Vision systems, image-based ID readers advance the world of industrial automation
Vision System on a Chip (VSoC) technology and machine vision-based 3D laser profilers are stepping up to the plate and hitting a homerun when it comes to improving read rates in the factory, says Cognex Corporation’s Market Development Manager John Lewis. But the bring-up of image-based ID readers and vision systems still presents some challenges in cost, ease of deployment, and electronics reliability.
LEWIS: Cognex Corporation, with a total worldwide headcount of about 1,000 employees, has shipped more than 850,000 systems, representing over $3 billion in cumulative revenue, since the company’s founding in 1981. Cognex provides vision systems, vision software, vision sensors, and surface inspection systems used in manufacturing automation. Cognex vision helps companies in virtually every industry improve product quality, eliminate production errors, lower manufacturing costs, and exceed consumer expectations for high-quality products at an affordable price. Typical applications for machine vision include detecting defects, monitoring production lines, guiding assembly robots, and tracking, sorting, and identifying parts. We also provide industrial ID readers.
Describe a practical scenario where your VSoC image-based ID readers would be used and what they would accomplish.
LEWIS: A snack food manufacturer with multiple brands ran into problems when they tried using a laser-based barcode scanner to direct boxes to different shipping areas. The height of the boxes (1.5 feet) made it necessary to position 3 feet above the conveyor line, and 3 feet away from the box, forcing the device to scan the barcode at a 45-degree angle, resulting in read rates of only 20 percent to 30 percent. As a result, the manufacturer had to assign a full-time employee over three shifts to manually divert the boxes when barcodes weren’t read by the existing laser scanner. The company also had to deal with the consequences of orders filled incorrectly, such as returned product that could not be resold.
To solve this problem, they switched to an image-based barcode reader, in this case a DataMan 500 from Cognex. These devices, which can read any label at any orientation within a 12-inch by 12-inch field of view, improved the read rate to 100 percent even though it reads from the same location as the previous laser-based scanner. This saved the company the cost of three full-time employees as well as the losses incurred by returned products, accounting for a total savings of approximately $250,000 annually.
How does VSoC technology work, technically speaking?
LEWIS: Cognex considers VSoC technology proprietary, however, it’s essentially a higher level of chip integration. The VSoC includes a three-quarter-inch XGA CMOS active pixel image sensor that can capture High Dynamic Range (HDR) images and a single instruction multiple data machine called a Linear Array Processor (LAP) optimized for real-time image analysis. An external DSP provides additional processing for data decoding, formatting, and communication.
What are the benefits of VSoCs compared to laser scanners or area scan image-based readers?
LEWIS: Decode speed – defined as the time required to capture an image and analyze it – is currently limited by the distance between the imager and the processor, the associated data transfer rates, and primarily the heavy analysis burden on the single DSP. Combining imager and processor on a single piece of silicon permits handling two tasks almost simultaneously, dramatically increasing decode speeds and overall frame rates.
Also, image-based ID readers provide a much higher level of reliability compared to traditional laser scanners. Traditional laser scanners are electro-mechanical devices that rely on an oscillating mirror to direct the laser beam across the barcode during operation. In contrast, image-based ID readers have a solid-state design with no moving parts that wear out and require repair or replacement.
Would it be possible to get the same capabilities using an FPGA rather than VSoC technology?
LEWIS: Probably. There’s usually more than one solution to any engineering problem. We felt VSoC was the most efficient path for us to meet the design requirements at the time.
Your company also recently announced a machine vision-based calibrated 3D laser profiler for harsh factory environments. What industry challenges does it meet?
LEWIS: The DS1100 is an industrial 3D sensor that uses laser triangulation to extract topographical information from the surface it’s scanning. Each variation in height on the surface results in high contrast within the image. The height information provides accurate, repeatable measurements below 5 microns. Target applications include gap-tolerances measurement detecting very small surface defects, and volume measurement for portion control in the food industry. Other applications include plane fitting to detect if components are slightly higher or tilted, angled in one corner, or out of place.
What are the three most significant technical challenges faced by developers of intelligent machine vision-based technology for manufacturing?
LEWIS: 1. Bringing down the cost of vision systems and image-based ID readers: As the cost to deploy vision and image-based ID solutions decreases, the number of applications where it can be cost-justified naturally increases. Whenever possible, we leverage Commercial Off-the-Shelf (COTS) electronic components such as DSPs and imaging sensors to reduce the cost of our products without compromising performance.
2. Make machine vision and image-based ID readers easier to deploy: Even more important than price is ease of use. By decreasing the level of expertise required to deploy and maintain products, we can decrease technical hurdles and other objections to ownership to increase the number of potential applications. Whether you’re connecting a vision system directly to a PLC or robot controller or managing multiple vision systems remotely from a networked PC or HMI, [there is a need] to provide tools that simplify integration and communications with other factory floor equipment.
3. Design and manufacture products that can perform reliably in harsh industrial environments: Our In-Sight 5000 Series vision systems incorporate a die-cast aluminum housing and sealed industrial M12 connectors to deliver an extremely rugged, self-contained vision system that meets IEC specifications for shock and vibration and achieves an IP67 (NEMA 6) rating for dust and wash-down protection.