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.

Robotic systems and their software design are based on the same principles found in other computer applications. However, while many computer systems to date are deeply rooted in concepts such as multi-processing, multi-threads, modularity, etc., robotic systems are still limited by mono-processing, centralized designs. The paper addresses these limitations by proposing a new philosophy for robotic system software design - software infrastructure $that allows for the design of an efficient, modular, fault-tolerant, and distributed software architecture. Two examples of this infrastructure applied to mobile robot navigation are also discussed.