  In the field of navigation and visual servo, it is common to calculate
relative pose by feature points on markers, so keeping markers in camera's view
is an important problem. In this paper, we propose a novel approach to
calculate field-of-view (FOV) constraint of markers for camera. Our method can
make the camera maintain the visibility of all feature points during the motion
of mobile robot. According to the angular aperture of camera, the mobile robot
can obtain the FOV constraint region where the camera cannot keep all feature
points in an image. Based on the FOV constraint region, the mobile robot can be
guided to move from the initial position to destination. Finally simulations
and experiments are conducted based on a mobile robot equipped with a pan-tilt
camera, which validates the effectiveness of the method to obtain the FOV
constraints.
