3D path following control for UAVs using L1 adaptive method

This paper considers the 3D path following problem of an Unmanned Aerial Vehicle (UAV), the objective is to steer the UAV along a given reference path, while the desired transient and steady performance is satisfied. To solve the problem, we make use of the typical multi-loop control structure in which the guidance loop controller directs the aircraft to the desired path, while the inner loop controller stabilizes the nonlinear dynamics and tracks the command generated by outer loop. By introducing a virtual target, the proposed Lyapunov based kinematic controller for outer loop can make the UAV asymptotically approach the defined path with smooth movements. Moreover, the developed inner loop controller is based on L₁ adaptive control method, which can provide guaranteed transient performance and guaranteed robustness in the presence of fast adaptation, without introducing or enforcing persistence of excitation, without any gain scheduling in the controller parameters, and without resorting to high-gain feedback. Finally, the controllers are validated by simulation.