Unmanned Systems Technology 021 | Robot Aviation FX450 l Imaging Sensors focus l UAVs Insight l Liquid-Piston X-Mini l Riptide l Eurosatory 2018 show report l Zipline l Electric Motors focus l ASTS show report

80 satisfied, but the method we’ve devised allows us to detect the degree of variance in control that indicates an early sign of a potential systems failure. “So we know to take that wing section off and put a new one on. Or if we have an issue with a motor, we take it off and replace it. Taking this ‘componentised’ approach speeds up servicing times.” These checks are run between missions as well as before a flight. The flight operations team maintains more than one UAV as flight-ready at any given time, to prevent delays if a control defect is found when the UAV is sitting on the launcher. Aircraft autonomy The catapult launcher sends the Zip into the air at its cruising airspeed within a second. Each route is a predefined ‘track’, with specified zones, coordinates and actions. For example, the company maintains detailed records of designated spots for holding patterns. “That means we know generally where the aircraft would begin to descend slowly in a spiral motion, so that it is gauging wind speed and variation, weather conditions and patterns, and so on,” Rinaudo says. “This means the aircraft can assess at what angle of pitch or roll it will make the delivery, and at what speed, to make sure the package is delivered safely and efficiently.” Construction of these critical delivery routes relies on survey flights, which take note of conditions in the air and on the ground, and of environmental and human factors such as new constructions, wildlife migrations or unseasonable weather. Also, the company uses an AI-based simulation environment called Parliament to regularly revise and improve the flight planning. For example, if a flight operator in Rwanda suspects that a Zip’s delivery approach needs to be changed to account for safety-relevant factors such as those above, the request is sent to the company’s headquarters in California. There, the Zipline engineering team uses Parliament to work out the best execution for whatever the alternative delivery approach is trying to achieve. That could entail flying around a new building or development project while avoiding any airspace that the company lacks enough permission or survey data to fly in. As Rinaudo explains, “Before we push the programming code for the new flight path back out into deliveries, it’s sent to our new testing facility, also in California, where our engineers repeatedly push the code to either its earliest level of failure or highest degree of success before deploying the new code for use in civilian airspace.” Delivery Based on the distance between the company’s distribution centre and the hospitals that the Zips service, blood tends to arrive between 15 and 40 minutes following the receipt of an order. As the Zip approaches the hospital and the location of the supplies drop, it descends to roughly 30-40 ft. The bay doors open, releasing the package and deploying the parachute. Then, having received a text message to tell them the blood has arrived, the hospital staff move to retrieve the box, after which they will test the blood. “As per hospital safety regulations, the staff need to be certain that it’s the right blood type, and that it’s arrived in a safe condition for transfusion,” Rinaudo says. Once the qualities of the medical product pass these tests, they are administered to the patient. Recovery After the package has been delivered, the UAV banks around onto its return flight path to the company’s landing/recovery structure at the distribution centre. Developed by Zipline and referred to as the ‘snap catch’, this is a trapezoidal metallic frame with a central cable line held between two swinging arms extending above the structure’s main supports. As the UAV approaches, the arms swing upwards to present the cable, which catches onto a 2 cm hook that extends from the Zip’s tail. The line extends from within the arms to give the aircraft enough slack to avoid damage, and bring it from cruising speed to a complete stop. The arms pan downwards as the motors stop running, the cable lowers the Zip until the nose is close to the ground, and a flight technician crosses the landing pad to remove and stow the power pack. Once a mission has been completed, the aircraft parts can be checked for any damage before they are returned to their storage racks, ready for another flight. Zipline is now looking to export its business model across Africa and beyond. It is conducting a growing number of FAA-approved trial flights in North America, and one location in the region is already being looked at as a distribution centre that would enable initial servicing of seven hospitals, with potentially up to 40 medical facilities joining the system. August/September 2018 | Unmanned Systems Technology In operation | Zipline The Zip cruises at 101 kph, and has a top speed of 128 kph for emergencies