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CoMac's new technology for keg inspection, in collaboration with Consorzio Intellimech

The milestones of our vision, which in more than 30 years of experience have enabled us to be recognized as one of the most important international players in this field, are the technological innovation and the great attention to the demands of our customers.

Posted on Tuesday, 1 February 2022 |
Category: Comac Plants

CoMac's mission is to design and manufacture automatic and semi-automatic plants for processing and packaging drinks in different containers, customising them according to specific technical and production requirements.

The milestones of our vision, which in more than 30 years of experience have enabled us to be recognized as one of the most important international players in this field, are the technological innovation and the great attention to the needs of our customers.

These principles are concretely applied through lean, flexible and intelligent industrial projects and processes, aimed at minimizing waste and giving value to time and available resources. For this reason, CoMac is always open to new solutions for the continuous improvement of its systems, also by relying on the collaboration and know-how of consolidated companies in the Bergamo area, where the company's origins proudly lie.

This is the case of Intellimech, a private consortium of large, medium and small companies aimed at interdisciplinary research in the field of mechatronics, of which CoMac has been a member since 2019.

The synergy between the two companies has resulted in a project dedicated to implementing a new methodology of inspecting the kegs, hence including it in future lines, designed and manufactured by the company.

 

Project overview


Among the containers that our plants process there are the kegs, which include various sizes in terms of diameter and height, but above all they have different type of fitting (i.e. the product inlet section).

In fully automated filling lines, where no intervention or visual control by the operator is required, inspection systems are needed to ensure that empty kegs are in the correct position (with the spear facing upwards) and there is no capsule (cap) on the keg’s neck. The technology used so far by these devices is based on the physical principle of induction.

Inductive sensors fulfill the requirement of detecting the keg orientation and eventually the presence of the capsule on its fitting thanks to their ability to detect the presence of metal components.

However, this technology remains a solution that requires “contact” and above all it is not able to ascertain the type of keg fitting. This means that the customer must physically check there is only one fitting type on the line.

This CoMac project is dedicated to inspecting the keg with the aim of overcoming this drawback. Artificial intelligence was implemented to perform the task of recognizing the fitting, as well as the presence of the cap and the collar.

More specifically, computer vision algorithms were developed to make predictions on images acquired during the production. The inductive sensor has therefore been replaced by a camera that takes an image every time the keg passes on the line.

 

Approach to the problem


An acquisition campaign was conducted to collect a diverse dataset of images containing kegs with and without fittings, with and without collars, for each type of keg.

Furthermore, synthetic data (2D color images) was used to train a convolutional neural network using domain randomization methodology.

Domain randomization proved to be an effective technique for training the neural network with simulated images. The keg in this case is shown to the model as just another variant, making the dataset richer in term of images. As a result, the model accuracy becomes higher.

Using the Grad-CAM (Gradient-weighted Class Activation Mapping) algorithm, it was possible to generate a “visual explanation” (activation map) of the internal functioning of the neural network. This approach allowed us to figure out which region of the image contributes most to determine the prediction, thus validating the final result.

An additional control, used to identify the keg orientation, was performed through a deterministic approach. In particular, a laser profilometer was used, designed to make precise profile measurements during dynamic processes.

Working at high frequency, the sensor detects the distance of each point on the keg’s metal surface, intercepted by the laser at every discrete instant.

This makes it possible to reconstruct the cross-section by linearly interpolating the detected points.

The profile variation in the central area is the discriminating element between the two profiles (upright versus downright).

The prediction is performed based on a differential calculation of the two profiles. In the case of fitting down, the derivative never exceeds a predetermined threshold value. When the keg is positioned upright, the derivative peaks at the fitting match, hence exceeding the threshold value.

 

Results


The total accuracy of the model exceeds 97%. The identification errors concerned in almost all cases "false positives", i.e. the kegs oriented correctly are classified as "to be overturned". However, in practical terms, a false positive has less impact than a false negative: a misclassification where the keg is oriented upright but classified as “to be discarded” is certainly more acceptable than letting a downright keg classified as “correct orientation" (upright) passing along the line.

The use of artificial intelligence algorithms in combination with the profilometer proved to be a technologically valid solution, considering that the inspection takes place " contactless", as no object physically interacts with the keg while the keg maintains its motion unchanged, without being stopped for control.

 

Conclusion


This innovative keg inspection system developed by CoMac R&D department following a long design project in collaboration with Intellimech, is now almost ready to be installed on our production lines.

It is specifically designed to be used on the most performing lines, where a very high degree of accuracy is required during the inspection phase.

The year 2022 begins with technological innovation and sees CoMac designing a new solution that meets the needs of a demanding, global and constantly-evolving beverage market.

Tag: Kegs
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