DMC implemented a vision system using four line scan cameras - two cameras acquire images of the products (4 per camera) before the package is closed and the other two cameras acquire images of the text printed on the outside of the packaging. DMC developed a LabVIEW program which runs in Real-Time on the NI embedded controller to acquire, process, and inspect images from all four cameras. The images of the product were inspected to ensure proper size, shape, positioning, absence of foreign objects, and presence of marking text. The text on the package is inspected for size, position, density, contrast, and sharpness. The system is capable of running inspections at the maximum speed of the machine: 1440 products and packages per minute.
The built-in FPGA on the NI embedded controller is utilized to count encoder signals, trigger the cameras, and initiate processing in the real-time code. After inspection is complete, results are sent to a PLC via EtherNet/IP communication so that the machine can reject bad packages at the end of the line.
A separate LabVIEW program runs on the Windows Touchscreen PC to provide the user with an interface to monitor and configure the vision system. A supervisor may enter a password to access and edit the recipe parameters that define the inspection criteria. This gives the system the flexibility to handle a variety of product types. The interface also calculates rejection rate statistics (separated by failure mode) and displays trend graphs to the operator, providing the operator with diagnostic information to help maximize yields.