112 “All the information from the robot’s sensors is fed through a Kalman filter to ensure it is using the best available information to give us its position,” Lander adds. “That information is coupled with sonar imagery collected in real time to build a map of the hull.” Building themap Building the map starts with developing the hull-referenced coordinate frame. “When we pilot the robot in place to go to the hull, we then give it a new orientation – basically taking north, south, east and west and translating it into up, down, left and right, using gravity to reset that because gravity will always tell you where down is,” Lander explains. The robot is then deemed to be located at a point on the hull where the equivalent of the equator and the Greenwich meridian cross, which becomes its datum point, fromwhich its subsequent movements are tracked. “As we build the picture, the sonar – we use a Blueprint Oculus – is providing feedback on what it sees,” Lander says. “It is accurate enough to identify weld beads on the hull, anodes, thruster gratings and so on.” These items are in known positions on the hull, contributing to the navigation solution, as are markings such as the Plimsoll line and depth indicators that the cameras can read, each of which acts like a signpost for the robot. “When it sees it the next time it can calculate how far away it is from a series of points, like taking a fix for dead reckoning,” he says. The HSR removes the micro-fouling using rotating brushes fitted with soft bristles, and is a purely mechanical process. Finding the best material for the June/July 2023 | Uncrewed Systems Technology As the EverClean service develops, multiple HSRs could live aboard ship and be deployed for cleaning whenever it’s stationary, such as waiting to enter a port The EverClean service will be managed by remote operations centres linked to deployed HSRs via satcom or cellular comms, with one operator eventually running several robots We will be able to report on areas of excessive growth, coating failure and anode wear, and detect any other anomalies between hull inspections
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