Calibration of a Computer Controlled Robotic Vision Sensor with a Zoom Lens

Abstract

Active vision sensors are increasingly being employed in vision systems for their greater flexibility. For example, vision sensors in hand-eye configurations with computer controllable lenses (e.g., zoom lenses) can be set to values which satisfy the sensing situation at hand. For such applications, it is essential to determine the mapping between the parameters that can actually be controlled in a reconfigurable vision system (e.g., the robot arm pose, the zoom setting of the lens) and the higher-level viewpoint parameters that must be set to desired values (e.g., the viewpoint location, focal length). In this paper we present calibration techniques to determine this mapping. In addition, we discuss how to use these relationships in order to achieve the desired values of the viewpoint parameters by setting the controllable parameters to the appropriate values. The sensor setup that is considered consists of a camera in a hand-eye arrangement equipped with a lens that has zoom, focus, and aperture control. The calibration techniques are applied to the H6 × 12.5R Fujinon zoom lens and the experimental results are shown.