110 “Combining a closed wing of this shape with a conventional, blended wing body isn’t something we’ve seen anyone else do, so we’ve been dealing with an unusual set of 3D aerodynamics and hence a CoG that moves in all dimensions: move a payload to the nose and you move the CoG, while also creating a lever arm that generates instability in roll and pitch,” Fainveits says. “Putting weight on the nose essentially means we need to put weight somewhere else higher up to make it easier for the autopilot and rotors to compensate. Fortunately, we wanted to target multi-mission applications from the outset, which meant we wanted to carry multiple payloads simultaneously; hence the many different integration hard points discussed earlier.” There remained, however, many variables to account for across different missions, payload integration profiles and flight stages. For instance, the wing AoA is different during hover and horizontal flight, which means the CoG moves forwards when transitioning from takeoff into forward flight or into hovering (position hold) mode, thus increasing the frontal load to the front propulsion set. “It was a huge challenge combining mechanical and software engineering to make sure the autopilot could account for those movements, and accordingly change the differential thrust across the rotors to maintain flight stability,” Fainveits says. “We started with a simplified mathematical model of how the CoG might change throughout flight stages and different mission subsystem setups, which acted as a first stage towards calculating where the CoG was, and how it changed with more and more accuracy over our development time.” The overall result is that the 025’s software bears hugely different control loops to those of the 007, with the company describing the new flagship product’s consistent functionality – regardless of payload integrations differing (within reason) between missions – as “adaptive autonomy”. Adaptive autonomy The 025’s proprietary autopilot computer is built around an STM32 H7-series CPU, powered by an ARM Cortex-M7 chip at its core. For navigation inputs, the 025 uses a u-blox GNSS receiver as standard, particularly the Swiss company’s F8N, or F9P, the former being reportedly the more accurate of the two, although the latter has the advantage in redundancy (and may be more certifiable). However, FIXAR will integrate most other suppliers’ GNSS products if customers have a preference, as this is increasingly happening in the uncrewed space. The two IMUs installed with the autopilot are MEMS devices: one is an MTi-series system from XSens and the other is an MPU-series IMU from TDK InvenSense. “The former is very high performance with very minimal drift; the latter isn’t so high performance and it drifts a little, but it’s very fast, so in essence the two cover each other’s weaknesses, and make for good state estimation algorithms February/March 2025 | Uncrewed Systems Technology The UAV’s four standard motors are KDE Direct devices, which collectively produce 3.5 kW for the craft during take-off
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