Improving Transparency of a Highly Automated Shuttle’s Minimal Risk Manoeuvre for Users by Internal Human-Machine Interfaces

Abstract

For Shared Automated Vehicles (SAVs), especially for highly automated driving (SAE 4) where no operator is on-board, user interaction with the automation system is an important factor for good user experience and acceptance of these mobility services. Even more so, when Minimal Risk Maneuvers (MRM) have to be performed by the system and the users are faced with uncertain situations. To reach the user´s trust and acceptance, a basic and intuitive understanding of the system and its functions is presumed to be beneficiary. One possible way of deepening a user´s understanding for a system is the system´s transparency. How this can be achieved through an automation´s interface in SAVs, how it should be designed and which information should be given to deepen the users trust and understanding, especially in MRMs, is still unclear. We investigated the impact of these factors using an online study, where participants as shuttle users evaluated varying internal Human-Machine Interfaces (iHMI) amid different scenarios of specific SAV usecases. The presented iHMIs varied in information expected to influence transparency and trust. Results of this study provide insights into an automated shuttle‘s user information needs in MRMs and are highly relevant to designing the interaction of shuttle users and the system´s interface.