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Advanced Imaging Magazine

Updated: January 12th, 2011 10:01 AM CDT

Lighting Manufacturer Integrates Vision into New Machine

Machine vision combines with motion hardware and software to solve a difficult task
The National Instruments Vision Assistant
© National Instruments
The National Instruments Vision Assistant is useful as a prototyping tool to see if algorithms can perform the necessary measurements and as a code generator for the larger application.
Sylvania web page
© National Instruments
By developing a system with software that easily integrates with its hardware, Sylvania saved weeks of time and created an extremely flexible and easy-to-use system.
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By Matthew Slaughter, National Instruments

Today, software is a crucial part of many systems, including machine vision systems. With machine vision processing software, engineers can take an image from a camera and turn it into something useful, be it a pass/fail indication, coordinates of a fiduciary marker, a serial number that's imprinted on a part or the value of a 2D code stamped on a product. There are hundreds of measurements engineers can make on an image, and once they extract these useful bits of information, they can use them in a variety of ways. Some engineers only need to store this data for quality assurance purposes, while others will use it as an essential part of the process their machine performs. In these applications, integration of the machine vision software into the rest of the system becomes crucial.

Sylvania Lighting, a world leader in the production of artificial light sources, required an application that involved the use of machine vision and motion hardware and software combined to solve a difficult problem. Sylvania's plant in Tienen, Belgium, which develops and produces metal halide lamps, was designing a new, smaller type of light source. The standard "pinch process" of using two metal blocks to press melted glass around electrode-foil wires to make the light was not suitable for these new lamps. The new process involved melting the glass directly around the foil. In the new setup, a CO2 laser melted the glass when the bulb was precisely placed in the correct location. This required development of not only a new machine, but also a new optimized production process.

One of the first steps in designing a new machine is outlining its requirements. Sylvania determined that the system would need to be extremely flexible and produce many different types of lamps. Along with this flexibility, Sylvania wanted to make sure that its new system was as easy to use as possible. The goal was to ensure that even a technician with basic training could manage to change between the manufacturing of one type of light bulb to the next. The software designers requested that they be able to interchange process steps and the order of those steps, in addition to writing their own sequential steps for use in the larger application. Safety also was a concern, and the designers wanted to make sure they had a foolproof way to guarantee system security and the safety of the engineers and technicians.

The flexibility they were looking for wasn't available in a PLC-based system, so Sylvania engineers decided to use a Microsoft Windows-based PC along with hardware and software from National Instruments. Their hardware included an NI PCI-7831R reconfigurable I/O board with an onboard field-programmable gate array (FPGA) for precise timing requirements, an NI PCI-7356 high-performance motion board, and an NI PCI-8252 IEEE 1394 camera interface board. The development software included NI LabVIEW, the NI Vision Assistant and NI LabVIEW FPGA.

LabVIEW is a graphical programming environment that provides a common platform for machine vision, motion, data acquisition, high-speed test and many more measurement types. Because of this, Sylvania could develop all of the software components for its complex machine within one programming environment. This environment also allows completely modular code, so the developers were able to create steps for each of the machine functions. They could change, run individually or reorder these steps based on application needs.

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