Research And Simulation Of Unmanned Surface Vehicle Trajectory Tracking Control

In order to compete for maritime resources,each country pays more and more attention to Marine development and shipping industry.Unmanned Surface Vehicle(USV),as an unmanned surface platform,can undertake long-term,large-scale and low-cost Marine scientific research and engineering tasks in the ocean.Therefore,it is widely applied in military and civil fields,and has become the research field of all countries.For some special operations,such as maritime reconnaissance and patrol,more accurate trajectory tracking control of unmanned surface vehicle is needed.Therefore,it is really important to study the tracking control of unmanned surface vehicle in theory and practice.Unlike air and ground vehicles,unmanned surface vehicles are subject to large disturbances in six degrees of freedom due to the influence of waves,currents and local winds.Therefore,in order to ensure that the unmanned surface vehicle can still perform tasks such as reconnaissance and patrol accurately in the complex marine disturbance environment,it is necessary to design a track control system for the unmanned boat,so as to ensure that the unmanned surface vehicle will not produce too much error with the preset track in the actual navigation process.In order to solve the tracking control problem of unmanned surface vehicle under the condition of model uncertainty and external interference,this paper mainly completed the following research work:Firstly,the six-degree-of-freedom motion analysis of the unmanned surface vehicle is carried out.The mathematical model of the unmanned surface vehicle in the three-degree-of-freedom is established by reasonable simplification,and the direct navigation and rotary performance of the model are verified by the steady-state linear trajectory tracking and circular trajectory tracking experiments,which explains the correctness and effectiveness of the unmanned surface vehicle’s model and provides the basis for the design of subsequent controllers.In order to simulate the trajectory tracking of unmanned surface vehicle under the conditions of ocean disturbance,the disturbance torque models of wind,wave and current were analyzed respectively,and the ocean disturbance environment module was constructed.Then it is applied to the mathematical model of the motion of the three-degree-of-freedom unmanned surface vehicle established above,and the simulation control experiment is conducted to obtain the direct navigation and rotary performance of the unmanned surface vehicle when it is disturbed by wind,wave and current alone.In this paper,a tracking precision index suitable for the mathematical model of the unmanned surface vehicle is proposed by referring to the previous literature.Firstly,a conventional PID trajectory tracking controller is designed to make the tracking simulation experiment of polygonal line trajectory and circular trajectory respectively under the circumstance of disturbance of marine environment.According to the simulation results,the conventional PID controller can achieve a certain degree of track control effect,but the tracking accuracy is not ideal enough.Therefore,considering the design of a track controller based on sliding mode control,through the comparative simulation experiment under the same conditions,the tracking error is significantly reduced and meets the set tracking accuracy index,which proves the superiority of its performance.Finally,the visual simulation of the unmanned surface vehicle trajectory tracking control is carried out to realize the visualization in the track control process,which is beneficial to the system designers to conduct online analysis and decision-making on the intelligent motion control and track planning of the unmanned surface vehicle.