Drone Inspection Flight Path Generation from 3D CAD Models: Power Plant Boiler Case Study

Robotic technologies for inspection purposes of large-scale structures have grown in interest. Such technologies are encouraged to reduce the risk in which human operators are involved and to reduce costs due to downtime of the equipment. In the Energy sector, high interest is placed on powerplant components where their correct operation is paramount. Inspired in the synthetic vision systems for aerial vehicles that use three-dimensional space (3D) to provide pilots with clear and intuitive means of understanding their flying environment, here we propose the use of the 3D Computer Aided Design (CAD) model of structural components of a power plant to define an off-line flight path for Unmanned Aerial Vehicles (UAVs). This method is feasible to implement because nowadays the CAD model of structural elements is readily available. Since this work focuses on structural inspection, only the surface characteristics of the model are required. To acquire, analyze and process the 3D model, first, the STL file is produced to obtain surface points and vectors normal to the surface. Later, by introducing other variables such as wall offset and controlled trajectory between each outline and each subsequent layer, the flight path is generated. This method would support efforts where the UAV is required to fly with no GPS available and/or beyond line of sight (BLOS). The effort was conducted using the MATLAB software and the multiple processes involved are discussed in detail. The final trajectory was validated using the Gazebo simulator which employs robust kinematic and dynamic models.