Research On Route Planning Technology Of Unmanned Vessel Based On Collision Avoidance Rules

The unmanned surface vehicle(USV)has the advantages of modularization,autonomy and intelligence.By assembling various sensors and actuators,it can efficiently complete complex tasks on water.It has been widely used in marine and military applications,as well as in aquatic environmental monitoring.USV needs to achieve efficient autonomous cruise in highly dynamic and complex unknown waters.Therefore,it is very important to study the path planning technology of real-time obstacle avoidance under different environmental information.In this paper,the topic of "Research on the path planning technology of unmanned vessel based on collision avoidance rules" is mainly studied,including the global path planning of unmanned vessel under static obstacles and the local path planning when it encounters unknown obstacles in the process of motion.The main research contents are as follows:(1)Research on global static path planning based on quadratic a~* algorithm.The common a~* algorithm has many turning points and is not smooth.A method of expanding search area is adopted,so that the angle of a~* algorithm to expand nodes is not only 45 °,so a shorter and more optimized path is planned,but with the increase of expansion nodes,the time cost is doubled.Therefore,based on the idea of vector cosine method,the a~* algorithm is optimized twice.Through the heuristic information search method,on the basis of ensuring a small path,it can also reduce the calculation time of invalid nodes of the path.(2)The decision model of collision avoidance based on collision avoidance rules is established.Although the current USV collision avoidance algorithm can complete collision avoidance to a certain extent,due to the complexity of the actual water environment and the non-human control characteristics of the surface unmanned vessel,it can not enjoy the responsibility of being evaded by other vessels like a manned vessel,so it is difficult to integrate into the actual scene for effective use.Therefore,based on the rules of collision avoidance at sea,this paper defines the scope of three kinds of collision conflicts: overtaking,encounter and crossing of USV,establishes the decision-making model of collision avoidance to determine whether there is a collision risk of USV,and the avoidance actions to be taken,so that the collision avoidance algorithm of USV has higher reliability.(3)Research on local dynamic path planning under rule constraints.Aiming at the dynamic obstacle collision encountered by USV,the optimized artificial potential field algorithm is selected to realize the local path planning.Based on the optimized potential field function,this paper deals with the shortcomings of the previous methods,such as the local minima and the target can not be achieved,and completes three kinds of simulation experiments under the rule constraints.The experimental results show that USV can correctly analyze the meeting situation with the current obstacle ships,and make effective and safe avoidance actions according to the collision avoidance rules,so as to complete the task of local path planning ?(4)Experimental verification of path planning algorithm based on hierarchical idea.Any single algorithm can not completely solve all the problems in the actual path planning,so this paper combines the two path planning methods,integrates their advantages,and carries out the algorithm verification experiment based on the hierarchical planning idea.First,the path nodes are planned by the global path planning algorithm,and then the local path is re planned.The experiment shows that when the CRI of USV is more than 0.4,it reaches the threshold of collision risk and begins to implement obstacle avoidance action.When the CRI is less than 0.4,it starts to resume after the threat is removed.Experiments show that the decision-making model based on collision avoidance rules in this paper can correctly analyze all kinds of encounter situations and avoid obstacles in time and effectively,ensuring the USV to navigate safely and reliably in complex situations.