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Development of an automated classification system for polished stone slabs and tiles

Periodic Report Summary - PROVIPS (Development of an automated classification system for polished stone slabs and tiles)

PROVIPS project aims at building an automatic stone slabs/tiles classification system, that through the introduction of some preliminary parameters and by the application of a systematic selection methodology and specific image acquisition system requirements, will provide the elimination of human errors, the saving of time and, thus, the reduction of costs of this traditionally lengthy and costly manual or semi-automatic industrial selection processes.

Since the beginning of the project (1 October 2008) activities were mainly addressed to the complete definition of the main end-user's requirements. It is of fundamental importance to develop a system which could be really helpful for the stone market and consequently it is really necessary to clarify which are the real needs. All partners participated in this phase of the project as it was constantly necessary to couple the expressed 'stone' requirements with the main technical characteristics and parameters of the technology (camera and sensor) that the consortium decided to use for the PROVIPS system development.

The work carried out so far promoted the definition and classification of the relevant parameters/attributes when inspecting stone tiles/slabs surface. It was established a CSSQPRO (Customised stone surface quality classification procedure), that is the first systematic selection methodology constructed by the definition of natural stone main visual requirements (pointed out case-by-case by end-users as their major selection necessities) that will be transformed into a software (algorithm) programme that will operate directly on the data acquired by the vision system. It requires the calibration of the vision system through its supply of various types of tiles/slabs recognised as of the same ICR (Internal Company Reference) by the end user. It allows to focus the separation decision on more detailed attributes, considered relevant to the end-users in a given separation of ICN's (Internal company name) in ICR's.

The integration of the CSSSQPRO in the PROVIPS prototype will finally constitute the objectified automatic stone slabs/tiles selection system, that will allow to end-users to change their tiles/slabs selection/separation procedures/programs of ICNs in ICRs, or to settle more than one programme for the separation of each ICN according to the market needs.

Since the third month it was possible to close the requirement processing task and provide the final specification of the PROVIPS system. Moreover the definition of the test and trials procedures was performed establishing the guidelines to obtain results from the analysis of the samples.

From a system development point of view the consortium is carrying out both the software development and the demonstrator assembly phases. Nowadays a first draft release of the classification software is available and the demonstrator first installation was performed as well. The demonstrator, waiting for the brand-new spectral camera development, is now equipped with an RGB camera and the draft software release is now capable to perform some evaluations on RGB images.

Besides the previous, great effort was addressed to the definition and to the further development of the sensor-camera system. In particular: the desired pixel structure was defined, and it was decided to used the modified buried photodiode technology for the sensor to be defined, instead of the photogate-based pixel structures as initially suggested; the pixel configuration and the readout circuitry have been defined and partially simulated; the floor-diagram and the system design of the 1 280 x 960 pixels imager was designed and the first simulations and the system design began in October 2009 (first tape-out of the entire imager is planned for end of February 2010).

An ad hoc project website (see online ) was created in order to constantly keep both the consortium partners (private sessions) and the rest of the world (public sessions) updated.