Potato chips, cell phones, razors, and baby diapers are just a few of the many everyday items made with the help of industrial machine vision. In fact, any product that is manufactured in either high volume, high accuracy, low cost, or a combination of all three can be made better, faster, and less expensively using machine vision.
Since the company’s founding 25 years ago, Cognex has relied on standard computer components developed for high-volume applications unrelated to machine vision. That meant using minicomputers in the early 1980s, switching to microprocessors in the mid-1980s, and employing ASICs starting around 1990.
When the high-volume applications had switched to desktop PCs, Cognex maintained a dual-pronged approach to vision system development, adapting vision tools for both environments in which they were required to operate: ISA-bus PCs and VME-based rack systems. Both backplanes provided the bandwidth needed to capture and analyze images of manufactured items, and communicate information about the object to the automation system. But these early systems required special-purpose hardware on which to run the vision algorithms until Intel introduced its MMX instruction set in 1997.
“Since then, we don’t see many customers creating new VME-based systems, though it is still used in some legacy systems,” said George Blackwell, director of product marketing for PC Vision at Cognex. Since Intel Pentium-class CPUs took center stage, most vision systems run vision algorithms, or tools, directly on the CPU of the host PC. The majority of PC-vision systems today use the PCI local bus standard for PCs. Yet, just like the past transition from ISA to PCI, during the next couple of years, PCI will yield to PCI Express.
“We expect high-speed, high-resolution, and line-scan applications to be the first to take full advantage of PCI Express,” said Blackwell. PCI Express offers tremendous advantages for handling large quantities of image data. For example, a four-channel frame grabber over PCI Express offers eight times the bandwidth of a four-channel PCI frame grabber.
Multi-core CPUs and Digital Standards
With little effort from vision suppliers, PC vision systems become faster as CPU speeds increase. But the days of ever-faster CPUs have given way to a trend toward multi-core CPUs, according to Blackwell. “PC vision manufacturers must now optimize their systems to take advantage of multi-core CPUs to increase performance. Customers requiring multi-camera vision systems will see the greatest performance improvement as images from separate cameras can be processed in parallel on separate CPU cores.”
Today’s PC-based machine vision systems also benefit from emerging digital communications standards such as FireWire (IEEE 1394) and Camera Link. Camera Link cameras enable higher resolution and higher-speed imaging to help customers address the most challenging manufacturing applications, including fine defect inspection, precision alignment and measurement, and continuous process inspection.
“First, the camera drivers are built into the Cognex software to simplify integration,” Blackwell explained. “Cognex FireWire systems also use the same application development software, identical vision tools, and proven acquisition engine as other Cognex PC vision systems. And finally, our FireWire implementation is optimized for the high speed typically required in machine vision applications.”