Robots on the road - Investigating potentials of eHMI-concepts for HRI to tackle critical situations in public spaces

Abstract

Robots in public spaces need to communicate with lay persons who are not directly involved in the robot task to coordinate their movements and resolve critical situations. Hereby, this communication aims at salience and clarity and at the same time needs to be unobtrusive. While in automated cars, communication with uninvolved road members has been investigated with the label external human-machine interface (eHMI) in human-robot interaction (HRI) this has not been systematically discussed. This study investigates some of the mainly discussed eHMI concepts (blinker lights, beep, and speech) for solving critical situations in HRI. Six critical situations were presented together with five communication strategies (presented as videos) in an online study with N = 175 participants. Mainly, criticality and trust were measured as dependent variables. Overall, situations including visually or hearing-impaired persons were perceived as most critical. For all situations, criticality was reduced with added interaction modalities. The combination of blinker lights and voice was ranked as the most preferred strategy for five situations and led to a reduction in criticality of all situations and higher trust in the robot. The relation between perceived criticality and trust was partially mediated by predictability and transparency. Design recommendations for solving critical situations through robots’ communication strategies in the public are discussed.