Paper:
Language: English:

Image Detection of Seam Line for Laser Welding Robot

Akihiko Matsushita^, Takafumi Morishita^,
Shun’ichi Kaneko^*, Hitoshi Ohfuji^,
and Kaoru Fukuda^

^*Graduate School of Information Science and Technology, Hokkaido University, North 14 West 9, Sapporo 060-0814, Japan
^**Sanko Steel, 3-515-1 Zenibako, Otaru 047-0261, Japan

Received: April 20, 2011

Accepted: August 10, 2011

Keywords: seam line, vision sensing, laser welding, robot control

Journal ref: Journal of Robotics and Mechatronics, Vol.23, No.6 pp. 919-925, 2011

Abstract

Automating robot laser welding requires that laser irradiation direction and laser focus positioning influencing welding strength be controlled precisely along the seam line. Since the edge of the welded object can be transformed in processing by such as cutting, bending and grinding, direct measurement is necessary to detect the seam line. A robust image detection method of seam lines is proposed for hand-eye laser welding system equipped with an optical microscope, a CMOS camera and two slit lasers for measurement. The seam line is detected indirectly to utilize the difference between local and global distribution of image of measurement lasers. Results of experiments demonstrated the effectiveness of our proposal.

Reference

[1] A. Matsushita, M. Yamanaka, S. Kaneko, H. Ohfuji, and K. Fukuda, “Basic Image Measurement for Laser Welding Robot Motion Control,” Int. J. of Automation Technology, Vol.3, No.2, pp. 136-143, 2009.

[2] A. Matsushita, T. Hokari, S. Kaneko, H. Ohfuji, and K. Fukuda, “Image Measurement on Curvature around Seam Line for Motion Control of LaserWelding Robot,” Int. J. of Automation Technology, Vol.4, No.6, pp. 536-541, 2010.

[3] M. Yamanaka, A. Matsushita et al., “A Graphical Measurement Method for Motion Control of YAG Laser Welding Robot,” Third Asia Int. Symposium on Mechatronics (AISM) in Sapporo, p. 128, Aug. 2008.

[4] A. Matsushita, T. Morishita et al., “Image Detection of Seam Line for Laser Welding Robot,” 4th Asia Int. Symposium on Mechatronics (AISM), pp. 373-378, 2010.

[5] K. Fukuda, H. Ohfuji et al., “Development of vision sensor for LASER welding (The 2nd report),” Sensing accuracy of welding points on curved surfaces, 2010 JSPE Autumn Meeting, pp. 623-624, Sep. 2009 (in Japanese).

[6] N. Torii, Y. Ashida et al., “Application of The Laser Vision System to The LaserWelding,” J. of Japan Laser Processing Society, Vol.13, No.4, pp. 240-244, 2006 (in Japanese).

[7] W. Wolf and K. Amano, “Process Monitoring for Laser Welding Applications,” J. of Japan Laser Processing Society, Vol.13, No.4, pp. 233-239, 2006.

[8] Y. Kawahito, M. Kito et al., “Adaptive Gap Control in ButtWelding with a Pulsed YAG Laser,” Trans. of JWRI, Vol.36, No.2, pp. 5-10, 2007.

[9] D. Iakovou, R. G. K. M Aarts, and J. Meijer, “Integrated sensors for robotic laser welding,” Proc. of the Third Int. WLT-Conf. on Lasers in Manufacturing 2005, pp. 1-6, Munich, June 2005.

[10] Z. Fang, D. Xu, and M. Tan, “Visual seam tracking system for butt weld of thin plate,” The Int. J. of Advanced Manufacturing Technology. Vol.49, pp. 519-526, 2010.