Online Update for November 10, 2006



November 10, 2006


Sponsored by
Rockwell Automation

New camera technology is allowing video metrology equipment to make many of the same non-destructive surface-shape measurements that coordinate measuring machines (CMMs) can, only faster—and with similar accuracy . The design has been used in applications such as paper quality control and label-quality inspection.

How Extreme are these Machines? Decide for yourself. Cast your vote! Click here. Sponsored by Control Engineering, Design News, and Rockwell Automation.

Digital video improves metrology system performance

Machine control, Software

Incorporating a multi-megapixel machine-vision camera into a video microscope creates a metrology instrument that rivals CMM precision for Digital Precision Corp. Photo: Toshiba Teli America.

The current generation of high-resolution digital video cameras is making it possible to achieve measurement precision with video microscopes that was previously achievable only with coordinate measuring machines (CMMs). With this new camera technology, video metrology equipment can make many of the same non-destructive surface-shape measurements faster and with similar accuracy, the main limitation being that video metrology works best for measuring flat objects in two dimensions.

CMMs achieve high measurement resolution by contacting component surfaces with a mechanical probe held by a robotic arm or gantry. Encoders in the robotic system determine exactly where the probe tip's center is in three-dimensional space, and the CMM's host computer uses that information to determine the contact point between the probe and the part's surface. By probing dozens of points over the part, the CMM builds up a 3-D model of the part's shape matching the accuracy and precision of the encoders' resolutions.

Video microscopes—which use a video camera and a precision lens to capture an image and then store it on a host computer for display or analysis—capture a far larger number of points that CMMs ever could, and do it in a fraction of a second.

Using a high-quality lens system calibrated for the field of view (FOV), image-analysis software running on the system's host computer can isolate and measure all the edges visible in the image. It then calculates the position of each edge in two dimensions. Such a system's advantages are much higher measurement speed and much better coverage of the part's features. The system's disadvantage is difficulty in measuring parts with high relief in the third dimension.

Selection challenges

When challenged with issues of performance and price in the design of newly-ordered video metrology machines, Digital Precision Corp. turned to Toshiba Teli America for cameras that would accurately capture video images of various size work pieces. These images in turn would be transferred for analysis using Digital Precision's proprietary software.

'After reviewing the two designs,' recalls Al Sabeh, a vice president at Toshiba Teli America, 'I recommended incorporating our new CSB4000F four-megapixel CMOS camera with FireWire and 2,008 x 2,047 [pixel] resolution.'

The CSB4000F's ultra-high resolution qualified it for use with large FOV measurement and inspection. Coupled with an FOV microscope, the camera can measure larger size parts, such as 50 x 50 mm, with better than 5 micron accuracy online or off-line without an expensive stage.

Digital Precision incorporated the camera into a modified version of their DP1-FV video microscope system (shown in Figure 1). The camera was the main modification to the system. The digital camera's greater than 4 Mpx resolution made it possible to achieve much higher measurement precision than a standard analog camera.

The new design still uses a MVZL macro video zoom lens with close-up attachment manufactured by Optem (now Qioptiq), and ZView DMP-2000 image capture and analysis software. The lens has a 6:1 optical zoom range from 18-108 mm effective focal length, and a f/2.5 maximum aperture, making it appropriate for metrology applications at working distances from 5.5 to 11-in. (140-279 mm). The software provides features that lend it to automated-metrology applications, such as one-touch calibration, image enhancement to clean up noisy images, and exporting of images and analysis results to other computers.

The design has now been used in a number of applications, such as paper quality control and label-quality inspection. According to Yan Yu, marketing manager at Digital Precision, current applications have moved quality control off-line, but they are looking at in-line applications as well. 'It is a simple matter of reconfiguring the system for automated applications,' she says.

Sabeh, from Toshiba-Teli agrees: 'One of the DMP2000 software's advantages is its ability to link with other applications, such as CAD package and statistical process control (SPC) software, in real time.'

C.G. Masi , Senior Editor, Control Engineering

For more information visit

See also:


No comments
The Engineers' Choice Awards highlight some of the best new control, instrumentation and automation products as chosen by...
The System Integrator Giants program lists the top 100 system integrators among companies listed in CFE Media's Global System Integrator Database.
The Engineering Leaders Under 40 program identifies and gives recognition to young engineers who...
This eGuide illustrates solutions, applications and benefits of machine vision systems.
Learn how to increase device reliability in harsh environments and decrease unplanned system downtime.
This eGuide contains a series of articles and videos that considers theoretical and practical; immediate needs and a look into the future.
Salary and career survey: Benchmarks and advice; Designing controls; Remote data collection, historians; Control valve advances; Hannover Messe; Control Engineering International
System integration: Best practices and technologies to help; Virtualization virtues; Cyber security advice; Motor system efficiency, savings; Product exclusives; Road to Hannover
Collaborative robotics: How to improve safety, return on investment; Industrial Internet of Things, Industrie 4.0: World views; High-performance HMI, Information Integration: OPC and OMG
This article collection contains several articles on the Industrial Internet of Things (IIoT) and how it is transforming manufacturing.
PLCs, robots, and the quest for a single controller; how OEE is key to automation solutions.

Find and connect with the most suitable service provider for your unique application. Start searching the Global System Integrator Database Now!

Getting to the bottom of subsea repairs: Older pipelines need more attention, and operators need a repair strategy; OTC preview; Offshore production difficult - and crucial
Digital oilfields: Integrated HMI/SCADA systems enable smarter data acquisition; Real-world impact of simulation; Electric actuator technology prospers in production fields
Special report: U.S. natural gas; LNG transport technologies evolve to meet market demand; Understanding new methane regulations; Predictive maintenance for gas pipeline compressors
click me