Basic Image Measurement for Laser Welding Robot Motion Control
Akihiko Matsushita*, Masahiro Yamanaka*, Shun'ichi Kaneko*, Hitoshi Ohfuji**, and Kaoru Fukuda**
*System Sensing and Control Laboratory, Hokkaido University
North 14 West 9, Sapporo, Japan
**SANKO-STEEL, Zenibako 3-515-1, Otaru, Japan
Laser welding, provides high-density energy, is easy to control, and is low in heat input but deep in depth, enabling it to be used for small-area precision welding. However, Automating welding using robots has been considered, but laser welding requires accurate alignment and direction of irradiation because of its capability of sensitive welding. In this paper, basic image measurement method is proposed for Hand-Eye Laser Welding System equipped with an optical microscope and a CMOS camera, as follows.
1) A core line detection method of a slit laser image that has robustness against variation of observation direction and speckle patterns is proposed.
2) The parameter identification method of laser planes utilizing the core line detection method is proposed for measurement.
3) It is derived measurement equations of the position and the posture of the metal plate from geometric consideration utilizing the identified parameters and the core line detection.
-  N. Torii and Y. Asida et al., "Application of The Laser Vision System to The Laser Welding," J. of Japan Laser Processing Society, 13-4, pp. 240-244, 2006 (in Japanese).
-  W. Wolf and K. Amano, "Process Monitoring for Laser Welding Applications," J. of Japan Laser Processing Society, 13-4, pp. 233-239, 2006.
-  Y. Kawahito and M. Kito et al. "Adaptive Gap Control in Butt Welding with a Pulsed YAG Laser," Trans. of JWRI, 36-2, pp. 5-10, 2007.
-  K. Mikame, "Application of Laser Processing for Automobile Parts," J. of Japan Laser Processing Society, 11-2, pp. 67-70, 2004 (in Japanese).
-  K. Inui and S. Kaneko et al., "Robust Line Fitting Using LMedS Clustering," Trans. of The Institute of Electronics, Information and Communication Engineers, J84-D-II No.1, pp. 48-55, 2001 (in Japanese).
-  F. Ullah and S. Kaneko et al., "Orientation Code Matching For Robust Object Search," Trans. IEICE on Inf. & Syst., Special issue, E84-D No.8, pp. 999-1006, 2001.
-  M. Yamanaka and A. Matsushita et al., "A Graphical Measurement Method for Motion Control of YAG Laser Welding Robot," Proc. of the Third Asia International Symposium on Mechatoronics (AISM), p.128, 2008.