98 such as pipes, wires or other occlusions, and where a sky view is available for GNSS. “Although you’re unlikely to get gusts of 20 knots in an industrial area with a lot of structures, it’s still important to make sure there aren’t really strong winds blowing, given how close to buildings the UAV flies,” Korol adds. The UAV internalises all self-tests and self-checks within the realm of possibility. Upon activation and throughout its flight it engages in autonomous condition-monitoring of the state of its GNSS feed, servos (for articulating the thrusters), thrust motors, batteries, internal network, computers and onboard collision avoidance sensors (a camera and Lidar). “If any subsystem is detected as not running in a nominal state, the user is alerted. And in some products we install a subroutine, which prevents take-off if that alert happens pre-flight,” Korol notes. “The IMU auto-calibrates, so if the end-user keeps moving it around, lifting or adjusting it, then it will refuse to take off until they’ve let it sit still and calibrate for a short while.” As a final precaution before take-off, once the motors are powered on, the UAV sits in a semi-powered mode, during which the rotors start spinning up and the servos begin operating, to evidence if anything might suffer a mechanical failure in-flight before actual flight happens. Once the mechanical flight systems have been proven for a few seconds, the autopilot allows take-off to commence. In-flight autonomy In the future, Skygauge aims to develop more automatic means of generating flight plans to ease workflows for themselves and customers, pending regulatory approval. Regulations sometimes require that at least the initial runs of ultrasonic inspections with the Skygauge UAV are performed by remote control, to ensure sufficient oversight, as well as similarity to past operational methods. But even these use a plethora of autonomous functions, including: autonomous approaches and contact handling by the UAV in every measurement, autonomous articulation of the thrusters to maintain contact against turbulence and contact-induced oscillations, and autonomous emergency return and landing subroutines. The future operating model is for users to tie all these functions together with autonomous take-offs and autonomous movements between inspection points. Usually, the mission is a two-person job: one person to operate and monitor the UAV (for instance, taking direct control if emergency situations demand) via the ground control station (GCS), while the other monitors the inspection via a laptop that receives data from the ultrasonic gauge in real time. The latter may also instruct the operator in real time, particularly on the quality of results being obtained and whether the flight plan must be interrupted to redo one or more inspection points. “When the UAV gets to the GNSS and altitude of a given inspection point, its flight-control system essentially locks it in to hover and station-keep there, at about a 50 cm distance between the arm with the gauge on it and the wall,” Korol says. “Then it starts its approach, slow and smooth, into the wall. It bumps the gauge into it, detects contact, and then the flight system locks in again and the gauge starts the inspection process; the reading usually being captured within two seconds or less before the UAV can move on to the next point. And the February/March 2024 | Uncrewed Systems Technology Once the motors and servos are powered on, the UAV sits in a semipowered mode to see if anything might suffer a mechanical failure in flight The IMU autocalibrates, so if the end-user keeps moving it around, lifting or adjusting it, then it will refuse to take off until they’ve let it sit and calibrate
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