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80 In operation | RISE BVLOS logistics system Mission clearances Significant risk analysis was conducted in order to qualify for the necessary flight permit, and encompassed ground- related and aerial risks. “The Joint Authorities for Rulemaking on Unmanned Systems [JARUS] published a document about risk analysis of specific UAV operations,” Lundqvist says. “It wasn’t mandatory but we conducted our own analysis according to JARUS’ recommendations, which led to us getting approval from the Swedish aviation authority for this flight.” Significant documentation regarding the UAV – including technical descriptions, development history, past flights and other examinations – also had to be submitted, as well as a full plan for the mission itself. “Even though we received a special operations flight permit to fly BVLOS in an urban environment, we were still restricted to a specific flight route, so we had to submit that route and we were absolutely forbidden from flying any other mission in the area,” Lundqvist recalls. “We were less limited in time, however, as we were given a month in which to perform the flight.” Gising adds, “Linkoping is a major aviation centre, with two airports – one military, one civilian – and multiple helicopter landing sites. So, even though we had our permit, to make the flight we had to be in contact with the military airport’s flight tower on the morning of the operation to request a time slot for our route. Once the flight was over, we notified them of that. “We actually have a Ping ADS-B receiver onboard that receives air traffic information, so we could have avoided any other aircraft so long as they too had a transponder,” he adds. The researchers also have a transceiver for transmitting the UAV’s position and registration number, but they were not granted permission to use it without a certified aircraft. Pre-flight checks Despite adding useful equipment such as an image processor for future machine vision integration and an ADS-B receiver to their UAS, the researchers have omitted dedicated GCS hardware from the requirements of their operational model. “The DSS hosts a web server, which enables a number of mission scripts corresponding to tests, checks and actions for the UAV, so anyone with access to our VPN can access the server from their computer or smartphone and run the script of their choosing,” Gising explains. “That is what we used to go through our checklist of subsystem tests, running scripts to test the autopilot, the GNSS, the motors and so on.” Gising and Nordahl checked and recorded the payload weight (before loading it), as well as the environmental conditions – the team wanted a maximum wind speed of 7 m/s and no precipitation, for safety and good data purposes. They then ran the onboard testing and flight planning scripts via the web server. Lastly, a final take-off clearance script on the web server had to be triggered before the UAV could be launched, even after passing all pre-flight safety checks. February/March 2020 | Unmanned Systems Technology The payload box was carried using an electro- permanent magnet gripper, to avoid relying on servos or other mechanical devices that could jam or break The team built an ‘RTK Pi’ box containing an RTK base, a battery and a 4G Raspberry Pi for RTK corrections