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

Robot Aviation FX450 | Dossier way around the tips to the low-pressure area above it. They also provide some extra lift, Guy says. He comments that all aircraft manufacturers that use winglets have their own philosophy about them, which results in many different designs, and that Robot Aviation has experimented with a couple of designs. The principal difference between them is the angle formed with the mainplane – they have gone from 90 to 45° – and they have become slightly smaller from one prototype to the next. The main wing is optimised for ISR for high altitude, as far as other considerations allow, Guy says. “It’s not a proper glider wing, but it’s robust in its handling qualities with the canard for stall prevention. It is also practical to operate from dirt roads: if you put a big glider wing on the aircraft then any barbed wire fences are going to rip them right off. I think it’s suitable for ISR missions.” Triple-redundant flight control The flight control system is centred on an autopilot from Micropilot, the core software for which was written by the manufacturer, while platform-specific functions and tuning were done by Robot Aviation. It is triply redundant thanks to three similar hardware and software systems. If any of them fails, the remaining two take over, and if one of those fails, the third takes the load. All of this is controlled by pass/fail voting logic. The autopilot contains three GPS receivers, a primary receiver that updates at 20 Hz and two secondary devices that update at 4 Hz, and supports differential GPS and carrier phase techniques such as real-time kinematics. The system retains its triple redundancy, including the wiring between the autopilot and the servos, until it reaches the Futaba servos, with one for each control surface. Guy calls them “pretty damn robust actuators” with proper separation and shielding on the cabling and military-standard connectors. There is also a triple-redundant air data system with three separate pitot tube and static port pairs. With 16 servo outputs in total, the autopilot can control elevons, flaperons, ailerons with servo flaps, separate flaps, V-tail and X-tail systems and differential thrust. That is more than enough to cope with the FX450’s combination of elevons, elevators and twin rudders, and the mixing required to control the vehicle in all anticipated conditions, including failure modes. It also runs logic that enables it to control the servos, change altitude and airspeed at given waypoints, fly user- definable holding patterns and implement error handlers to take predefined actions if GPS or comms are lost, or if it detects a battery problem.