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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53 unmanned systems inside December 2016/January 2017 ENGINEERING. PRACTICE. POLICY. times vibrate, affecting the robot arm's perfor- mance. "Some of that vibration we could not eliminate mechanically," Chen said. "We fac- tored it in as an external disturbance into the trajectory-planning algorithm." Chen noted this robot could do more than painting. "This is a platform technology that you can mount something else on for other pur- poses—for instance, you can paint a very thin layer of cement to make a surface very smooth, so this machine could do surface preparation as well as painting, or spray water to do clean- ing," Chen said. "We also have another robot to do quality assessments of finished buildings— checking defects in construction. And we are working on painting outer walls, although that research is ongoing." Drones for Art In the future, robots may move beyond coating monotonous surfaces to painting more com- plex images. "The challenge is that robots right now only paint one single color," Chen said. "PictoBot uses a water-based paint, and if it finished with one color and wanted to paint with an- other, it'd need to f lush the whole system. To make PictoBot paint two or many different colors at once, like an inkjet painter, you'd need a new painting head. I think that's doable, but not at the moment." One researcher investigating the possibil- ity that drones could be used to draw murals is Paul Kry, an associate professor at McGill University's School of Computer Science in Montreal. He and his students are program- ming tiny quadrotor drones to create draw- ings dot by dot, an artistic technique known as stippling. Retrof lector markers on the palm-sized drones let a camera-equipped computer with motion-capture software pinpoint where each drone is in space. The computer steers the drones back and forth toward and away from a surface to draw. "THERE'S A HUGE ELEMENT of safety with drone painting, and there can be substantial labor savings, and higher consistency and quality. Put that all together and it's a hell of a combination." John Salvatore, CEO of the Carlstar Group, former CEO of BASF Construction Chemicals Americas The drones are equipped with a miniature arm that holds a bit of ink-soaked sponge. They collide with surfaces with their brushes, dab- bing until they paint, say, portraits of Alan Tur- ing, Grace Kelly, and Che Guevara, among oth- ers. Each drawing is composed of a few hundred to a few thousand black dots of varying sizes. The researchers were able to get about 70 dots from each drone before they drained their batteries. The scientists also experimented with tethering the drones so they did not need to replace their batteries, and giving them ink- wells the drones could get new ink from. Kry noted that even very slight air currents can knock the featherweight drones off course, so they want to scale up to larger drones. One problem with drawing complex images with quadrotor drones "is that you have to tilt to f ly left or right," Kry said. "Placing a mark or drawing a line on a wall with precise control with only four motors is challenging. Ground- based robots have absolute control, and perhaps can point nozzles in more hard-to-reach places." Still, eventually drones could be deployed to paint artwork on hard-to-reach outdoor sur- faces, including curved walls, Kry said. Cur- rent advertisements often involve placing gi- ant vinyl stickers on walls which do not unroll well on irregular surfaces. "Drones may paint curved shapes, like the ceiling of the Sistine Chapel," Kry said. Dahlstrom and Chen both stressed that auto- mation will not put human painters out of jobs. "Mostly these robots do large areas—if you can do fine painting of every edge and corner, people have value," Chen said. "Robots don't really replace human jobs. They just make our jobs easier." "We're moving people from dangerous situa- tions," Dahlstrom said. "I was talking with the CEO of a company in the oil and gas industry, and he said that in his 30 years in the indus- try, he had to tell four mothers that their sons are never coming home again. If we can pre- vent those conversations from happening, we should be doing it."