How to Open an Interaction Between Robot and Museum Visitor? Strategies to Establish a Focused Encounter in HRI

On the basis of a video corpus of human-robot-interaction in a museum guide scenario, we address the challenge how a robot could determine the appropriate moment of opening an interaction with a visitor. Considering such openings as a stepwise coordinated process, we used a wizard-of-oz setup to investigate the wizard's timely decisions about when to look at the visitor resp. to verbally greet him/her (during early stages called pre-beginnings). Analysis is based on both robot internal and external data and combines qualitative sequential case analysis and quantification. Analysis reveals features for classification of two visitors types and corresponding opening strategies.