Sensing free surface of arc weld pool using specular reflection: Principle and analysis

R. Kovacevic, Y. M. Zhang

Research output: Contribution to journalArticlepeer-review

53 Scopus citations


The weld pool surface provides important information for understanding arc welding processes. In this study, a novel vision sensor is proposed to measure the three-dimensional shape of the free weld pool surface. A pulsed laser is projected on to the weld pool through a specific grid. Specular reflection from the pool surface is sensed using a high shutter speed camera. The three-dimensional weld pool surface shape is clearly shown by the specular reflection. To determine the shape of the pool surface, an image processing technology has been developed to extract the skeleton of the specular reflection from the acquired image. The imaging principle is analysed to determine the correlation between the reflection and the weld pool surface. If the weld pool surface is known, the corresponding specular reflection can be directly calculated using the imaging model which is derived based on the reflection law. However, no explicit models can be obtained to determine the weld pool surface using the reflection and sensor parameters. To solve this difficulty, an iterative algorithm is proposed. The weld pool surface can now be calculated in 1 second from the specular reflection of the weld pool surface. A higher calculation speed is currently being pursued.

Original languageEnglish
Pages (from-to)553-564
Number of pages12
JournalProceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture
Issue number6
StatePublished - 1996


  • GTAW
  • Machine vision
  • Pool depression
  • Pool surface
  • Weld pool

ASJC Scopus subject areas

  • Mechanical Engineering
  • Industrial and Manufacturing Engineering


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