Handshake request motion model with an approaching human for a handshake robot system

Humans shake hands as a sign of greeting when they first meet one another to express a feeling of rapport. A handshake is an embodied interaction that involves physical contact. For interactions involving a human and a robot, if the robot generates a handshake motion that is emotionally acceptable to humans, it will lessen any feeling of aversion that the human has when initiating an interaction with the robot. Thus, in our previous study, a handshake request motion model was proposed, in which the robot generates a handshake approaching motion before actually shaking hands with the human. In this model, the robot stretches its hand out to a human to request a handshake. Furthermore, the effectiveness of the model was demonstrated by experiments using a handshake robot system when the human and robot remained stationary. However, in handshakes between two humans, one of them usually requests to shake hands with the other who approaches him or her in order to promote an embodied interaction. Therefore, in this paper, a handshake request motion model with an approaching human is proposed, based on an analysis of human handshake motions. In this model, the robot generates the request motion for a handshake when a human approaches the robot. Furthermore, a switching handshake control is developed where the robot generates either the request motion, or the response motion, for a handshake according to the motion of the approaching human. The effectiveness was demonstrated by a sensory evaluation.