Haptic Feedback Powered by Ultrasound
Ultra-Haptics is a system for creating haptic feedback in mid-air. Waves of ultrasound displace the air, creating a pressure difference. By causing many waves to arrive at the same place simultaneously, a noticeable pressure difference is created at that point. With this method, we are able to create multiple, concurrent points of haptic feedback in mid-air.
Jason Alexander, Mark T. Marshall, Sriram Subramanian, Adding Haptic Feedback to Mobile TV. Extended Abstracts of the International Conference on Human Factors in Computing Systems. April 2011. [PDF, 289 kB][ACM Digital Library]
Jason Alexander, Mark T. Marshall, Sriram Subramanian, Increasing the Appeal of Mobile TV Using Haptic Feedback. CHI 2011 Workshop on Video Interaction – Making Broadcasting A Successful Social Media. May 2011. [PDF, 63 kB]
- Be Moved By Ultrasound. WIRED Magazine UK. August 2012.
- Ultra-tangible technology manipulated with ultrasound levitation. WIRED.co.uk 13 July 2012.
- One touch towards the future. Bristol University. July 2012
Creating Focal Points:
- Waves of ultrasound displace the air creating a pressure difference. This is called acoustic radiation pressure.
- By focussing many ultrasound waves to a point in mid-air, we can create a noticeable pressure difference.
- We create a focal point by triggering ultrasound tranducers with specific phase delays so that all sound waves arrive at the point concurrently.
Human Perception of Ultrasound:
We modulate the ultrasound so that it is perceived as a vibration on the skin. Changing the modulation frequency or pulsing the feedback gives different textures. By giving each feedback point a different modulation frequency, we can have different feedback, with different textures applied to the user at the same time.
Talking About Tactile Experiences
A common problem with designing and developing applications with tactile interfaces is the lack of a vocabulary that allows one to describe or communicate about haptics. In this paper we present 14 categories for a human-experiential vocabulary (H-E-Vocabulary) based on findings from a user study using the explicitation interview technique. The H-E-Vocabulary is tied back to neurophysiological and psychophysical data on the human hand and is illustrated with example design implications for haptic systems.