Principles for external human-machine-interfaces

Abstract

Automated vehicles will soon be implemented in our today’s traffic system. This development will lead to a novel mixed-traffic environment where connected and automated vehicles (CAV) will have to interact with other road users (ORU). Enabling this interaction, external Human-machine-interfaces (eHMI) show major benefits regarding trust and acceptance of CAV in multiple studies. However, a harmonization of eHMI signals seems to be necessary since the developed signals vary extremely and sometimes even contradict each other. Therefore, the present paper proposes guidelines for designing eHMI signals, taking important factors like how and in which situations a CAV need to communicate with ORU into account. The authors propose 17 heuristics, the so-called eHMI-principles, as requirements for the safe and efficient use of eHMIs in a systematic and application-oriented manner.