Supplementary data for the paper 'Bio-inspired intent communication for automated vehicles'

Various external human-machine interfaces (eHMIs) have been proposed that communicate the intent of automated vehicles (AVs) to vulnerable road users. However, there is no consensus on which eHMI concept is most suitable for intent communication. In nature, animals have evolved the ability to communicate intent via visual signals. Inspired by intent communication in nature, this paper investigated three novel and potentially intuitive eHMI designs that rely on posture, gesture, and colouration, respectively. In an online crowdsourcing study, 1141 participants viewed videos featuring a yielding or non-yielding AV with one of the three bio-inspired eHMIs, as well as a green/red lightbar eHMI, a walk/don’t walk text-based eHMI, and a baseline condition (i.e., no eHMI). Participants were asked to press and hold a key when they felt safe to cross and to answer rating questions. Together, these measures were used to determine the intuitiveness of the tested eHMIs. Results showed that the lightbar eHMI and text-based eHMI were more intuitive than the three bio-inspired eHMIs, which, in turn, were more intuitive than the baseline condition. An exception was the bio-inspired colouration eHMI, which produced a performance score that was equivalent to the text-based eHMI when communicating ‘non-yielding’. Further research is necessary to examine whether these observations hold in more complex traffic situations. Additionally, we recommend combining features from different eHMIs, such as the full-body communication of the bio-inspired colouration eHMI with the colours of the lightbar eHMI.

各类外部人机交互界面（external human-machine interfaces, eHMIs）已被提出，用于向弱势道路使用者传递自动驾驶车辆（automated vehicles, AVs）的行驶意图。然而，目前尚未就何种eHMI设计最适用于意图传递达成共识。自然界中，动物已演化出通过视觉信号传递意图的能力。受自然界意图传递机制的启发，本文研究了三种分别基于姿态、手势与色彩的新型且具备潜在直观性的eHMI设计方案。在一项在线众包研究中，1141名受试者观看了搭载三种仿生eHMI之一的自动驾驶车辆（分别执行让行或不让行动作）的视频，同时还观看了搭载红绿光条eHMI、基于“通行/禁止通行”文本的eHMI，以及无eHMI的基线场景视频。受试者被要求在认为可以安全横穿道路时按住按键，并完成评分类问题作答。综合上述测量指标，即可评估受试eHMI的直观性。研究结果显示，光条eHMI与文本型eHMI的直观性优于三种仿生eHMI，而三者的直观性又高于基线场景。但存在一个例外：仿生色彩eHMI在传递“不让行”意图时，其表现得分与文本型eHMI相当。未来仍需开展进一步研究，以验证上述结论在更复杂的交通场景中是否依然成立。此外，本文建议整合不同eHMI的优势特征，例如将仿生色彩eHMI的全身式意图传递与光条eHMI的色彩标识相结合。