Visual sensing and recognition of welding environment for intelligent shipyard welding robots

Automation of welding process in shipyard is ultimately necessary, since welding site is spatially enclosed by floors and girders, and therefore welding operators are exposed to hostile working conditions. To solve this problem, recently a robotic welding system for closed block assembly has been developed. For complete autonomy, this system needs a sensor system for the weld seam tracking and the recognition of the working environments. In this paper, a three-dimensional laser vision system is developed based on the optical triangulation technology in order to provide robots with work environmental map. This sensor system composed of three laser stripes and two visions is used to detect the welding positions and to recognize the 3D shape of the welding environments. The algorithm architecture for the welding environment recognition is divided into two parts. The first is the conventional 3D scanning module, and the second the plane generation module utilizing on Hough transform. The design of the sensor system and the algorithm for sensing the structured environment are described and discussed in detail.