Unmanned Systems Technology 036

50 complements the camera’s 110 º FoV in air, although its FoV under water is roughly 80 º owing to refraction. As indicated, although the Seasam can be used as an ROV with a tether for direct control, power and image streaming, it is also designed to function as an autonomous UUV. Batteries with a capacity of 6.6 or 10.4 Ah can be fitted, enabling 2.5 or 4 hours of tether- independent operation. Sensors for inertial data, depth information and GPS readings (when surfaced) are installed as standard. The Seasam also has a number of autonomous behavioural functions. Its built-in sonar for example allows a combination of sonar and visual data collection, giving it an obstacle sense & avoid capability. It can also follow divers, for applications such as manned- unmanned teaming in inspections, documentary filming and marine biological research. Notilo Plus also says it has developed and released a cloud-based data storage and analysis platform, called Notilo Cloud. It says this makes the Seasam an end- to-end solution, simplifying inspection operations and allowing data processing and visualisation for underwater asset management. Long-endurance missions While UUVs are being made smaller for shorter, routine missions or to work in larger (homogenous or heterogenous) groups and perhaps in tandem with divers, long-endurance missions are spurring designs of much larger vehicles. This is to allow them to carry the required energy to enable the longer operations, along with the payload sensors needed to gather the quality of data to justify the costs of developing and deploying them. The US Navy’s upcoming 15.5 m- long Orca extra-large UUV (XLUUV) for example is on track to become the biggest uncrewed subsea vehicle in service, now that a facility for constructing its hull structures has been completed, in Hampton, Virginia. Another, larger facility for prototyping, production and testing of unmanned systems is also being built as part of the facility, and is scheduled to be completed by the end of this year. The Orca will incorporate key design points from Boeing’s developmental Echo Voyager XLUUV. It is expected to have a range of about 6000-6500 nautical miles (at a cruising speed of 3 knots), and have a payload capacity of 8 t – capabilities made possible by its size and hybrid- electric propulsion system. Much like the hydrogen-powered – and similarly large – Cellula February/March 2021 | Unmanned Systems Technology Insight | UUVs The Orca XLUUV’s technologies will be based on the r&d carried out for Boeing’s Echo Voyager (Courtesy of Boeing) While UUVs are being made smaller for shorter missions, long-endurance ones are spurring designs of much larger vehicles