Quantifying information transfer through a head attached vibrotactile display: guidelines for design and control
Vibrotactile displays can extend the perception capabilities of visually impaired persons. Placing such devices on the head promises easy attachment and detachment without reducing other interaction abilities. However, the effectiveness of head-attached vibrotactile displays has never been thoroughly tested. This paper presents the results obtained from experiments with 22 subjects equipped with a display containing 12 coin-type motors equally-spaced in a horizontal plane around the upper head region. Our display allowed single motor activation as well as multi-point stimulation with up to six simultaneously active motors. We identified the strength of minimum and comfortable vibrotactile stimulation, measured the precision in perceiving the accurate number of active motors as well as the precision in localizing the stimuli on the head. While subjects identified the correct number of active motors in 94% of the cases when presented with only one active motor, this precision dropped to 40% for two, down to 5% for five simultaneously active motors. This strongly suggests to avoid multi-point stimulation even though we showed that the precision of localizing a stimulus is barely affected by the number of simultaneously active motors. However, localization precision varied significantly with the region of the head suggesting that the most front and most back regions of the head should be avoided if high precision is required.
M. K. Dobrzynski, S. Mejri, S. Wischmann and D. Floreano,
IEEE Transactions on Biomedical Engineering, vol. 59, no. 7, pp. 2011-2018, 2012