Uncrewed Systems Technology 047 l Aergility ATLIS l AI focus l Clevon 1 UGV l Geospatial insight l Intergeo 2022 report l AUSA 2022 report I Infinity fuel cell l BeeX A.IKANBILIS l Propellers focus I Phoenix Wings Orca

94 “We started by importing 3D models of the wind farm into our simulator, and mimicking underwater currents as well as the power and thrust dynamics of our propulsors while dealing with those currents,” Chia recounts. “Our test pilot used that simulator to experiment with how the vehicle could achieve stable hovering and movement through the distributed thrust across the seven motors.” Adaptive autonomy Once underwater, the HAUV autonomously recognised the shape of the structure, which triggered it to approach and begin looking for key features. This included trained recognition of the cable protection systems at the structure’s base, as well as observing the foundation rocks that obscured these systems to ensure it captured clear images of them. Although the A.IKANBILIS’ nominal endurance is 8 hours, in the environment around Nordsee One it was able to achieve only about 3 hours. The reason for that are the currents, which as mentioned are strong enough to heave any vehicle around and thus severely disrupt the quality as well as quantity of images, whether 2D or 3D. Throughout the survey, therefore, the HAUV’s various thrusters worked persistently to maintain its position in all 3 axes while capturing 2D and 3D imagery, with the vehicle working at an average of about four times its typical power consumption throughout. “This practical endurance will increase in the future – we’re looking to integrate more than 1 kWh of battery capacity, and we don’t anticipate much challenge in doing so, but our first priority was to make sure the autonomy engine was stable,” Chia explains. Schmoekel adds, “The propulsion configuration in its current form worked great. Essentially the stability and precise point-to-point imaging it performed was typical of the sort of work-class inspection an observation-type ROV one might otherwise use, but with none of the downsides. Despite the strong northerly currents we get in the German North Sea, the HAUV could still safely manoeuvre around the wind turbine’s monopile, following along potential signs of wear when it ‘thought’ it had to.” Chia notes that a lot of work went into developing the ideal kind of thrusters for hovering: most off-the-shelf AUV ones “are designed to go forwards, fast”, she says. “Most HAUV missions are centred on simply arriving at the mission location as quickly as possible, so you can then survey at a low forward cruising speed, so there aren’t really any thrusters out there for remaining as still as possible for high-resolution inspections.” BeeX therefore developed its propulsion configuration in-house, optimising its motor-propeller combinations and integrations to achieve balanced, distributed thrust and hydrodynamics in all axes of movement (similarly to a multi-rotor). Even with strong lateral currents, the vehicle was never moved to any significant degree. As the vehicle carries out a survey, two LED lamps on its front face (integrated just below the HD camera) provide up to 4700 lumens to illuminate the objects being inspected. The camera is optimised for ensuring effective visual data capture underwater, as well as perception and positioning. “The lack of GNSS under water means AUVs need to rely on acoustic positioning in order to localise and navigate,” Chia comments. “We actually use quite a simple off-the-shelf HD camera but that, combined with a 3D imaging sonar used in a dual-purpose mode and with our software algorithms enables a multi-layer approach to achieve robust autonomous navigation without GNSS or the extra infrastructure and costs of a USBL or LBL system for acoustic navigation.” BeeX’s in-house positioning system calculates its best estimate of the vehicle’s position in the x , y and z axes based on a fusion of inertial, camera and sonar data, while its autonomy algorithms take into account the likelihood that the wind farm will cause disturbances (given that metal can reflect acoustic signals and concrete will absorb them). Chia notes that any uncrewed underwater vehicle relying on raw navigation data December/January 2023 | Uncrewed Systems Technology In addition to the onboard camera and sonar, customers can perform additional payloads, with the autonomy and inspection intended to work with or without visibility in the water