Adel Nasser’s scientific contributions

With the rise of renewable energy installations, in-line with the worldwide goals for sustainable energy, inspection became a crucial factor for the longevity of these systems. This is especially true for wind turbines where the system performance is impacted by the condition of the system's components, particularly the blades. However, human inspections are dangerous and costly, suggesting that robots can enhance such operations. That said, the need for multiple robots to undertake several types of inspection creates other issues such as drone swarm communications and additional costs. As such, this work aims to introduce a multi-modal design for a robot capable of inspecting multiple areas on the wind turbine independently. The design was tested using Solidworks simulations for stress analysis, demonstrating sufficient robustness and maintaining its overall form under different robotic configurations. The paper also highlights the aerodynamic modelling of the robot using Ansys Fluent at high-speed conditions expected in wind farms. Finally, we highlight the different mechanisms and locomotion methods required for convenient operation of the robot while testing them within a simulated environment, illustrating their feasibility in the required environment. I. Nomenclature = Identity matrix = Turbulence kinetic energy (J/kg) = Characteristic length of the airfoil (m) p = Pressure (Pa) = Reynolds number S = Source term (kg/m 3) = Inlet velocity of the fluid (−1) U = Flow velocity (m/s) + = Distance from the first grid cell to the surface = rate of dissipation of turbulent kinetic energy (2 −3) = Fluid viscosity (Pa s) = Fluid density (kg/m 3) = Stress tensor (N/m 2) = specific turbulence dissipation rate (−1)

With the ever-increasing demand for harvesting wind energy, the inspection of its associated infrastructures, particularly turbines, has become essential to ensure continued and sustainable operations. With these inspections being hazardous to human operators, time-consuming and expensive, the door was opened for drone solutions to offer a more effective alternative. However, drones also come with their own issues, such as communication, maintenance and the personnel needed to operate them. A multimodal approach to this problem thus has the potential to provide a combined solution where a single platform can perform all inspection operations required for wind turbine structures. This paper reviews the current approaches and technologies used in wind turbine inspections together with a multitude of multimodal designs that are surveyed to assess their potential for this application. Rotor-based designs demonstrate simpler and more efficient means to conduct such missions, whereas bio-inspired designs allow greater flexibility and more accurate locomotion. Whilst each of these design categories comes with different trade-offs, both should be considered for an effective hybrid design to create a more optimal system. Finally, the use of sensor fusion within techniques such as GPS and LiDAR SLAM enables high navigation performances while simultaneously utilising these sensors to conduct the inspection tasks.