Creating the illusion of shape for virtual environments

Current virtual reality systems suffer from being almost wholly based on the visual sense. There are many important applications where complementary tactile and kinaesthetic feedback would considerably enhance the illusion of being immersed in the virtual environment. This paper concentrates on the use of two technologies, shape memory alloy wires and electrorheological fluids to create 2-D programmable surfaces which can be felt by the user in conjunction with the traditional visual display. The technologies are used in different ways. An array of SMA driven tactors is used to create a hard or soft surface which tries to mimic the shape of the required virtual surface. The E-R fluid, following the approach of Monkman (1992), is used as a subcutaneous layer beneath a compliant surface. Areas of this layer can be “rigidised” or “fluidised” under computer control. If the user drags his/her finger across the compliant surface little resistance to motion is felt in the “fluidised” wires but an appreciable resistance is felt in the “rigidised” areas, thereby creating the illusion of the presence of an object