The Design And Implementation Of Autopilot System For USV

Ummanned Surface Vehicle is a kind of intelligent surface vehicle which does not depend on personnel control,gathering the functions of autonomous navigation,real-time environment sensing,data monitoring and so on in it,and has extremely wide application in military and civilian applications.The autopilot system of the USV is the key to achieve the unmanned operations and perform related tasks.The path planning and path following problem in the process of unmanned ship movement and the design and implementation of the USV autopilot system are focused on in this thesis,in which the USV autopilot system with automatic driving capability is designed.First of all,in order to study the USV’s control problem in depth,the plane 3-DOF mathematical model of the USV is first established in this thesis.This model is the basis for the unmanned ship’s motion control and the validity of the model was verified by simulation experiments.Secondly,by describing the obstacle avoidance process when the unmanned ship enters and exits the port,the path planning problem of the USV is introduced.The defects of the traditional artificial potential field method such as the target inaccessibility problem and the local minimum problem are solved by improving the traditional artificial potential field method algorithm,and the effectiveness of the improved algorithm was verified by simulation.For the path following control of the USV,the Serret-Frenet coordinate system is introduced in this thesis to describe the unmanned ship’s path tracking problem.For pathfollowing problems under the waypoint constraints,a path following control based on PID cross-tracking error compensation is proposed,which converts the cross-tracking error during path following into compensation angle to compensate the desired angle during tracking control;Based on the stright line path following problem,a first-order Nomoto model is proposed to convert the unmanned ship’s path tracking problem into a linear equation of state,and a model predictive controller is designed to follow the desired path.In order to solve the general path following problem,the USV’s path following problem is converted into a virtual velocity and angle control law under a complete unmanned ship’s plane motion mathematical model,and a sliding mode controller is designed.The validity of the algorithm is verified by the experimental results.Finally,an autopilot system of the USV is designed in this thesis.At the same time,based on the functional requirements of unmanned ships,the hardware and software of the various subsystems of the unmanned ship autopilot system were implemented.Eventually,the system operation effect of the USV autopilot system is verified by field experiments.The experimental results show that the USV autopilot system designed in this thesis has strong feasibility.