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« Haptics group at the University of Pennsylvania | Main | Real world touchscreens »

Haptography Haptic Photography

Technical Q&A with Heather Culbertson from the Haptics Group at the University of Pennsylvania

DA: What are you researching at the moment? Is there a particular unsolved problem that you would love to solve?

Haptic texture feedback for stylus-based tablets

Currently I am working on providing realistic haptic texture feedback for stylus-based tablets.

If you pick up a tool such as a pen and gently drag its tip across the table, a rock, or the fabric of your shirt you are able to feel variations in the textures even though you are not directly touching them with your finger. This is because the contact between the tooltip and surface causes the tool to vibrate, which is in turn felt by your hand. These vibrations vary based on the texture, how hard you press with the tool, and how fast you move the tool.

My research focuses on ways to model and recreate these vibrations as a person drags a stylus across a virtual surface.

Haptography (haptic photography)

The modeling approach relies on data recorded from dragging a specially sensorized tool across real textured surfaces. The tool measures the induced vibrations as well as the speed and force the person used. From this data I am able to make mathematical models to represent the feel of the surface for reproduction on the tablet.

We've coined this method of data recording and modeling as haptography (haptic photography) because it allows a person to record the feel of an interesting interaction in much the same way that traditional photography allows a person to visually record an interesting scene or object.

Once the data is recorded and the model is made, I am able to recreate the feel of the surface on a tablet computer. The only additional hardware needed on the tablet side is a voice-coil actuator, which is attached to the stylus. The voice-coil works in much the same way as a speaker, but instead of outputting sound it outputs vibrations. These vibrations are much more controllable than the vibrations made by eccentric mass motors commonly found in cell phones and allow us to accurately reproduce the modeled vibrations to a user as he drags the stylus across a virtual texture. Thus we are able to create realistic textures on a completely smooth screen.

One unsolved problem I would love to solve is to apply my research to bare-finger touchscreens. I think everyone would agree that it would be really cool to be able to touch a screen with your finger and feel the buttons or different textured surfaces. But we are not yet to the point where we can display this tactile information without the additional voice-coil actuator hardware. This is something I would love to work on in the future though.

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