Research On Path Planning And Autonomous Collision Avoidance System Of Unmanned Surface Vehicle

Unmanned Surface Vehicle(USV)is a kind of intelligent water platform with autonomous navigation capability.It has the characteristics of small size,high speed,and high degree of flexibility and automation,which is increasingly used in civil and military fields.With the increasing attention of countries to marine resource exploration and maritime rights,USV will assume a more and more important role in the future.Autonomous collision avoidance system is one of the key technologies for smart and safe navigation,which directly determines the level of intelligence of USV.Taking into account the practical navigation environment and the motion characteristics of USV,this paper studies the path planning and collision avoidance technology of the vehicle according to the order of global first and then local.The problem of optimal path planning for USV in the global scope is studied.The potential field generated by FMM is used as the basic model of path planning.On this basis,considering the complexity of the marine environment and the limitations of the vehicle's own kinematics ability,the obstacle safety distance and heading constraints of USV are analyzed and introduced into the potential field model.Then an optimal path planning algorithm for USV is proposed and it's effectiveness is verified by simulation tests.The problem of dynamic obstacle avoidance for USV in the local area is studied.Firstly,according to the distribution of local obstacles and the requirements of the rules for collision avoidance at sea,the collision risk and the type of encounters between USV and obstacles are calculated and analyzed.Then a local collision avoidance strategy based on the velocity window of USV is proposed.The reachable velocity space of USV is discretely sampled to generate a set of predicted trajectories,and an objective function is introduced to evaluate the collision risk and rule consistency of each trajectory,so as to obtain the optimal velocity command for collision avoidance.The effectiveness of the method under single and multiple obstacles situations is validated by simulation tests.Based on the universal USV platform framework,a low-cost small USV collision avoidance system platform is designed.Through the coordinated processing and functional integration of the global path planning algorithm and the local collision avoidance method,an USV autonomous collision avoidance system simulation software is designed with MATLAB/C++ mixed programming language.Based on the designed software,a typical maritime map is selected to carry out the integrated simulation test on USV's collision avoidance,the feasibility and superiority of the collision avoidance algorithms are verified.