Experimental Studies on Therapeutic Robotic Hardness for Stress Relief Effects

Abstract

With the development of soft robotics, the number of soft robots equipped with flexible actuators or sensors is expected to increase. In this paper, I investigated the appropriate robotic hardness for developing a robot with psychological and physiological stress relief effects through experiments comparing the effects obtained by interacting with robots having the Asker C hardness of about 0, 3, and 6. As a result, I confirmed that psychological and physiological stress relief effects obtained by interaction with the robot having the Asker C hardness of about 6 were significantly lower than that obtained by interaction with robots having the hardness lower than that, especially in terms of reducing tension and depression, improving vigor, and increasing the percentage of alpha waves. On the other hand, there was no significant difference between psychological and physiological stress relief effects obtained by interaction with robots having the Asker C hardness of about 0 and 3. These results suggest that the higher robotic softness within the discriminable range of robotic softness, the higher psychological and physiological stress relief effects obtained by interaction with robots. In addition, I found that it is necessary to set the softness of robots to be below the range of the adaptation-level of softness expected by users.