Dataset for finger motion and contact by a second finger influence the tactile perception of electrovibration

Electrovibration holds great potential for creating vivid and realistic
haptic sensations on touchscreens. Ideally, a designer should be able to
control what users feel independent of the number of fingers they use, the
movements they make, and how hard they press. We sought to understand the
perception and physics of such interactions by determining the smallest
125 Hz electrovibration voltage that fifteen participants could reliably
feel when performing four different touch interactions at two normal
forces. The results proved for the first time that both finger motion and
contact by a second finger significantly affect what the user feels. At a
given voltage, a single moving finger experiences much larger fluctuating
electrovibration forces than a single stationary finger, making
electrovibration much easier to feel during interactions involving finger
movement. Indeed, only about 30% of participants could detect the stimulus
without motion. Part of this difference comes from the fact that relative
motion greatly increases the electrical impedance between a finger and the
screen, as shown via detailed measurements from one individual. In
contrast, threshold-level electrovibration did not significantly affect
the coefficient of kinetic friction in any conditions. These findings help
lay the groundwork for delivering consistent haptic feedback via
electrovibration.