Research On Multi-UAV Conflict Free Path Planning Algorithm In Low-altitude Airspace

The rapid development of modern science and technology has brought the vigorous development of the UAV industry.It poses a huge challenge to the existing low-altitude airspace pattern.The rational and feasible path planning for UAVs in a certain airspace is one of necessary means to alleviate the tension in low-altitude airspace.It is meaningful to ensure that UAVs plan a free collision,least comprehensive path under low-altitude airspace,and path optimization strategies for multiple UAVs in the face of conflict risks,and improve operational safety in low-altitude airspace and UAV operational efficiency.This article is to carry out the following research on issue:Firstly,the low-altitude airspace where the UAV is located is studied.By analyzing the simplified indicators affecting the complexity of the low-altitude airspace,the improved Voronoi diagram method is used to divide and optimize the low-altitude airspace to form a complex balanced UAV operation management unit.Then the basic mountain threat model and the electromagnetic interference threat model are established according to the external environment constraints.By superimposing them to form the simulation planning space and constructing the mathematical model that satisfies the performance constraints of the UAV.A comprehensive cost function is defined.The fuzzy costing method is used to determine the weight coefficient of the comprehensive cost function,and an example is given to verify the feasibility of this method.Then,an improved B-RRT* algorithm is proposed for the path planning problem of the UAV in dense obstacle environment.By studying the basic flow of the relevant algorithm,and improving it in the way of generating nodes.Combining the performance constraints of the UAV with the random tree node expansion process,the algorithm efficiency is improved by limiting the generation direction of the sampling points to the backward sector and dynamically adjusting the adaptive step size,and the improved B-RRT* algorithm stability and superiority is verified.Finally,considering the multiple UAVs risk conflict in three dimensional space,the method of path optimization based on Gauss pseudospectral method is studied.After the analysis,the UAV path optimization is transformed into the optimal control problem.Then Gauss pseudospectral method is used to discretize it into the nonlinear programming problem at the Gaussian distribution point and solve it,which result is the obtained path.At the same time,it is verified that the two UAVs will have an optimization strategy for online path deployment after adding the protection zone.