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Industrial Sensor Does Inexpensive 3-D Measurement
‘Smart pixels' perform time-of-flight measurements
Charles J. Murray, Senior Technical Editor -- Design News, September 10, 2009
A new image sensor measures size, shape and volume of products in industrial applications ranging from packaging to material handling to food processing.
Known as the 3D Image Sensor, it's said to be the first sensor that can detect objects in three dimensions at a price that's acceptable for the industrial market. As a result, the device is already seeing use in automotive plants, as well as in food and beverage plants, where it performs such chores as measuring the level of potatoes in a bin or the volume of bottles in a six-pack.
"Up to now, there's been no really good solution to show the level of potatoes in a bin," says Garret Place, product manager for ifm efector, inc., maker of the new sensor. "In packaging and material handling, they can't afford to solve the problem with a $10,000 sensor."
The new sensor solves the problem for about $1,450. In contrast, existing 3-D systems typically cost between $6,000 and $12,000, the company says.
The 3D Image Sensor accomplishes that by employing time-of-flight measurement techniques and so-called "smart pixel" technology. During operation, the sensor's transmitter sends out an optical signal. Reflected light is detected by the sensor, and time-of-flight is calculated at every smart pixel. In all, the system uses 3,072 pixels, arranged in a 64 x 48 grid.
"Instead of having one time-of-flight measurement, you have 3,072 time-of-flight measurements," Place says. "With all those measurements, you can create a 3-D image, instead of a 2-D image."
Because the system captures the scene around it without moving parts and without needing excessive calculation power, cost is reduced.
Moreover, the 3-D nature of the system enables it to serve in food processing applications where products may be stacked in variable piles containing hills and valleys. Because it captures the entire scene of such situations, including their depth, the sensor is able to provide a more reliable picture of the surroundings than a 2-D or 1-D sensor could. Similarly, beverage manufacturers are employing the sensor's volume calculation ability to determine if a six-pack of two-liter bottles is missing a bottle. The technology is also being employed for measurement of fruit and bread dough, as well as pill bottles and pallets.
"With this technology, you don't need a bunch of expensive time-of-flight components," Place says. "Because we can do all the calculations on one smart pixel, we can do 3-D measurements without all the costly components."
www.ifm.com
