Investigation of impressions for approach motion of a mobile robot based on psychophysiological analysis

This paper investigates impressions of approach motions of a mobile robot based on psychophysiological analysis. In one of our previous studies, we suggested that actuation noise caused by the robots tended to raise the sympathetic nervous system (SNS) response of heart rate variability. In another experiment it was observed that blocking out either the sound or the sight of the robot motion attenuated the electrodermal activity (EDA), which reflects the SNS. From these investigations, one candidate for motion rules for human-friendly robots was deduced such that robots must reduce their motion speed in the immediate vicinity of human. To confirm validity of the motion rule, we constructed an experimental setup with a mobile robot approaching humans at several speeds, and investigated the human impressions by means of psychophysiological methods. The experimental results showed that robot motion adjacent to humans tended to increase EDA responses. We found especially that the approach motion tented to give stronger stimuli to humans than motions at a distance. The faster approach motion tended to increase EDA responses, but there was no significant statistical difference from the response to slower approach motion. From factor analysis of the subjective ratings two factors were extracted, which were interpreted as "relief of mind" and "observation on motion.