Delft University of Technology, the Netherlands.
Technical University of Munich, Germany.
Hum Factors. 2019 Dec;61(8):1353-1370. doi: 10.1177/0018720819836343. Epub 2019 Mar 26.
In this article, we investigated the effects of external human-machine interfaces (eHMIs) on pedestrians' crossing intentions.
Literature suggests that the safety (i.e., not crossing when unsafe) and efficiency (i.e., crossing when safe) of pedestrians' interactions with automated vehicles could increase if automated vehicles display their intention via an eHMI.
Twenty-eight participants experienced an urban road environment from a pedestrian's perspective using a head-mounted display. The behavior of approaching vehicles (yielding, nonyielding), vehicle size (small, medium, large), eHMI type (1. baseline without eHMI, 2. front brake lights, 3. Knightrider animation, 4. smiley, 5. text [WALK]), and eHMI timing (early, intermediate, late) were varied. For yielding vehicles, the eHMI changed from a nonyielding to a yielding state, and for nonyielding vehicles, the eHMI remained in its nonyielding state. Participants continuously indicated whether they felt safe to cross using a handheld button, and "feel-safe" percentages were calculated.
For yielding vehicles, the feel-safe percentages were higher for the front brake lights, Knightrider, smiley, and text, as compared with baseline. For nonyielding vehicles, the feel-safe percentages were equivalent regardless of the presence or type of eHMI, but larger vehicles yielded lower feel-safe percentages. The Text eHMI appeared to require no learning, contrary to the three other eHMIs.
An eHMI increases the efficiency of pedestrian-AV interactions, and a textual display is regarded as the least ambiguous.
This research supports the development of automated vehicles that communicate with other road users.
本文研究了外部人机界面（eHMI）对行人穿越意图的影响。
文献表明，如果自动驾驶车辆通过 eHMI 显示其意图，可提高行人与自动驾驶车辆交互的安全性（即不安全时不穿越）和效率（即安全时穿越）。
28 名参与者使用头戴式显示器从行人视角体验城市道路环境。接近车辆的行为（让行、不让行）、车辆大小（小、中、大）、eHMI 类型（1. 无 eHMI 的基线，2. 前制动灯，3. 《霹雳游侠》动画，4. 笑脸，5. 文字[WALK]）和 eHMI 时机（早、中、晚）有所变化。对于让行车辆，eHMI 从不让行状态变为让行状态，对于不让行车辆，eHMI 保持不让行状态。参与者持续使用手持按钮表示他们是否感到安全穿越，并计算“感到安全”的百分比。
对于让行车辆，与基线相比，前制动灯、《霹雳游侠》动画、笑脸和文字的“感到安全”百分比更高。对于不让行车辆，无论是否存在或使用哪种 eHMI，“感到安全”的百分比都相同，但较大的车辆让行的“感到安全”百分比较低。与其他三种 eHMIs 不同，文本 eHMI 似乎不需要学习。
eHMI 提高了行人与 AV 交互的效率，而文字显示被认为是最不模糊的。
本研究支持开发与其他道路使用者进行通信的自动驾驶车辆。
