Vision system reduces keg filling line stoppages
A vision system developed by Olmec UK is being used to check that the correct beer kegs are present in the correct orientation on the filling lines at Molson Coors brewery. The vision system inspects the special filling tube in top of the keg, known as the spear, to determine whether the keg can proceed for sterilisation and filling. Around 2.5% line stoppages are directly attributable to attempting to fill the wrong keg types, since trying to fit a particular filling head to the wrong spear can cause significant damage. The introduction of the vision system has reduced this figure to 0.5%.
The filling line at Molson Coors is used for a wide variety of brands and therefore many different keg types are used. For each sterilisation and filling session, the appropriate filling heads are fitted for the particular brand. Kegs arrive back from outlets such as pubs, hotels, clubs etc for sterilisation and refilling in random fashion. There are various barrel shapes and sizes and they could be loaded onto the conveyors upside down so the spear is hidden, or the spear may have been covered with a protective cap, or have some sort of debris, or rainwater in them etc.
A GigE Vision camera with red ring light illumination is positioned above the filling line to image the tops of the kegs as they pass by. Since there are several different keg diameters, the system is set up to record an image every 100 ms, ensuring that an image of the spear will be recorded regardless of the barrel diameter.
Images are evaluated using a combination of a grey scale classifier system and statistical critical dimension measurement based on the popular Sherlock software. Since the appearance of the spears may be distorted by the presence of debris or rainwater in them, the vision system contains up to 50 images of each different spear type to allow for such variations.