Displaying the Driving State of Automated Vehicles to Other Road Users: An International, Virtual Reality-Based Study as a First Step for the Harmonized Regulations of Novel Signaling Devices

Abstract

Additional signaling devices for highly automated vehicles (AVs) that can communicate their driving state to other road users can simplify the integration process in existing road traffic. This paper presents the results of an international, virtual reality-based study conducted in China, South Korea and the USA in which subjects assume the role of a pedestrian and are placed in direct encounter situations with an AV in a parking lot. A novel communication interface consisting of three displays is attached to the AV's front and used to show additional information about its driving state. In total, three encounter scenarios are investigated: the AV approaches from the left, front and right outside of the pedestrian's line of sight. The influence of different symbol types on the subject's moving behavior, recognition of intention and perceived safety is investigated. The results show that additional signals ensure a better perception of the AV's intention and increase the perceived safety. The moving behavior of subjects is significantly changed when additional signals are used during driving tasks compared to the same tasks without such signals. The change of moving behaviour is similar in encounter situations where the AV approaches from the left and front but differs in encounter situations from the right. These results could equally be proven for all nationalities, which shows that a uniform, international solution for additional signaling devices of highly automated vehicles is possible.

I See Your Gesture: A VR-Based Study of Bidirectional Communication between Pedestrians and Automated Vehicles

“…Besides, future AVs may have to detect explicit gestures of vulnerable road users for safety reasons (e.g., detection of an extended arm of cyclists [34,36]) and to comply with traffic rules (e.g., being responsive to signals used by traffic police [31][32][33]). Furthermore, as others [8,10,37] have shown as well, the present study demonstrated that an eHMI makes visible the invisible. at is, it may be hard for pedestrians to detect the initiation of deceleration of an approaching vehicle; an eHMI makes such information salient, thereby improving subjective clarity.…”

How do pedestrians distribute their visual attention when walking through a parking garage? An eye-tracking study

“…That is, participants tend to follow the eHMI's instructions, provided the message is unambiguous (De Clercq et al, 2019;Fridman et al, 2019). A recent experiment performed in a virtual parking garage concurs that eHMIs that communicate the car's upcoming deceleration contribute to a decrease in crossing time of pedestrians (Singer, Kobbert, Zandi, & Khanh, 2020).…”

“…An example of this is the current state of automation; that is, whether the automation is currently active or not. Another idea could be to have an eHMI of an automated car displaying when it is about to drive away a few seconds before the car will do so (Eisma et al, 2020;Singer et al, 2020). We see this type of anticipatory eHMIs as an interesting subject for follow-up research.…”

“…The first reason was practical: A parking garage is shielded from direct sunlight, which is beneficial for the quality of the measurements from the infraredilluminator-based eye-tracker. The second reason was that many nonformalised interactions between pedestrians and vehicles could be expected in a parking garage, such as interactions with cars moving in or out a parking space (as also pointed out by Singer et al, 2020). A third reason is the fact that parking garages are a candidate environment for the introduction of automated vehicles (e.g., Banzhaf, Nienhüser, Knoop, & Zöllner, 2017).…”

A Systematic Review of Virtual Reality Applications for Automated Driving: 2009–2020

“…In mixed traffic situations, where automated and non-automated vehicles share the road, eHMIs can provide additional information, such as the driving state and intent, to other road users. In a VR simulator study, Singer et al (2020) explore a communication interface between the automated vehicle intending to park, and pedestrians. The user study results reveal that additional signals achieve a better perception of the vehicle's intention, and improve perceived safety.…”