Proposal of a psychophysiological experiment system applying the reaction of human pupillary dilation to frightening robot motions

In coexistence systems comprising humans and robots, grasping the critical volume of acceptable robot motion conditions over which humans feel any fear is primarily important. In the paper, we propose to make use of the physiological reaction that human pupils dilate in a frightening situation and apply the reaction to our psychophysiological experiment system of investigating frightening robot motion conditions. First, we describe the experimental setup which is mainly composed of an eye movement tracking system capable of detecting the change in the pupillary diameter of subjects and is synchronized with the robot system so that we can identify the robot motion which arouses human fear. Second, we define the latent time as the longest one by offering the subjects unexpected approach of the robot, because the further back in time the latency is defined, the farther the robot is away from the subject, which means the system offers safer robot motion conditions. Finally, we show the procedure of identifying frightening robot motion conditions using the latent time, draw the volume of acceptable motion in a multimodal manner from the data obtained through the experiments in which the robot is controlled either to accelerate or to jerk uniformly, and compare the two cases to mention that uniformly jerking motion of the robot arouses human fear more easily