Did you see it hesitate? - Empirically grounded design of hesitation trajectories for collaborative robots

Unwanted conflicts are inevitable between collaborating agents that share spaces and resources. Motivated by the use of nonverbal communications as a conflict resolution mechanism by humans, this study investigates the communicative capabilities reflected in the trajectory characteristics of hesitation gestures during human-robot collaboration. Hesitation gestures and non-hesitation human arm motions were recorded from a series of reach-and-retract tasks and embodied on a 6-DOF robot arm. A total of 86 survey respondents watched and scored recordings of these motions according to whether they recognized hesitation gestures as exhibited by both the human and the robot. Using the survey's statistical evidence indicating that hesitation trajectories embodied in an articulated robot arm can be recognized by human observers, we identified trajectory characteristics of hesitation gestures. The contribution of our work is an empirically grounded robot trajectory specification that provides communicative cues for conflict resolution during collaborative reaching scenarios.