COGNEX inspects ceramic tiles

Citation

(2007), "COGNEX inspects ceramic tiles", Sensor Review, Vol. 27 No. 3. https://doi.org/10.1108/sr.2007.08727caf.004

COGNEX inspects ceramic tiles

COGNEX inspects ceramic tiles

Ceric Automation in France, found itself faced with the challenge of implementing a robust and reliable solution checking tiles for one of their clients. The sheer variety in the appearance of the tiles after the “firing” process and the complexity of the job meant that the only possible solution was machine.

The humble tile long having been thought of as purely functional has become a decorative element in its own right. Manufacturers today need to have resource to a certain level of creativity in order to satisfy both traditional and more original tastes. Tiles are available now in all kinds of shapes, sizes and textures in an endless range of colours. A tilemaker could easily have a range of 100 different tiles with many different colours and features. It is in this context that Ceric Automation found itself entrusted with a project for one of its tile manufacturing clients calling for the creation of a materials-handling system. Knowing the extent to which the tile industry had become sophisticated in its customer offering, Ceric knew their task was going to be far from simple.

Challenge: find the best eyes for these robots

After having been moulded and dried, the tiles need to be fired. They arrive haphazardly along a conveyer belt to be positioned precisely by robots on individual supports on another belt leading to the oven. The robots need to pick and place the tiles on the next conveyor belt without any breakage or false rejects. Even though these tiles are of similar shape, they are different colours and textures and are likely to have certain anomalies which are not necessarily a cause for rejection. Cerci toyed with the idea of realigning all of the tiles mechanically in order to solve the problem. However, this was not a viable option considering other aspects such as the extent to which the tiles differed in size, shape and texture.

Vision: the only real-time solution

Taking into consideration technical constraints such as a dusty and badly lit atmosphere, the need for a very low false reject level plus the differing aspects of each tile, it was clear that a machine vision system was the only possible solution. Ceric set about finding a company that could solve their problem. The challenge at hand regrouped many of the classic difficulties of machine vision and many of those consulted were not capable of handling the task in real time or of taking on the risks inherent in such a project – with the exception of one. Cognex proposed to install a vision system positioned above the line to inspect the coloured face of the tiles. After having tested this prototype, Ceric decided to use this solution which has been in place now for ten months guiding the materials handling system for their client.

The system in place is made up of two Fanuc robots and one Cognex In-Sight 5100. The In-Sight 5100 is a robust camera meeting IP67 standards. Armed with the powerful localisation software, PatMax, In-Sight is capable of confronting the most difficult applications.

Reliable recognition even in difficult conditions

PatMax is a powerful tool that ensures the In-Sight 5100 captures the image of each tile regardless of the dim light and dusty atmosphere. Considering each tile arrives every 2s, this is extremely impressive in challenging conditions. PatMax also ensures that the exact position of each tile is captured and recorded. These details are communicated via Ethernet to the robots who use this information to find each tile, pick it up and place it on the next conveyer belt. The In-Sight 5100 is also capable of “remembering” 80 different models which means there is no need for additional programming or production interruption for the different models passing through the conveyer belts.

Stéphane Faivre-Duboz, from Cognex France commented, “The challenge presented by this application is one of the most complex that a vision system would ever have to confront.” Dealing with multiple variations of colour and texture such as we encountered in these tiles, remains one of the most difficult problems in the vision sector. The powerful performance of these recognition algorithms, the durability, flexibility and ease of use of the In-Sight family of cameras are what lies behind the strength of the Cognex solution.

Ceric is in a position now where it can confidently propose their vision guided robot solutions to their clients, not only in France, but all over the world by relying on the support and international presence of Cognex.