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43 Test centres | Focus Unmanned Systems Technology | February/March 2018 Naturally, flights in autonomous mode should then be conducted. Checks here on data such as the validity of the aircraft’s orientation according to its inertial navigation unit, or its coordinates according to the GNSS, should be repeated to minimise the rate of errors and ensure reliable flight information. It follows that from testing the GNSS data, the flight path taken by the UAV during autonomous testing should also be evaluated. It should match the path the UAV was directed to take by the GCS pilot (as well as the path taken during the pre-flight simulation, if one was run). If a UAV is designed to offer differing levels or modes of autonomy, each one should be thoroughly tested in flight to continue verifying adequate performance by all onboard systems. The lead pilot should also check that when switching from manual to autonomous mode, the flight controller and servos continue to operate normally. The rudder, ailerons and elevator should continue moving fully, whether directly controlled by the GCS pilot or not, within the space of each mission. It also worth checking that when the autopilot computer is remotely deactivated, the microcontroller allows the UAV to be flown in manual mode again – with no loss of data accuracy in flight, navigation or information about power, and that there is no change in the performance of the data link. Validating the flight-critical subsystems and handling qualities in manual and autonomous modes can be conducted over a multitude of flying patterns, airspeeds and crosswinds, and in visual range and beyond visual line-of-sight (BVLOS) – licences permitting. Such validation should ensure that there are no particular operations or environments that can lead to errors in system performance. Mission testing Naturally, given the wide range of UAV configurations being developed for different applications, markets and agencies, repeated testing of the vehicle’s intended mission envelope is critical to ensuring that the feasibility of any such excursions are sufficiently evaluated. Some tests in this regard are the same across mission sets. Testing a UAV’s ability to operate BVLOS missions for example are valuable in countless commercial, defence and civil applications. Many end-users might for example want a UAV that climbs at 900 ft/ minute in a given set of atmospheric conditions, in which case it is key to validate the craft’s ability to safely achieve and hold that climb rate, whether manually or autonomously. Others are more specific. An agricultural UAV, for example, would be expected to perform multiple flights with a payload such as a multi-spectral camera capable of producing digital surface models or normalised difference vegetation images, to prove its capability to acquire actionable information in a safe and timely fashion. Alternatively, an aerial mapping system might need to be tested with any number of payloads to prove its compatibility with the flight computer and other interconnected systems, while then flying in the paths and patterns typical of mapping UAVs. These might be flying in lengths across a 50 x 50 m area or a long, winding flight for mapping a corridor such as a road or powerline. A UAV should autonomously maintain the necessary altitude and airspeed to capture the required detail for a consistent orthomosaic. Tests of complex algorithms such as those for swarm navigation or extended aerial comms relay missions bear close attention as well, with repetition and extensive troubleshooting to confirm that they operate as needed. Testing with different antennas and other technology is recommended, to identify which systems produce the best overall configuration for achieving the stated objectives and simulation-defined parameters. Centres such as the Warm Springs FAA UAS Test Range allow testing of a UAV at various altitudes and distances, in manual and autonomous modes, to ensure it operates as expected in all flight paths (Courtesy of The Hidden Touch)