Unmanned Systems Technology 036

52 Robotics Solus-LR ( UST 30, February/ March 2020), the Orca’s missions are expected to last for months at a time, with the craft autonomously returning to port for refuelling and maintenance a few times a year. For missions of shorter duration, up to 10 days, the Dive-LD AUV from Dive Technologies is being developed. While shorter than the Orca’s and Solus-LR’s endurances, it is still far longer than most UUVs. Notably it features a free-flooding hull measuring 1.2 m wide and 5.8 m long, and made from 3D-printed parts. Most recently, the Dive-LD has successfully completed sea trials using power from Kraken Robotics’ SeaPower pressure-tolerant lithium-polymer batteries. Kraken Robotics says the SeaPower system in the Dive-LD consists of up to six 311 V battery units, each with a capacity of 15.5 kWh for a total system capacity of 93 kWh. Each 150 kg battery includes an integrated and independent battery management. The SeaPower batteries are rated to 6000 m, which matches the Dive-LD’s depth rating. This follows an established trend for UUVs being designed to operate at this depth, for critical missions such as deep-sea search & rescue, salvage or mineral surveys. Dive Technologies and Kraken Robotics have entered into an agreement in which Kraken will supply its subsea batteries for the Dive-LD. It has also acquired a licence to have two of the AUVs built for its own use in commercial deep-sea data collection. The first Dive-LD for Kraken is under construction in the US, and will be delivered to Kraken’s Unmanned Maritime Vehicle Facility in Nova Scotia for sea trials beginning this spring. Also, for its acoustic positioning and comms needs, the AUV incorporates Sonardyne’s AvTrak 6. This combines a transponder for USBL and LBL navigation as well as a bidirectional acoustic modem with a data rate of up to 9 kbit/s. A Sonardyne Sprint-NAV is also installed, for onboard navigation data. The system housing contains an INS (built using three ring-laser gyros and accelerometers), a 600 kHz Doppler velocity log and a pressure sensor, and as expected it is also rated to 6000 m. Summary UUV manufacturers are adopting myriad new designs to offer solutions to marine industries. In the short time that the market has existed, UUVs have already evolved to take the forms of snakes, birds, rays and crustaceans – the last of these proving the trend of ‘carcinisation’ in robotics, as predicted by Prof Adrian Thomas of Oxford University (in UST 34, October/November 2020). Many of these new UUV types require entirely new mathematical models for performing locomotion, manoeuvring and sensor fusion, meaning potentially very complex algorithms at the outset of their development. But with the oceans acting as a boundless heat sink for densely packed high-performance processors, underwater robots stand to be able to incorporate hugely complex and sophisticated AI and algorithms for advancing their capabilities and range of behaviours. Accelerated developments in underwater SLAM, machine learning, swarm intelligence and other forms of advanced intelligence technology can be expected to follow. They can only enhance the availability and value of hydrographic surveys, infrastructure monitoring, subsea construction and other critical components of what is becoming known as the Blue Economy. February/March 2021 | Unmanned Systems Technology Insight | UUVs The Dive-LD is being designed to operate down to 6000 m, with missions lasting up to 10 days (Courtesy of Dive Technologies) In the short time that the market has existed, UUVs have evolved to take the forms of snakes, birds, rays and even crustaceans