114 We all forget small things from time to time, or we come to do a repair job and realise we can’t complete it because we are missing a small but vital part. In most circumstances it’s a minor annoyance, but if you are 12 miles offshore after a boat or helicopter transit and a climb up a ladder to the top of a 100 m high wind turbine, the logistic inconvenience is of a whole new order, writes Peter Donaldson. To tackle this problem, the Swiss-Danish ADD2Wind project team is developing the capability to deliver small parts, tools and other pieces of equipment at short notice using a small, autonomous helicopter. The team is led by Dr Anders la CourHarbo of Aalborg University, with Prof. Dr. Christophe Eck of Lucerne University in charge of flight operations. The UAV is the 85-90 kg Scout B-100 from AeroScout Unmanned Aircraft Technology, which has a payload capacity of 18 kg, and it has been fitted with a payload winch and a special delivery bag. Initial flight testing took place at two onshore locations, with the payload delivery practised on a wind-turbine nacelle mock-up in Switzerland, followed by a beyond-visual-line-of-sight (BVLOS) delivery flight to a Siemens-Gamesa onshore wind turbine in Tim, Denmark last summer. Using the mock-up, which is just a few metres off the ground but subject to turbulent winds coming off the surrounding forest, allowed the team to determine how long they would need to make the delivery once the helicopter has arrived at the turbine, along with many other crucial details. These included working out the best approaches to the turbine’s platform, assessing the performance of proximity sensors, gauging how accurately the helicopter can hover and discovering whether the payload is prone to swinging problems. This was done with VLOS so an operator could take control of the aircraft and drop the payload if necessary. While the Scout B-100 can maintain a hover within 30-50 cm of the target position, the release mechanism had a tendency to swing after dropping the payload, which was cured with modifications to this mechanism and to the winch. The next step took them to Denmark to validate the reliability and robustness of the vehicle’s video and data links in BVLOS flight, with tests including 360° turns. During flights at the helicopter’s maximum speed of 10 m/sec and 100 m above ground level, the team also recorded 86 data parameters, which, among other things, helped prove that the UAV followed the required track and maintained the commanded velocity very accurately. Delivery to the Siemens-Gamesa turbine, while successful, took place under benign conditions with the blades stationary and the orientation fixed, and the B-100 was filmed by an accompanying camera drone, with an additional camera installed on the nacelle. During the approach an operator on the ground could see the image from the UAV’s downwardpointing camera. Nonetheless, the payload bag was released automatically after it touched down, the winch cable and release mechanism rewound, and the UAV made its return flight. The team’s next step is to demonstrate delivery to an operating offshore turbine. Only then will they be able to free offshore technicians of the terror of bringing the wrong spanner. June/July 2024 | Uncrewed Systems Technology PS | UAV deliveries to offshore wind farms Now, here’s a thing Crucial details included working out the best approaches to the turbine’s platform and assessing the performance of proximity sensors
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