Unmanned Systems Technology 012 | AutoNaut USV | Connectors | Unmanned Ground Vehicles | Cobra Aero A33i | Intel Falcon 8+ UAV | Propellers | CES Show report

26 Dossier | AutoNaut H-Scientific writes the command and control software for its RCW autopilot interface and its credit card-sized MicroSpectre single-board autopilot aboard the vehicles in ‘native’ code that runs on its ARM processors. The MicroSpectre has an integral MEMS gyro-stabilised magnetic compass and accepts a wide range of communications protocols such as NMEA 0183 standard comms, allowing it to communicate with all kinds of devices including, for example, a Teledyne RDI Doppler velocity log, MEMS motion reference units, fibre optic gyros and other inertial sensors. Advanced control modes include heading, waypoint track following and station-keeping. The MicroSpectre hardware is integrated into waterproof enclosures by both AutoNaut and H-Scientific. Meanwhile, AutoNaut writes some of its own code for the Open Source Sensor Interface (OSSI), supporting easy integration of sensors in-house and by its customers. The company writes most of this code in Python, a versatile language that is compatible with a wide range of operating systems. The OSSI can be configured to the user’s requirements, Poole emphasises, but the code can run on both Windows and Linux-based operating systems, so sensor processing software can be run on board. Depending on the type of comms system in use and the transmission frequency, the basic electronic systems draw about 500 mA when deployed. That would be typical of the standard navigation hardware and an Iridium modem transmitting every three to five minutes, Poole says. Comms systems The standard comms installation includes narrowband and broadband links, both satcom and terrestrial, for local and global operations. H-Scientific provides the short-range 2.4 GHz system that provides local control during launch and recovery and with any support boat in use. A UHF radio is an alternative means of doing this, while Iridium RUDICS modems are embedded in the enclosures with H-Scientific’s command and control hardware. AutoNaut also offers a 5 GHz wi-fi link alongside these systems for point-to- point data offload at about 100 Mbit/s over longer ranges and sensor data offload over global range at about 150 kbit/s using Inmarsat’s Fleet Broadband satcom service. “The RUDICS system we use offers a cost-effective command and control, and low bandwidth data offload capability at relatively low cost and power,” Poole explains. “Users are constrained owing to the low Earth orbit constellation where sometimes a ‘call’ will drop out, but for the data we transfer, we have a very reliable and efficient comms path with Iridium.” Meanwhile, Inmarsat’s 150 kbit/s service offers an uninterrupted ‘call’ for the transfer of larger files, encoded video and still images along with other streams of data, he notes. “This can be a great asset, enabling ‘real time’ data transfer. The terminals are quite large and power-hungry, and Inmarsat is quite expensive, with operators paying by the megabyte,” he says. Navigation safety Navigation and collision avoidance inputs to the H-Scientific autopilot/ command and control system come from commercial off-the-shelf GPS sensors and AIS modules. There are several GPS sensors on board, and the company typically uses AIS class B, which transmits the AutoNaut’s position over VHF to nearby vessels. This is supplemented by a February/March 2017 | Unmanned Systems Technology Custom-made by AutoNaut, these cradles support the two hull sections as they are joined or separated and, with a joining bar, form a launch/recovery trolley for ramp launch and recovery (Photo: Peter Donaldson)