UltraHaptics promises free-space tactile interfaces

May 04, 2015 // By Julien Happich
Founded in 2013, Bristol-based startup Ultrahaptics relies on a compact array of ultrasound transducers to send inaudible sound waves through the air, using phase-shift techniques to precisely control the focus and intensity of the acoustic radiation pressure into something tangible.

While the ultrasound transducers lie flat in what could look like a thick mouse mat, the air pressure differences created at the focus points (where all sound waves meet at the same time thanks to the phase delays) can be felt like invisible contours projected into the air. Different textures can be created by varying the modulation frequency or pulsing the feedback effect on the skin.

To make things even more interesting, the company can combine these haptic effects with real-time video tracking of a user’s fingers, so as to follow the user’s gestures with a consistent feel, for example progressively defining and unveiling the contour of a large virtual object as the user swipes his fingers across it.

“The feedback force that can be felt ranges from 10 to 4Pa, maybe the equivalent of tenths of grams, but that’s significant enough for our hands’ tactile receptors to resolve”, comments Tom Carter, co-founder and CTO of UltraHaptics.

In blind demos (running the haptic effects without any visual cues), the company claims it is now at a stage where it can create invisible, yet easily recognized primitive shapes such as a sphere, a cube, a pyramid or a cone, floating above the mat.

“In a user study, people were asked to come up to the interface and guess primitive shapes, and they guessed right 80% of the time” Carter said.

There are several ways UltraHaptics can create these floating shapes.

“We could always produce haptics in a limited space so people would feel it when they reached where the haptic effect took place, or with gesture tracking, we could adapt in 3D where to produce the effects, at the point of your fingertips”, explained Carter.

“To create the entire shape, we need from a hundred to a thousand points at the same time, but with finger-tracking, it is much more effective to create only the points of the object that the