Large View Visual Servoing of a Mobile Robot with a Pan-Tilt Camera

Vision being the most important human sensor and feedback system is considered to play a prominent role in the future of robotics. Robust techniques for visual robot navigation are essential in service robotics tasks. This contribution presents a novel approach to large view visual servoing of a mobile robot with a pan-tilt camera. A predictive camera control scheme guarantees that the image features remain in the cameras field of view. In a demonstration the robot is manually guided through the environment and reference images of landmarks are taken at distinct waypoints. During autonomous navigation the robot later follows the demonstrated path solely based on the visual feedback provided by the landmarks. The camera gaze is controlled independent of the robots egomotion which enables the robot to track landmark features across larger distances and orientations. Therefore, fewer visual landmarks are required to describe a smooth path through the environment. In order to control the robot motion independent of the gaze the observed features are transformed from the image plane into a virtual camera plane. The rotational, lateral and longitudinal motion are controlled separately by selecting appropriate image features that decouple the rotational and translational velocity component. This property is particular useful for traversing confined indoor spaces such as corridors, in which landmarks are located lateral to the direction of robot motion