34 code. They focus with similar dedication on very robust enclosures to keep their ASICs safe and sealed, and they use advanced, embedded Kalman filtering for taking in multiple PNT-critical data sources, and intelligently recognising and rejecting erroneous inputs.” A plan for every servo A detailed system of fault trees and similar reliability analysis tools are routinely leveraged to inform Insitu’s minimum requirements on servo lifetimes and tolerances. With these, the company has periodically looked across the industry to identify ideal matches, although Todorov and Hartley note that, historically, a mixture of hobby- and industrial-grade devices were often the best that could be found. As well as comparing unfavourably to the highly reliable and SWaP-optimised servos made especially for the uncrewed market today, these would rarely come with any reliability data, so Insitu has long since developed its own internal testing processes for evaluating servo MTBF. “Depending on the criticality of the application, we can tolerate some margin for failure in the control surfaces. If we lose one, we can often maintain normalised flight control, but in missions where we can’t tolerate even one failure, the MTBF estimate is very useful for informing servo inspection, testing and replacement schedules for servos,” Todorov notes. A touch of FLARES Programming and testing has contributed to FLARES’s development in some surprising ways, as Hartley relates: “In a computational sense, FLARES is surprisingly simple, because the multicopter’s manoeuvres aren’t complicated. The really interesting launching code is on the ScanEagle and Integrator’s side: we’ve added logic to both flight-control systems, such that the operator indicates in pre-flight planning whether they are catapultlaunching or FLARES-launching. “If it’s the latter, the aircraft is tasked with detecting when FLARES spins up its rotors, when it ascends, when it reaches the ideal height for mission commencement and, most importantly, when it starts dashing to give a viable speed for release and hence launch. Then, the ScanEagle starts running queries as to whether it is moving at a good airspeed, a good altitude – essentially, are all the conditions right to support a drop into free, fixed-wing flight?” Once the launch conditions are acceptable, the operator is notified, who then provides a green-light trigger to the June/July 2024 | Uncrewed Systems Technology Dossier | Insitu ScanEagle VTOL & Integrator VTOL Careful choices of GNSS and antennas contribute to autopilot function and to recovery, which through FLARES functions via mid-air rope capture, as it did with SkyHook FLARES 3, the latest version of the system, integrates redundant electric motors, ESCs, batteries and more
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