Image Processing for Automated Robotic Welding

Abstract

The construction of seagoing ships needs a lot of micro panels with maximal dimensions up to 16 x 4 m. About 2000 – 2300 micro panels with different sizes and about 20 – 25 various kinds of design are to weld for a medium size containership from 1700 – 2400 TEU. These are fillet welds mainly between stiffeners and the panel plate. There are two different techniques to make panels: For very long and parallel stiffeners are weld gantries in use for both side fillet welding, but for longitudinal and transversal stiffeners robotic welding is mainly used. Up to now the welding robot is linked and programmed by the CAD/CAM-system of the yard. This needs the offline programming more or less weeks before production and in this time the design of the panels can change. It is also an organizational problem to have the right CAD-program at the right time on the welding robot and to guarantee a flexible production process independent of the size and design of the micro panel. Therefore a way out is the flexible image processing. Developed by IMG and used by WADAN yards, MTW image processing system for welding robots delivers a very fast automatically generated program. The system, consisting of a laser line scanner with a scanning rate of 1 m/sec and a fast working calculation unit, gives a three-dimensional picture in less than 3 minutes all over the 16 x 4 m panel. After the shake hand process between the image processing system and the robot programming system the accuracy of the robotic positioning is ± 0.5 mm. This new developed 3-dimensional geometrically recognising and robot programming system allows a very fast and flexible production system for micro panels without any link to the central computer aided yard system. This “stand alone system” is independent, more flexible and shows, beside of other advantages, a high productivity.