Interactive robots participating in our daily lives should have the fundamental ability to socially communicate with humans. In this paper, we propose a mechanism for two social communication abilities: forming long-term relationships and estimating friendly relationships among people. The mechanism for long-term relationships is based on three principles of behavior design. The robot we developed, Robovie, is able to interact with children in the same way as children do. Moreover, the mechanism is designed for long-term interaction along the following three design principles: (1) it calls children by name using radio frequency identification tags; (2) it adapts its interactive behaviors for each child based on a pseudo development mechanism; and (3) it confides its personal matters to the children who have interacted with the robot for an extended period of time. Regarding the estimation of friendly relationships, the robot assumes that people who spontaneously behave as a group together are friends. Then, by identifying each person in the interacting group around the robot, it estimates the relationships between them. We conducted a two-month field trial at an elementary school. An interactive humanoid robot, Robovie, was placed in a classroom at the school. The results of the field trial revealed that the robot successfully continued interacting with many children for two months, and seemed to have established friendly relationships with them. In addition, it demonstrated reasonable performance in identifying friendships among children. We believe that these results demonstrate the potential of current interactive robots to establish social relationships with humans in our daily lives.

This paper reports our novel approach to developing a social robot. The developed robot is able to identify relationships among humans from their physical behaviors as it establishes long-term relationships with humans. This interactive humanoid robot attracts humans to interact with it and, as a result, induces them to perform their group behaviors in front of it. The robot recognizes friendly relationships among humans by simultaneously identifying each person in the interacting group. We conducted a two-month experiment in an elementary school. As a result, the robot successfully continued friendly interaction with many children for the two months, and demonstrated reasonable performance in identifying friendships among children. We believe this ability to maintain friendly relationships with humans and to identify human relationships is essential to behaving socially.