Research On Autonomous Cooperative Formation Control For UAVs

In recent years,the UAV formation flights have been extensively studied.Compared to a single UAV flight,formation flights have many advantages,such as more precise positioning,reasonable formation can also increase the endurance of the UAV.In recent years,the theory of multi-agent consistency has developed rapidly.The maintenance of multi-UAV formation is the primary problem of formation control.The collision avoidance of UAV cluster is the primary problem of cluster movement.Therefore,this paper study the formation maintenance of UAV formations based on consistency theory,and also study the collision avoidance of UAV clusters using artificial potential field method.Firstly,studied the multi-UAV formation control algorithm.Firstly,the nonlinear motion equation of UAV is feedback linearized into a double-integration system.The UAV's information interaction mode is modeled as the topology in graph theory.The virtual structure method is used to control the formation,the coordination variable is used as the speed of the UAV and the calculated position between the current position of the UAV and the relative vector of the formation reference point.In the case where there are time-varying delays in both speed and position information and design the formation keeping control algorithm enables the virtual leader to fly on a given flight path,and other UAV can form a given geometric formation according to the consensus protocol and following the virtual leader,finally,given the upper bounds of the allowable time-delays.At the same time,this paper also studied the UAV formation maintenance problem under the unpredictable speed of the leader.Each UAV estimated the speed of the leader through the position information and then achieved the formation flight through the corresponding control algorithm.Finally,the sufficient conditions is given for the stability of the control algorithm.Secondly,studied the collision avoidance of UAV clusters.The repulsion field and the gravitational field are constructed between the UAVs.The repulsion field is constructed between the UAV and the obstacle.The UAV cluster obstacle avoidance control algorithm with collision prediction is designed and proved to be effective in avoiding obstacles and avoiding collision between the UAVs.Compared with the collision-free prediction algorithm,it can effectively reduce the flight distance around the obstacle.Finally,combining artificial potential field method with formation keeping algorithm based on consistency theory.Because although the consensus algorithm has separation effect when two UAV approach each other,the separation speed is slow and the UAV may collide with other UAVs,and the combined control algorithm achieves formation maintenance through a consensus algorithm when the potential energy is zero,and when the distance between the UAV is less than a certain value,the repulsive field makes the two UAV far away,when the distance between UAV is larger than a certain value,the gravitational field makes it close.When the UAV detects an obstacle,the repulsive force field makes the UAV smoothly passes the obstacle.