Three-dimensional localization of thin-walled sheet metal parts for robotic assembly

This article presents a technical demonstration of a system for determining the threedimensional spatial location of complexly shaped, thin-walled sheet metal parts grasped by robots during assembly. For successful part assembly, the precise location of grasped parts (essential for successful mating of parts) must be achieved. A localization system is implemented to determine the accurate position and orientation of a sheet metal part that has been picked up by a robot from an arbitrary location. The proposed localization system employs a novel sensing method, utilizing laser-based proximity and edge detectors, to extract the part feature data in real time. These geometrical feature data are incorporated into an existing localization algorithm, which is based on the singular value decomposition formulation of the part localization problem. The sensingmethod is particularly effective in measuring 3-D feature geometry (i.e., thin edges) of sheet metal parts. An experimental single-robot test bed has been developed to demonstrate the feasibility of the part localization concept for a single sheet metal part. The experimental results obtained from the test bed demonstrate that the system can be effectively used for the localization of thin-walled sheet metal parts. © 2002 Wiley Periodicals, Inc.