Taming the eHMI jungle: A classification taxonomy to guide, compare, and assess the design principles of automated vehicles' external human-machine interfaces

Dey, Debargha; Habibovic, Azra; Löcken, Andreas; Wintersberger, Philipp; Pfleging, Bastian; Riener, Andreas; Martens, Marieke; Terken, Jacques

doi:10.1016/j.trip.2020.100174

Cited by 173 publications

(150 citation statements)

References 23 publications

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“…So far, a large number of studies have examined the effectiveness of eHMIs that display the AV's state and intentions (for reviews, see [5][6][7]); for example, a VR-based study by De Clercq et al [8] found that pedestrians feel safer to cross in front of an AV with eHMI (e.g., text or front brake light) compared to without eHMI. A variety of other studies also show that eHMIs provide performance improvement or enhance subjective clarity for pedestrians relative to control conditions without eHMI [9][10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

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

Epke

Kooijman

Winter

2021

Journal of Advanced Transportation

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Automated vehicles (AVs) are able to detect pedestrians reliably but still have difficulty in predicting pedestrians’ intentions from their implicit body language. This study examined the effects of using explicit hand gestures and receptive external human-machine interfaces (eHMIs) in the interaction between pedestrians and AVs. Twenty-six participants interacted with AVs in a virtual environment while wearing a head-mounted display. The participants’ movements in the virtual environment were visualized using a motion-tracking suit. The first independent variable was the participants’ opportunity to use a hand gesture to increase the probability that the AV would stop for them. The second independent variable was the AV’s response “I SEE YOU,” displayed on an eHMI when the vehicle yielded. Accordingly, one-way communication (gesture or eHMI) and two-way communication (gesture and eHMI combined) were investigated. The results showed that the participants decided to use hand gestures in 70% of the trials. Furthermore, the eHMI improved the predictability of the AV’s behavior compared to no eHMI, as inferred from self-reports and hand-use behavior. A postexperiment questionnaire indicated that two-way communication was the most preferred condition and that the eHMI alone was more preferred than the gesture alone. The results further indicate limitations of hand gestures regarding false-positive detection and confusion if the AV decides not to yield. It is concluded that bidirectional human-robot communication has considerable potential.

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Section: Introductionmentioning

confidence: 99%

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

Epke

Kooijman

Winter

2021

Journal of Advanced Transportation

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“…In their questionnaire study on pedestrians' impressions of AVs in a shared space, Merat et al (2018) found that pedestrians would like to receive information about the AV's intended path in addition to whether the AV has successfully detected them. As of present, over 70 eHMI concepts have been proposed (Dey et al 2020), many of which are thought . Mean intuitiveness rating versus the keypress percentage in the 7.5-8.5 s interval for yielding vehicles in the 'Towards yielding' condition, for four levels of lateral deviation (mean of 2 videos for no deviation, mean of 4 videos for the other deviation levels).…”

Section: Discussionmentioning

confidence: 99%

“…An eHMI could convey the AV's intentions or provide instructions to the pedestrian (e.g., De Clercq et al 2019;Faas and Baumann 2019;Hudson et al 2018). Literature indicates that as many as 70 eHMI concepts have been proposed so far, each of which allows the AV to send explicit signals to other road users (Dey et al 2020).…”

Section: Introductionmentioning

confidence: 99%

Automated vehicles that communicate implicitly: examining the use of lateral position within the lane

2021

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It may be necessary to introduce new modes of communication between automated vehicles (AVs) and pedestrians. This research proposes using the AV's lateral deviation within the lane to communicate if the AV will yield to the pedestrian. In an online experiment, animated video clips depicting an approaching AV were shown to participants. Each of 1104 participants viewed 28 videos twice in random order. The videos differed in deviation magnitude, deviation onset, turn indicator usage, and deviation-yielding mapping. Participants had to press and hold a key as long as they felt safe to cross, and report the perceived intuitiveness of the AV's behaviour after each trial. The results showed that the AV moving towards the pedestrian to indicate yielding and away to indicate continuing driving was more effective than the opposite combination. Furthermore, the turn indicator was regarded as intuitive for signalling that the AV will yield.

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“…Besides, there is a huge variety of design concepts and applied measures, but again, there is no consensus on best practice approaches of external communication. A variety of meta-analyses [10,[14][15][16][17] approached this problem by examining and categorizing existing concepts in order to derive guidelines for further concept development and research in this field. They found that visual eHMIs, such as textual or symbolic displays, LED strips, or projections, are the most prevalent form of external communication due to their ability to convey difficult messages and interrelationships in a quickly understandable way.…”

Section: Related Workmentioning

confidence: 99%

“…Hence, we determined the following first research question for our work. Prior studies and meta-analyses of approaches to eHMIs also demonstrate a wide variety of design prototypes and guidelines [14][15][16], yet there is no agreement on the ideal design and content used for eHMIs. These examinations also showed that visual communication design concepts were most prevalent.…”

Section: Introductionmentioning

confidence: 99%

Understanding the Headless Rider: Display-Based Awareness and Intent-Communication in Automated Vehicle-Pedestrian Interaction in Mixed Traffic

Forke

Fröhlich

Suette

et al. 2021

MTI

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Automated vehicles do not yet have clearly defined signaling methods towards other road users, which could complement natural communication practices with human drivers, such as eye contact or hand gestures. In order to establish trust, external human–machine interfaces (eHMIs) have been proposed, but so far, these have not been widely evaluated in natural traffic contexts. This paper presents a user study where 30 participants interacted with a functional display-based visual eHMI for an automated shuttle in mixed urban traffic. Two distinct features were investigated: the communication of (1) its awareness of different obstacles on the road ahead and (2) of its intention to start or to brake. The results indicate that the majority of participants in general regarded eHMIs as necessary for automated vehicles. When reflecting their experience with the eHMIs, about half of the participants experienced an increased comprehension and safety. The combined presentation of obstacle awareness and vehicle intentions helped more participants to understand the shuttle’s behavior than the presentation of obstacle awareness only, but fewer participants regarded this combination of awareness and intent to be safe. The strength of the found effects on subjective responses varied with regard to age and gender.

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Taming the eHMI jungle: A classification taxonomy to guide, compare, and assess the design principles of automated vehicles' external human-machine interfaces

Cited by 173 publications

References 23 publications

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

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

Automated vehicles that communicate implicitly: examining the use of lateral position within the lane

Understanding the Headless Rider: Display-Based Awareness and Intent-Communication in Automated Vehicle-Pedestrian Interaction in Mixed Traffic

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