Comfortable passing distances for robots

If autonomous robots are expected to operate in close proximity with people, they should be able to deal with human proxemics and social rules. Earlier research has shown that robots should respect personal space when approaching people, although the quantitative details vary with robot model and direction of approach. It would seem that similar considerations apply when a robot is only passing by, but direct measurement of the comfort of the passing distance is still missing. Therefore the current study measured the perceived comfort of varying passing distances of the robot on each side of a person in a corridor. It was expected that comfort would increase with distance until an optimum was reached, and that people would prefer a left passage over a right passage. Results showed that the level of comfort did increase with distance up to about 80 cm, but after that it remained constant. There was no optimal distance. Surprisingly, the side of passage had no effect on perceived comfort. These findings show that robot proxemics for passing by differ from approaching a person. The implications for modelling human-aware navigation and personal space models are discussed.