It offers more efficient packaging processes with the detection of three-dimensional objects.
Gerhard Schubert GmbH presented a new milestone in the field of image detection. A 3D scanner makes a three-dimensional vision a reality. This innovation increases the potential of TLM’s packaging lines in the pick and place process and in quality control.
The 3D scanner is placed above the conveyor belt which, for example, supplies the TLM line with packaging products, components for combined packaging or elements for assembling multi-part packaging. Based on the image data provided by the scanner, Vision System TLM generates a three-dimensional shape of each product or object.
More precise monitoring: Quality control
The height profile provides new control parameters for quality control. Using data from a 3D scanner, Vision System TLM can determine the volume and weight of each product. Adjustment of the nominal/actual value is also possible for the height and/or length of the pile when the products are placed edgewise in the boxes, since after each unloading process the currently reached height and/or length is also recorded. The TLM line with an integrated new scanner can detect 3D defects, such as a crack in the enamel, and automatically reject defective products.
New possibilities for selection and placement processes
Another attractive area of application of this innovation is the prioritization of product collection. For example: Vision System TLM detects where some products overlap. The first robots in the Pickerline preferably pick up products that are taller. The result is an increase in the efficiency of the selection and placement process.
Volume and weight data serve as the basis for a very precise grouping process. Robots can complete each of the product formations to be within a definable weight range. Exercise products can also be grouped by size, especially by height.
Permanent Visibility: Tape Impurity Tolerance
When a 3D scanner is applied, the Vision System tolerates impurities in the strip, as long as they do not exceed a certain height threshold. In addition, products can be detected better than before, even in low-contrast environments. Such difficult conditions are no longer an obstacle to image detection.
Approved field test
The first TLM Pickerline with a 3D scanner has already been put into operation at the factory of the Belgian candy manufacturer. Confectionery products are processed on such a line. The applied 3D scanner has a length of 1200 mm and has seven line cameras and six light projectors located at a distance of 100 mm. This achieves a height resolution of 0.5 mm in the measurement range of 60 mm height. The decisive factor in this application was to guarantee the detection of the product despite the crumbs and, above all, the chocolate residues left on the conveyor belt.
Operation and technology of 3D scanners
The company Gerhard Schubert GmbH started the development of image processing 30 years ago. Gerhard Schubert wanted his packaging robots to learn to see. Something he achieved at the time with his team of researchers specializing in image detection.
Since 1996, Schubert has been using line sensors for the Vision System. The first device was a transmitted light scanner. An incident light scanner and a color incident light scanner followed. These types of scanners will also be applied in the future. They work reliably in continuous operation and are easy to put into operation. Like all TLM system components, they fit into the company’s modular machine concept.
A 3D scanner also has all these features. The development is based on the stereoscopic principle, that is, the scanner captures two views of each product from different viewing angles. The calculated height profile contains the height of each point recorded in space in both views. The conveyor belt is equivalent to zero height. In other words, the Schubert 3D scanner is a stereophonic 3D scanner.
For the purposes of modular construction, several color line sensors are placed next to each other and at a certain distance. The fields of view of the color line sensors extend to the optical axis of their two adjacent sensors, right and left. Each physical point on the products, as well as on the conveyor belt, that is seen by two adjacent sensors immediately contributes to the elaboration of the height profile of the scene. The Vision System then reconstructs the three-dimensional images using the height profile.
A light projector is always located between the two sensors, which projects light strips slightly overlapping the fields of view of both sensors. The light pattern is subject to a sophisticated regularity that enables unambiguous attribution of image elements in stereo views. In order to localize the projection angle of the light pattern in overlapping areas, the 3D scanner alternately uses two different colors (eg red and blue).
The 3D scanner additionally has white illumination for color images. Color images are reconstructed from stereo recordings without distortion or parallax. Both colored light strips and white lighting can be switched on and off alternately to avoid unwanted mutual effects.