Ultra-Haptics – Using Sound Waves to Create Tactile Feedback

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Arthur Berman

User Interface - Haptics are technologies that interface with the user through the sense of touch.  Many such systems have been conceived and commercialized.  This week, I learned of one under development that seemed quite unique.  Called Ultra-Haptics, it is a system for creating haptic feedback in mid-air.

The system is under development by a team at the Bristol Interaction and Graphics group within the Department of Computer Science at the University of Bristol (Bristol, UK).  In the Ultra-Haptic system, an array of ultrasonic transducers emit very high frequency sound waves that are used to displace air, creating a pressure difference.  This is called acoustic radiation pressure.

A focal point can be created by triggering the array of ultrasound transducers with specific phase delays so that all sound waves arrive at a given point at the same time.  (This sounded to me much like the means used to steer the beam in a phased array radar system.)  By causing many waves to simultaneously arrive at a given point, a noticeable pressure difference can be created at that point.  With this method, the team is able to create a multi-point haptic feedback system that allows users to simultaneously experience haptic feedback at multiple locations in mid-air.

In the Ultra-Haptic system, the ultrasound is modulated such that the sensation produced on the skin is perceived as a vibration.  Changing the frequency of the modulation gives rise to different sensations or “textures.”  By giving each feedback point a different modulation frequency, it is possible to apply several different feedback sensations to the user at the same time.

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A video illustrating the Ultra-Haptic system in operation can be found below.

The most recent scientific article produced by the team appeared in a paper entitled “UltraHaptics: Creating Haptic Feedback Using Ultrasound.”  The paper was presented at the March 2012 SET For Britain Poster Competition. This is an event conducted for early-stage and early-career research scientists, engineers and technologists.  In this case, the authors were Tom Carter, Mark T. Marshall and Sriram Subramanian.

The Ultra-Haptics system can be deployed in different ways.

The first is, perhaps, obvious.  By mounting the system to the back of a device, feedback can be applied onto the hand holding the device.

The second is, perhaps, more unique.  By positioning the Ultra-Haptics system around the edge of a tabletop computer or tablet, it can apply lateral forces across the surface.  This could allow the user to feel a gradient when using a mapping application or provide tactile feedback to a user carrying out a teleoperation.

In a variation of this second mode of operation, the system is also capable of moving tangible objects that have been placed on the surface.  Think about this statement.  The common situation is to use a physical object to manipulate digital content.  This configuration of the Ultra-Haptic system enables the reverse situation.

Given the unique potentials of the Ultra-Haptic system, it will be interesting to see if it achieves full development and reaches commercialization.  Insight Media will keep an eye on the technology and let readers know the latest.  -Arthur Berman

 University of Bristol, Jason Alexander, +44 117 954-5208,  jason@cs.bris.ac.uk 

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