Increasingly autonomous robots become more and more prevalent in daily life and their proximity to humans may affect human well-being and comfort. Consequently, researchers have begun to study the effect of robotic presence on humans and to establish distance rules. However, studies on human-robot proxemics rely on various concepts (e.g. safety, comfort, perceived safety and expectation conformity) to measure the appropriateness of distances which can affect the outcomes. The impact of using diverging operationalization has not been studied explicitly, thus the first aim of our research was to fill this gap. In two experiments (combined N = 80), placing participants in indirect hallway human-robot interactions, we found that the way appropriateness is operationalized has a significant impact on the results for lateral passing and frontal approaches. The second goal was to gain new insights into the influence of robot appearance on appropriate proximity. Using an ad-hoc created appropriateness scale we reveal that for robots displaying human faces on screens, closer distances are perceived to be appropriate. Our study provides valuable insights into the relationship between measurement methods, robot appearance, and appropriateness, and offers practical recommendations for future research and development in the field of social robotics.

It is predicted that the number of autonomous vehicles will increase in the forthcoming years. In this context, this research deals with autonomous micro-mobiles, specifically autonomous cargo bikes. In the development of (partially) autonomous vehicles, it is important to consider the safety perspective of vulnerable road users, such as pedestrians, already during development to enhance acceptance and widespread use. We investigated the safety parameters of speed and distance. For this purpose, videos with varying distance and speed parameters were filmed from a third-person perspective. These were then distributed via online questionnaires and evaluated by subjects regarding the subjective perceived safety. The results show that perceived safety increases with increasing passing and yielding distance and decreasing passing speed. Even at very short distances and relatively high speeds, the behavior of the cargo bike was still considered safe. These results can serve as reference values in the development of autonomous micro-mobiles. Further, the high safety perception should encourage planners and decision-makers to give these technologies a chance and boldly tackle the mobility revolution and test possible substitutes for motorized individual transport.

Autonomous robots of different kinds become more and more salient in our everyday life and because the spatial proximity of robots has an effect on the well-being of humans, researchers try to find and give appropriate guidelines regarding spatial proximity. In doing so, these studies rely on a few different concepts (e.g., safety or comfort) and on a rather large variety of different measurement approaches thereof. From psychology we know that the conceptual framing, as well as the way we measure (number of items, labels of scales, and wording) can affect the outcome of such studies. We present the first study that addresses and evaluates the consequences of these different conceptual and methodological approaches. We found that there is significant interaction between the different measurement approaches and the determined appropriate distance. This interaction was significant for both lateral passing distances and frontal approaches. This can have real-life effects, since the appropriate distances determined in studies such as the present may directly influence actual programming algorithms. Furthermore, by using three different types of robots, we were able to show that the humanization of mechanoids can lead to the acceptance of smaller distances by humans.