ANALYSIS OF CAMERA BEHAVIOR DURING TRACKING

A camera is mounted on a moving robot and can rotate, relative to the robot, about two axes. We show how the optical now field can be used t o control the camera's motion to keep a target at the center of the ca mera's field of view, but that this is not always possible when the ta rget lies close to the plane defined by the camera's two axes of rotat ion. When the target is held at the center of the camera's field of vi ew, then the magnitude of the camera's angular velocity about one axis never exceeds the magnitude of the flow vector associated with the ta rget, but the angular velocity about the other axis is dependent on th e inverse distance of the target from this axis, and hence can became large as this distance becomes small. Situations, where the magnitudes of the camera's angular velocity and acceleration become large, are c onsidered in the special case where the relative motion between the ro bot and its environment is purely translational. The tracking strategy is experimentally evaluated using computer-generated optical flow fie lds.