Summary This paper considers the leader‐follower formation flight of fixed‐wing unmanned aerial vehicles (UAVs) subject to velocity constraints. A novel distributed sliding mode control law is proposed for each UAV, whose kinematics is described by a unicycle model with a saturated angular velocity and a bounded linear velocity within an interval. The designed control law of each follower UAV only uses its own information and the information of its leader UAV. Driven by the designed control law, the desired formation is achieved with rigorous proof, while the follower UAVs' constraints of both the linear and angular velocities are satisfied. Moreover, the follower's speed adjustment range is relaxed and not required to be strictly larger than their leaders'. Finally, numerical simulations are presented to verify the results.

In this paper, we present our recent advances in both theoretical methods and field experiments for the coordinated control of miniature fixed-wing unmanned aerial vehicle (UAV) swarms. We propose a multi-layered group-based architecture, which is modularized, mission-oriented, and can implement large-scale swarms. To accomplish the desired coordinated formation flight, we present a novel distributed coordinated-control scheme comprising a consensus-based circling rendezvous, a coordinated path-following control for the leader UAVs, and a leader-follower coordinated control for the follower UAVs. The current framework embeds a formation pattern reconfiguration technique. Moreover, we discuss two security solutions (inter-UAV collision avoidance and obstacle avoidance) in the swarm flight problem. The effectiveness of the proposed coordinated control methods was demonstrated in field experiments by deploying up to 21 fixed-wing UAVs.

In recent years, the problem of multi-agent encirclement has attained much attention and was extensively studied. However, few work consider the factor that the on-board calculation as well as the communication capacity in the multi-agent system is limited. We investigate the encirclement control by employing the newly developed bearing rigidity theory and event-triggered mechanism. Firstly, in order to reduce the onboard loads, the event-triggered mechanism is considered in the framework and further an event-triggered control law based on bearing rigidity is proposed. The input-to-state stability (ISS) of networked agents is also analyzed by using the Lyapunov method and the cyclic-small-gain theory. In addition, the lower bound for the inter-event times is provided. Finally, to verify the efficiency and feasibility of the proposed encirclement control law, numerical experiments are investigated.

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Due to the nonlinear and asymmetric input constraints of the fixed-wing UAVs, it is a challenging task to design controllers for the fixed-wing UAV formation control. Distance-based formation control does not require global positions as well as the alignment of coordinates, which brings in great convenience for designing a distributed control law. Motivated by the facts mentioned above, in this paper, the problem of distance-based formation of fixed-wing UAVs with input constraints is studied. A low-gain formation controller, which is a generalized gradient controller of the potential function, is proposed. The desired formation can be achieved by the designed controller under the input constraints of the fixed-wing UAVs with proven stability. Finally, the effectiveness of the proposed method is verified by the numerical simulation and the semi-physical simulation.

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