Formation flight refers to the state in which multiple UAVs keep flying in a specific configuration. Compared to single UAVs, UAV formation can increase the search area, enhance flight performance and raise the success rate of missions. UAV formation control is the premise for a safe and efficient mission. In this paper, the standard consensus algorithm is improved according to the characteristics of the UAV motion model and the demand of actual flight, and an improved consensus-based formation control algorithm is proposed. First, the 3-DOF kinetic equations of UAVs are established based on the decoupled autopilot model, and the constraints on acceleration, velocity and angular rates are defined considering the maneuverability and flight performance of UAVs. The formation control is also carried out in the horizonal plane and vertical direction respectively. Based on the state control, the DOFs of UAVs are transformed using the geometrical relationship between different states of UAVs, and the formation control algorithm is designed integrating the configuration information. Furthermore, a constraint handling strategy named 'minimum adjustment’ is developed to enable the command signals to meet all the constraints. The collision between UAVs is avoided by optimizing the climbing acceleration of UAVs with the Particle Swarm Optimization (PSO) algorithm. Simulation results demonstrate the ability of the proposed formation control algorithm to form or change the formation. The states and configuration of the UAV formation can quickly converge to the specific values, and the states of UAVs satisfy all the constraints.
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