A study on vision sensors for seam tracking of height-varying weldment. Part 2: Applications

Many efforts have been made to develop an automatic welding system in order to improve the quality and productivity in welding shipping containers and LNG (Liquefied Natural Gas) storage tanks which consist of many sheet metals having linear weldments with height variation. A vision sensor which can provide 3D geometry information about objects is investigated primarily, because it is difficult to apply the arc sensor to automatic welding of thin plates. However it is difficult to determine the proper configuration of sensory system including a CCD camera and diode laser to specific weldments because of the interference and relative motion among vision sensor, welding torch and weldment. Therefore, to develop a vision sensor with high performance for a specific workpiece, the sensory system should be analyzed for various configurations of sensors and weldment shapes by using a mathematical model. In this study, the measuring efficiency of vision sensor predicted by its model and the criterion for data deficiency was in significant agreement with experiments for typical corrugations of shipping containers and LNG tanks. It was found that the results obtained from the mathematical model were very useful in designing the vision sensor for automatic welding of linear weldments with height variation.