Image processing for automatic welding in turbid water

摘要

Wet underwater welding is a key to improving offshore construction and maintenance cost performance. Automatic wet welding with local dry space provided by a water curtain provides high-quality mechanical properties on weld metal. The mostimportant factor in maintaining high weld quality is precise nozzle positioning. Light cutting by slit laser beam shows potential for shape recognition in air. Waterproof containers for the laser emitter and video camera are used for underwater seamtracking of weld line in turbid water. Acrylic windows on the laser emitter and video camera shortened the total light path length in turbid water and improved image quality. Laser light was dimmed by scattering in turbid water but detected groovegeometry, enabling good seam tracking. A trial to get a clear image used a fiberscope camera in the welding nozzle and detected root gap width precisely. Welding conditions such as molten pool geometry were also detectable.