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

80 driven propeller, it uses wings and small changes in buoyancy to achieve forward motion; its pitch and roll are controlled using adjustable ballast that is actually the vehicle’s battery, which powers the sensor systems. It moves through the water in a sawtooth-like pattern and surfaces regularly to determine its position. Navigation is achieved using a combination of GNSS fixes while it is on the surface and internal sensors that monitor its heading, depth and attitude during dives. The propulsion uses very little energy so that it can be deployed for up to ten months at a time, compared with a day or two with other AUVs. While its top speed is low, at half-a-knot (25 cm/s), its long endurance allows it to travel thousands of kilometres in a single deployment. At 1.8 m long and weighing 52 kg for the standard version, it can carry a 2 kg payload and be deployed easily from small vessels to work at depths down to 1000 m. Payloads The SeaGlider system is modular, and can accommodate many kinds of sensors depending on the application. It can be used for physical, chemical or biological oceanography and environmental monitoring, but with its long mission time it can also be used as a data gateway to receive information from other systems, and act as a navigation aid. With its low-impact propulsion system it is also being used to actively and passively monitor animals in the sea via the noises they make, and to profile the different ocean currents. A 2 m version called Ogive doubles the payload to 4 kg, so it can support systems for profiling currents with echo sounders and dissolved oxygen sensors. SeaGlider was originally developed in the 1990s at the University of Washington in Seattle with funding from the US Office of Naval Research and, as of 2012, more than 190 Seaglider AUVs have been delivered to research institutes, naval organisations and commercial operators around the world through a relationship with iRobot in Massachusetts. It is now produced by Kongsberg at its Lynnwood facility in the US, not far from the University of Washington, under a new technology licence. As well as building new SeaGlider vehicles, the centre will also refurbish or upgrade existing systems, and plans to start shipping the new SeaGliders in the first half of 2015. Gliders aren’t the only AUVs to use the torpedo shape. Kongsberg also supports two other AUV platforms – Hugin, which was developed in-house; and Remus, which was acquired when Kongsberg bought a US company called Hydroid, both using traditional propulsion systems. Hugin is being targeted at remote subsea surveys as it can travel to depths of 1000-4500 m using a more traditional electric motor and propeller, with different payloads for applications such as high- resolution, high-speed seabed mapping, imaging and site inspection as well as pipeline and subsea structure inspection. It can also be used for search operations. The Hugin comes in three variants – the 1000, 3000 and 4500. The 1000’s larger diameter of 75 cm compared to the 30 cm of the SeaGlider, as well as its modular design, allows larger sensors to be used such as a high-resolution interferometric synthetic aperture sonar that can be used at depths of 1000 m. The vessel also supports a multi-beam echo sounder, sidescan sonar, still image camera with HD resolution and 10x zoom, a turbidity sensor to measure the ‘cloudiness’ and quality of the water and a methane sensor for detecting leaks from pipelines. A key characteristic of the Hugin payload system is that all its sensors can operate together, and the data is time-stamped at source to allow accurate location-tagging of the data. Payload options The vehicle body is modular and made from carbon fibre laminate material covering a composite known as syntactic foam to manage the buoyancy, and this is deliberately extremely stiff to make sure there is accurate orientation between the payload sensors and the navigation system. The Hugin 1000 consists of three main sections to make it easier to adapt the vehicle to different payloads and battery configurations, while the Hugin 3000 and 4500 have an even larger diameter, of 1 m, and a single payload bay to make it easier to integrate larger sensors. The pressure containers used to protect the sensors are made from either titanium or sea-water resistant aluminium, depending on depth requirements. The Hugins are also equipped with a hydro-acoustic comms link that provides good connections in the range of tens to a few thousand bits per second over several kilometres with carrier frequencies of around 25 kHz, although Spring 2015 | Unmanned Systems Technology The propulsion uses very little energy so that it can be deployed for up to ten months at a time, compared with a day or two with other AUVs Kongsberg’s SeaGlider uses wings and small changes in buoyancy to achieve forward motion