Physiologically Expressive Robotic Hand as a Lifelike Presence

In this study, we propose a robot hand that demonstrates a combination of various voluntary grips and involuntary physiological expressions on the skin as a tactile expression representing emotions. The robot hand is implemented using skin expressions such as variable gripping strength and speed, goosebumps, perspiration, and temperature, which can be tactually perceived by the user. The focus is on how human impressions of the robot change in human–robot touch communication, and we evaluated the combination of various conditions. By combining involuntary physiological expressions on the skin (goosebumps, sweating, and body temperature) with the grip of a hand robot as a tactile voluntary expression, we investigated the influence of the difference in expression between the robot’s fear–stress context and the normal context on the impression of the robot. We particularly focused on how the robot’s tangible expressions affect the user’s emotions, such as fears corresponding to the experimental context, and we analyzed whether this would lead to a sense of empathy, discomfort, etc. We confirmed that the user’s empathy, which could not be elicited by involuntary expressions alone, tended to be elicited by a combination of voluntary and involuntary expressions and that this tendency differed depending on the type of involuntary expressions.