Technology that lets you 'feel' textures on touchscreen

In a game-changing invention, engineers at Disney Research, Pittsburgh, have developed a new technique that allows you to feel the texture of objects seen on a flat touchscreen.

The novel algorithm enables a person sliding a finger across a topographic map displayed on a touchscreen to feel the bumps and curves of hills and valleys, despite the screen's smooth surface.

The technique is based on the fact that when a person slides a finger over a real physical bump, he perceives the bump largely because lateral friction forces stretch and compress skin on the sliding finger.

By altering the friction encountered as a person's fingertip glides across a surface, the Disney algorithm can create a perception of a 3D bump on a touch surface.

The method can be used to simulate the feel of a wide variety of objects and textures.

"Our brain perceives the 3D bump on a surface mostly from information that it receives via skin stretching," said Ivan Poupyrev, who directs Disney Research, Pittsburgh's Interaction Group.

"Therefore, if we can artificially stretch skin on a finger as it slides on the touchscreen, the brain will be fooled into thinking an actual physical bump is on a touchscreen even though the touch surface is completely smooth," Poupyrev said in a statement.

In experiments, researchers used electrovibration to modulate the friction between the sliding finger and the touch surface with electrostatic forces.

Researchers created and validated a psychophysical model that closely simulates friction forces perceived by the human finger when it slides over a real bump.

The model was then incorporated into an algorithm that dynamically modulates the frictional forces on a sliding finger so that they match the tactile properties of the visual content displayed on the touchscreen along the finger's path.

A broad variety of visual artifacts thus can be dynamically enhanced with tactile feedback that adjusts as the visual display.

"The traditional approach to tactile feedback is to have a library of canned effects that are played back whenever a particular interaction occurs," said Ali Israr, a Disney Research, Pittsburgh research engineer who was the lead on the project.

"This makes it difficult to create a tactile feedback for dynamic visual content, where the sizes and orientation of features constantly change. With our algorithm we do not have one or two effects, but a set of controls that make it possible to tune tactile effects to a specific visual artifact on the fly," Israr said.

The new research will be presented at the ACM Symposium on User Interface Software and Technology in St Andrews, Scotland.