A new fabric-based softness display

This paper describes a new bi-elastic fabric-based display for rendering softness. Bi-elastic means that the fabric exhibits properties which render it elastic in at least two substantially perpendicular directions, and preferably in all directions. The device described here is based on tissue stretch to provide different levels of softness. More specifically, a thin layer of bi-elastic fabric is placed on the top of a hollow cylinder and tied to an external circular crown which can be moved up and down, relaxing or stretching the fabric. A camera placed just beneath the fabric allows for the measurement of the contact area involved in the haptic exploration. The system is also endowed with a graphical user interface, which gives a real-time visual rendering of the interaction of the fingertip with the display. In this paper, design, realization and control implementation are discussed, and performance of the display is evaluated by means of a set of psychophysical tests. We also compare performance in terms of softness perception of different simulated materials with that obtained using another softness display.