Machine vision system for the inspection of reflective parts in the automotive industry

Specular surfaces inspection remains a delicate task within the automatic control of products made by plastic plating. These objects are of very varied shape and their surface is highly reflective acting like a mirror. This paper presents steps to follow in order to detect geometric aspect surface defects on objects made by plastic plating. The projection of a binary fringes pattern is used and enables to reveal the defects near the transition between a dark fringe and a bright fringe. Indeed, the surface imperfections provoke important light rays deviations. By moving this dynamic lighting, and thanks to a saturated camera, the system brings an aspect image where the defects appear very contrasted on a dark background. A simple image processing algorithm is then applied leading to a very efficient segmentation. To obtain such resulting images, the translation step, the duty cycle and also the number of images are constraint. This article finally shows how to adjust these parameters according to the various sizes of defect and to the objects shape.