Research On Global Path Planning And Following Control Method For Unmanned Surface Vehicles

Unmanned Surface Vehicles(USV),as a small,intelligent and multiple operation platform,are gradually widely used in the exploration and development of marine resources and marine safety.Because of its broad application prospects in the civil and military fields,USV has become a research hotspot of experts all over the world.For this reason,this paper studies the global path planning algorithm and path following control algorithm of unmanned surface vehicle.The specific contents are as follows:1.A global path planning scheme of unmanned surface vehicle based on improved ant colony algorithm is proposed.Firstly,in order to avoid falling into local optimal solution or no solution when the ant colony algorithm searches the path,an improved heuristic information strategy is proposed to change the average path length;secondly,in order to prevent the ant colony algorithm from converging to the global path solution prematurely and expand the global solution space,an adaptive adjustment strategy for information volatilization is proposed,which uses local pheromones to update and global information in the later stage of the search;Finally,in order to ensure the safety of the navigation of the unmanned surface vehicle on the sea,an improved state transition probability strategy is designed based on the yaw angle deviation factor of the unmanned surface vehicle,which makes the optimal global path smooth,and the effectiveness of the algorithm is verified by simulation experiments.2.Considering the uncertain interference of complex wind and wave environment at sea,an adaptive path following control method based on disturbance observer compensation is proposed to follow the global optimal path obtained in this paper.In order to compensate for the influence of environmental disturbances such as currents on the drift angle From the perspective of kinematics,an improved ILOS guidance algorithm based on flow disturbance observer compensation and obstacle Lyapunov function(BLF)is proposed.Firstly,the position error of the unmanned surface vehicle is transformed into the position error in the Serret-Frenet(SF)coordinate system,then the longitudinal guidance law,the directional guidance law and the virtual target motion guidance law are respectively designed to calm the position error of unmanned surface vehicle and calculate the expected angle.Finally,for the control disturbance caused by uncertain environment such as wind and waves,the second-order disturbance observer is designed to estimate the environmental disturbance under the known upper bound,combined with the backstep method and the sliding mode variable structure.The adaptive strategy enables the following of the longitudinal speed anddirection of the unmanned surface vehicle.The closed-loop system is finally uniformly bounded by Lyapunov stability theorem.It is proved theoretically that the unmanned surface vehicle can follow the expected path,and the effectiveness of the algorithm is verified by simulation experiments.3.Considering the nonlinear model uncertainty disturbance and the unknown upper bound of the marine environment disturbance,a fuzzy observer is designed to estimate the model uncertainty parameters,and a robust adaptive path following control method based on fuzzy observer compensation is proposed.The fuzzy observer system is used to observe and linearly approximate the uncertain nonlinear term of the unmanned surface vehicle and the environmental disturbance of the unknown upper bound,then compensate it in the controller.Finally,the Lyapunov stability theorem is used to prove The robust adaptive path following control system under the fuzzy observer is finally consistent and bounded,and the effectiveness and versatility of the algorithm are verified by simulation case analysis under different conditions.