Resource conflict arises when people share spaces and objects with each other. People easily resolve such conflicts using verbal/nonverbal communication. With the advent of robots entering homes and offices, this thesis builds a framework to develop a natural means of managing shared resources in human-robot collaboration contexts. In this thesis, hesitation gestures are developed as a communicative mechanism for robots to respond to human-robot resource conflicts.

In the first of the three studies presented in this thesis (Study I), a pilot experiment and six online surveys provided empirical demonstrations that humans perceive hesitations from robot trajectories mimicking human hesitation motions. Using the set of human motions recorded from Study I, a characteristic acceleration profile of hesitation gestures was extracted and distilled into a trajectory design specification representing hesitation, namely the Acceleration-based Hesitation Profile (AHP). In Study II, the efficacy of AHP was tested and validated. In Study III, the impact of AHP-based robot motions was investigated in a HumanRobot Shared-Task (HRST) experiment.

The results from these studies indicate that AHP-based robot responses are perceived by human observers to convey hesitation, both in observational and in situ contexts. The results also demonstrate that AHP-based responses, when compared with the abrupt collision avoidance responses typical of industrial robots, do not significantly improve or hinder human perception of the robot and human-robot team performance.

The main contribution of this work is an empirically validated trajectory design that can be used to convey a robot’s state of hesitation in real-time to human observers, while achieving the same collision avoidance function as a traditional collision avoidance trajectory