from customer reviews about a shirt they're considering buying, to paying for a soda at a vending machine.

But even the best technology is useless if no one wants to use it, so Mottley and his students are applying for their patent, with the aim of enlisting the aid of a manufacturer to make the system as user-friendly for the visually impaired as possible. Soon they hope to have the system integrated into a new building on the University campus being designed especially for biomedical engineering, as well as to be included in a large-scale upgrade of signage and markings that has been planned for the University.