Designing wearable vibrotactile device for communication

Feedback plays an important role for human-computer interaction designs for information communication. Despite the widely use of visual and auditory feedback, there is an increase desire for using vibrotactile feedback in human-computer interaction designs, especially for those developed for hands- and eyes-free controls. However, the current use of vibrotactile feedback for information communication is still limited. In particular, most vibration feedback on current devices rely on vibration interval time as a critical feature for vibration discrimination. So users need to wait till all sub-vibrations stop vibrating in order to recognize a vibration pattern. This no doubly increases users’ total waiting time. Therefore, the present study investigated a set of vibration stimuli that were generated by different input voltages than by interval time.

The first experimental study analyzed the perception of pair-wise dissimilarity among the selected vibration stimuli and identified a sub-set of vibration stimuli with maximized pair-wise dissimilarity. Then the later experimental study analyzed the immediate usability and learnability of the selected vibration stimuli when these stimuli were coded to notify different mobile applications. All the experimental studies were conducted using a research platform developed by the author.

Results from the first experimental study indicated that the majority of subjects could discriminate among 4 or 5 of the vibrations based on their perception of vibration intensity. Moreover, results from the second experimental study showed that subjects achieved an average response accuracy rate of 82.3% (SD=18.0%, 95% CI= [79.7 %, 84.9 %]) and an average response time of 2.83 seconds (SD = 0.83 seconds, 95% CI = [2.71, 2.95] seconds). Thus the overall user performance (i.e. accuracy rates and response time) measured from the present study were close to the average user performance as identified from previous vibration studies, even the present studies applied more complicated vibration parameters for information coding. In addition, results from the post-test questionnaires suggested that the vibration notification design in this study was perceived as useful, although results indicated there was still a need to improve the ease of use of the proposed designs.