Representing Interpersonal Touch Directions by Tactile Apparent Motion Using Smart Bracelets.

We present a novel haptic interaction to vibro-tactually connect an interpersonal touch using bracelet devices. A pair of bracelet devices identifies the user who is actively touching and the other who is passively touched, defining the direction as being from the former to the latter. By controlling the vibrational feedback, the pair induces a tactile apparent motion representing the direction between two hands. The bracelets are comprised of our developed interpersonal body area network module, an acceleration sensor, and a vibrator. The devices communicate with each other through electrical current flowing along the hands to identify the direction by sharing accelerations just before a touch and to synchronize the feedback in less than ten milliseconds. Experiment 1 demonstrates that the vibration propagated from a bracelet device to the wearer's hand is perceivable by another. Experiment 2 determines sets of optimal actuation parameters, stimulus onset asynchrony, and duration of vibration to induce the tactile apparent motion based on a psychophysical approach. In addition, vibration propagation between hands is observed. Experiment 3 demonstrates the capability of the developed device to present the haptic interaction.