German engineers from the University of Bayreuth have developed an ultrasonic haptic display that allows them to display Braille numbers non-contact.
The device can create several zones in the air at the same time, where the ultrasonic waves are focused and create a pressure that a person can distinguish. At the same time, visually impaired people on such a device can recognize characters from four points in 88% of cases, which will allow the future use of such technologies for contactless interaction.
The device consists of an array of ultrasonic emitters – 16 to 16 pieces. The system gives commands to each emitter at different times, but if you select the appropriate phase for each, then at a certain point they will signal at the same time. Moreover, if you modulate the signal with a certain strength, then the human skin can feel a certain pressure.
The authors used to modulate the frequency signal from 100 to 200 hertz, and for the best distinguishability of the points, they used their own frequency for each of them. The device also includes a Leap Motion sensor to track the position of the hand. It allows you to automatically adjust the focus points so that they are close to the palm of your hand – even if it moves.
During the test, the developers conducted a system experiment on 11 visually impaired people. They needed to bring their hand to the display and read the number shown there. Moreover, the accuracy of the experiment amounted to 88%.