Unmanned Systems Technology 018 | CES show report | ASV Global C-Cat 3 USV | Test centres | UUVs insight | Limbach L 275 EF | Lidar systems | Heliceo DroneBox | Composites

42 February/March 2018 | Unmanned Systems Technology Ground tests Examining a UAV in a hangar or lab environment often marks the first time that all the different subsystems are assembled in a single, connected architecture. Before this, individual components will generally have been tested by their manufacturers or elsewhere. Such systems integration tests often goes overlooked or is underdone as the design and development phases run on and crowd them out. It is critical therefore that, in addition to checking each system is functioning within normal parameters – before every flight, as well as the first – that all the microelectronics are debugged, soldered and reworked as needed. Also, mechanical or material parts that need to be replaced can be fitted, and all avionics firmware updates installed. Checking the data links – assuming there are primary and back-up links in the design – can first be conducted through a range check. This involves deliberately attenuating the output power of the links to see how much of the signal gets through. This should be conducted in the same environment as the flight test to improve the reliability of the results. Also, verifying the procedures by which a back-up link takes over from the primary link, or how control may be passed from one GCS to another (if it falls within the test programme) is critical to ensuring safe control over the aircraft. Testing the navigation systems tends not to be complicated, and can easily be conducted with the aircraft on the ground. The tests may involve no more than physically tilting a UAV in the various axes during a simulated flight mode to simulate pitch, roll and yaw, and checking that the output readings from the inertial navigation system match. If checking the attitude control system as well, a similar test can be conducted to inspect the deflections of the elevators, ailerons and rudder. Verifying a UAV’s ability to identify and recognise entry into waypoints is also a useful ground test for navigation. This can be simulated, or the vehicle can be towed behind a road vehicle to the waypoint coordinates to see when it ‘arrives’ at the designated location. And although it may not be directly related to the condition of a UAV, checking the weather conditions before flying is advisable in order to ensure accurate data analysis when examining the flight logs after each mission. This should include the speed and direction of wind, degree of visibility, temperature, cloud ceiling and any rainfall. Manual and autonomous flight testing The first recommended step in actual flight testing is to carry out a manual flight, with the GCS engineer or lead pilot having direct control over the UAV. This enables the test crew to ascertain that the aircraft has sufficient command capabilities and does indeed operate safely in the air and perform as expected. This maiden flight also acts as an effective control or comparison for the flights to follow that can be expected to use varying levels of autonomy. All performance and specification results obtained during this flight should be compared with the benchmarks set by any simulated flights conducted so far. This ensures that any deviations between parameters such as position data, waypoint navigation or airspeed do not deviate unacceptably from expected values. Guide to testing In addition to universal performance- focused testing, unmanned vehicles should be tested in their specific application (Courtesy of Nevada Institute for Autonomous Systems)