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Enhancing the realism of virtual environments by physically touching a virtual object using tactile augmentation has been actively explored by many researchers. To achieve the desired sensation two difficulties need to be overcome, namely that of controlling the computer generated 3D form in an intuitive manner as well as rapidly producing a physically tangible computer ~ntrolled 3D form. A novel system for controlling a 3D computer model has also been developed which has interfaced a shape memory alloy (SMA) tactile array, with a 3D computer modelling system. The system allowed the 3D form of the computer model to be replicated on the array, the shape of which could be modified by the user touching the array oftactors. A novel system of rapidly generating controllable 3D forms has been developed, based on a magneto-rheological (MR) fluid. A prototype 5x5 MR fluid tactile display has been designed, modelled and extensively studied. The essential characteristic of MR fluid is its ability to reversibly change from a free-flowing liquid to a solid when exposed to a magnetic' field. The change in behaviour is rapid and occurs within milliseconds, with controllable yield strength. While MR fluid has been widely studied by researchers, most of the work has focused on the shearing deformation in its post-yield regime, and very little is known about the mechanical response ofMR fluid under direct deformation. There also appears to have been no previous studies undertaken on the dependence of normal force within the materials pre-yield regime on the magnetic field applied. Vane tests have been adapted to determine the static shear yield stress of the energised IIfluid'' and a method to determine the material strength under indentation has been developed. It was shown'that both shear and compressive deformation was proportional to the applied magnetic field, over a given range. The influence of compression on the MR fluid static shear yield was also investigated and it was demonstrated that it had a minimal affect at low values of compressive strain whereas the affect was more significant at increased strain.

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