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 cont ainers and LNG (Liquefied Natural Gas) storage tanks which consist of many sheet metals having linear weldments with height variation. A vis ion sensor which can provide 3D geometry information about objects is investigated primarily, because it is difficult to apply the are senso r to automatic welding of thin plates. However it is difficult to dete rmine the proper configuration of sensory system including a CCD camer a and diode laser to specific weldments because of the interference an d relative motion among vision sensor, welding torch and weldment. The refore, to develop a vision sensor with high performance for a specifi c workpiece, the sensory system should be analyzed for various configu rations 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 agr eement with experiments for typical corrugations of shipping container s and LNG tanks. It was found that the results obtained from the mathe matical model were very useful in designing the vision sensor for auto matic welding of linear weldments with height variation. (C) 1998 Else vier Science Ltd.