An world-independent approach for the calibration of mobile robotics active stereo heads

This paper describes an approach for calibrating active stereo heads for which no prior knowledge of the world coordinate system is required. During an automated procedure derived from this approach, the mobile robot can be loosely positioned in front of a calibration pattern. Through our procedure, both the camera calibration and the neck-eye calibration are obtained. With this set of calibration matrices, the XYZ coordinates of a landmark can be determined with respect to the robot coordinate frame. The so calculated XYZ coordinates are accurate regardless of the orientation of the stereo head, even for orientations that were not used for calibration. This paper validates our approach by presenting results as accurate as a few millimeters in the calculation of the XYZ coordinates of objects at 1.5m from the stereo head.