Users' Internal HMI Information Requirements for Highly Automated Driving

Abstract

The introduction of highly and fully automated vehicles (SAE levels 4 and 5) will change the drivers’ role from an active driver to a more passive on-board user. Due to this shift of control, secondary tasks may become primary tasks. The question that arises is how much information needs to be conveyed via an internal Human-Machine Interface (iHMI) to fulfill users’ information requirements. Previous research on iHMI regarding lower automation levels has shown that user require different information respectively. The present study focuses on how users’ information requirements change for highly automated driving (SAE level 4) when the on-board user is distracted with a secondary task opposed to when the user is nondistracted. Twelve participants experienced different driving conditions and were asked to rate their attention distributions to other traffic participants. Results show clearly that users rated their attention distribution to other traffic participants significantly lower in automated distracted mode compared to automated non-distracted mode and manual driving. Furthermore, the question of users’ information requirements was translated into iHMI design preferences. For this purpose, four different iHMI prototypes based on a 360° LED light-band communicating via color-coded interaction design, which proved to work well for lower levels, were evaluated regarding the information richness level sufficient for users for highly automated driving (SAE level 4). Results show that the sufficient information richness level is conditional upon gender. Implications for future research and applied issues will be discussed.