October 2007 Mechanical Engineering Departments: Tech Focus, Pt. 2

This section was edited by Executive Editor Harry Hutchinson.

Technology Focus part 2:
Instrumentation and Control

Camera Speeds Trouble-shooting
by Alan S. Brown

Maybe your robotic grippers fail to grip, or the creases on your printing and folding unit look like they were done by your teenage son. You could try to eyeball the system and find the problem, but automated equipment moves far too fast for such low-tech approaches.

That's where the new line of Phantom Miro high-speed digital cameras from Vision Research Inc. of Wayne, N.J., can help. They're not cheap—the least expensive Miro costs about $15,000—but at speeds of up to 2,200 frames per second, they can slow even the fastest industrial process to a crawl.

That's not really a surprise. According to marketing director Rick Robinson, the cameras were originally developed for NASA and the military. They were used to analyze the separation of rocket stages in flight or the detonation of shaped explosives. Eventually, automakers picked up the technology to understand how cars crumpled and protected passengers during crashes.

Quicker than the eye: After freezing rockets and crash dummies in mid-flight, Vision Research's cameras have grown portable and user-friendly enough for assembly lines.

The high speeds are possible because of a custom-developed, high-speed sensing element based on CMOS transistors rather than the slower charge-coupled devices found on conventional digital cameras. Unfortunately, CMOS sensors need a dedicated system to keep them cool. They also require a custom electrical bus with memory fast enough to capture thousands of detailed images each second.

All this advanced engineering came with a price: Those early cameras didn't qualify for anybody's idea of "user-friendly." They were big, boxy, and heavy, and came with a battery as large as the one found in the family sedan.

Thanks to ever-shrinking electronics and smart redesign, the new Miro cameras are a quarter of the size of the originals. They weigh significantly more than ordinary digital cameras, but are light enough to move from place to place or to mount on a tripod to keep the camera from jiggling.

Vision Research says the Miro cameras were designed with industrial troubleshooting in mind. The heavy batteries have been replaced by rechargeables that fit inside the camera. The electronics are smaller and require less cooling. The high-speed memory has been replaced by conventional computer memory, and users can save video streams to flash memory cards or to a laptop. There is a large LCD touch screen to select frame speeds and other settings.

The Miro 1 costs under $15,000 and can take 640 x 480 pixel images at up to 500 frames per second. The Miro 2 has twice the speed and more options. The Miro 3 is designed specifically for crash testing, and can survive 100 g of acceleration. The Miro 4 offers higher resolutions at up to 1,000 frames per second.

So how fast is that really?

"I sometimes take one home with me on the weekend to play with," Robinson said. "I tried taking a picture of my dog drinking water. I always thought dogs curved their tongues forward to splash the water into their mouth. With the camera, I saw that they actually curve their tongue backward, so the water gets into their mouth through surface tension."

Our eyeballs can pick out that kind of detail, but only if we slow down the motion enough to see it.