Heading Control Of USV At Sea Based On Improved Active Disturbance Rejection Control

Unmanned surface vessel(USV)is a surface vehicle that can achieve autonomous control due to its small size,high maneuverability,strong concealment and long endurance.It plays an important role in the exploration of marine resources.However,when unmanned surface vessel encounter disturbances such as wind,wind and current,the uncertainty of the system will increase,which reduces the accuracy of unmanned surface vessel' course maintenance.In order to improve the accuracy of unmanned surface vessel heading the control,this paper combined with the Active Disturbance Rejection Control(ADRC)technologies for unmanned surface vessel heading control for research.The main research contents of this paper are as follows:(1)On the basis of understanding the composition of unmanned surface vessel course control system.Based on the momentum theorem,a three degree of freedom(dof)mathematical model of forward,lateral drift and bow motion of unmanned surface vessel is established.In order to analyze the motion of unmanned surface vessel more accurately,the corresponding servo model of the steering gear was established.Considering that the unmanned surface vessel would encounter the disturbance of wind,wave and current,the mathematical model of the disturbance of wind,wave and current was established.The PID control principle is analyzed,and the unmanned surface vessel's course control system based on PID control is designed.The established simulation model is analyzed under the condition of no environmental disturbance and no environmental disturbance,namely wind and wave current disturbance,respectively.The simulation platform used is Matlab/Simulink.(2)When the unmanned surface vessel's course control system based on PID control faces the disturbance of wind,wind and flow,the system's robustness cannot meet the actual requirements.Aiming at the limitations of PID control in the face of the disturbance of wind,wind and flow environment,the ADRC is introduced into the unmanned surface vessel's course control system.The simulation experiment of the course controller based on ADRC is carried out without and with environmental disturbance.Too many parameters are in accordance with the need of the ADRC setting and setting is difficult problem,since the ADRC linearization,using Linear Active Disturbance Rejection Control(LADRC)to replace the ADRC,LADRC compared the ADRC since the ADRC greatly reduces the need to the number of controller parameters in the setting.The simulation results show that it is feasible to introduce LADRC into the course control system,but at the expense of some system qualities.(3)In order to further optimize the direction control system of unmanned surface vessel,the Firefly Algorithm(FA)was combined with the ADRC.In order to solve the problem that the ADRC needs to set too many parameters without sacrificing the performance of the system as a prerequisite,some modules of the ADRC were proposed for parameter optimization.The simulation experiments of the course control system are carried out under the condition of no interference and interference.The output course and rudder angle curves of unmanned surface vessel under different experimental conditions are analyzed.The experimental results of the improved ADRC are compared and analyzed with those of the previous experiments.The results show that the improved ADRC has a strong robustness to the disturbance of wind and wave flow environment.At the same time,it also shows that the application of FA in parameter optimization is effective and efficient,and the feasibility of the combination of FA and ADRC is fully verified.Based on the improved since the ADRC algorithm of unmanned surface vessel course control system dynamic performance and static performance is good,the response speed,small amount of overshoot and fewer steering needed,system adaptability is strong,after parameter optimization of the ADRC has a certain degree of practicality,clear overall system architecture,design difficulty is not great.