WuFu glasses use ultrasonic waves to create tactile images for the blind

Intended towards visually impaired, the “WuFu” is an open hardware and open source aid that makes use of ultrasonic distance measurement, employed by the bat to fly without colliding with other bats in the dark. Drawing its name from the Chinese phrase “five bats” representing a symbol of luck and a long life, the visual aid carries the ultrasonic waves to sensors on opaque glasses and translates them, using two motors attached to the wrists of the wearer, into vibrations. Therefore, the glasses create tactile images of the surrounding space for the users, so they could move freely on their own, while a compass sensor tracks the direction of the user to keep him/her on the right path.  Found here.