Navigation of blind people is extremely restricted because they use the stick for obstacle detection while following the front sides of houses and shops, memorising all locations they are becoming familiar with. In a new, unfamiliar setting they completely depend on people passing by to ask for a certain shop or the closest post office. Crossing a street is a challenge, after which they are again completely disoriented. In a society in which very sophisticated technology is available, from tracking GPS-RFID equipped containers in an area of hundreds of meters to GPS-GIS car navigation to Bluetooth emitting the sound of movie trailers to mobile phones in front of cinemas, one can question what it may cost to provide the blind with the most elementary technology to make life a little bit easier. This technology may not replace the stick, but should complement it: alert the user to obstacles a few meters away and provide guidance for going to a specific location down town or in a shopping mall.

The goal of this project is to develop a prototype which costs less than 400 euro and which can be easily assembled by a technician. This system is lightweight, easy to put on and carry, i.e., not being a hindrance when walking with the stick, simple to use, and robust. The system consists of two small boxes and a wireless earphone-microphone unit. The first box, to be worn in front at breast height, contains two minicameras and an electronic compass. Its weight is negligeable and its width about 15cm. This box is connected to a second box with only one cable. The second box is worn in a side purse with a strap around the neck. It contains a powerful miniportable with WiFi and Bluetooth, a GPS receiver with antenna fixed to the strap, and an RFID sensor. This box measures about 4x20x20cm and weights about 1kg including batteries for an autonomy of at least 8 hours. An integral part of the prototype is a list of off-the-shelf components and step-by-step instructions for assemblage and software installation, including designs of the breast unit and side purse with strap such that they can be made using a preferred material, from denim to leather.

All hardware being based on off-the-shelf components, like Bluetooth GPS, compass and RFID, also USB webcams, the main part of the project is devoted to software development, the functionality, and an extremely simple user interface. Concerning vision, there are two main functions: (1) To detect possible obstacles, in front at a distance of 2-3m, like loose or missing stones (Portuguese calcada), static objects like benches, poles, trash cans and plant pots, and moving objects like people and animals, especially those on collision course. (2) To aid in heading forward, indicating front sides of houses and shops, but also the centering on narrow sidewalks. To be discussed with end-users are additional functions, like detecting zebra road crossings which are not secured by traffic lights with audible signals, and staying within their borders while crossing.

GPS, RFID and the compass serve to aid more global navigation using a GIS (geographic information system). The GIS resides on a remote server and queries are relayed by WiFi. However, GPS has a limited precision and may not be available in narrow streets and with clouded sky, and indoor reception is never possible. If WiFi reception is possible, a local GIS with a radius of about one hundred meters is updated on the system, such that at positions where WiFi is not available the user can still query the system. If both GPS and WiFi fail, the user can still be guided using the local GIS and the compass, but for calibrating the user's position it is necessary to mark important landmarks and shops by active RFID tags, using a sensor with a range of 2-3m. An implicit assumption of using WiFi and RFID technology is that authorities, both municipalities and managers of shopping malls, are willing to invest (little) money in it because of the benefits it brings to the blind and others with severe visual impairments.

Most important is the design of the user interface. The system may not disturb normal navigation with the stick, it may not distract attention to normal sounds, and it must alert the user with a minimum of sounds. Likewise, the speech interface must be based on a minimum of queries and simple instructions. Right from the start of the project, ideas and solutions will be discussed with end users through ACAPO, the Portuguese association of the blind and amblyopes, and extensive field tests will be conducted. As for any new technology, blind people must learn how to use the system and become familiar with it, which is a learning process similar to that of using the stick. Only if blind people are willing to accept the system, this project will be a success. The participation of the blind through ACAPO is therefore an essential part of this project.