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Closed loop control of laser welding processes using cellular neural networkcameras: Measurement technology

: Blug, A.; Abt, F.; Nicolosi, L.; Carl, D.; Dausinger, F.; Höfler, H.; Tetzlaff, R.; Weber, R.

Liu, X.:
28th International Congress on Applications of Lasers & Electro-Optics, ICALEO 2009. Congress proceedings. CD-ROM : November 2 - 5, 2009 - Orlando, FL; Laser Materials Processing Conference, Laser Microprocessing Conference, Nanomanufacturing Conference, poster presentation, gallery
Orlando, Fla.: LIA, 2009 (LIA 612 = 102)
ISBN: 978-0-912035-59-8
International Congress on Applications of Lasers & Electro Optics (ICALEO) <28, 2009, Orlando>
Fraunhofer IPM ()

Today, image processing using coaxial camera setups is used to monitor the quality of laser material processes such as laser welding, cutting or ablation. This article proposes a sensing system for the next step: Using image based quality features to form an instant feedback signal in order to maintain the process in the desired state. The key component of the system is a camera based on Cellular Neural Networks (CNN). This technology enables real time image processing which is necessary for a robust feature analysis in highly dynamic laser processes. It is used to control the laser power of a welding system by the contour of the full penetration hole. Compared to conventional systems, the frame rate for both, acquisition and evaluation rises from about 1 kHz to 14 kHz. This paper presents the measurement technology including algorithms and some welding results which demonstrate that the full penetration state is maintained even under rapidly changing process conditions such as steps in material thickness or variation of speed. An in-depth discussion on welding results is found in [1]. (Figure Presented).