Using an internal 360° LED-Band in Highly Automated Vehicles to reduce Subjective Uncertainty

Kurzfassung

Self-driving vehicles are increasingly becoming part of our mobility. The vision of implementing highly automated vehicles (HAVs) that can fully perform the driving task without human intervention is expected to bring various benefits like higher comfort, traffic efficiency and more safety. But HAVs will also fundamentally change the role of humans in the vehicle; instead of driving themselves, they will become passengers. The loss of control and insufficient information can lead to experienced subjective uncertainty. The development of HAVs must address this higher need for information to avoid subjective uncertainty and thus support the formation of trust and acceptance in this new technology. LED-bands installed in the interior of HAVs have been proven to be a well understood and intuitive internal human-machine interface (iHMI) to communicate perceptual information via light signals. However, their use in HAVs needs to be further researched in urban traffic, where especially the interaction with vulnerable road users (VRUs) is a major challenge, both technologically and from a user perspective. Studies showed that visualising perceived VRUs on the LED-band (perception-based iHMI) can reduce subjective uncertainty. This work elaborated on these findings and two online studies were conducted with the aim to investigate to what extent a perception-based iHMI, compared to a less informative iHMI, is suitable to reduce aspects of subjective uncertainty and what impact different VRUs have. Furthermore, the first study evaluated in a within-subjects design which onset of information display is suitable for visualising a VRU on the LED-band and based on these findings, the second study compared in a mixed factorial design two display concepts for visualising several VRUs, whereby each group experienced one perception-based iHMI concept only. Participants In both studies, participants watched virtually created video sequences in which they experienced interaction scenarios between an HAV and various VRUs from the user's perspective in the traffic environment of a shared space. Results of both studies showed, that compared to no LED-band or a static LED-band (only displaying the automation status) a perception-based iHMI is suitable to optimize specific aspects of subjective uncertainty: participants reported a significantly lower experienced criticality, increased certainty about an appropriate reaction, as well as a better understanding and predictability of the HAV. The first study (N = 106) also demonstrated that particularly an earlier onset of information display, which was from visibility in the scenario shown, proved to be suitable for reducing aspects of subjective uncertainty compared to a later onset. The second study (N = 154) found, that for the interaction with multiple VRUs, both a display concept visualising only closer VRUs or one that visualises also more distant VRUs are similarly well suited to reduce aspects of subjective uncertainty. Partially, an influence of the VRU on the aspects of subjective uncertainty was found, especiallyAbstract II a kid as VRU had been associated with a higher experienced criticality of the situation. Regardless of an effect by the VRU the decisive factor for a negative or positive expression of the aspects of subjective uncertainty had been the iHMI design. Overall, the studies indicate, that a 360° LED-band is a well-accepted and understood iHMI through which subjective uncertainty during the use of HAV can be reduced by providing perception-based information.