Issue 39 Unmanned Systems Technology August/September 2021 Maritime Robotics Mariner l Simulation tools focus l MRS MR-10 and MR-20 l UAVs insight l HFE International GenPod l Exotec Skypod l Autopilots focus l Aquaai Mazu

94 Digest | Aquaai Mazu in the water for 8 months to test their durability, and we learned a lot about how to improve them.” She adds that this version of the robot was the fifth prototype, styled as the Nammu (named after the Sumerian sea goddess), and that the Nammus at Kvaroy are to be replaced by Mazus in due course. Since then, Aquaai has opened a subsidiary in Norway to reduce the shuttling between California and Kvaroy, as well as its other European customers who make up the bulk of its clients. There is great potential for using the Mazu as a cost-effective tool in risk mitigation and post-disaster water quality or environmental surveys. For example, it could swim along populated coasts and beaches to report on water quality or even the presence of sharks in the vicinity, or monitor sand banks in canals and ports to prevent ships from getting stuck. These factors have driven the iterations to improve the UUV over the past several years. The aim has been to optimise its fishlike guise and movement, and ensure it can operate reliably and consistently across different marine environments from one hour to the next, all without breaking the bank in terms of r&d and the parts required. “Simeon Pieterkosky, our chief visionary officer, grew up on a farm, so he knew that farmers would never buy a platform costing hundreds of thousands of dollars or that was too complicated to use – it had to be a system that anyone could afford and operate, not just the major oil & gas companies,” Thompson adds. Soft hull Additive 3D and SLS manufacturing have been pivotal in customising the different hulls of each iteration of the UUV to withstand the particulars and extremes of different marine environments. “The hull is made from a Neoprene material,” Pieterkosky explains. “It’s a simple, flexible, rubber-like platform that is essentially designed to withstand impacts and swim by adopting different kinds of swimming patterns allowed by fish vertebrae. “There are some tricks to getting the skin right in each iteration though, such as the thickness needed in different parts of the robot. The skin covering the tail is only 1.5 mm thick, the main reason being that if we allow an air bubble in there, we’re allowing excess buoyancy that throws off the robot’s balance. “So no printed component is thicker than 2.5 mm; anything thicker will create air bubbles inside the print, and obviously, the thicker the skin, the harder our servos have to work.” As with Dive Technologies ( UST 37, April/May 2021), 3D printing also enables great speed in how the robots can be redesigned and iterated. All structural materials on the robot are therefore 3D-printed, including the casings, trays and tail assemblies. “We carefully control the robot’s buoyancy, so that we can just throw it into the water without needing any calibrations or whatever – or the expense of a complex launch & recovery system,” August/September 2021 | Unmanned Systems Technology The Mazu’s hull is a Neoprene skin that gives it favourable hydrodynamics, impact absorption and an energy-efficient ‘swimming’ form of propulsion At the time of writing, Kvaroy’s Nammu UUVs were being replaced with Mazus, which will enable more energy-efficient operations, a larger payload capacity and power redundancy in the event of blackouts