基于改进DWA的多无人水面艇分布式避碰算法

Distributed collision avoidance algorithm for multiple unmanned surface vessels based on improved DWA

针对多艘无人水面艇(USV)相遇自主避碰问题,考虑可能存在异常行驶的USV,基于改进动态窗口法(DWA)提出一种包含碰撞风险检测和行驶职责划分的分布式避碰算法.首先,引入障碍物预测轨迹和权重因子改进传统DWA的距离评价函数,提高USV躲避多个动态障碍物的能力,同时,结合国际海上避碰规则(COLREGS)引入新的规则评价函数约束USV的避让动作;然后,引入期望速度和航向改进现有碰撞风险检测算法,减少因碰撞风险变化导致的轨迹波动;接着,针对COLREGS仅规定两船相遇时的行驶职责划分问题,提出一种考虑异常USV的多USV职责划分方法;最后,基于Matlab实现多USV相遇自主避碰仿真.实验结果表明,即使存在异常USV,分布式避碰算法依旧保证正常USV能够作出符合COLREGS的安全避让动作.

A distributed algorithm is proposed to solve the problem of unmanned surface vessels(USV)avoiding collision with other normal and abnormal USVs based on the improved dynamic window approach(DWA).The algorithm also includes collision risk detection and responsibility division for driving.Firstly,prediction trajectories of obstacles and weighting factors are utilized to improve the distance evaluation function of the traditional DWA,which can avoid multiple dynamic obstacles better.While a novel rule evaluation function considering international regulations for preventing collisions at sea(COLREGS)is introduced to constrain actions of USVs.Secondly,an existing collision risk detection method is modified by adding desired velocity and course to reduce the fluctuation caused by changes of collision risk.Then,we propose a responsibility division method for multiple USVs to handle the problem that COLREGS only specify the method for two ships encounter,which takes abnormal USVs into consideration.Finally,simulations of multiple USVs collision avoidance are realized based on Matlab.The results show that USVs utilizing the distributed collision avoidance algorithm can make safe actions in accordance with COLREGS even if there are abnormal USVs.