Real-time automated visual inspection system for contaminant removal from wool

In the textile industry, scoured wool contains different types of foreign materials (contaminants) that need to be separated out before it goes into further processing, so that the textile machines are protected from damage and the quality of the final woollen products is ensured. This paper presents an automated visual inspection (AVI) system for detecting and sorting contaminants from wool in real time. The techniques were first developed in the lab and subsequently applied to a large-scale factory system. The combinative use of image processing algorithms in RGB and HSV colour spaces can segment 96% of contaminant types (minimum size around 4 cm long and 5 mm in diameter) in real-time on the lab test rig. One of the most important aspects of the system is to use the non-linear colour space transformation and merge the threshold algorithm in HSV colour space into the image processing algorithms in RGB colour space to enhance the contaminant identification in real time. The real-time capability of the system is also analysed in detail. The experimental results demonstrate that the factory AVI system could identify and remove the contaminants at a camera speed of around 800 lines/s and the conveyor speed of 20 m/min in real time.