Non-contact ultrasonic Braille help the blind to withdraw money from an ATM

German engineers have learned to use ultrasonic haptic display for non-displaying the numbers of Braille. It is able to create in the air at the same time several areas in which ultrasonic waves are focused and create pressure are distinguishable skin. The authors tested different modes of operation of the device, and showed that in one of these blind people can recognize the symbols of the four points in 88 percent of cases. Such a display can be useful when working with confidential information — for example, when interacting with the ATM. The article will be presented at the conference DIS 2020, and its Preprint published on arXiv.org.

Traditionally, to display information for blind use Braille, consisting of six raised dots on a flat surface. In recent years, interactive Braille displaysthat work on the same principle, but is able to display different text. Such devices are rarely used primarily because of the high cost, but also because of other factors. For example, if we are talking about confidential information, an observer can peep it. In addition, to use the same display in public places quite unhygienic. Alternatively you could use the reading of the information system of speech synthesis, but it also confidenziale.

Engineers from the faculties of Bayreuth University under the guidance of jörg müller (Jörg Müller) proposed the use of ultrasonic haptic display for displaying information on a publicly accessible device for the blind. They used a commercial deviceconsisting of an array of ultrasound emitters (16 by 16 pieces). The principle of operation of the display is that it gives commands to each emitter at different times. If you pick the appropriate phase for each emitter, then at some point they will come at the same time. And if you modulate the signal in the range of the distinguishable hand, the person will feel considerable pressure and vibration at a particular point in space. The authors used to modulate the signal frequency from 100 to 200 Hz, and for better visibility of the points they used for each of these its frequency.

In addition to the array of emitters in the display also has a sensor Leap Motion for hand tracking. This allows you to automatically adjust the focus point so that they were close to the palm of your hand, even if it is slightly moving.

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