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

29 vessels ranging from small USVs/ASVs upwards, with intended applications including shallow-water bathymetry, pipeline and cable surveys, and surveys of rivers and coastal waters. They are increasingly sophisticated, offering features previously available only in larger, heavier and more expensive sonars while consuming less power. These include, for example, separate transmit and receive heads, adjustable swathe widths, greater ranges of water depths at which they can image the seafloor, range resolution measured in millimetres, larger acoustic bandwidths and higher ping rates. Their acoustic processing software handles both FM and continuous wave signals, and support of third-party software is becoming more common. AUV and ROV operations The Mariner is also intended to support other unmanned systems, and it can carry a range of payloads to help with this, including positioning and comms systems such as USBL equipment and acoustic modems. With these, the Mariner can improve AUV and ROV underwater localisation capabilities, and can also function as a comms gateway for them. Maritime Robotics is currently running several research projects into the autonomous launch & recovery of underwater vehicles, ROVs in particular. “We are considering what is feasible with our existing ASVs, but we are also considering new ASV designs designed for robust launch & recovery,” says Hovstein. The types of ASV now under consideration in these projects include both relatively small 100-300 m depth- rated AUVs and ROVs, such as the LAUV, the BlueROV and the BluEye ROV, as well as larger vehicles rated for depths of 3000 m and more. “We see a lot of potential in the use of robots to support other robot operations, leading to huge cost and time savings for deploying autonomous vehicles,” says Hovstein. “For example, with the underwater vehicles, if you still need to hire a big ship to deploy and recover the vehicles or to relay data, that will come at a cost. When our ASVs are able to support the underwater vehicles though, you can cut the cost of renting support vessels and/or use the vessels for other purposes.” The technical challenges encountered in these types of operation tend to centre on weather and comms, he says. “In some parts of the world, for example northern Norway, the conditions can make operations difficult, so we aim to develop systems that can operate in Arctic environments. In other regions, communication from shore-side control centres can be challenging, but the advent of 5G, and the back-up of satellite comms in combination with our research work to increase autonomy, make it possible to address these problems.” Structure, materials and manufacture For the Mariner to be able to stand up to years of operations in tough physical conditions, the primary material used in it is polyethylene, with both hull and superstructure made from it. The engineering team chose monolithic polyethylene because it is much easier to work with than a composite material, it does not corrode so it needs no protective coatings and it is virtually maintenance-free. It also exhibits very high resistance to impacts and general wear and tear, even in the Arctic, and it is easy to repair if it does get damaged. Monolithic polyethylene, Hovstein adds, is an easy material from which to make prototypes, and easy to modify. Unmanned Systems Technology | August/September 2021 The Mariner’s deck hatches open to reveal a cavity for the removable, sensor-deploying moon pool module and batteries for the redundant electric propulsion system