The Disney Research laboratory has come up with a psychophysical model based on an algorithm which broadens the range of tactile feedback sensations from a touchscreen.

3D Haptic Effects for Touchscreens on the Way

Now that the touchscreen revolution is an established fact, many researchers are working on developing new types of haptic feedback for touchscreen devices. After all, few would dispute the fact that being able to actually feel the contours on a screen image will substantially boost tactile feedback and radically enhance the user’s immersion. While researchers at the University of Bristol have been working on a  haptic technology project based on ultrasound, other pioneering work has shown how mechanical vibrations and pulses can be used to provide simulated haptic feedback by applying stimuli to the user’s finger. However, when it comes to the potential for mass production, this approach has a number of drawbacks in terms of cost, reliability and energy consumption. By comparison, an approach based on varying the friction between finger and touchscreen instead of using mechanical vibration seems quite promising. Here the construction techniques and the materials used seem more suited to mass production.  So far however little work has been done on the design and evaluation of the basic techniques which are able to generate a wide range of sensations.


Home-grown algorithm generating a model which perceives ‘3D bumps’


Observing the effects of compressing a film between finger and touchscreen, researchers worked out that the force feedback stands in a direct relationship to such standard mathematical functions as sinusoidal profiles. By extension, this enables the development of an efficient user interface, but does not however allow transmission of information on the 3D geometric forms which are supposed to make up the interface content. Now a study by Disney Research has shown that providing a sensation of hills and valleys is the best way of simulating 3D. The research team have come up with an algorithm that dynamically modulates the frictional forces on a sliding finger so that they match the tactile properties of the visual image displayed on the touchscreen along the finger’s path. They have thus created a psychophysical model – i.e. a model of form perception based on the frictional force applied to the screen. The advantage of this technique also lies in the fact that unlike traditional tactile systems, where the stimulus works on ‘passive’ skin, here it is the movement which makes it possible to tune tactile effects in a way that resembles our natural way of exploring surfaces and textures.


Game, navigational and Augmented Reality applications


The Disney Research algorithm enables the creation of realistic 3D tactile functionality on a screen for a wide variety of images which feature aspects of our daily lives. The user can be made to perceive in 3D forms as complex as facial features. There are plans to use the technology in a range of interactive applications such as video games, navigation, maps and infographics.  The ‘3D tactile bumps’ could in fact be modified dynamically depending on changes in the components of the graphic interface. Tactile depth can also be achieved directly from ‘depth measuring’ cameras, which are widely used these days in systems such as Kinect.  Last but not least, it is quite likely that the Disney algorithm will be used to create haptic applications in the field of Augmented Reality.

By Pierre-Marie Mateo