One of the neatest items on display at Schubert's stand was its latest prototype top loading machine (TLM) with a virtually empty switch cabinet. In this design, the servoamplifiers are part of the TLM robot within a decentralised controller system and thus no longer take up space in the control cabinet. In addition, the number of electronic parts has been significantly reduced.
This prototype machine, which was demonstrating the picking and packing of infusion bags, also incorporated Schubert's latest innovation in the field of image recognition: a 3D scanner positioned over the conveyor belt, determining the three-dimensional data of the products to be handled from that position, like volume and product weight if the density is consistent.
See the demo TLM packaging line incorporating the 3D scanner line in action here:
Spatial vision increases the performance capabilities of the TLM packaging lines both in the pick-and-place process and quality control.
Information on the volume and weight serves as the basis for a high-calibre grouping process. The robots are able to complete the individual product formation in such a way that its weight lies within a defined range. This type of weight optimisation can save the customer up to 3% in raw materials, depending on the application.
Schubert has supplied this explanation of the new vision system:
Schubert is not new to this field of technology – the company began developing image processing 30 years ago. Founder Gerhard Schubert wanted his packaging robots to learn to see, and working with his research team for image processing, this was achieved over time.
Since 1996, Schubert has been using line sensors for the Vision System. The first unit was a transmitted light scanner. This was followed by the reflected light scanner and colour reflected light scanner. These scanner types will also be used in the future. They operate reliably in continuous operation and are easy to commission. As with all TLM system components, they are easily added to the company's modular machine concept.
The new 3D scanner also has all of these features. Development is based on the stereoscopic approach, i.e. the scanner captures two views of each product from different angles. The calculated height profile includes the height of each point in space captured in both views. The conveyor belt represents zero height here. Therefore, the Schubert 3D scanner is a stereo 3D scanner.
Multiple colour line sensors are arranged next to one another at a set distance, making the scanner modular in nature. The field of view of each colour line sensor extends to the optical axis of the two neighbouring sensors on the left and right sides. Every physical point of the products, as well as those of the conveyor belt, which is imaged by two neighbouring sensors immediately contributes to the creation of the scene's height profile. The Vision System then reconstructs the 3D images from the height profile.
Light projectors located between the sensors project slightly overlapping bands of light onto the fields of view of the two neighbouring sensors. The light pattern is the result of an ingenious principle which enables unambiguous assignment of the image points in the stereo views. To locate the projection angle of the light pattern in the areas of overlap, the 3D scanner uses two different colours in an alternating fashion (e.g. red and blue).
The 3D scanner also features white-light illumination for capturing colour images. The colour images are reconstructed from the stereo captures without distortion or parallax. Both the colour light bands and the white illumination can be switched on and off in an alternating fashion to prevent undesired reciprocal effects.
