Ultrasound haptic system projects readable Braille into thin air
For people who rely on Braille, reading displays and signs in public can be a challenge, but a new system could help make things easier. HaptiRead is a haptic feedback device that uses ultrasound pulses in precise patterns to reproduce Braille text in midair.
Braille is often used in public places as fixed nodes on a sign, or more dynamically as Refreshable Braille displays that use lines of pins that rise and fall to change texts. But there are plenty of problems with both of these. It can be difficult to direct users to begin interacting with them in the first place, limited information can be presented, the moving parts can clog up over time, and, of course, there are hygiene concerns with many people touching the same surface.
HaptiRead is designed to address all of those issues. The system is a panel made up of 256 ultrasound transducers, emitting frequencies of up to 200 Hz – strong enough for a user to feel the pressure on their skin. This kind of technology has previously been put to work to create things like holograms you can touch.
But HaptiRead has an arguably more noble goal in mind. This device projects up to eight haptic points in the air as far as 70 cm (27.6 in) away, which can be arranged to represent different characters in the Braille alphabet.
A built-in Leap Motion depth-sensing camera figures out where a user’s hand is and directs the ultrasonic points towards it. That can help guide a user towards the device in the first place. Plus, there are no moving parts to clog up, and users don’t need to actually touch a surface, removing hygiene issues. The system can also be set up to display more complex information, such as charts and graphics.
The researchers experimented with how to best present the text. They ran through three different methods – constant, where all dots in a cell were presented at the same time, row-by-row, where rows of dots were projected sequentially, and point-by-point, where only one dot was displayed at a time.
The team tested HaptiRead on 18 sighted and 11 blind participants, asking them to feel a projected Braille cell and identify which character was represented. In both sets of participants, the point-by-point method had the best results – the sighted group scored an average accuracy of 94 percent, while the blind group scored 88 percent. The participants also reported that point-by-point was less mentally demanding than the other methods.
The team says there’s still much more testing and development to do, but this preliminary study shows that the HaptiRead technology has promise.
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