Multi-Dimensional Perception of Two-Channel Skin-Stretch: Effects of Cue Pattern and Spatial Configuration.

Assistive robots lack natural proprioceptive feedback, often forcing users to rely on vision. With recent advances, haptic interfaces can now accommodate the multidimensional nature of proprioceptive information. Skin-stretch is one promising haptic modality to provide proprioceptive information that resembles natural body mechanisms and conveys both magnitude and direction information, enabling compact multi-channel designs. While prior studies have examined perceptibility and channel interference, the ability of participants to integrate information across multiple channels remains not well understood. This study evaluates how effectively users can combine two skin-stretch channels to interpret two-dimensional cues. 21 non-disabled participants judged, in collocated and non-collocated placement, the linear projection of stimuli under four patterns of skin-stretch variation. Participants could generally perceive and integrate both channels into a coherent understanding of two-dimensional cues, though some non-uniformity in interpretation was observed. Channel proximity showed no clear effect on performance or workload. These findings provide the first systematic investigation of multi-channel integration in skin-stretch feedback and inform the design of scalable proprioceptive haptic feedback interfaces for assistive robots.