Human Behavior and Comfort During Load Carrying to Autonomous Mobile Robot

To improve logistics operations, humans and autonomous mobile robots (AMRs) are expected to interact more in smart cities, such as leaving packages on AMRs for street pickup. However, how humans walk and pass objects to AMRs when approaching each other has not been systematically investigated. We conducted three psychophysical experiments to clarify the behavior and comfort of humans when carrying a package and placing it on an AMR, by (1) changing the AMR speed and final stop distance between the AMR and participant, (2) changing the stop distance and physical weight of the package, and (3) comparing participants’ behaviors and responses between high and low robotics experience groups while changing the stop distance and package weight. Motion trackers quantified the participants’ walking speed and hesitation probability (i.e., the frequency of temporary pauses during walking). Perceived heaviness and comfort were recorded using a questionnaire during each trial. The participants’ speed decreased and hesitation probability increased when the stop distance of the AMR decreased. The participants felt more comfortable with a closer approach, whereas the package weight did not affect their behavior. By contrast, they felt uncomfortable when the AMR remained still. The level of robotics experience had no influence on the results, suggesting that humans regard the approaching AMR as a load-carrying assistant and not as something entering their personal space. Comfortable human–AMR interaction can be achieved during load carrying if the AMR closely approaches a person without instilling a feeling of entering their personal space.