Robot Body Guided Camera Calibration: Calibration Using an Arbitrary Circle

This paper presents a novel camera calibration method for a system consists of a sensor-less mobile robot and an external camera. This method can estimate the focal length and the viewing direction of the camera relative to a plane where the sensor-less mobile robot moves from a single image of an arbitrary circle on that plane. Since it is easy to let a four-wheel mobile car to move along a circular locus, our method does not requires specially designed calibration objects for camera calibration. The method does not use the position of the center and the radius of the circle and the circle is allowed to be partially occluded. Through computer simulations and experiments with a real camera and a robot, we have confirmed that our method is more robust than the Homography based calibration using four point correspondences.