Non-contact Method for Producing Tactile Sensation Using Airborne Ultrasound

Comments

Franck Norman

Drew

Summary

The authors sought to create a new method of interacting with 3D objects with tactile feedback. Although there has been previous methods implemented, one method, the Cyber Glove, is not optimal because it provides tactile feedback at all times from the glove touching the skin. They proposed using ultrasound as the way to provide tactile feedback. Their method is based on acoustic radiation pressure. When the airborne ultrasound is applied on the surface of the skin, almost 99% of the incident acoustic energy is reflected on the skin. This removes the need to place an ultrasound reflective medium on the skin. Their prototype device consists of an annular array of airborne ultrasound trandsucers, a 12 channels amplifier circuit, and a PC. It was designed to produce a single focal point along the center axis perpendicular to the radiation surface.

They measured the total force using an electronic balance. The measured force was 0.8 gf (gram-force) and 2.9 gf at 250 mm and 0 mm respectively. To measure the spatial resolution, a microphone probe was attached to an XYZ stage. They measured that the diameter of the focal point was about 20 mm in diameter, and the maximum intensity decreases as the distance of the focal point from the array increases. When they measured the temporal properties of the radiation pressure, they noticed that the radation pressure decreases at the onset of radiation pressure each half period.

They did a user study and said that they felt vibrations when the radiation pressure was modulated. If it was constant, they can only feel on and off pressure.

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Discussion

I feel like that this experiment is not going to be very useful in future applications. Although the idea is innovative, using ultrasound doesn't seem to be very useful in current interactions. There would also need to be a way to detect the position of the hand without the use of sensors on the hand itself. Also, within the paper, I would've liked to have seen more of a user study. It gives no statistics of what the study was. I assume that the participants just put their hand over the array and felt something.

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Takayuki Iwamoto, Mari Tatezono, Hiroyuki Shinoda. Non-contact Method for Producing Tactile Sensation Using Airborne Ultrasound. EuroHaptics 2008. pp. 504-513