Effects of Upper Body Vertical Oscillation of a Humanoid Robot on Human Reaction Time to the Robot's Movement Initiation and Cessationin a Virtual Environment

When humanoid robots move within human living environments, it is crucial for safety that humans can promptly react to the robots' movements. In this study, we investigated the impact of vertical oscillations of a robot's upper body, designed to mimic human walking motion, compared with cosine wave motion and a fixed condition, on human reaction time to the robot's movement initiation and cessation in a virtual environment. The results revealed that vertical oscillation enabled quicker human reactions to the robot's movement initiation and cessation than when there was no oscillation.