Unmanned Systems Technology 002 | Scion SA-400 | Commercial UAV Show report | Vision sensors | Danielson Trident I Security and safety systems | MIRA MACE | Additive manufacturing | Marine UUVs

81 Marine UUVs | Insight data rates of up to 25 kbit/s are possible with shorter links. This allows a tracking vessel to receive payload data from the AUV in real time, and can be used as a quality measure to make sure a survey is covering all the necessary regions of the sea floor, for example. Offshore services group DOF Subsea, in Norway, for example is using Hugin for tasks such as geophysical surveys, inspecting subsea facilities and environmental inspections, as well as quick inspection of pipelines, using sidescan sonar, multi-beam sonar and high-resolution still and video cameras. Software developed over the past three years by Kongsberg allows Hugin to follow as close as 3 m directly above the pipeline, something that has not been possible previously with standard positioning sensors. This gives more effective monitoring of the pipeline without needing to have an operator guiding the AUV. Battery technology is vital for powering both the electric propulsion system and the AUV’s sensors down to depths of 4500 m. The standard rechargeable lithium-ion battery supports a mission time of 75 hours at 4 knots, and is made from commercial battery cells with built-in safety systems to prevent overcharging or fast discharging. This is used down to 1000 m, but for the 3000 and 4500 versions of Hugin, a non-rechargeable aluminium oxygen semi-fuel cell (ALHP FC) is used. This is a specially developed derivative of a fuel cell that generates power from aluminium and oxygen stored in the cell, and the largest of these can support 100 hours of use at 4 knots and down to 4500 m. Saab, in Sweden, also uses the torpedo shape and traditional propulsion for its latest autonomous underwater craft, the AUV62, which starts shipping later in 2015. It is fully autonomous and operates in one of two modes – it can be programmed to follow a route of predefined waypoints, or in a rule-based mode where the route changes depending on the data from its sensors and a fixed set to rules that determine what actions to take as a result of that data. It can be used to solve a specific task within an area of up to 20 sq km and up to 500 m depth, travelling at speeds of up to 20 knots. To do this requires obstacle avoidance algorithms and highly accurate positioning, so the AUV62 uses dual sonar systems on its sides and high-resolution sonar to fill the gaps, giving a positioning accuracy of better than 4 cm 2 . Modular design It can also communicate with its parent vessel either while it’s surfaced, using a wireless local network or satellite comms link, or submerged via a hydro-acoustic link. There is also a nose-mounted camera for object identification as it travels around, and it can capture data for 3D images of objects for commercial imaging applications. The AUV62 varies from 4 to 10 m long depending on the payload, and is 53 cm in diameter. Its modular design, with swappable payloads, enables it to be used for missions such as seafloor profiling, detecting and tracking subsurface installations such as cables and pipelines, and environmental surveys All of this is a long way from the early submersibles, and demonstrates the growing importance of commercial applications for AUV systems, both within the craft and the system interfaces. While mine clearance is still an important application driving r&d, increasing the range and depth of an AUV with smaller form factors and more efficient propulsion is allowing the technology to be used for pipeline monitoring and oceanographic tasks. This is increasing the volume of systems in the market and providing more momentum for AUV technology development. With new technology centres such as the CMIS being set up specifically to develop autonomous craft for marine applications, the focus is increasing on AUV technologies for the next few years. Unmanned Systems Technology | Spring 2015 Saab’s AUV62 is fully autonomous