Research On Path Planning For USVs

With the development of unmanned surface vehicles,researchers’ focus gradually incline from the path planning of single unmanned surface vehicle to the path planning of multi unmanned surface vehicle formation.The cooperative formation of unmanned surface vehicles has the advantages of wide detection area,improved system autonomy and enhanced faulttolerant capability compared with one single unmanned surface vehicle.Therefore,this paper takes the leader follower formation system of unmanned surface vehicles as the main research object,and studies the formation forming,path planning and obstacle avoidance.In this paper,the USV formation path planning problem is divided into two problems,which are formation initialization and overall path planning.In order to solve the problems of distance control and internal collision in the formation initialization process of USV,this paper proposes a segmented speed strategy and a priority algorithm of USV based on the distance of close points.The segmented speed strategy can be compared with the expected distance according to the current distance between the follower USV and the leader USV,and can reduce or increase the speed of the follower USV to generate the desired formation according to the current distance greater than or less than the expected distance.Aiming at the problem of internal collision,this paper proposes a priority algorithm based on the distance between adjacent points,which gives different priority to the following unmanned ship.The speed of high priority of USV is faster,and the speed of low priority of USV is lower,so as to prevent collision.When the formation is formed,the path planning of USV formation is carried out.In this paper,the fast marching square method is applied to the path planning of USV formation.However,the traditional algorithm will slow down the speed of USV formation or stop the process in the simulation process.In this paper,a path planning algorithm of unmanned aerial vehicle formation based on fast marching square method with uncertainty is proposed.The algorithm focuses on the influence range of velocity map between USV and reduces the redundant calculation process.The experimental results show that compared with the traditional algorithm,the algorithm can make the formation far away from the area with no obstacles and low speed,maintain the stability of the formation,and significantly reduce the calculation time.In this paper,an obstacle avoidance scheme based on formation decision-making is proposed to solve the problem of overall obstacle avoidance of unmanned surface vehicle formation.Considering the two obstacle avoidance methods of isomorphic formation transformation and heterogeneous formation transformation,and the limited number of heterogeneous formations in formation reference database,the cost function of formation transformation is introduced to integrate the formation difference and energy consumption in unmanned surface vehicle formation transformation,and then quantitative analysis is made In the formation reference database,the least cost obstacle avoidance formation is selected to pass through the obstacle area.The experimental results show that the algorithm can select the optimal formation before the formation of unmanned aerial vehicles enters the obstacle area,and can realize the decision-making mechanism.