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79 In the future, the operational and technological r&d will be handed from RISE to OWL (Optimised Warehousing and Logistics), a start-up in the Netherlands formed by the various project partners, who will commercialise the autonomous logistics solutions described above. Vehicle and mission-critical tech The researchers used a Tarot 960 hexacopter as their testing platform. It is made from carbon composite and CNC- machined aluminium, and is 960 mm across and roughly 400 mm tall. “We chose powertrain components carefully as we knew we’d be flying over a populated area,” Gising recalls. “For flight control and navigation, we chose Pixhawk 2.1 running Ardupilot as our autopilot and carrier board, and a Raspberry Pi as the ‘companion’ computer for interfacing with the autopilot data and making decisions based on it.” The battery is a 22,000 mAh pack, which enabled the test flight to carry 2 kg of Thai food (selected mainly as a placeholder for any 2 kg item, including tools, documents, and so on) for 1.7 km before delivering it and flying back. The expected maximum range is 7 km. “There are many things that could be improved as development proceeds of course,” Gising says. “For example, we are limited in our forward speed because of the un-aerodynamic package – a more streamlined payload parcel could enable us to double the speed and range. That said, a 7 km radius is enough to cover most major city centres.” There are two other key technologies that were critical to the flight’s success. As Lundqvist explains, “The first is our own Drone Safety Service [DSS], a software layer we use for all our UAV applications and payloads testing. We wrote it with smart functions such as Return to Launch and a filter that automatically screens unrealistic commands, such as UAVs flying for miles in the wrong direction owing to an application error.” The DSS was developed during work RISE did with the Swedish Defence Research Institute, in which software was being written to enable UAVs to autonomously determine their next- best point of viewing during survey and monitoring missions by analysing stored map information and selecting a new GNSS position. “From that project basis, you can see why we needed something that would filter out bad waypoints. For example, one line of application code could convince the UAV that flying to Greenland was a good idea,” Gising says. “So we’ve used the DSS as middleware ever since, including as an interface to cloud-based services, and awareness notification systems to alert the pilot when they’re near an airport or in other dangerous airspace, which EU regulations are likely to make mandatory soon.” The second key technology is an electro-permanent magnet (EPM) gripper installed in the undercarriage of the Tarot, which serves as the delivery and release mechanism for the goods being delivered. “We wanted to avoid using hooks or actuators, as any moving mechanisms are potential points of failure,” Lundqvist says. “So we went with this system instead, which none of us have seen on a BVLOS delivery before.” The gripper secures its package by emitting three short, 300 A pulses to create a 100 kA/m field in the aluminium nickel cobalt (AlNiCo) magnets. This causes an alignment of the magnetic domains in the AlNiCo in a particular orientation which forms a magnetic circuit between the gripper and the delivery box on the underside of the UAV. Gising explains, “The EPM doesn’t depend on power to maintain the magnetic force; the power controls it by de-polarising or re-polarising the permanent magnet, to release or engage the grip respectively. The permanent magnet is what keeps it gripping, with about 200 N of force, so the drain on the battery during flight is negligible.” RISE BVLOS logistics system | In operation Unmanned Systems Technology | February/March 2020 Selecting the right motors and propellers was critical, given that the mission would be flown directly over civilians