A Vibrotactile Device for Display of Virtual Ground Materials in Walking Yon Visell 1,2 , Jeremy R. Cooperstock 1 , Bruno L. Giordano 1 , Karmen Franinovic 2 , Alvin Law 1 , Stephen McAdams 1 , Kunal Jathal 1 , and Federico Fontana 3 1 CIM and CIRMMT, McGill University, Montreal, Canada 2 University of the Arts, Zurich, Switzerland 3 Dept. of Informatics, University of Verona, Verona, Italy Abstract. We present a floor tile designed to provide the impression of walking on different ground materials, such as gravel, carpet, or stone. The device uses affordable and commercially available vibrotactile actua- tors and force sensors, and as such might one day be cost-effectively used in everyday environments. The control software is based on a lumped model of physical interactions between the foot and the ground surface. We have prototyped a measurement scheme for calibrating the device to match real-world ground materials. 1 Introduction In a 1939 paper, J. A. Hogan describes an incident in which Marcel Proust en- tered the courtyard of the Princess de Guermantes’ residence in Paris when “his feet came to rest on two uneven flagstones, and as he balanced from one to the other a delicious sensation swept through his body” (Hogan, 1939). The author continues, “How came he by these sensations? . . . Suddenly it was revealed to him. It was Venice. One day, long since past, he had stood in the baptistry of St. Mark’s in Venice, balanced on two uneven flagstones.” The interactive device we present here was motivated by the idea that a simplified audio-haptic stimulation, delivered to a walking user, might success- fully evoke real-world materials provided certain of their features are preserved. Proust’s experience with the flagstones in Paris provides a literary example of the power of such associations. The tiles we are developing explore the extent to which pedestrians can be provided with the illusion that they are walking on materials such as gravel, earth, or pavement, through the interactive variation of a vibrotactile signal delivered to the feet via the surface of a floor tile (Figure 1). Prior research has addressed the rendering of virtual haptic surface textures by means of manually operated haptic devices, and similar information is often conveyed via non-force reflecting vibrotactile feedback. Significant attention has also been devoted to the development of virtual haptic locomotion interfaces (overviewed in [6]). Some of these, such as the Hap- ticWalker [10], have aimed to represent the shape of the ground (stairs, inclines,