112 Yet another challenge centred on dealing with the high temperatures caused by the combination of direct sunlight and reflections from the windows. “It could effectively feel 20 oF warmer than it actually is. And if it’s already 100-plus degrees, that can be extreme,” he says. “Electronics don’t love extreme heat, so we had to invest in creating a cooling system that can mitigate those temperatures. As we think ahead, we might need further iterations of the cooling system for environments with higher humidity.” All this technology ultimately supports the deployment of a simple brush and squeegee combination on the end of the Agilus 2 robotic arm. “The brush design we use is really akin to window cleaning brushes from 50 or 60 years ago,” Blum says. “We have adopted a geometrical shape that’s very close to traditional brushes, although we don’t use horsehair.” Distributed symmetrically among the synthetic bristles are water nozzles that keep them moist so they can clean the windows effectively, with the help of the Lidar. “Essentially, the Lidar is localising and creating a border for each window, so we’re localising on the window frames and giving the arm a ‘paint between the lines’ scenario,” Blum says. “We recalculate the cleaning path more than 200 times a second to make sure the arm follows the most efficient path and that the robot can react in real time to any disturbances.” AI decision-making This is where AI comes in, although Blum is careful about its definition. “This isn’t generalised or even generative AI – we are talking about making correct decisions based on variable parameters,” he explains. As the basket is moving, the system needs to decide how much counterpressure the robot is going to apply. “Essentially, the arm is both creating and damping down forces against the window at the same time, so we need to create as stable a working environment as possible,” he says. The software environment is Linuxbased, with code written largely in C++. “This gives us the best ability to react in real time,” Blum says. “For example, we need to limit how many Python libraries our software needs to look through in order to make decisions, because that takes time. When a wind gust comes along, you don’t have that time.” The hardware this software runs on is an Allen Bradley programmable logic controller. December/January 2024 | Uncrewed Systems Technology Robotic arm, AI, computer vision and machine learning: Kuka Safety sensor system: Airskin Programmable logic controller: Allen-Bradley Networked comms: Allen-Bradley Water filtration and de-ionisation: Ionic Systems Force/torque feedback sensors: OnRobot Lidar: Ouster Control station: Panasonic Some key suppliers The Ozmo relies on a power/data cable and a water hose that run from the building roof, both of which presented engineering challenges (Courtesy of Skyline Robotics)
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