Real time seam tracking system for automated fusion arc welding

Abstract

The demand for a simple and inexpensive yet flexible real time seam tracking system for automated fusion arc welding processes is ever increasing. To date, few techniques have been implemented in industry on a commercial basis, employing mostly thermovision devices, e.g. infrared vision cameras, infrared scanning radiometers, etc. or laser illuminated seam tracking systems. From the literature it appears that the use of simple vision sensors such as charge coupled device (CCD) cameras, which can monitor the surface temperature gradients as well as seam tracking operation in real time economically and reliably, has not yet been fully explored. It is thus conceived that further work is required in investigating real time seam tracking and adaptive control using image processing techniques and CCD cameras as they are inexpensive and robust as well as being sufficiently flexible. This highlights the importance of the present work, in which an attempt is made to extract geometrical parameters of the welding arc and to locate the weld seam ahead of the welding torch using images sensed by a simple CCD monochrome camera. The developed system has been tested successfully for fusion arc welding of butt joints with arc offsets, which are induced intentionally during experimentation.