Hyper haptics: Invisible, touchable 3D shapes created with blasts of ultrasound

Computer scientists from the University of Bristol have devised a machine that generates floating 3D shapes that you can feel, but can’t see. The possibilities that such a technology would enable for virtual and augmented reality scarcely need to be mentioned here. We took a look at some of the specs on this device to see just what it might be capable of.
We previously discussed ultrasonic haptic interfaces that can create the illusion of touching different surface textures by sending different frequencies of vibration through your fingers. These devices, at least in theory, can provide a nice virtual touchscreen for typing in a completely contact-free way. Creating actual shapes that you can feel is a whole new ballgame.
While previous researchers have tried to accomplish this using various kinds of air jets and mini-vortices, ultrasound has emerged as as the new method of choice to create illusory haptic objects.

The new device creates multiple points in the air — an “acoustic radiation force” as the authors call it — where sound waves come together constructively with enough energy to induce a shear wave in your skin. This wave activates specific kinds of receptors in your skin that are tuned to adapt to stimuli in predictable ways. Some receptors turn off quickly, while others continue to send neural spikes to the brain as long as the stimulus is present. The multiple sound waves are generated by a two-dimensional phase array with 320 separate transducers.
To track the intersection of the hand and the virtual objects the researchers use a Leap Motion controller that has a range 100cm and a field of view of 140 degrees. The ultrasonic transducers are fairly powerful — they can generate a sound pressure of up to 20 Pascals at a distance of 30cm with a 60-degree angle of directional spread. To control them the researchers used XMOS L1-128 processors running at 400MHz — fast enough to output drive signals with a refresh rate of 2MHz. This kind of speed lets the device generate shapes on the fly. With real-time generation like this, new shapes do not have to be preprocessed ahead of time.
Even more exciting than that is the ability to create dynamic objects that move or change entirely. Those who got to test the device reported easy identification of basic shapes and patterns like spheres, cubes, cones, and pyramids. The researchers envision their device will make possible a whole new generation of “eyes-off” controls for everything from the cockpit to the operating room. The ability to maintain visual focus on the task at hand, while being able to simply feel your way around a control space would be invaluable.
We aren’t sure if and when a consumer version of the product may be available, but it is certainly something we might hope to add to next years holiday gift guide.

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