Dubins Path Generation and Tracking in 3D for UAVs

Excessive maneuvering may pose risk of damage to the aircraft. This paper presents methods to solve this problem. Specifically, the shortest path between two given points in the 3D space of an unmanned aerial vehicle (UAV) is generated, and the generated path is traced. Moreover, the designed controller is introduced. The path generation algorithm is based on the existing path generation algorithm pertaining to the Dubins curve. The path generated by this algorithm can satisfy the constraints regarding the minimum allowable turning radius; moreover, the algorithm involves rapid computation and can be applied for path generation in real time. Notably, in this algorithm, the shortest path to fixed initial and final points is geometrically obtained in a 2D plane; however, real aircraft path generation problems must be implemented in 3D. Therefore, a path in 3D space is generated by deriving a solution through a numerical technique, using the same principle as that of the problem in 2D. Furthermore, the line-of-sight guidance algorithm corresponds to basic waypoint guidance. The proposed 3D path tracking approach is implemented using a nonlinear controller, resembling those of line-of-sight guidance algorithms. The controller guarantees, under certain assumptions, asymptotic tracking of the path, in terms of both the position and attitude. Finally, we adopt a sliding mode controller, which is a robust controller that can ensure high control performance and stability even under uncertainties. The proposed controller satisfies the constraint through the saturation function, specifically, by introducing the constraint on the angular velocity to the existing sliding mode controller. The stability of the designed controller is verified considering Lyapunov stability, and the performance of the proposed algorithm is verified through numerical simulation.