Research On Path Planning And Following Control Of USV In Complex Environment

In recent years,unmanned surface vehicle(USV) has become an important equipment for human to explore the ocean.And with the deepening of human's understanding of the ocean,USV related technologies have been continuously developed,and higher autonomy has become the development goal of USV.In the inspection project of offshore wind farm,there are many disadvantages in the traditional manual inspection.Thus it has a very good prospect to use USV to complete the inspection task.In view of the global path planning,local path planning and path following based on path points involved in USV's inspection of offshore wind farms,this thesis mainly studies the following three parts.Specific research contents include:Firstly,the research on global path planning is carried out.After introducing the traditional genetic algorithm and simulated annealing algorithm,the advantages and limitations of the two algorithms are obtained through the analysis of the two algorithms.Then the improved genetic algorithm-simulated annealing algorithm is proposed for its disadvantages.Based on the simulation model of a wind farm,the global path planning simulation experiment of USV is carried out,and the effectiveness and superiority of the improved GA-SA algorithm are verified by the experiment.Secondly,this thesis studies the local path planning based on the artificial potential field method.In view of the shortcomings of traditional methods,this thesis adds velocity field and regression potential field in the gravitational field,acceleration field in the repulsion field,and escape potential field when USV falls into local minimum.The traditional artificial potential field method and the improved artificial potential field method in this thesis are respectively simulated through the simulation platform.The effectiveness and superiority of the improved artificial potential field method proposed in this thesis are illustrated through comparative experiments.Finally,based on global path planning and local path planning,a path following control method based on switching Los guidance law and s-plane controller is proposed,and a heading angle optimization method based on gradient descent method is proposed.In order to verify the effectiveness and feasibility of the proposed path following control method,this thesis developed the "KV-1" USV test platform.The test platform is used for many bow control tests,speed control tests and path following control tests of multiple path points.The experimental results show that the designed path following control method based on path points is stable and reliable,which can complete different types of path following tasks well,and has certain engineering value.