Flight envelope constrained UAV shipboard landing control within an identified quiescent period

UAV shipboard landing poses significant challenges in terms of safety and efficiency, due to the oscillatory ship motion caused by wave interactions and wind gusts, especially in rough sea states. To solve this issue, a flight envelope constrained fixed-time control strategy is proposed to achieve a reliable UAV landing on a maneuvering ship. Firstly, a sliding data window autoregressive model is designed to predict the ship's roll and pitch motions, which are accordingly utilized to identify an appropriate quiescent period for safe landing. Subsequently, a barrier-function-based nonsingular terminal sliding mode controller is developed to eliminate the tracking errors within the identified quiescent period, while ensuring the errors remain bounded to satisfy flight envelope constraints. In particular, lumped disturbance components are estimated by integrating a fixed-time disturbance observer and compensated in the controller. The key advantage of the proposed approach is that it well balances the control requirements between precise landing position and safe landing attitude, guaranteeing both steady-state performance and transient behavior of the tracking error. Finally, comparative Gazebo simulations in different sea state scenarios are conducted to verify the satisfactory control performance. 5 Production and hosting by Elsevier Ltd on behalf of Chinese Society of Aeronautics and Astronautics. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/).