Comparing Subjective Perceptions of Robot-to-Human Handover Trajectories

TL;DR

This study investigates whether different robot handover trajectories influence human perceptions of safety and naturalness, finding no significant differences among tested trajectories, thus suggesting other factors may play a more critical role.

Contribution

The paper provides empirical evidence that trajectory shape alone does not significantly impact subjective perceptions in robot-to-human handovers.

Findings

No significant differences in safety and naturalness perceptions across trajectories

Subjective perceptions are not affected by trajectory shape alone

Future research should explore other variables like speed and communication signals

Abstract

Robots must move legibly around people for safety reasons, especially for tasks where physical contact is possible. One such task is handovers, which requires implicit communication on where and when physical contact (object transfer) occurs. In this work, we study whether the trajectory model used by a robot during the reaching phase affects the subjective perceptions of receivers for robot-to-human handovers. We conducted a user study where 32 participants were handed over three objects with four trajectory models: three were versions of a minimum jerk trajectory, and one was an ellipse-fitting-based trajectory. The start position of the handover was fixed for all trajectories, and the end position was allowed to vary randomly around a fixed position by $\pm$3 cm in all axis. The user study found no significant differences among the handover trajectories in survey questions relating to safety, predictability, naturalness, and other subjective metrics. While these results seemingly reject the hypothesis that the trajectory affects human perceptions of a handover, it prompts future research to investigate the effect of other variables, such as robot speed, object transfer position, object orientation at the transfer point, and explicit communication signals such as gaze and speech.