ShiverPaD: A Glass Haptic Surface That Produces Shear Force on a Bare Finger

We discuss the design and performance of a new haptic surface capable of controlling shear force on a bare finger. At the heart of the ShiverPaD is the TPaD variable friction device. It modulates the friction of a glass surface by using 39 kHz out-of-plane vibrations to reduce friction. To generate shear forces, the TPaD is oscillated in-plane (i.e., "shivered") while alternating between low and high friction within each cycle. In previous research, the ShiverPaD produced shear forces using in-plane vibrations below 100 Hz. In this research, we develop a new ShiverPaD that produces force using 854 Hz vibrations, where human sensitivity to vibration is diminished. The new device is used to display a virtual toggle switch and a variety of virtual edges. A human subject study is conducted to demonstrate that users can easily trace virtual edges displayed on the surface of the ShiverPaD.