Design of External Human-Machine Interfaces for Different Automated Vehicle Types for the Interaction with Pedestrians on a Shared Space

Toward a Holistic Communication Approach to an Automated Vehicle's Communication With Pedestrians: Combining Vehicle Kinematics With External Human-Machine Interfaces for Differently Sized Automated Vehicles

“…However, no effect of the vehicle size was found on pedestrians' trust and perceived safety. This stands in contrast to previous findings by Lau et al ( 2021a ) who showed that a smaller AV was perceived as safer and affectively more positive compared to a larger AV. Nevertheless, this study's video sequences presented only short interactions and, thus, a realistic interaction could have been limited.…”

“…In this study, both AVs were perceived as more trustworthy and safer when they were equipped with a dynamic eHMI compared to a static eHMI or no eHMI at all. Furthermore, the participants indicated a higher willingness to cross when a dynamic eHMI was presented which is consistent with previous findings (Clercq et al, 2019 ; Dey et al, 2019 ; Schieben et al, 2019a , b ; Ackermans et al, 2020 ; Kaleefathullah et al, 2020 ; Lau et al, 2021a ). Nevertheless, it needs to be pointed out that the online-based experimental approach and the experimental setting could have had an effect on pedestrians' subjective evaluation which needs to be addressed in future studies for further interpretation and comparison (Fuest et al, 2020 ).…”

“…Light-based eHMIs present a promising solution to transmit explicit information (Mahadevan et al, 2018 ; Schieben et al, 2019a ; Dey et al, 2020a ; Faas et al, 2020 ). Moreover, light-based eHMIs could present different levels of information richness, e.g., the VAS, the vehicle's intention, or the vehicle's perception (Schieben et al, 2019a ; Faas et al, 2020 ; Lau et al, 2021a ; Wilbrink et al, 2021 ). Previous research showed that pedestrians preferred a dynamic eHMI that presented explicit information about the vehicle's intention plus the VAS and were not satisfied with the mere static presentation of the automation status (VAS) (Faas et al, 2020 ; Lau et al, 2021a ; Wilbrink et al, 2021 ).…”

Investigating the Interplay between eHMI and dHMI for Automated Buses: How Do Contradictory Signals Influence a Pedestrian's Willingness to Cross?

“…The independent variables "eHMI status" (eHMI off vs. static eHMI vs. dynamic eHMI) and "vehicle behavior" (non-yielding vs. yielding) were manipulated systematically within-subjects. The eHMI status was displayed with a LED light-band eHMI in the colour cyan which has been previously evaluated for a bus [12]. The condition no eHMI served as baseline.…”

“…However, research showed that pedestrians behave more cautiously when interacting with larger vehicles [9,10] which could be explained by a higher perceived risk of getting injured by pedestrians [11]. Focusing on the design of eHMIs for different vehicle types, a study by Lau et al [12] investigated the application of eHMI communication strategies on an automated bus and revealed eHMIs as contribution to a well-working interaction in terms of pedestrians' perceived safety and perceived information quality [12]. However, current research also pointed out negative effects of eHMIs, e.g., overtrust, which can affect the overall safety in urban traffic [13][14][15] and, therefore, need to be investigated for larger vehicle types, e.g., buses, particularly as negative effects here in a pedestrian interaction might lead to serious accidents or even fatalities.…”