Characteristics and individual differences of human actions for avoiding harm to eyes from a robot

To investigate harm-avoidance actions in human beings in close contact with a robot, we conducted psychological experiments in which one of the sharp end effectors of a robot was made to approach the eyes of a facing participant suddenly. We define three parameters for analyzing harm-avoidance actions: avoidance reaction time, maximum avoidance acceleration, and maximum avoidance speed. Results suggest that avoidance reaction time depends on the initial distance between the human eyes and the approaching object, but not on the type of work being performed. We derive a novel nonparametric multiple comparison for statistically testing multivariate data on human actions. Results show that bivariate data for avoidance reaction time and maximum avoidance speed differ for most participants. These findings are expected to contribute positively to determining human-robot conditions for safe coexistence.