Research On Formation Reconfiguration And Formationkeeping Control Algorithm For Three Dimensional Unmanned Aerial Vehicles

It is crucial for the multiple unmanned aerial vehicles(UAVs)formation to achieve formation keeping and formation reconfiguration in the flight course.In this paper,the distributed control idea is utilized to research formation-keeping control,and the optimal control theory is used to make research on formation-shape reconstruction control.Firstly,based on the leader-follower formation flight control mode,this paper presents a kind of elastic distance vector in the three-dimensional space.It describes the distance between two adjacent UAVs as a function related to the flight velocity in the formation,adding a flexible control method for formation control.Based on this,the error control model between the formation leader and followers is established.For the formation keeping,ignoring the information communication delay and assuming the formation topology is stable,this paper designs a distributed feedback optimization controller containing only the position state.In addition,the stability of the system is proved according to Lyapunov function method.For the control algorithm,the flight control simulations of triangular and linear formation are carried out respectively.It verifies the performance of the controller and shows the effectiveness of the elastic distance vector.For each algorithm,a group of comparison simulation is conducted with the fixed non-elastic UAV formation,and the results show that the formation with elastic distance vector has the advantages of low control cost when the UAV formation makes a sudden maneuver.For the formation reconfiguration,the model of UAV kinematic model is facilitated and the corresponding control model with elastic distance error is given.From the angle of reducing the control cost,the problem of formation reconfiguration is transformed into a fuel optimal control problem.Combining with the actual environment and control conditions,the constraints such as the minimum safety distance of formation,the maximum communication distance,the upper and lower limits of formation control input and reconstruction time are considered.The optimal approximation solution to the problem is obtained by discretization of the model using the Legendre Pseudospectral Method(LPM).The simulation results show that the proposed method can make the UAV formation obtain the optimal reconfiguration flight trajectory under a variety of constraints.At the same time,the objective function can be optimized to achieve the purpose of minimum fuel consumption.