Distributed fixed-time time-varying formation-containment control for networked underactuated quadrotor UAVs with unknown disturbances

This paper focuses on the fixed-time time-varying formation-containment (TVFC) control problem for multiple underactuated quadrotor unmanned aerial vehicles (QUAVs) with unknown disturbances. A two-layer control framework comprising reference trajectory generators and trajectory tracking controllers is proposed. Under undirected communication topology, the first layer includes two fixed-time distributed reference trajectory generators for leaders and followers. The generated trajectories can be in accordance with the TVFC control requirements. In the second layer, two fixed-time tracking controllers are proposed, and a fixed-time disturbance observer (FTDO) is developed to ensure the robustness and timeliness of the control system. Meanwhile, the intermediary control input developed in the translational controller can be used to obtain the desired attitude by the attitude extraction algorithm. To handle the derivative calculations of variables in the rotational controller, an exact tracking differentiator is adopted, and the closed-loop stability of the control system is proved mathematically. In the end, the proposed control methods are verified through simulations and two comparison simulations are presented to show the superiority.