South Korea: Hite Brewery uses Germany-made control system to inspect multiple label locations

At 50,000 beverage bottles per hour, inspecting the labels, caps, and fill levels is one of the most demanding applications facing a machine-vision system. High-speed manufacturing lines require high-speed image acquisition, which places additional-sometimes excessive-burdens on image-processing systems. This was the situation the Hite bottling plant in Jeon-Ju, Korea, faced when looking for an automated inspection solution for two beer-bottling lines, Vision Systems Design released October 25. The company needed to inspect front, neck, and back labels for different bottle sizes and different product lines. Hite turned to bottling-machine-vision specialist Stratec Control Systems for help.

Stratec developed a system based on its BV 3000W universal image-processing system, composed of three Marlin series FireWire cameras from Allied Vision Technologies, Stratec high-brightness LED flashlamps, MVTec Halcon image-processing software, and an image-processing platform that uses a Kontron ETX 3.0 computer-on-module board attached to a Stratec proprietary motherboard to handle the I/O in conjunction with a dedicated tracking-controller unit for real-time communications with high-speed PLCs common to bottling lines (see Fig. 1).

To meet the customer’s throughput needs, Stratec selected each component to maximize data bandwidth, reduce image-processing requirements, and separate real-time operations from non-real-time operations. Bottles enter the inspection workcell from upstream conveyors/accumulators, passing in front of a camera one at a time. After the inspection is completed, the bottles that pass inspection proceed downstream toward packaging equipment; rejected bottles are determined before packaging by downstream systems.
To ensure that downstream systems have the reject data based on inspection results in time to act, the system needs nearly real-time communication between the camera and various image-processing boards and real-time deterministic communication between the vision system and the downstream systems. Stratec accomplished this by splitting the Windows-based vision-processing platform from the downstream communication electronics.

The system uses a 640 × 480-pixel, F033B Marlin-series FireWire camera from Allied Vision Technologies. In addition to offering true partial readout capabilities from a CCD sensor to boost frame rates, the Marlin series has a built-in IEEE 1394 output. A FireWire interface imposes a lower CPU load at high frame rates compared to USB, so this was a high-performance, low-cost solution. In a similar way, MVTec Halcon image-processing software offers a universal frame-grabber interface, allowing the flexibility to use any available and supported frame-grabber/camera combination should the application require a change in hardware. Halcon also runs multiple image-processing threads from separate cameras in parallel, which increases throughput.

High-speed inspection puts increasing demands on illumination sources because cameras operating at faster shutter speeds (this system operates at 1/2500 or 1/5000 s) require more light to generate adequate images. For lighting, project-specific, self-designed LED flashes based on high-brightness LEDs are used. For the label-control portion of the Hite bottling-inspection application, intense light surrounding the bottle was needed, leading to a combination of six LED arrays positioned about key points around the bottle (see Fig. 3).
Click here to enlarge image

Inspecting the SKU regions on each label posed a challenge with regard to the light source. Since the SKU region is highly reflective, direct illumination was combined with diffuse illumination. The flash and the cameras are built into sealed, industrial-grade cases.

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