Unmanned Systems Technology 026 I Tecdron TC800-FF I Propellers I USVs I AUVSI 2019 part 1 I Robby Moto UAVE I Singular Aircraft FlyOx I Teledyne SeaRaptor I Simulation & Testing I Ocean Business 2019 report

83 which, at 460 x 102 x 90 mm, was too large to fit into the Gavia’s hull. With an operating power requirement of 150 W (and a peak draw of 300 W), the T-50S can be integrated into the SeaRaptor with little issue, while typical AUVs would struggle owing to their smaller size and batteries. When set at 200 kHz, the T-50S can survey up to 575 m away from the vehicle across a swathe of up to 165°. If an item of interest is then found at a distance from the AUV, the SeaRaptor can later be commanded to navigate closer and use the T-50S at 400 kHz. This roughly doubles the image resolution, therefore helping to identify the nature of the object, be it an airline wing section, a coral reef or a tail section where a black box might be found. “For this particular deep-ocean search- and-recovery application, we worked with Teledyne Benthos to modify one of their existing USBL systems to act as a new sensor for the SeaRaptor,” Reynisson adds. “The result was a black box pinger locator, which will acoustically detect range, bearing and elevation from a ping. But instead of that being a USBL navigation system from a ship-side transducer, the customer will use this to listen for a pinger, for example from an airliner’s black box.” In addition, the SeaRaptor is fitted with acoustic pingers for its own use. If a ‘critical state’ is detected, such as a malfunction detected by the BMS or a sudden loss in mobility, they are powered on automatically so that a recovery vehicle can locate it. Recovery and post-processing As mentioned, the ‘ascent’ weight allows the SeaRaptor to return to the surface without needing to use its thruster. Unlike the descent weight though, this one is typically integrated within the hull, to prevent it interfering with the vehicle’s hydrodynamics during a survey. While returning to the surface, the AUV’s quad-core CPU can process the hundreds of gigabytes of survey data using Teledyne CARIS Onboard post-processing software, although this processing can also be carried out in real time during a mission. The CPU typically processes the data at a ‘one- for-one’ rate – one minute to process a minute’s worth of multi-beam echo sounder images. Upon surfacing, the SeaRaptor can be set to deliver its coordinates to the operator’s vessel or GCS via Iridium, wi-fi or any other user-specific comms link, and loiter in that position to avoid running into any surface traffic. In its initial design specification, the SeaRaptor releases a buoyant flotation section from the centre of its hull with a 30 m Kevlar line linking it to the AUV. This float is recovered by the crew, the line is attached to the A-frame, and the AUV is hoisted back into its container, using a rotatable snubber ring to lock on and prevent the vehicle swaying in the air (similar to methods used in ROV recovery). After recovery, the operator can download the processed data via a wi-fi link, although Teleydne Gavia is developing a removable hard drive option to speed up this phase. Various maintenance procedures can then follow. Batteries are charged or swapped out, control surfaces are checked for seaweed, and heavy freshwater rinsing is performed. “Rinsing is critical because the SeaRaptor uses so many different materials – titanium, aluminium, stainless steel – which can react adversely with each other, so you need to rinse off the salt, and care for the connectors and O-rings,” Reynisson comments. “We also integrate ‘sacrificial anodes’ that will take on the corrosive element if there’s any ground between the materials – those may need to be swapped out and investigated for the cause of corrosion.” Conclusion The company continues to develop the various technologies across the SeaRaptor system to account for the different environments, launch-and- recovery requirements, and mission profiles of the fast-growing market for deep-ocean UUV engineering. Unmanned Systems Technology | June/July 2019 An A-frame hydraulic winch equipped with a docking head is used for launching and recovering the SeaRaptor from the water