Surface defect detection of 3D objects using robot vision

Purpose – The purpose of this paper is to develop a robot vision system for surface defect detection of 3D objects. It aims at the ill-defined qualitative items such as stains and scratches. Design/methodology/approach – A robot vision system for surface defect detection may counter: high surface reflection at some viewing angles; and no reference markers in any sensed images for matching. A filtering process is used to separate the illumination and reflection components of an image. An automatic marker-selection process and a template-matching method are then proposed for image registration and anomaly detection in reflection-free images. Findings – Tests were performed on a variety of hand-held electronic devices such as cellular phones. Experimental results show that the proposed system can reliably avoid reflection surfaces and effectively identify small local defects on the surfaces in different viewing angles. Practical implications – The results have practical implications for industrial objects with arbitrary surfaces. Originality/value – Traditional visual inspection systems mainly work for two-dimensional planar surfaces such as printed circuit boards and wafers. The proposed system can find the viewing angles with minimum surface reflection and detect small local defects under image misalignment for three-dimensional objects.