Unmanned Systems Technology 021 | Robot Aviation FX450 l Imaging Sensors focus l UAVs Insight l Liquid-Piston X-Mini l Riptide l Eurosatory 2018 show report l Zipline l Electric Motors focus l ASTS show report

69 Riptide Autonomous Solutions | Digest Underwater cameras can consume a lot of power in a small vehicle that also needs to power subsea lights, Smith says. He points to the LED strobe light the company uses to locate the UUV when it returns to the surface so that it can be recovered. “It’s an 18 W LED that we can run at 5-6 W, but if you compare that to the sonars that are 8-10 W, it’s bad when the LED draws the most power.” With the prospect of a 1000-mile range and month-long operations, the company is also adding satcom via the Iridium network. This will need more integration of the mission planning systems. “We are putting this on the deeper ocean-going vehicles – that gives new mission waypoints, and means a user can adapt missions on the fly,” Smith says. That though has an impact on the design of the craft. “For the 7.5 in version we have integrated the Iridium receiver into the control fin so we don’t have to take a drag hit. “That adds more volume than we have on the A-size, so that will have a top hat,” says Smith. This will be a bulge on top of the fin to accommodate the satellite antenna. “We consider ourselves sensor- agnostic – the customers have their preferences, using sensors from Kraken Robotics or Edgeteco,” he says. He points to Kraken’s side aperture sonar sensor, which is rated down to 6000 m, as a key example. “That flexibility adds to the burden on the engineering, but everyone wants something different, so we have really set things up to give that flexibility and not make every integration difficult,” he says. Swarming It also allows the use of multiple UUVs in a coordinated swarm. “When every vehicle is $1 million it costs a lot, and when it runs for 12 hours you can’t do much,” says Smith. To link the vehicles underwater, a COTS acoustic modem is fitted into the nose of the UUV, replacing a rubber bumper. This works with an additional board that fits into the signal stack. Later in 2018, Riptide is to demonstrate eight or ten vehicles operating collaboratively and linked by acoustic modems in a swarm. It is working with Teledyne and Drapers Labs to use the latter’s Maritime Open Architecture Autonomy (MOAA) software on the BeagleBone Black boards. The MOAA update is available for all the Riptide UUVs being used by the US Navy, but it is of course not open source code that is available publicly. Unmanned Systems Technology | August/September 2018 The nose provides an interface for a conformal acoustic modem, houses standard vehicle sensors, the UUV’s mission altimeter and computer, and a display for vehicle status The body of the craft can be used in a number of ways for different payloads and with dry or flooded (black) sections