Susceptibility to periodic vibrotactile guidance of human cadence

In this paper we introduce a new guidance method that employs periodic vibrotactile cues to help users walk at a desired speed. We also explore walker´s susceptibility to periodic vibrotactile guidance (PVG): specifically, adjustments of their stride frequency in response to cues that are clearly perceived; and finally, how long users can maintain their stride frequency after the guidance cue stops. While wearing a vibrotactile display on one wrist, each participant was given five vibrotactile tempos, logarithmically spaced across the participant´s walking frequency range. We compared realtime stride frequency with cue tempo under conditions that varied cue tempo and presence / absence. Our results suggest that most individuals (here, 13 of 15) can synchronize their cadence with a vibrotactile cue with 95% accuracy (mean error, all participants: -1.5%, SD = 8.1) for a guidance tempo within their physical ability. Once a tempo was matched, walkers could maintain it for at least 30 seconds after the cue was turned off, showing promise for intermittent guidance as a solution to stimulus adaptation and annoyance. This finding informs design of spatiotemporal guidance systems, by showing how the informationally narrow but nevertheless underused haptic channel may have utility in guiding pedestrians´ speed, without a need to learn abstracted signals, and through a continuous control system.