Tech developed by Disney Research, Pittsburgh, makes it possible to change the feel of real-world surfaces and objects, including touch-screens, walls, furniture, wooden or plastic objects, without requiring users to wear special gloves or use force-feedback devices.
Left: A new tactile tech modifies the user’s tactile perception, it provides a layer of texture on a teapot. Right: The device is small enough to be fixed in the sole of a shoe
Surfaces are not altered with actuators and require little if any instrumentation. Instead, Disney researchers employ a newly discovered physical phenomenon called reverse electrovibration to create the illusion of changing textures as the user's fingers sweep across a surface.
Aweak electrical signal, which can be applied imperceptibly anywhere on the user’s body, creates an electrical field around the user’s fingers that is responsible for the tactile feedback.
The technology, called REVEL, could be used to create “please touch” museum displays, add haptic feedback to games, apply texture to projected images on surfaces of any size and shape, provide customised directions on walls for people with visual disabilities and enhance other applications of augmented reality (AR).
“Augmented reality to date has focused primarily on visual and auditory feedback, but less on the sense of touch,” said Olivier Bau, a postdoc at Disney Research. “Sight and sound are important, but we believe the addition of touch can create a really unique and magical experience.”
The research Bau and Ivan Poupyrev, a scientist at Disney Research, will be presented at the SIGGRAPH 2012. The electrovibration effect was first reported in 1953. It’s a sensation that people sometimes feel when they slide a finger across a smooth metal surface of an ungrounded electrical appliance.
With the dry, outer layer of skin serving as an insulator, a small alternating current applied to the conductive metal surface can generate an attractive force between the surface and asmall electrical charge induced in the fluids of the finger's deeper tissues as the finger moves across the surface.
No current actually passes through the skin and the amount of induced charge is negligible, but it results in a perception that the surface is rubbery. Bau and Poupyrev discovered that the same sensation could be created by applying the small alternating current anywhere on the user’s body instead of the surface – reverse electrovibration.
By tracking the finger’s position using an external sensor, the researchers can manipulate the electrovibration to make the user feel bumps, edges or changes in texture corresponding to particular locations on the surface.
“The amount of current used is extremely low,” Poupyrev said. “The static electric spark we feel when touching a doorknob, is a higher current and, even so, presents no safety concerns.”
The surfaces themselves require no extensive modification, though they need to be coated with an insulatorcovered electrode, or “REVEL skin.” The surfaces themselves require no extensive modification, though they need to be coated with an insulatorcovered electrode, or “REVEL skin.”
Anodized aluminum objects or capacitive touch-screens can be used without any modification, while a REVEL skin can be manufactured on walls or other surfaces using off-the-shelf materials.
One simple method is to coat a surface with a conductive paint and add a coat of conventional household paint as an insulating layer. The surfaces must also share a common electrical ground with the REVEL signal generator.