Research On Measurement And Control Technology For Automatic Berthing Of Azimuth Thruster Unmanned Surface Vehicles

In recent years,Marine engineering equipment has been developing towards the direction of intelligence and self-determination,and the unmanned surface vehicles has rapidly become the research focus at home and abroad due to its superior self-determination and flexibility.As one of the crucial functions of the unmanned surface vehicles,automatic berthing requires a highly flexibility of the unmanned surface vehicles.The conventional rudder and thruster system is difficult to work very well.The azimuth thrusters has the ability of 360 degree azimuth rotation,coupled with lateral thruster,can significantly improve the maneuverability of the unmanned surface vehicles,which can better meet to the requirements of automatic berthing in complex environment,so it is of great significance to study the automatic berthing measurement and control technology of azimuth thruster unmanned surface vehicles.With the title of "Research on Measurement and Control Technology for Automatic Berthing of Azimuth Thruster Unmanned Surface Vehicles",this paper analyzes the kinematics,dynamic and automatic berthing characteristics of Azimuth Thruster Unmanned Surface Vehicles,establishes a mathematical model for automatic berthing of Azimuth Thruster Unmanned Surface Vehicles,studies the methods of path tracking guidance,local path planning and course control in the process of automatic berthing,designs the hardware and software of the automatic berthing measurement and control system of the Unmanned Surface Vehicles,and verifies the feasibility of the automatic berthing method and the effectiveness of the automatic berthing measurement,and control system of the unmanned surface vehicles through simulation experiments and real boat experiments.It has high academic value and engineering application value.The main contents of the paper are as follows:(1)Based on the kinematic and dynamic characteristics of azimuth thruster unmanned surface vehicles,the mathematical model of the plane motion of azimuth thruster unmanned surface vehicles is established,the propulsion structure based on the linkage control of the azimuth thruster and the bow thruster is analyzed,and the thrust model of azimuth thruster unmanned surface vehicles is established.Finally,according to the characteristics of theautonomous berthing of unmanned surface vehicles,the interference force model of the berthing environment of the unmanned surface vehicles is established,and the mathematical model of azimuth thruster unmanned surface vehicles is established.The model is modified in low speed domain and shallow water area,and the mathematical model of automatic berthing of the unmanned surface vehicles is established,which provides support for the follow-up control method research and simulation verification.(2)Based on the determined berthing path,the process of automatic berthing of unmanned surface vehicles is divided into three parts: path tracking guidance,local path planning and heading control.Analyzes the influence of forward distance on LOS method,introduces the fuzzy control theory,and proposes a tracking method for automatic berthing path of unmanned surface vehicles based on Fuzzy-LOS.At the same time,aiming at the obstacle avoidance problem when automatic berthing,VFH+ algorithm is adopted to design the local path planning algorithm for automatic berthing of unmanned surface vehicles.Finally,the automatic berthing control of unmanned surface vehicles with obstacle avoidance function is realized by combining the algorithm of unmanned surface vehicles heading control based on double closed-loop cascade PID.(3)Based on the demand of automatic berthing control of unmanned surface vehicles,design the overall framework of measurement and control system of unmanned surface vehicles automatic berthing,which is divided into main control,sensor acquisition processing system,propulsion system,communication system and power supply system,and select and design the hardware of each subsystem.At the same time,the system software is divided into data acquisition module,independent berthing path tracking guidance module,automatic berthing local path planning module,automatic boat course control module and communication module according to different functions,and design the parameters of each software module and data protocol,and achieve the automatic berthing measurement and control system of unmanned surface vehicles.(4)Conduct simulation experiment of automatic berthing base on the mathematical model of azimuth thruster unmanned surface vehicles.By comparing the control effect of double closed-loop cascade PID algorithm and traditional single-loop PID algorithm in the heading control of unmanned surface vehicles,the superiority of the double closed-loopcascade PID algorithm is verified.And verified the feasibility of autonomous berthing path tracking guidance algorithm base on Fuzzy-Los and autonomous berthing local path planning algorithm base on VFH+ by the simulation experiment of automatic berthing of unmanned surface vehicles in the environment with or without obstacles.Finally,configure the parameters of the course controller of unmanned surface vehicles by real boat experiment,and verify the effectiveness and safety of the automatic berthing measurement and control system of unmanned surface vehicles.