Issue 37 Unmanned Systems Technology April/May 2021 Einride next-gen Pod l Battery technology l Dive Technologies AUV-Kit l UGVs insight l Vanguard EFI/ETC vee twins l Icarus Swarms l Transponders l Sonobot 5 l IDEX 2021 report

91 EvoLogics Sonobot 5 | Digest integrate any multi-constellation receiver, including those capable of receiving signals from the newest L5-tier satellites and RTK base stations. “Having the computer architecture in our own hands makes us open to adding all sorts of sensors and links for navigation, survey and telemetry,” Dr Lange comments. “As standard, we include an 868 MHz back-up data link for redundancy with the main 2.4 GHz link, and our modems can work as a mesh network even with acoustic comms systems. For example, if a customer is surveying a large area of lake bed or infrastructure with one of our AUVs or ROVs, the underwater vehicles could transmit some data acoustically through the Sonobot 5 without needing to surface.” EvoLogics engineer Philipp Bannasch adds that the COTS mesh network radios they have inspected thus far do not give sufficient control or customisability, which prompted the company to start engineering its own systems in-house some eight years ago. The radios are now used in a wide range of the company’s systems. A ruggedised tablet GCS that is available with the USV system allows users to plot and monitor their target waypoints for navigation and sonar pulses. These can be selected individually, or the operator can also use EvoLogics’ predefined polygon-based grids, to automatically plot an efficient back-and-forth mapping route. Users typically perform an initial survey of the shorelines before applying one of the automatic grids for the main body of water to be surveyed. Operators can also define actions at individual waypoints, such as station- keeping or activating different sensors. Mission sensors and object recognition The Sonobot 5 is designed to carry a wide range of sensors. As standard, this includes a 200 kHz single-beam echo sounder, a 270 kHz multi-beam echo sounder and a 700 kHz sidescan sonar, although alternatives for the single-beam and sidescan sonars are available, with an overall payload capacity of 3 kg. “A single-beam sonar is good enough for simple bathymetric surveys of shallow waters, at depths of 1-3 m, while multi- beam sonar works better for measuring much deeper and larger areas,” Tietz explains. “And the sidescan works as a middle ground, for imaging at depths down to 40 m and ranges of up to 100 m.” A forward-looking camera is also installed for users who want a view from the USV’s perspective, such as for inspecting under bridges or piers. For the most part, the single-beam echo sounder has been sufficient for hydrographic surveyors, but the company notes that its more powerful sonars are seeing particular uptake by public service providers such as police forces, who are looking for ways to quickly and accurately search lake and river beds for missing people or vehicles. Bannasch says, “We’ve also developed state-of-the-art convolutional neural networks for deep learning and onboard data processing, as we see these technologies becoming more and more important, especially since it’s actually really difficult for security authorities to perform search & rescue missions underwater. “Vehicles and people who have driven into lakes become obscured by silt very quickly, so we’ve trained and trialled our neural network to be able to recognise bodies or parts of cars in sidescan sonar imagery while not mistaking rocks or debris as potential clues or points of interest when searching.” Successful trials have been performed in lakes using dummies, car parts and bicycle parts to test the effectiveness of the recognition algorithms. Upon identifying potential signs of where the victims or vehicles are, the USV will geo-stamp their approximate locations with GNSS coordinates and transmit them to the operators in real time so that divers know immediately and exactly where to look. Future plans The recognition software is expected to be applied to the Sonobot 5’s above- water sensors as well, on the forward- looking camera and potentially also on a future Lidar system which will be integrated if needed, to provide intelligent surveying and autonomous collision avoidance capabilities. This software is also being applied to EvoLogics’ UUVs, with the Sonobots carrying USBL transceivers for fully autonomous swarm navigation and localisation to enable wide-area ocean surveys and real-time monitoring. Larger versions of the Sonobot are expected in the future for carrying more sensors, computers and other mission-critical electronics. Unmanned Systems Technology | April/May 2021 Sonobot 5 Catamaran USV Weight: 27 kg Dimensions: 1300 x 920 x 805 mm Draft: 120 mm Maximum speed: 18 kph ​Operating speed:​ 3.6 kph Max endurance: 15 hours (9 hours typical) Some key suppliers Design software: Blender Computer systems design: in-house GNSS: u-blox GNSS: Javad GNSS: various others AHRS: Xsens Basalt composite: Alpha-Sigma Single-beam echo sounder: in-house Multi-beam echo sounder: Imagenex Sidescan sonar: Hydra Batteries: in-house Mesh radios: in-house Specifications