This article addresses a flight-stability problem for the multiple unmanned aerial vehicles cooperative formation flight in the process of the closed and high-speed flight. The main objective is to design a cooperative formation controller with known external factors, and this controller can keep the consensus of attitude and position and reduce the communication delay between any two unmanned aerial vehicles and increase unmanned aerial vehicles formation cruise time under the known external factors. Known external factors are taken into consideration, and longitude maneuvers using nonlinear thrust vectors were employed with unsteady aerodynamic models, according to the attitude and position of unmanned aerial vehicles, which were employed as corresponding input signals for studying the dynamic characteristics of unmanned aerial vehicles formation flight. In addition, the relative distance between any two unmanned aerial vehicles was not allowed to exceed their safe distance so that the controller could perform collision avoidance. An analysis of formation flight distance error shows that it converged to a fixed value that well ensured unmanned aerial vehicles formation flight stability. The experimental results show that the controller can improve the speed of a closed formation effectively and maintain the stability of formation flight, which provides a method for closed formation flight controller design and collision avoidance for any two unmanned aerial vehicles. Meanwhile, the effectiveness of proposed controller is fully proved by semi-physical simulation platform.

Aiming at the flight-instability of the closed-loop system in windy field of three fixed-wing unmanned aerial vehicles (UAVs) formation. In this paper, we design a multi-UAV formation controller to address the flight-stability of multiple UAVs. The problem of flight-stability can be converted to the analysis of dynamic response and steady-state error. The robust control compared with thin membrane control method, it can realize the high speed and close cooperative formation of precision combat. Adding thin membrane is not only capable of reducing the body vibration and steady-state tracking error, but also owns better robustness. The proposed controller can control leader's speed so that follower can track leader in the case of decoupling, while maintaining the consensus of relative speed. The simulation results show that the designed controller integrates the advantages of robust control and thin membrane vibration attenuation. Moreover, this control method can not only improve the response speed, convergence time and stability of the control system, but also realize the aim of the precision cooperative combat ability.

Aiming at the collision between the unmanned aerial vehicles (UAVs) in tracking motion target due to the inconsistency information, we design the unmanned aerial vehicle (UAV) formation cooperative tracking controller and analyze the flight-stability of the designed controller in the case of only knowing the UAV local information. Recently, a Lyapunov guidance vector field approach is proposed to achieve the desired circular trajectory in the paper. The path planning of a single UAV and the Multi-UAVs cooperative formation tracking motion target are simultaneously studied. In the ideal case, a guidance vector field method is proposed for the heading convergence, which has the advantage of analyzing and solving the collision problem between the unmanned aerial vehicles (UAVs). Further, a variable airspeed controller is used to maintain the UAV cooperative formation flight in a circular orbit, and an adaptive estimate is introduced to ensure the flight-stability of a circular orbit in the case of unknown wind and moving targets. In the process of the UAV formation tracking motion targets, we use a variable airspeed controller to achieve the desired angular spacing. In this paper, the designed controller laws are decentralized based on the local information. Meanwhile, the simulation shows that the designed controller has a good the flight-stability in the process of tracking motion target.