Body Language of Humanoid Robots for Mood Expression

Bodily expression of affect is crucial to human robot interaction. Bodily emotion expression concerns explicit body actions that typically interrupt ongoing functional behaviors. Instead, we design bodily mood expression by integrating affective cues with functional behaviors without interrupting them. We propose a parameterized behavior model with specific parameters that control pose and motion dynamics of the behavior. Modulating those parameters results in different behavior appearance through which the robot mood is expressed. We applied the model to behaviors of the NAO robot, and conducted a user study to identify principles to be used for parameter modulation, experiments that evaluated whether the mood can be recognized by participants with or without a context, and experiments that address the effect of the mood expression on participants in human-robot interaction in a laboratory setting and a real life setting. Results showed that our approach for bodily mood expression of a humanoid robot is effective.