| In the past several decades,unmanned aerial vehicles(UAVs)have been broadly applied in the military,manufacture and our daily life.With the great development of economy,single UAV operations can no longer meet people’s urgent demand of improving operational efficiency and high production quality.Therefore,the multi-UAV formation collaborative control technology is put forward to solve this problem.The consistency theory uses a distributed framework for information exchange,and it has less computational complexity,so it is widely used in the field of UAVs formation coordination.In this dissertation,a quad-rotor UAV is regarded as a research model for designing algorithms.According to the high-order consistency theory and the improved artificial potential field method,a collaborative control algorithm for optimizing multiUAV formation and a collaborative obstacle avoidance algorithm applied for multi-UAV formation were designed.The main research contents of this article are as follows:Firstly,this dissertation gives brief summary relating to the graph theory and matrix knowledge to make preparations for exploring under which conditions the consistency theory can reach to stability criterion,introduces the two related coordinate systems of the multi-UAV and their conversion relationship,and establishes the mathematical model and the three-dimensional model of the UAVs.Secondly,this dissertation designs the control algorithm of multi-UAV formation cooperative.Based on the feedback linearization method,the non-linear model of the quad-rotor UAV is simplified into four linearized differential equations.Then based on the four linearized sub-equations,combined with the high-order consistency theory of the linear system,a formation cooperative control protocol is designed for the quad-rotor UAV.The cooperative control protocol uses Lyapunov equation and orthogonal linear transformation method to prove the stability of the control protocol under variable topology and asymmetric time delay.At the meantime,the cooperative control protocol’s stability criterion is obtained.Through simulation in the Matlab/Simulink,it is proved that the system controlled by the high-order consistency protocol can gradually reach consistency.Then,the collaborative obstacle avoidance algorithm applied for formation UAVs is put forward.It is proved that this algorithm can be expanded to three-dimensional space.The proposed algorithm can make up disadvantages existing in the traditional artificial potential field method.By simulating in Matlab/Simulink,the effectiveness of our improved algorithm is validated.Based on the UAV inter-aircraft obstacle avoidance algorithm,the improved artificial potential field method is combined with the secondorder consistency control protocol,and the collaborative obstacle avoidance algorithm for the formation of UAVs in space is designed.Through the comparison of experiments in Matlab/Simulink,the superiority of formation UAVs in using this algorithm to perform cooperative obstacle avoidance tasks is proved.Finally,this dissertation realizes the visual simulation verification of multi-UAV formation based on the FlightGear.In the Matlab/Simulink,a mathematical model used for controlling the quad-rotor UAV is designed,and then a high-order consistency formation control algorithm is implemented based on this model.The flight data calculated in Matlab/Simulink is packaged to the FlightGear display terminal,and data communication between drones is realized through the FlightGear multi-UAV formation server in the Ubuntu system,thereby the three-dimensional visual simulation verification of the multi-aircraft formation is implemented. |
