Study On Tracking Of Small USV Based On Model-free Adaptive Control

As a member of unmanned systems,in the field of military and civilian USV(Unmanned Surface Vehicle)gradually show its prospect of application and value.It has ability of marine exploration,environmental monitoring,target surveying,communication relay and other uses.Therefore the development of USV technology has attracted more and more attention and more research scholars have devoted to USV research work in.Tracking control technology is a foundation to USV autonomous navigation and the effect of tracking control directly determines the quality of USV complete the task.So USV tracking technology is the key research direction of the USV and has high research significance.In this paper,the "Dolphin No.1" micro USV is taken as the research object.The motion characteristics of USV are analyzed from the point of view of kinematics and dynamics,and the mathematical model of the three degree of freedom maneuverability of the USV is obtained.As the brief introduction of Model Free Adaptive Control method(MFAC),the USV heading and speed control subsystem is designed based on MFAC algorithm and the speed subsystem satisfies the hypothesis of the control algorithm,however,the heading subsystem is not satisfied.According to the characteristics of the USV course subsystem this paper proposes an improved MFAC algorithm,and proves the stability and convergence of the algorithm.Meanwhile,the simulation experiment is carried out to prove the improved MFAC controller in the subsystem of the heading and speed,compared with the PID controller.For the problem caused by the micro USV uses low cost sensors causing the low precision and high noise information of heading.Therefore proposing an improved unscented Kalman filter applied to the heading control subsystem,the simulation experiment results verify the validity of the method.In this paper,the research of the tracking control method of USV is studied from two aspects: path following and trajectory tracking.In the condition of environmental disturbances and model perturbation,for the path tracking control problem,the Lookahead-based steering method and improved MFAC algorithm are designed to a path following controller based on the following error is introduced into the heading control subsystem,through the USV heading control to achieve the convergence of the tracking error,thereby eliminating the influence of flow interference.For the trajectory tracking control problem,the pure pursuit guidance and the improved MFAC algorithm are designed to the USV trajectory tracking controller based on the tracking error is introduced into the speed control subsystem,through the speed control subsystem eliminate the tracking error.The simulation experiment results show the effectiveness of the tracking method,compared with the PID tracking controller.The "Dolphin No.1" micro USV has been built,and the river and tank experiments are carried out to verify the feasibility and effectiveness of the above tracking method and compared with the PID method.