Image Based ID Readers Improve Efficiency in Vitamin Retailer Warehouse
As distribution facilities increase the level of automation and set higher quality standards, the need for ID code reading increases and code reader accuracy, speed, size and price all become more important. For example, a dietary supplement company recently built a state-of-the art distribution center from scratch, utilizing the latest technology to increase productivity and ensure order accuracy. Each package is scanned in the order induction area, again as it passes each picking bay to determine whether it contains products stored in that bay, in the quality control area, and several more times to select the correct loading dock. The challenge for the integrator that designed and installed the automation system was to find an ID reader that could deliver near 100% read rates, handle line speeds of 30 packages per minute, read codes on boxes, shipping labels, packing labels and invoices all while taking up the smallest possible amount of space at an economical price. The Cognex DataMan 300 image-based ID reader met all of these requirements and 18 of these image-based readers are playing a key role in the facility’s efficiency.
Order fulfillment workflow
The dietary supplement company has developed a large and growing online business and is opening brick and mortar stores as well. The company worked with Carter Controls to provide the conveyor, sortation and manifest processing equipment for its new distribution center. The order fulfillment process begins with the system automatically determining the appropriately sized box for an incoming order based on the size and number of items in the order. A carton erector makes the carton and merges it into the system on a conveyor running at a speed of 28.5 to 30 packages per minute. The order induction station prints the invoice and drops it into the box and prints a packing label and applies it to the box. The box travels past a series of Pick2Light paperless pick and put systems that provide an efficient and accurate form of manual product selection and placement. Cameras positioned at the entrance to each Pick2Light bay scan the barcode on each packing label to make the decision of whether or not to divert the package into that particular bay. Packages are diverted only if the order includes items that are stored in that bay.
At each Pick2Light station, operators are guided visually by lights to the exact location from which the ordered articles are to be picked. With an inbuilt sensor, the device also signals when the wrong item has been picked. When the box is filled with product, it goes to a quality control area where the code is read again and the box is weighed. The system checks the weight of the box to see if it matches the weight of the products it should contain. If there is a mismatch, the box diverts to an offline manual station where operators resolve packages that the quality control station has rejected. First the operator removes the invoice and puts it flat on the table so a camera can capture an image of it for archiving. Then the operator manually makes any corrections needed to the order.
Just past the quality control station, another station drops collateral such as coupons into the package. The package then travels to the manifest station where a shipping label is printed and the shipping label and packing labels are read and checked to be sure they match. The dietary supplement company uses a number of different shippers and devotes a shipping bay to each shipping company. The warehouse automation system determines the best shipping company for each order and prepares a shipping label. The main conveyor line travels past each of the shipping bays and at the entrance to each bay a camera reads the shipping label on each box and based on the label the box is diverted into the appropriate bay.
Vision system selection
It was very challenging to find an ID reader or vision system that could meet all of the requirements of this application, said Marcus Lepage, Senior Software Engineer, Application Development for Carter Controls. “Space is very tight in the facility so size is an important consideration. The read requirements vary from the fairly simple task of reading the packing label to the much more challenging task of reading the code on the side of the boxes. The speed of the reader is also important. While the line is not traveling at an enormous speed, the readers need to take many images of each package as it travels past in order to ensure near perfect read rates. With 18 ID readers used in this facility, cost is also an important consideration.”
“The large number of vision systems in this facility made this application particularly price-sensitive,” Lepage continued. “Fortunately Cognex had recently introduced the DataMan 300 series of readers which meets all the requirements of this application at a surprisingly low price point.” DataMan 300 readers utilize the 1DMax+ code reading algorithm to achieve high read rates even on damaged 1-D linear bar codes. The DataMan 300 fits in a compact 2 inch by 2 inch package that easily fit throughout the plant. DataMan 300 ID are fast enough to capture and process images every 25 milliseconds which makes it possible to take 30 images of each package as it goes by and provide essentially 100% read rates.”
Code reading algorithms
Cognex DataMan 300 ID readers use 1DMax code reading algorithms with Hotbars technology that provide the capability to read even damaged linear bar codes at a high rate of speed. Images nearly always require rotation to a horizontal projection line prior to decoding and interpolation is used as part of this process to estimate pixel values at points in between squares of the pixel grid. Interpolation methods are based on a model of rotation in the continuous plane, but a discrete pixel grid cannot accurately represent rotation at the small scales characteristic of fine features, and the result is some blurring of the signal.
Hotbars technology has as its mathematical foundation a model of the behavior of the pixel grid itself, which allows blur to be reduced while maintaining perfect accuracy and good noise reduction. Hotbars’ enormous signal extraction speed comes from using a novel and extremely efficient algorithm that is well-matched to contemporary digital signal processor (DSP) architecture. The efficiency of the computation itself and the way that memory is accessed makes Hotbars signal extraction much faster than prior methods. Just as important, the ability to extract many more 1-D signals every millisecond has been used to eliminate decoding shortcuts, thereby reducing failure modes and improving read rates.
Upper level software
Carter Controls wrote the upper level software in the C# language to communicate with devices such as image-based ID readers, printers, servers and databases and make them available to application programs. The barcode readers themselves are connected with Cat5 Ethernet cable. Carter Controls used several different methods to communicate with the ID readers. The upper level software communicates with the imagers using a TCP/IP socket connection. The programmable logic controller (PLC) communicates with the readers using the Ethernet/IP protocol. The fact that the readers handle both of these as well as many other communication protocols simplified the application development process.
“This application demonstrates how the latest image-based barcode reader technology can improve distribution center productivity,” Lepage concluded. “In the past, laser barcode scanners would have been used on this application but we would have concerns about read rates, especially where we had to read the box. The DataMan barcode readers used in this application deliver more robust and reliable performance, such as in reading the relatively low contrast barcodes on the sides of the box. Yet the cost of high performance image-based readers has dropped to the point where they cost the same as or less than laser scanners. These image-based barcode readers also are much easier to communicate with so they reduce the overall time and cost required for system implementation. All in all, these small, inexpensive, fast and powerful imagers contributed to the implementation of a highly automated, state-of-the-art distribution center that performs with a high level of reliability at an economical cost.”
For more information, contact Cognex, One Vision Drive, Natick, MA 01760-2059 USA. Tel (Toll Free): 1-877-COGNEX1 (1-877-264-6391), Fax: +1 508 650-3344, Email: email@example.com,Web: http://www.cognex.com/