Influence of robot motion and human factors on users' perceived safety in HRI

Besides the human physical safety also their perceived safety need to be taken into account in human-robot interaction (HRI). For this reason, the Expectable Motion Unit (EMU) concept was developed, a velocity scaling scheme relating the robot speed and instantaneous human-robot distance to the occurrence of human startle or surprise reactions. Since the perception of safety is highly subjective, the warranty of the EMU concept is expected to be dependent on human factors. Thus, human factors may be incorporated in the concept. Building up on the previous robot-focused analyses of the EMU, in this paper, we analyze the influence of human factors on perceived safety in robot approaching scenarios including 29 participants without the application of the EMU concept as well as in the same scenario with 15 participants under the application of the EMU concept. We report that the influence of sociodemographic factors is not significant which highlights the generalizability of the EMU concept. On the other hand, the experiments show that a strong habituation effect exists. This implies that the robot motion should be highly defensive during the first interaction with lay users. In general, the EMU concept proved its suitability by successfully reducing the influence of robot motion parameters on human perceived safety.