Between-Tactor Display Using Dynamic Tactile Stimuli for Directional Cueing in Vibrating Environments

Torso-worn vibrotactile devices have been used in many studies on directional cueing and navigation in environments where visual feedback is limited. These devices aim to indicate directions with high resolution while using the smallest possible number of vibration motors (tactors). Resolution can be increased using between-tactor displays, but their performance in vibrating environments (e.g., a helicopter) are unknown. This study proposes a between-tactor display using dynamic stimuli and verifies its effectiveness when the user sits in a vibrating chair. We developed a waist belt device that displays 12 directions using 6 tactors. Static stimuli display virtual (between-tactor) locations by constantly vibrating two adjacent tactors equally, whereas dynamic stimuli move the virtual vibration position back and forth between tactors. We performed two studies in which participants felt tactile stimuli and used a joystick to move a cursor on a screen to a target in the perceived direction. Direction recognition accuracy and task completion time were measured under combined conditions of two belt orientations (tactor alignments), with and without chair vibration, and with and without audio white noise to mask tactor sound. In all conditions, dynamic stimuli increased recognition accuracy while maintaining task completion time compared to static stimuli.