A mobility aid for the blind with discrete distance indicator and hanging object detection

This paper describes a low cost mobility aid for the blind using ultrasonic sensors. Mobility is one of the main problems encountered by the blind in their daily life. This suggested device uses commonly available ultrasonic sensor to detect obstacles (including hanging object) on the way within a distance of three meters. In this head mounted device ultrasound beams are transmitted at a regular time interval. If any object is present on the way, the emitted ultrasound will be reflected back to the sensor. The distance of the object is then measured and converted to discrete levels of 1 meter, 2 meters and 3 meters. These discrete levels are then used either to produce three audio signals (with different tones) or three different tactile vibrators.