Guidance of a person by combining moving and scaling projections from a mobile robot

Conventional mobile guide robots have a problem as they cannot control the positions of people around the robot, and thus the path of the robot is blocked when people gather near the robot. To guide gathered people to move away from the robot, the robot had to give explicit instructions by voice or display, such as “please clear the way” or “please move that way.” Such repeated instructions from robots are not comfortable for humans. This study proposes new guiding behaviours for a projector-equipped mobile robot that naturally leads a person away from the robot without explicit instructions. The proposed method guides a person through a combination of projection movements and scaling based on a person's tendency to move to a position where the projection can be easily viewed. An experiment with 15 participants showed quantitatively that the proposed guiding behaviours could lead people away from the robot without explicit instructions based on human behavioural measurements.