An automated industrial conveyor belt system using image processing and hierarchical clustering for classifying marble slabs

Although there are many industrial machines used in marble industry classification of marble slabs in terms of quality is generally performed by human experts Due to economic losses of this rather subjective process automatic and computerized methods are needed in order to obtain reproducible and objective results in classification With the aim of remedying this insufficiency in marble industry a new electro-mechanical system which automatically classifies marble slabs while they are on a conveyor belt and groups them with the help of a control mechanism is proposed The developed system is composed of two parts the software part acquires digital images of marble slabs extracts several features using these images and finally performs the classification using clustering methods The hardware part is composed of a conveyor belt a serial port communication system pneumatic pistons a programmable logic controller (PLC) and its control circuits all employed together for grouping the marble slabs mechanically Although similar studies exist this paper proposes three novelties over the existing systems Firstly a new hierarchical clustering approach is introduced for quality classification without requiring a training set Secondly a new feature set based on morphological properties of marble surface Images is proposed Finally an electro-mechanical system is designed for accomplishing the task of sorting out the classified marble slabs In the literature only a system with a labeling mechanism has been presented Our system on the other hand comes with a complete conveyor belt acting as an element that links the production line with the proposed system This allows the possibility of embedding the proposed system into the production line of a marble factory It has been observed that although the performance of the developed system is not as high as neural network based systems that use training it could still be employed in industry when there is no available training set of samples With this advantage it provides an increase in the quality control standards of marble slab classification since marbles are classified with an objective and uniform-through-time criterion (C) 2010 Elsevier Ltd All rights reserve