Research On Path Planning And Dynamic Obstacles Avoidance For Unmanned Surface Vehicle Based On Electronic Chart

With the continuous advancement of the strategic position of oceans and development of the technology Unmanned Surface Vehicle(USV),achieving autonomous path planning and obstacles avoidance is one of the key technologies of USV.Therefore,planning a global path that is safe,feasible,and good performance,and local path planning for unknown and dynamic obstacles to achieve safety avoidance,are the current research direction of USV path planning.In this paper,Aiming at the problems of the poor real-time performance of global path planning and the weak global search performance of local path planning,a hybrid path planning algorithm for USV is proposed to realize global path pre-planning under known environmental information and to avoid unknown dynamic obstacles in real time.1.Aiming at solving the problems of USV global path planning in complex environment,a global path planning and smoothing method based on Improved Ant Colony Optimization is proposed.The grid method is used to build environment modeling.The path smoothness and the distance heuristic factor are introduced into the heuristic function,in addition,obstacle factor is added into transition probability,which improve the abilities of path optimization and static obstacle avoidance.Combining heuristic factors to improve pheromone update standard and setting adjustment pheromone volatilization factor increase the adaptability of the algorithm.And then the key nodes of the optimal path are extracted and smoothed by B-spline Curve to further guarantee path smoothness and security.2.Aiming at solving the problem that how to circumvent the unknown obstacles while USV is engaged on actual navigation,a local path planning method based on the Improved Artificial Potential Field Method with “International Regulations for Preventing Collisions at Sea” is proposed.According to “Regulations for Preventing Collisions” and the ship hull structure of USV divides encounter scenarios finely.A dynamically regulated ship field and collision hazard function model are built to achieve targeted obstacles avoidance according to the collision hazard values.Segmentally handling the gravitational function to improve the path barrier capability,relative speed and target influencing factors are introduced in the repulsion function to solve problem of target inaccessibility.And the adaptive conditioning potential field under different scenarios is implemented with the introduction of collision hazard values by the potential field function.3.This paper presents a dynamic path sub objective point selection method based on the barrier needs of different scenarios to return to the original planning path after achieving the safe barrier avoidance of unattended ships.The hybrid path algorithm is simulated and under the electronic chart(EC)and multiple unknown dynamic obstacle environments.According to the simulation results,the proposed algorithm is able to plan a smooth global path with high security and comprehensive performance,and return to the original path after safety avoidance for unknown obstacles in the environment,thus effectively realizing the requirement of shipless hybrid path planning.