William S. Gribble
Robust control of a vision-based agent requires tight coupling between sensing and action. For mobile robots performing visually-guided navigation, this means closed-loop control of motion with respect to sensed features, landmarks, or other relevant parts of the visible environment. Real vision sensors have limited fields of view. This makes true closed-loop control with respect to an arbitrary set of landmarks impossible with practical vision systems, since only a fraction of the environment can be seen at any one time.