Tactile Vision Substitution Systems

Since the pioneering work performed by Bach-y-Rita et al. [Nature 221 (1969)] several different technologies have been explored to construct devices which are able to provide blind subjects with a substitution for vision making use of their tactile perception. Such devices are called tactile vision substitution systems (TVSS). In general three classes of stimuli, mechanotactile, electrotactile and thermotactile, have been exploited. A comprehensive overview including also applications of tactile displays for sighted people in the context of virtual reality can be found in the nice book by G.C. Burdea : Force and touch feedback for virtual reality, John Wiley & Sons, Inc., New York (1996).

Modern microelectronics offers the fascinating opportunity to develop intelligent vision chips with properties adapted especially to the specific application. The image processing can be done by means of commercially available fast digital computers or analog networks. Nature applies the analog way in the retina. The reduction of pixelinformation to relevant parameters (e.g. edges) happens before the information is transfered to the brain. The Heidelberg TVSS project has focused on the development of vision chips and analog network chips.

In order to optimize the necessary image processing an improved understanding of tactile perception is required. There are virtually no flexible and programmable output devices for tactile patterns available on the market. The Heidelberg group has therefore developed two tactile displays. One system, the VTD, has been successfully tested with students of the school for blind persons in Ilvesheim. Another one is being used in cooperation with the group of Prof. Sampaio of the Université Louis Pasteur in Strasbourg for basic research in the field of tactile sensory perception. This pneumatic display (PTD) is operated with air pressure and can thus be used in the strong field of an fMRI magnet.

Last update of this page: 2011-05-19_