Determining Shape and Size of Personal Space of a Human when Passed by a Robot

Abstract

Autonomous mobile robots that operate in environments with people are expected to be able to deal with human proxemics and social distances. Previous research investigated how robots can approach persons or how to implement human-aware navigation algorithms. However, experimental research on how robots can avoid a person in a comfortable way is largely missing. The aim of the current work is to experimentally determine the shape and size of personal space of a human passed by a robot. In two studies, both a humanoid as well as a non-humanoid robot were used to pass a person at different sides and distances, after which they were asked to rate their perceived comfort. As expected, perceived comfort increases with distance. However, the shape was not circular: passing at the back of a person is more uncomfortable compared to passing at the front, especially in the case of the humanoid robot. These results give us more insight into the shape and size of personal space in human–robot interaction. Furthermore, they can serve as necessary input to human-aware navigation algorithms for autonomous mobile robots in which human comfort is traded off with efficiency goals.

The effect of robot speed on comfortable passing distances

“…Our main finding is that perceived comfort increases with passing distance following an inverted Gaussian. In our other work, the same relationship is found ( Neggers et al, 2022 ), and as we show in that paper, the same relationship can be found in the work of Pacchierotti et al (2006) . This gives further proof that an inverted Gaussian is an appropriate way of describing the relationship between passing distance and perceived comfort.…”

“…It is still not clear whether the same rules of human social navigation apply to robots. In our earlier study ( Neggers et al, 2022 ), we found that a passing distance of 80 cm was indeed considered comfortable, but in this study, people were not moving but stationary.…”

“…On the shape of this personal space is still some discussion, Hall considered it to be circular ( Hall, 1966 ), but other researchers found egg-shaped ( Beck and Ollendick, 1976 ; Bailenson et al, 2001 ), elliptical ( Helbing and Molnar, 1995 ) or asymmetrical ( Gérin-Lajoie et al, 2008 ) shapes of personal space. For a more detailed overview of these shapes you can read the work by Rios-Martinez et al (2015) or by Neggers et al (2022) .…”

“…Much fewer lab studies aim to quantify personal space in a dynamic context ( Pacchierotti et al, 2006 ; Neggers et al, 2022 ). More often human-aware robot behavior in navigation is tested in a complete navigational model, such as the Human-Aware Motion Planner by Sisbot et al (2007) .…”

“…There are almost no studies that focus on quantifying human comfort and robot efficiency for passing or overtaking scenarios. In our own earlier work ( Neggers et al, 2022 ), we investigated passing distances for a static person. We found that human comfort is a nice smooth function of passing distance and that passing at the back of the person was perceived as less comfortable compared to passing at their sides or at the front.…”