32 Dossier | Schiebel Camcopter better load distribution and good reserves of leftover processing bandwidth for new features today.” Despite this space, Schiebel is researching how best to add a fourth PowerPC externally to the main three to carry the load of customer-specific algorithms (as companion computers increasingly do in UAVs). However, the PowerPCs and their software have always been designed with open architectures, albeit with clearly defined interfaces, for customers to interact with the system, extract data, and configure protocols and functions for requirements such as new payloads or third-party ground-control station (GCS) software. Flight control network The computer processes flight data from the S-100’s GNSS, IMU, air data sensors, transponders and other missionspecific inputs (including position and heading relative to waypoints, be they preprogrammed or changed mid-flight) to ensure correct speed and direction. Both are managed via a plethora of electronically controlled servo actuators; three act on the main rotor, one adjusts the tail rotor, and another actuates the engine throttle. Should one of the main rotor servos fail in flight, the software integrates extensive compensatory behaviours to keep the UAV as safe and stable in the air as possible (and Schiebel has judged for now that integrating a fourth main rotor servo would cause more issues than benefits). Additionally, throughout standard flight, numerous software subroutines ensure the vehicle stays within the limits of safe flight physics, including laws keeping it from flying faster or slower than allowed, or exceeding safe angular rates. The software model integrates comprehensive data on the helicopter’s capabilities, and on how dynamic adjustments to flight laws must be made based on the helicopter’s surroundings, with particular regard to ambient environmental conditions such as wind and gusts. Hunter adds: “People sometimes look at our flight control arrangement and mistakenly imagine applying it [unfavourably] to a crewed helicopter, but they don’t realise that with a UAV, you have a completely different situation. If, for instance, a crewed heli’s tail rotor malfunctions mid-flight, that’d be hell for the pilot, but if that happens in the Camcopter, it actually doesn’t matter. “The S-100 can spin, it can lurch, it can autorotate, and it remains completely controllable throughout all of those; there’s just no-one onboard to suffer flight sickness. And pilots need to look out the windows to see where they’re landing – the Camcopter doesn’t care. It can land backwards, it can land while tilting; it doesn’t need any outside visual cues. We can afford to operate completely differently than crewed helicopters, because the UAV can do things completely safely that might be dangerous for a piloted helicopter.” Safe automatic take-off and landing on large and small vessels in all sea states first relies on the GCS, which is equipped with GNSS and IMU to measure and predict the behaviour of the vessel. For redundancy, third-party ship movement information can be fed into Schiebel’s system. “The airborne platform then utilises its own dual GNSS and IMU setup, and the very specific and unique Schiebeldesigned software algorithms and routines, while taking the behaviour of the moving platform and the aircraft into account, to perform the coupling of the aircraft to the moving vessel and its deck,” Hecht adds. “This allows full automatic take-off and landing procedures. If, for any reason, it is desired by the customer’s operational concept, the open architecture can accept additional relative positional data from third-party sources, such as DeckFinder.” While Schiebel has expertise in programming CAN and ARINC buses, data signals back and forth between the autopilot and the servos today continue to be carried over standard serial interfaces, such as RS-485, the company having found these to be highly reliable over the last 20 years and hundreds of thousands of flight hours. “We tend to use whatever bus is in the servo actuators, sensors or payloads that a customer agrees to use, or insists on us using, so we have nothing against CAN bus. We understand its programming and advantages, and we’ll install it if it becomes necessary, as readily as ARINC 825, Ethernet or any other bus,” Hecht adds. “Our architecture is open and so ready to adapt to any interface of the future. Maybe, if we talk again in two years, our standard bus will be totally different.” August/September 2024 | Uncrewed Systems Technology All carbon-fibre production and autoclaves are kept in-house at Schiebel’s facility
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