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Application story

Machine vision ensures orderliness in high-bay warehouses

Since storage space is becoming increasingly expensive, it is necessary to use it as efficiently as possible with high bay systems. For Kiefel GmbH, a member of the Brückner Group, phil-vision worked closely with Kardex to develop the VIS.tray system, a solution for maximum utilisation of available space that is optimally integrated into the Kardex high-bay towers.

For example, Kiefel GmbH stocks up to 14,000 parts in a high-bay system at the Freilassing site on around 1400 m² of storage space with a footprint of 120 m². The main objectives for switching to a Kardex high-bay tower system were to achieve more storage space on a smaller footprint than before and to make the warehouse more comfortable. One challenge in designing the system was the variety of goods to be stored, which vary greatly in type and size and range from labels and small parts to tools, motors, and bulk materials.

Size and weight must be right

Since there was no standard system available that could detect the free areas, phil-vision developed a machine vision system that helps to identify free areas on the trays. During the storage process of a tray, images of the current loading status are captured, and the loading weight is queried via the control system of the high rack. The system calculates the current weight information of each tray via the current drawn by the motors that move the trays in and out. The difference between the maximum and the actual load is equivalent to the maximum weight that a new part may weigh when being put into storage.

The images of the trays as well as the present loading status are stored in a database so that the employees can easily decide which tray has enough space to accommodate new parts by scrolling through the images. If the sum of the weight already stored and the new parts to be added still lies below the maximum permissible load, the employee can request the selected tray via a connected touch panel PC with one click and store the new parts.

Shortly before the tray with the new goods is put back into the high rack, a new image is captured and stored in the database, overwriting the previous image in the process. This way the images are always up to date.

       

Standard components for image capture

The selection of suitable vision components for integration in the output stations of the Kardex towers was not trivial, since on the one hand the entire width of the trays of around 300 x 80 cm had to be captured, and on the other hand the space for mounting the cameras was limited and the distance to the objects was relatively small.

The solution is based on a system of two colour cameras with fisheye lenses, which is connected via GigE Vision to the embedded multi-touch PC of the respective high-bay tower. However, the images captured by the system are distorted due to the lenses, therefore an algorithm had to be developed to compensate the distortion of the two images and to combine them. These 'stitched' images then show, undistorted and in colour, the complete storage area of the respective tray and are then saved into the system.

Custom user interface

During installation, the control between the high-bay rack and the machine vision system proved to be complex and required close cooperation between phil-vision and Kardex in order to implement the system in accordance with all of Kiefel's wishes.

The clear representation of the space and weight conditions on the trays contributes greatly to the fact that free storage spaces for new parts to be stored are found very quickly. Since this process saves a great deal of time, the storage system was very quickly accepted by all those involved.

It also offers a very fast solution to problems caused by potentially incorrect operation by the employees. If a part is put into storage by mistake without being scanned first, it can be found again easily and quickly by simply checking all current images on the monitor.


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