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Evaluation of a head motion synchronization system in the communicative process between human and robot

An aging population is world-wide social problem which affects many developed and developing countries. In this regard, many social robots based on reactive system have been developed to provide companionship for elderly adults with neurocognitive impairments such as dementia. However, these systems remain a problem such that no interactive dynamics of body gestures between human and robot has been considered. In this research, therefore, we developed a head motion synchronization system using mutual entrainment and implement it in a communication robot. This system was evaluated by conducting one-way face-to-face human-robot communication experiments with young native Japanese speakers under three conditions, namely unreactive, reactive and interactive conditions. Head motion synchrony analysis revealed a leader-follower relationship for the reactive model and a mutual entrainment of head motion for the interactive model. Also, questionnaire survey results showed the degree of empathy for interactive condition was significantly higher as compared with reactive and unreactive conditions. In addition, the degree of naturalness for interactive condition was significantly higher as compared with unreactive condition. Hence, these indicate that empathy was shared through mutual entrainment of head motion, which could provide a smooth interface in human-robot communication. This system would be extended to elderly adults as an assistive system for the elderly's rehabilitation.