Unmanned Systems Technology 025 | iXblue DriX I Maintenance I UGVs I IDEX 2019 I Planck Aero Shearwater I Sky Power hybrid system I Delph Dynamics RH4 I GCSs I StreetDrone Twizy I Oceanology Americas 2019

96 with one another, depending on the end- user’s application. “The 2200 and 2205 can be supplied enclosed in a pressure vessel, or the core electronics can be provided as boards for mounting onto a chassis so that the end- user can integrate the system into their own AUV or ROV pressure housings,” Doug McGowan said. The arrays are typically mounted on the sides or bottom of the UUV in order to have a clear view of the seafloor, and away from the thrusters to avoid acoustic or vibratory disturbances. The sidescan sonars are available with frequencies from 75 to 1600 kHz, and their sub-bottom sonar frequencies can range from 500 Hz to 24 kHz. Applications include archaeological and geological surveys, marine pipeline and construction inspections, assisting in subsea debris search and dredging operations, and supporting harbour security and mine countermeasures. Fluidion unveiled its Fluidion Drone USV at the show, a system designed for conducting water quality surveys, including microbiological tests for E. coli, Enterococci and similar microbiological issues. The system is roughly 1.8 m long and weighs 45.35 kg, and is typically transported by light vehicle or by hand as a two-man portable vessel. It comes with four mechanically independent thrusters, with the option for another two to be integrated if desired. “We have created a fully configurable platform for integrating and deploying not only our own sensor payloads, but also third-party multi-parameter probes,” said Andreas Hausot. Fluidion makes a range of sensor payloads, including the Alert microbiology analyser. This is a 7 kg sonde powered by a vacuum pump and using the company’s proprietary MEMS and microfluidic sensor technology for measuring colony-forming units – estimates of the number of viable bacteria or fungal cells – in water samples. Under remote operation, the USV’s data link gives a roughly 1.6 km control range, and the battery pack provides three to four hours’ endurance depending on the speed and distance of use. Hydromea’s patented disc drive thruster was among the products being displayed by Blue Link at the show. The system is a hubless, rim-driven thruster that measures about 95 mm across and 14 mm long. As Alexander Bahr explained, the company originally developed the thruster as it could not find one on the market that was small enough or (more important) thin enough to achieve the desired controllability and manoeuvrability of its Vertex AUV (detailed in UST issue 16), which uses the thrusters for its control surfaces. Making the thruster 14 mm thick was therefore key to reducing its hydrodynamic profile when integrated in a vertical orientation. “When we showed just a standalone demo unit at an earlier trade show, it attracted a lot of interest, so we decided to make it commercially available,” said Bahr. The use of a hubless design greatly reduces the propensity for debris to become entangled in it, and the rotor- stator arrangement creates a gap between the two to flush out any debris without affecting energy efficiency. Each thruster weighs 135 g in air, and provides up to 25 N of thrust, with a maximum current consumption of 21 A. “We are selling a version with a built-in motor controller and closed-loop control, which allows for very slow rotational speeds and fast reversals,” Bahr said. “It runs oil-free, and its fully encapsulated design should allow for operation to full ocean depth, although that still needs to be tested.” Blue Link was also exhibiting Hydromea’s Luma 250LP optical modem, which gives 250 kbit/s short-range (6 m) bidirectional underwater comms. Its low power requirement (a maximum of 5 W at peak transmission mode) means it is suited to battery-operated applications such as landers where data is to be loaded to or from a modem-equipped ROV or AUV. The modem’s dimensions are 100 x 50 x 30 mm, and it can operate at depths down to 6000 m. “At Ocean Business 2019 [April 9-11] Hydromea will be releasing the Luma 500ER, which has a higher data rate – 500 kbit/s – and a greatly increased transmission range, of more than 50 m,” Bahr added. Prevco Subsea attended the show to introduce its updated dual-poppet pressure relief valve (PRV). “PRVs are used to relieve internal pressure from a subsea pressure vessel in the event of an unwanted pressure build-up,” said Stephen Ashley. “This April/May 2019 | Unmanned Systems Technology The Fluidion Drone is designed for water quality surveys