Combining Route Planning and Visual Servoing for Offshore Wind-Turbine Inspection Using UAVs

Offshore wind turbines are crucial assets in the generation of sustainable energy, but their location makes the inspection complex. In this context, UAVs (Unmanned Aerial Vehicles) can help to automatize the inspection process by reducing costs, risks and operation time. This paper combines route planning and visual servoing for the fast and efficient inspection of offshore wind turbines using UAVs. The route planner encodes the inspection problem into a graph and, over this, integer linear programming is used to obtain the optimal sequence of inspection points. However, differences between the expected and the actual positions of the wind turbines might appear and the information collected by the UAV after simply executing the inspection plan might be useless. To cope with that, a visual control method allows the UAV to track the wind turbine. The method relies on a partitioned image-based visual servoing approach to keep the wind turbine in the field of view of the camera as the UAV moves between inspection points. Simulation results under realistic conditions demonstrate the benefits of the proposed approach.