Using Human-Human Handover Data to Analyze Giver and Receiver Timing Relationships During the Pre-Handover Phase

The fluency of handover between two agents is important to ensure safety and success of handover. In this work, we study the relationships between the timings of giver and receiver motions in human-human handover interactions, in order to inform human-robot handover. We use giver and receiver hand trajectories from the Human-Object-Human (HOH) handover dataset to study movement during the pre-handover phase, prior to the point of transfer. We find that human receivers adopt a largely proactive behavior, and plan and start motion early in the pre-handover phase. We also find that human receivers spend much of their motion moving in coordination with the giver, rather than after the giver has reached the transfer point. Further, we find that human receivers may predict future movement of the giver from early giver motion, and adjust their start times accordingly to ensure coordinated grasp at transfer. Our findings suggest that robot receivers should adopt a predictive giver-aware approach to plan motion early, and robot givers should recognize that human receivers may expect giver behavior to be human-like and predictable.