Providing pedestrians and other vulnerable road users with a clear indication about a fully autonomous vehicle status and intentions is crucial to make them coexist. In the last few years, a variety of external interfaces have been proposed, leveraging different paradigms and technologies including vehicle-mounted devices (like LED panels), short-range on-road projections, and road infrastructure interfaces (e.g., special asphalts with embedded displays). These designs were experimented in different settings, using mockups, specially prepared vehicles, or virtual environments, with heterogeneous evaluation metrics. Promising interfaces based on Augmented Reality (AR) have been proposed too, but their usability and effectiveness have not been tested yet. This paper aims to complement such body of literature by presenting a comparison of state-of-the-art interfaces and new designs under common conditions. To this aim, an immersive Virtual Reality-based simulation was developed, recreating a well-known scenario represented by pedestrians crossing in urban environments under non-regulated conditions. A user study was then performed to investigate the various dimensions of vehicle-to-pedestrian interaction leveraging objective and subjective metrics. Even though no interface clearly stood out over all the considered dimensions, one of the AR designs achieved state-of-the-art results in terms of safety and trust, at the cost of higher cognitive effort and lower intuitiveness compared to LED panels showing anthropomorphic features. Together with rankings on the various dimensions, indications about advantages and drawbacks of the various alternatives that emerged from this study could provide important information for next developments in the field.

中文翻译：

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比较自动与人行通信的最新技术和新兴的增强现实接口

为行人和其他弱势道路使用者提供关于完全自动驾驶车辆状态和意图的清晰指示，对于使他们共存至关重要。在过去的几年中，已经提出了各种外部接口，它们利用了不同的范例和技术，包括车载设备（例如LED面板），短距离的道路投影以及道路基础设施接口（例如，带有嵌入式功能的特殊沥青）。显示）。这些设计是在不同的环境中使用样机，经过特殊准备的车辆或具有异构评估指标的虚拟环境进行实验的。也已经提出了基于增强现实（AR）的有前途的接口，但是尚未测试其可用性和有效性。本文旨在通过比较常见条件下的最新界面和新设计来补充此类文献。为此，开发了基于沉浸式虚拟现实的模拟，重新创建了以不规范条件下在城市环境中横穿行人的情况为代表的著名场景。然后进行了一项用户研究，以利用客观和主观指标来研究车辆与人行互动的各个方面。尽管没有一个界面在所有考虑的尺寸上都明显突出，但其中之一的AR设计在安全性和信任度方面取得了最先进的结果，与显示拟人化的LED面板相比，其付出了更高的认知努力和更低的直观性产品特点。加上各个维度的排名，