Vision systems are used in the food industry to ensure product and packaging quality. They provide a second pair of eyes for sorting, identifying and monitoring products. By highlighting packaging problems early in the process, firms can avoid the problems defective items could cause, such as leaky products or jams on the production line.
FIGURE 1. 51R75 case pack system can detect the total number, the correct color or whether a lid is missing.
MCSVision Inc. (Glen Ellyn, IL, USA;) is a supplier of OEM vision systems, integration services and complete turnkey solutions. MCSVision has been using Point Grey cameras in their high speed vision systems for quality assurance on factory assembly lines. They have created customized vision systems to inspect a wide range of products, from bottling and plastics, to cat food bags and precision leveling devices.
One of MCSVision’s products, the 51R75, is a conveyer-based case pack inspection system developed for a customer wanting to inspect cases of dried fruit containers with plastic lids. The system inspects the total number of containers and presence of a lid and uses the RGB information in the image to check for correct color. The system also keeps a recallable record of the defects, which allows the operator to pull up a table to see exactly when a product was rejected and for what reason (cocked cap, wrong color, etc.).
FIGURE 2. Software notifies the user that one of the lids is the wrong color.
An embedded PC with a Core™2 Duo processor from Intel® (Santa Clara, CA, USA; www.intel.com) and a PLC from Allen Bradley (Milwaukee, WI, US; www.ab.com) is used to control the camera, lighting, and other hardware components. The PLC tracks presence of a case using a photoelectric detector from Banner Engineering (Minneapolis, MN, USA; www.bannerengineering.com). The 51R75 uses a Point Grey color 1024x768 Flea2 FL2-08S2C camera to look at the top of the containers within the case as they run through.
“We have been using Point Grey cameras in our vision systems for quite some time and have been very pleased with the high quality of the products,” says Jim O’Reilly, President of MCSVision. “The reliability of the Flea2 cameras in a constantly vibrating environment has been key for these types of applications, and the speed of the Flea2’s IEEE 1394b (FireWire) 800 Mbit/s interface has enabled the 51R75 to perform inspections at a rate in excess of 650 cases per minute."
The control hardware and PLC are housed in a liquid-cooled wash-down enclosure to ensure years of reliability and energy efficiency. The enclosure for the camera and light sources can also be washed down. Upon detection of a case, the PLC sends a trigger signal to the Flea2 camera, which opens the electronic shutter and begins image acquisition. For illumination, the 51R75 uses a white LED system that is produced by MCSVision and contains a microprocessor for intelligent sensing (patent pending).
FIGURE 3. Flea2’s IEEE 1394b 800 Mbit/s interface enables a 650+ cases per minute inspections rate on the 51R75 system.
Image acquisition and camera control is performed by Point Grey's FlyCapture camera driver and software. Captured images are streamed over a 25-foot FireWire cables to a PCI Express FireWire card on the host PC, where they are processed by MCSVision's proprietary image processing software to inspect the case. By developing the software in-house, MCS has the ability to quickly modify either the inspection algorithms or the operator GUI to suit their client's needs.
MCSVision recently demonstrated the 51R75 case pack and the 4-camera 51R84 360-degree label inspection systems (featured in the March 2008 issue of Insights) at the Robots, Vision & Motion Control Show in Rosemont, IL. “We are also looking at integrating Point Grey’s FirePRO LDR (Long Distance Repeater) into the 51R84 for those applications that require the host computer to be separated by up to 100 meters from the rest of the system,” says O’Reilly.
FIGURE 3. 51R84 360-degree label inspection systems uses both the Flea2 and LDR.
The FirePRO LDR is the world’s first repeater system to use a GigE physical layer to transport FireWire data using GigE signaling, allowing IEEE 1394b 800 Mb/s data to be transmitted in real-time over 100 meters of standard Category 5e cable. The low-latency GigE PHY ensures the network complies with IEEE 1394b timing requirements. O’Reilly adds, “The LDR would allow us to take advantage of the strengths of FireWire, such as its reliability in multiple camera applications, and the cable length of GigE. This could be a benefit to those customers who want to increase the distance without changing cameras, drivers, or existing enclosures.”