Real time Arc-Welding Video Observation System

The arc welding process emits high radiations in the spectrum of IR, visible and UV light. Widely available cameras cannot map the 120 dB high contrast ratio between the surrounding and the welding process to an image. CCD cameras suffer additionally the blooming where highly exposed pixels flood their neighbors with electrons, so that these are sensed as white. Greyscale cameras based on C-MOS technology are available, with a sufficient contrast ratio. Without any additional technique its applicability for welding observation is restricted to uniformly glaring processes. Pulsed welding processes arouse a flicker effect, which diminishes the quality fundamentally. This article presents an observation system for real-time videos applicable to a wide variety of arc welding processes. The used high dynamic grey level camera is optically synchronized on the welding process and delivers an alternating sequence of under- and overexposure images. In a subsequent algorithm, the image data is merged and results in a video which covers a wider range of contrast dynamics, where the glaring arc, the weld pool and the surrounding scenery is clearly visible at once. This system can be used for stick-out detection to control the welding arc length, weld-pool observation for spread detection and path guidance directly at the process. This work is granted by the MTKI-CT-2005-029652 Marie Curie Actions funded by the European Commissio