Extraction and Evaluation of Greeting Speech-Timing and Characteristic Upper Body Motion for Robots to Gain Attention of Older Adults

Greeting is important for socially assistive robot to smoothly initiate conversations with older adults. Because of their decreased cognitive function, older adults may occasionally be unaware of the presence of a robot. The purpose of this study was to investigate and evaluate the characteristic motion and utterance time for greeting older adults in comparison with those for greeting non-older adults. The motion and utterance for greeting a seated target imitating an older adult and greeting a non-older adult were measured. The utterance times of the greeting and motion parameters such as the maximum joint angles were calculated from the measured data. The parameters were compared using statistical methods. According to the results, the hip bending angle in older adults was 36.6° greater than in the non-older adults. The utterance lag for greeting the older adults was 0.7 s longer than that for greeting the non-older adults at this time. The impressions of the robot that greeted the participants based on the extracted motion parameters were compared to verify these parameter differences. Although the greeting styles did not differ significantly, it was verified that the robot’s greeting was more impressive than that of a computer-graphics robot.