3D sensing bolsters robotic guidance

An article written by Hang Hogan for Photonics – With prices falling and performance rising, 3D vision, or depth sensing, is showing up in new applications, including allowing robots to map places and tasks, such as figuring out how best to avoid people. Other uses include pick-and-place, combined assembly and inspection, and moving shelves of items from one location to another.

These and other applications depend upon inexpensive and powerful 3D vision, and there are several competing technologies. All have strengths and weaknesses, with different working distances, resolutions, throughput, and price points. Each has a significant market presence, in part because there is no single best solution for every situation.

“Depending on the required performances and market constraints, all these technologies find applications,” said Alexis Debray, a technology and market analyst in optoelectronics at Yole Développement SA.

For 3D vision, the competing technologies include many flavors of lidar and time-of-flight cameras, which send out bursts of light and measure distance by the amount of time it takes to get a return signal. There is also structured light, which determines distance by measuring distortions in a light pattern projected onto an object. Another technique is laser triangulation, which extracts depth from the location the laser spot appears in a camera’s field of view. Finally, stereoscopic depth sensing uses the differences between two camera images to calculate distance.

Except for stereoscopic imaging, these approaches require some form of illumination. This can be a benefit in an industrial setting where lighting is uncertain, but it does increase power consumption, a possible issue when running on a battery.

Power and illumination

Some of these technologies have seen a significant improvement in both power and size. For instance, structured light depth-sensing capabilities — that in 2009 consumed 10 W and were the size of a brick — today require only 250 mW and a thumbnail-size device using time-of-flight technologies, said Mitch Reifel, vice president of sales and business development for time-of-flight sensor maker pmdtechnologies AG of Siegen, Germany, and San Jose, Calif... Full article

Image: Artist’s conception of 3D imaging in an automotive application. 3D imaging is playing a key role in pick-and-place, assembly, and inspection. Courtesy of Newsight Imaging.