Inside Unmanned Systems

OCT-NOV 2017

Inside Unmanned Systems provides actionable business intelligence to decision-makers and influencers operating within the global UAS community. Features include analysis of key technologies, policy/regulatory developments and new product design.

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33 unmanned systems inside October/November 2017 ENGINEERING. PRACTICE. POLICY. Drones can be used to assess dangerous particulate matter in the air, following where it goes and how it changes over time. Current monitoring techniques for aerosols of this particulate matter "are either bulky or low-throughput," Ozcan said. For instance, air sampling stations typically use beta-attenua- tion monitoring or tapered element oscillating microbalance instruments that usually weigh roughly 30 kilograms, cost about $50,000 to $100,000, and require specialized personnel or technicians for regular system maintenance ever y few weeks. A lthough commercially available, portable particle counters only cost roughly $2,000 to $8,000, they sample the air at rates of less than 2 to 3 liters per minute, and accurate measurements of either very- high or very-low concentrations of particles is challenging for these devices. Moreover, neither of these options provides microscopic images of captured particulate matter for de- tailed analysis, Ozcan added. "We thought this very light-weight and ver- satile microscope platform would be a good fit as a payload for a drone to perform three- dimensional air quality monitoring—to see the particles in air that people do not normally see with their bare eyes," Ozcan said. Airborne Microscopes In the beginning, Ozcan said, he and his lab had no experience with drones. "A major effort of ours for this application with drones was to reduce the weight of the device so we can fit it into a smaller, more portable and cheaper drone," he told Inside Unmanned Systems. Their efforts have resulted in a mobile im- aging system they call c-Air. "So far the c-Air device weighs about 600 grams," Ozcan said. The device can screen 13 liters of air per minute and generates microscopic images of scanned particulate matter, providing statis- tics of particle size and density distribution with a sizing accuracy of roughly 93 percent. They also integrated the device with a smart- phone application to control c-Air and display results. The device relies on cloud computing to remotely, rapidly and accurately analyze ac- quired images of particulate matter. Artificial- intelligence machine-learning algorithms can be used, said Ozcan and his colleagues, to adaptively tailor c-Air to identify specific par- ticles in the air, such as various types of pol- len and mold. It won the Vodafone Wireless Innovation Project prize in 2016. The device uses a pump to drive air into a nozzle, inside which particulate matter can latch onto a sticky coverslip. Red, green and blue LEDs then illuminate this coverslip so a color CMOS (complementary metal-oxide semiconductor) image sensor—the same kind used in most digital cameras—can take pic- tures of the particles from a distance of just 400 microns, a span about four times the aver- age width of a human hair. The researchers are currently using c-Air with a DJI Flame Wheel, a roughly 1-kilogram quad-rotor drone. However, "any medium- sized drone—for instance, the DJI Phantom— should satisfy our application," Ozcan said. " THIS DATA CAN HELP YOU KNOW WHAT YOUR POLLUTION SOURCES ARE AND HOW MUCH EACH EMITS SO YOU CAN PUT IN MITIGATION MEASURES BEFORE IT GETS BAD AND GO AFTER THE ONE PERSON WHO'S BEING THE BAD GUY INSTEAD OF PENALIZING EVERYONE." Catherine Cahill, director, UAF Alaska Center for Unmanned Aircraft Systems Integration (ACUASI) They tested the c-Air by measuring the air quality over an Environmental Protection Agency-approved air-quality monitoring sta- tion for several hours. The researchers con- firmed that the c-Air's measurements closely matched those of the station. They also used c- Air to map the air quality around Los Angeles International Airport (LAX) over 24 hours, and confirmed that the impact of LAX on par- ticulate matter concentrations was detectable

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