Rendering Affective Touch With an Array of Pneumatic Unit Cell Actuators

Rendering affective touch through haptic interfaces has gathered significant interest due to its ability to elicit emotional responses. Among various forms of affective touch, this study focuses on stroke stimuli. An illusory stroke stimulus is rendered using eight discrete Pneumatic Unit Cell (PUC) actuators on the left forearm. The study systematically investigates how rendering parameters—including the traveling speed of the illusory stroke, the stimulus onset asynchrony (SOA) of consecutive indentations, and indentation pressure—affect the perceived pleasantness and continuity of the stimulus. Results reveal that higher speeds significantly improved both pleasantness and continuity, with speed emerging as the most influential factor. In contrast, SOA has no significant effect on either perceived pleasantness or continuity. Indentation pressure shows a moderate impact on pleasantness, with high pressures reducing pleasantness but having no significant effect on continuity. Additionally, a positive correlation is observed between perceived pleasantness and continuity, underscoring the relevance of the continuity illusion created by sequential indentations with discrete actuators in evoking pleasant sensations. These findings demonstrate the potential of PUC actuators for creating affective touch stimuli and provide preliminary insights into the influence of rendering parameters on affective touch in human-machine and human-robot interactions.