A distributed system for computer vision quality control of clinched boards

Clinching technology allows to join metal sheets by using a cold press. The quality control of joint points, a type of joint buttons, is performed by experts observing the shape of the joint button on the basis of their experience. VISICON IST Research and Development project (partially funded by the European Commission) has realized algorithms and a distributed quality control system for assessing in real time the production of clinched galvanized metal boards. The solution is based on computer vision, software engineering, process modeling, and knowledge representation through object-oriented modeling. The image processing algorithm is based on the G Transform. The transform presents interesting properties and is computationally cheap. The VISICON solution has been validated by using a large set of data and statistical analysis for the detection of joint buttons and for their quality assessment. The paper reports a description of the distributed real-time architecture of the VISICON computer based quality control system, the main aspects of the computer vision processing for quality assessment and the results of the validation phase.