Evaluation on Human Perception of Various Vibrotactile Encoding Methods Through a High Density Haptic Feedback Interface.

High density (HD) haptic interfaces have become increasingly common for entertainment thanks to advancements in virtual reality technology, however their flexibility may make them a useful sensory substitution interface for motor rehabilitation. Yet little research has explored how users interpret different haptic feedback encoding methods. Therefore, this study's objective was to evaluate the effectiveness of various encoding methods for conveying information based on existing sensory substitution strategies, one being a line motion tracking task and the other a direction tracking task. The first encoding method was Perceived Position Encoding (PPE), where information was encoded into the perceived position of stimulation. The second was Perceived Intensity Encoding (PIE), encoded information into the perceived amplitude of the stimuli. Twenty-one participants performed tracking tasks using both the PIE and PPE methods. The results showed similar performance in line motion tracking between the PIE and PPE methods, although the extra motors used in the PPE method appear to introduce uncertainty in users. Nevertheless, users were significantly more accurate with direction tracking when using PPE. These findings highlight the need for task-specific encoding methods, and showcase the versatility of the HD haptic vest as a tool for augmented feedback in motor rehabilitation.