Three Dimensional Route Planning Of UAV Formation Under Complex Constraints

With the expansion of Unmanned Aerial Vehicle(UAV)application field,UAV research has entered the stage of complex mission execution in formation,and more sophisticated formation route planning and control are needed to adapt to complex application scenarios.When carrying out tasks like aerial refueling,long-distance formation transportation,high-precision positioning,multi-angle imaging,we must consider the formation stability,formation obstacle avoidance,high-speed three-dimensional obstacle avoidance and formation disbanding and reorganization when necessary.This topic has carried on the preliminary exploration to this.After the synchronous anti-jamming controller is designed to solve the stability of formation structure,the route planning algorithms of formation avoiding static obstacles and high-speed obstacles are studied respectively from static planning and dynamic aspects.The main four research contents are as follows:1.Aiming at the problem of UAV maintaining formation priority when individual is disturbed.The synchronous control theory is used to ensure the UAV to fly synchronously so as to keep the formation.The formation controller is designed,and the synchronization error PD control is added to the position and attitude controller,so that when one UAV changes its position and attitude due to disturbance,other UAVs can respond synchronously.Through MATLAB / Simulink simulation,the results show that the controller can quickly return to formation when the UAV is disturbed,and the damage degree of formation is reduced by 59%,which indicates that the synchronization error control is suitable for fixed formation control.2.In the static formation planning,the A-star algorithm is selected for the static path planning of the fixed formation.Firstly,the mature two-dimensional A-star algorithm is extended to three-dimensional.According to the constraints of UAV,the range of A-star algorithm is determined,the number of extended nodes is reduced and the cost function is improved.In particular,in the aspect of aircraft altitude control,according to the requirements of cruise altitude,a hyperbolic altitude cost function is proposed,which enables UAVs to select the optimal flight altitude in the flight altitude region.Simulation results show that the new algorithm can effectively improve the search efficiency and make the planned route meet the constraints and mission requirements of UAV.On this basis,the static planning of UAV formation with fixed formation is studied.The UAV formation is regarded as a whole,and the formation center is taken as the planning node,so that the distance between the extended nodes and the obstacles is larger than the formation radius.3.In the dynamic planning,a new artificial potential field function is specially designed for the high-speed obstacles whose speed is higher than the UAV itself.Firstly,the repulsion field with the influence of target points is used to solve the problem of target unreachable in artificial potential field method.Secondly,in view of the situation that the potential field will have unnecessary influence on the UAV and even fall into the local optimal situation,the collision cone judgment is added.After that,because the existing artificial potential field method can not avoid high-speed obstacles and increase the repulsion force can not be avoided smoothly.The velocity potential field theory is proposed to change the direction of resultant force,that is,the repulsion force which is perpendicular to the velocity of the obstacle and the UAV itself is added to the repulsion field.The improved velocity potential field method is compared with the original potential field method.The results show that the speed potential field method can avoid high-speed obstacles with different speeds faster and better,and only the velocity potential field method can make UAV avoid obstacles with higher speed than itself,which proves the advantages of speed potential field method in high obstacle avoidance.4.In order to solve the problem of disbanding and reorganizing the formation in high speed obstacle avoidance,the obstacle avoidance system is designed,and the collision cone criterion is used to judge whether the formation needs to be disbanded to avoid obstacles.When the UAV does not detect obstacles,the virtual structure method is used to maintain the formation.When encountering dynamic obstacles,the formation is disbanded and the designed velocity potential field method is used.In order to avoid the collision of UAVs in the formation,the internal obstacle avoidance potential field is added.In order to combine formation keeping and dynamic obstacle avoidance,a collision cone judgment controller is designed to judge when to return to formation.The designed controller and route planning method are verified by simulation.In the simulation process,UAV formation can achieve stable formation and high-speed obstacle avoidance,which provides reference for the application of UAV in the environment with complex moving obstacles,and expands the application field of UAV.