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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50 unmanned systems inside December 2016/January 2017 AIR NEW MARKETS issues. Paint companies might even take a prod- uct offering that normally has a five-year war- ranty and say that if it's applied properly within specifications, it has a 10-year warranty." Right now the Apellix system can paint a little faster than a person. "However, the drone can paint continuously, whereas people have to stop and move themselves to spray again," Dahlstrom said. "By not having to put up a scaffold and re- position itself, our estimates suggest that it can paint eight to 12 times faster than a person." "There's a huge element of safety with drone painting, and there can be substantial labor savings, and higher consistency and quality," John Salvatore, CEO of the Carlstar Group and former CEO of BASF Construction Chemicals Americas, said of Apellix. "Put that all together and it's a hell of a combination." Making It Work Flying while administering paint presents unusual technical challenges. To make sure propeller wash does not affect the paint spray, Apellix tinkered with the size of the drone's spray wand and propeller blades, as well as the distances it should keep from walls, Dahlstrom added. To avoid problems caused by the paint spraying onto the drone and its propellers, Apellix coats the Worker Bees with Gentoo, a clear super hydrophobic nanoparticle material from business partner UltraTech International in Jacksonville, Fla. "If paint does get on, you can brush it off with a damp cloth or sponge," Dahlstrom said. The fine control of the Worker Bee's distance from the surface to be painted is also impor- tant to success. "If a spray nozzle is too close to a surface, the paint bounces off, but if it's too far, it atomizes and not enough catches," Dahlstrom said. The exact desired distance can vary "depending on paint viscosity, the nature of the surface, hu- midity, or temperature—the sunny side versus the shady side of a house. Good intuitive paint- ers know this intuitively from doing it years and years, but even then, you can't expect people to keep spray wands exactly the same distance from a wall the entire time they are painting. Drones can keep the proper distance from the wall and prevent overspray or underspray. We're replacing human judgment with science." One major challenge Apellix faced is how to enable its drones to f ly very close to surfaces, and sometimes even touch them. "The drone sometimes has to have a probe touch the wall to, say, measure the thickness of a deposited f ilm," Dahlstrom said. The problem there was that when their drone en- countered resistance from a wall, it perceived it as resistance from wind and thought it was getting blown off position. To compensate, it accelerated into the "wind." "We had a lot of drone crashes," Dahlstrom said. "But crashing isn't that bad. We tell our developers it's good—if they're not crashing, they're not iterating fast enough." To prevent these crashes, "we reprogrammed the autopilot, and added sensors," Dahlstrom said. "We have two sensors that give the exact distance to the wall. If one is slightly off, it cor- rects the angle, so a probe can hit the wall per- fectly straight on—if the drone touches the wall at an angle, it can do things you don't want, like crashing." Adding the umbilical cord was also a challenge. "Drones were never intended to have a mate- rial-transfer system put on them," Dahlstrom said. "The umbilical cord not only drags on the drone as it moves along, but you have this oc- casionally semi-rigid cord with high-pressure material within it that can actually push the drone around, so we have software to mitigate that from happening." Adding an umbilical cord did help solve a different design problem, however—keeping the wind from pushing the drone around. "We have noticed adding a tether to the middle of the drone helps it hold position well, just as adding a tail to a kite helps it f ly much better," Dahlstrom said. Photo courtesy of NTU Singapore "THE DRONE CAN PAINT continuously, whereas people have to stop and move themselves to spray again. By not having to put up a scaffold and reposition itself, our estimates suggest that it can paint eight to 12 times faster than a person." Robert Dahlstrom, founder and CEO of Apellix