Multi-touch surfaces offer easy
interaction in public spaces, with people being able to walk-up and use
them. However, people cannot feel what
they have touched. A team from the
University of Bristol’s Interaction and Graphics (BIG) research group has developed
a solution that not only allows people to feel what is on the screen, but also
receive invisible information before they touch it. UltraHaptics, is a system
designed to provide multipoint, mid-air haptic feedback above a touch surface.
UltraHaptics uses the principle of acoustic radiation force where a phased
array of ultrasonic transducers is used to exert forces on a target in
mid-air. Haptic sensations are projected
through a screen and directly onto the user’s hands. The use of ultrasonic
vibrations is a new technique for delivering tactile sensations to the
user. A series of ultrasonic transducers
emit very high frequency sound waves.
When all of the sound waves meet
at the same location at the same time, they create sensations on a human’s
skin. By carrying out technical evaluations, the team has shown that the system
is capable of creating individual points of feedback that are far beyond the
perception threshold of the human hand.
The researchers have also established the necessary properties of a
display surface that is transparent to 40 kHz ultrasound. The results from two
user studies have demonstrated that feedback points with different tactile
properties can be distinguished at smaller separations. The researchers also found that users are
able to identify different tactile properties with training. Finally, the
research team explored three new areas of interaction possibilities that
UltraHaptics can provide: mid-air gestures, tactile information layers and
visually restricted displays, and created an application for each.
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