Unmanned Systems Technology 019 | Navya Autonom Cab | Batteries | UGVs Insight | UAV Factory UAV28-EFI | Swiss Aerobotics Hummel | UMEX 2018 report | Antennas | Oceanology International 2018 report

68 Digest | Swiss Aerobotics Hummel Fight control However, most UAVs use pitot tubes for speed measurements, and measuring the angle of attack (AoA) is mostly too complex for these sensors and so is reserved for larger aircraft. So Weiss built a proof-of-concept solid-state AoA and airspeed sensor to provide the key data for the autopilot and flight control system. This new control approach requires additional capabilities in the flight control software. The company therefore worked with fellow Swiss company UAVenture on customising a version of its AirRails flight control software (FCS) and autopilot to make it suitable for the Hummel. The UAVenture flight controller has been developed with hybrid VTOL UAVs in mind and will run on autopilots that are compatible with the PixHawk open source software. UAVenture works on open source software and contributes to projects such as the PixHawk PX4 autopilot. A key advantage of teaming with UAVenture was that thousands of hours had already been spent on developing and testing, with a focus on stability and reliability for mapping, surveying and surveillance. The FCS runs on most PixHawk-compatible hardware and manages every aspect of the mission autonomously, from take-off right through to landing as well as all transitions between multi-rotor and fixed-wing flight modes. Using this approach to transitioning also had a major impact on the design of the airframe, particularly the flight surfaces. The Hummel has a foam- based airframe that has been optimised to balance the design of the control surfaces with ease of manufacturing. That made it easier to vary the design and helped the craft to survive crashes while the autopilot software was being developed and tested, as it is relatively easy to repair or replace. The wings have a foam core, which is simple and easy to manufacture, but the fuselage is a full carbon-moulded laminate – for the very large parts there are stiffeners within the structure. The lighter, more spherical parts don’t need a sandwich structure as they are inherently more stable. However, for many delivery and survey applications the higher speed of the platform is not an advantage as the range is limited. That prompted Swiss Aerobotics to look at a different application for the Hummel as a counter- UAV platform. For intercepting rogue UAVs, the vertical take-off, high speed, short range and large payload capacity are all advantages. “You have to be bigger than most of the drones you want to catch, so the scaling helps,” says Weiss. “I don’t need to scale the batteries though, as the mission time will typically be very short – you get there, catch the rogue UAV and come back.” This shift in application however meant Swiss Aerobotics had to develop new technologies for target acquisition to capture a rogue UAV. The aim is that these technologies can be used on other UAV platforms as well as the Hummel to provide a counter-UAV capability. There are different ways of detecting unfriendly UAVs, from smartphone apps that notify a user of an unauthorised aircraft in the vicinity to ground-based radar and audio systems. Data from ground stations can be fed into cloud-based applications, where the data is authenticated and the counter- UAV can be sent autonomously to the approximate intercept point. It then uses onboard detection systems to track and follow the rogue UAV and then capture it with another onboard April/May 2018 | Unmanned Systems Technology The engineering trade-off between battery weight and range was a key consideration You have to be bigger than most of the drones you want to catch, so scaling helps – I don’t need to scale the batteries though