Research On Distributed Cooperative Formation Flight Control Technology For Multi-UAV

The UAV has been widely used in the recent war,the using of UAV has expanded the traditional sense of the concept of war mode,it is not only to reduce the cost of war,but also to protect the safety of personnel.The UAV formation technology is proposed and developed based on this advantage,and the technology will enable the UAV to complete the reconnaissance,combat missions,it will not be ignored in the future war.However,with the rapid development and wide employment of the network technology,cooperative manner in networks may improve the operational efficiency greatly.There are also some significant challenges for distributed control and decision problems,such as the influence of the constraints conditions,i.e.,network delays,time-varying network topologies and uncertain disturbances.It is not only the original impetus to cooperative control and decision of muiti-UAV,but also it is an important manifestation of enhancing the autonomy of the UAV.In addition,it has an important practical significance for the UAV system to track a specified tracking under the expect formation structure in finite time,and ensure real-time obstacle avoidance and formation between individuals of collision avoidance control during the flight.The formation control technology of UAV is studied based on the consensus theory in this paper.The main research contents of this paper and the research results are as follows:Firstly,the communication topology of multi-vehicle system is described by the theory of algebraic graph theory,based on the model of multi-vehicle system with simple dynamics.Analysising the type of communication delay in the system,summed it up and classified into the UAV information update delay and information exchange time delay between UAVs.In order to deal with the problem simple,the two classes of delay are normalized to symmetric,with the same changing.The distributed formation control protocol is designed by considering the two types of communication delay,and the system model is analyzed by introducing the concept of the planar formation center.The multi-vehicle communication topology may change due to the interference or the failure through the analysis of practical application,and describing the communication topology between vehicles in switching structure.Under this concept,the researching of complex multi-vehicle systems is turned into analysising for the connectivity of the topology structure in each switching topology,and it is greatly reduces the difficulty of analysising and calculation complexity of the system.At the same time,we analysis the system stability based on Lyapunov theory by constructing a Lyapunov candidate function in each subset of switching.We find the sufficient conditions for the stability of multi-vehicle systems by solving a linear matrix inequality(LMI).By selecting the parameters of the controller,the upper limit of the time delay of the multivehicle system is obtained under the premise of ensuring the stability of the system.Numerical simulation and results verify the correctness of the theoretical analysis and the feasibility of formation control.Secondly,analysising the characteristics of the two kinds of time delay for multi-UAV system of three-dimensional particle dynamic model.In order to be much closer to the actual variation of time delay,processing the two classes of delay for different and nonuniform,i.e.,time-varying.The distributed formation control protocol is designed based on the consensus theory with the consideration of such nonuniform communication delay,the system model is transformed for facilitates analysising by introducing the concept of space formation center.The stability of the system is analyzed based on Lyapunov theory under the jointly communication topology structure,and the sufficient conditions for the stability of the multi UAV system are got by solving the linear matrix inequality.The formation keeping performance of the multi-UAV formation flight control system is verified through simulating of the actual formation flight task,the formation restructuring and the formation keeping of the whole system is well when the individual UAV leaves from the formation.Then,we focus on the finite time tracking and formation control problem of the multiUAV system based on three-dimensional particle dynamic model under jointly-connected communication topology structure of the whole system.A nonlinear finite-time tracking and formation control protocol is designed from a given concept of finite-time tracking with the formation,the finite-time convergence of the system is analyzed based on Lyapunov theory,and the formation controllability in a finite-time period of multi-UAV system is got.The control parameters which make the multi-UAV system converge quickly is found by analyzing the stability of the system.The feasibility of finite time tracking and formation control of the whole system is proved,the formation keeping ability and dealing with fault formation reconfiguration capability effectively of the multi-UAV system are verified through the close to actual environment of numerical analysis.Finally,the obstacle avoidance and collision avoidance formation flight control of multi UAV system are studied based on the theory of artificial potential field.The collision avoidance control principle of the classical artificial potential field is analyzed,and the repulsive force field function is improved,the potential field method is extended to threedimensional space as well.The dynamic constraints of the multi-UAV system is introduced,the state feedback between UAVs are adopted to maintain the entire formation structure,and the variable weight control method is used to realize obstacle avoidance and collision avoidance control research of the multi-UAV formation flight system.Finally,through the numerical analysis of the obstacle avoidance control of static and dynamic obstacles,the feasibility and theoretical analysis of the proposed formation obstacle avoidance and collision avoidance method are verified.In summary,some reasonable schemes and approaches are proposed to deal with the control problem for multi-UAV formation flight,which provide theoretical support for the development and application of multi-UAV formation flight control in this paper,and it has a strong engineering and practical value.