Research On Path Following Control System Of Underactuated USV Based On Velocity Change LOS

Unmanned Surface Vehicle(USV)play an important role in the development of the maritime economy as an unmanned intelligent device and are increasingly used in military and civilian applications due to their high autonomy,mobility and stability.Among the various key technology areas concerning USV,the motion control system,which determines the safety and stability of USV,is currently a research topic of great interest.In this thesis,an USV platform for hydroacoustic communication and path-following control experiments is built with a culverted twin-propeller propelled USV,and the path-following control problem of a single USV is also investigated.The main work of the thesis is as follows.Firstly,this thesis introduces the basic components of the USV system and analyses the motion control system of the USV in detail,giving the horizontal three-degree-of-freedom motion model of a traditional bow-rocking USV.In the guidance law aspect,the Line-of-sight(LOS)guidance principle is analysed,and in the controller aspect,the traditional Proportional Integral Derivative(PID)control principle and the Fuzzy PID Control(FPIDC)principle are analysed.Secondly,this thesis investigates the hardware construction and software design development of the Raspberry Pi-based USV platform.In terms of hardware construction,the USV is equipped with multiplexed communication devices,sensor devices,fixed winches,shipboard communication machines and other devices.In terms of software design,the serverside software is designed to support multi-way communication and control from the upper computer,remote control and the web side of the hydroacoustic laboratory;the upper computer software integrates the control and monitoring function,which can obtain the position and attitude information and real-time camera screen uploaded by the server side,and issue commands to control the USV.In the actual test,the hardware and software work stably and can complete the experimental tasks of path following and lifting the transducer at specified depth well.Finally,this thesis investigates the path following control method of underactuated USV based on Velocity Change LOS(VCLOS)and FPIDC.On the one hand,linear interpolation or cubic spline interpolation is performed for a limited number of input path points,and the first virtual waypoint is set to strictly track the starting point of the path.On the other hand,the design of the speed reduction belt for the path bending angle reduces the speed smoothly to improve the tracking performance of the USV.Guidance law and speed control law are designed to complete kinematics control,and dual-channel FPIDC controller is designed to complete dynamics control.Simulation and real ship test results show that the proposed VCLOS-FPIDC control method has better tracking performance than the traditional LOS-PID control method on a variety of paths,and the method is able to cope with a variety of tasks such as closed linear tracking and closed curve tracking with good results,which has practical significance.