Research Of Multiple UAVs' Cooperative Control Under Dynamic Environment

In recent years,the technology of unmanned aerial vehicles is a hot issue,both in the area of military and civil use.With more and more diverse combat missions to be carried,the environment of combat has become increasingly complex.Although the UAV technology is also developing rapidly,one single unmanned aerial vehicle which has limited capacity still cannot take all the complex tasks.Therefore,the cooperation of multiple unmanned aerial vehicles has become a hot spot for researchers.The cooperation of path planning for multi-UAVs is the basis and premise of UAV mission,the purpose of which is to plan a feasible flight trajectory from the initial point to the target point for each UAV based on the specific tasks and coordinate the interrelationship between multi-UAVs to achieve the highest overall performance.However,the flight environment is extremely complex in detection and combat environments actually.There will be a variety of sudden situation,in which circumstances it is necessary to pre-plan a path for UAVs not only in the known environment but also to amend or re-plan a real-time path to meet the actually dynamic environment.Based on the research of the existing theory,this paper promotes an idea of extending the configuration space and introducing the synergistic coefficients to solve the coordinative problem of multi-UAVs in dynamic environment.This paper mainly includes the following contents:(1)This thesis researches the basic modeling method of UAV trajectory planning.We analyze the physical performance of UAVs,introduce the problems of path planning,and transform them into the form of mathematical functions.This thesis also analyzes and summarizes different algorithms of path planning for the unmanned aerial vehicle.(2)After the analysis of the UAV flight environment,we decide to adopt and improve the rapid expansion of random tree algorithm which has a lot of good features.The improvement of the selection of random points,the introduction of the trajectory to evaluate the heuristic information,the cutting of the redundant RRT nodes,and the smoothing of the route path make the fast path planning of the single unmanned aerial vehicle to realize.(3)This thesis researches the problem of the single UAV trajectory planning in dynamic environment.Through introducing the time axis,the configuration space is extended to the space of configuration-time(CT)to solve the planning problem under dynamic environment with obstacles of which the motion state is known.(4)This thesis researches the multi-UAVs cooperative control technology.For solving the multi-UAVs time domain collaboration problem,we introduce the "synergy coefficient",analyze the influence of timing and time constraints,and make the overall assessment of the trajectory.For solving the multi-UAVs airspace coordination problem,we change this problem into the path planning problem under the dynamic environment,which in other words,regard the other UAV as a "pseudo-dynamic obstacles." Finally,we successfully design a novel cooperative control algorithm for multi-UAVs under multi-constrains.