Research On Motion Control Of Remotely Operated Vehicle Based On Sliding Mode Control

There is a wealth of mineral resources in the sea,and our country has broad territorial sea area,which has great prospect for mining.The underwater vehicle plays a vital role in the exploration of Marine resources and the maintenance of offshore platforms.The underwater vehicle can be divided into two types: Remotely Operated Vehicle(ROV)and Autonomous Underwater Vehicles(AUV).The AUV is mainly used in surveying and mapping,exploration and other working conditions.While the ROV is more commonly used for underwater fixed-point operations carried a variety of tools,which requires ROV to have a good control accuracy and multiple automatic control functions.In this paper,the motion control technology of ROV is studied and an ROV control system is designed.The main work contents are as follows:Firstly,the research progress in related fields was researched by referring to relevant literatures,and the research direction was determined.Participated in the overall ROV scheme design and scheme selection of all parts in ROV mechanical structure in the project.Designed the ROV control system,including the selection of sensors,main control chips and other hardware,designed the control system program execution process and wrote relevant codes.The establishment of mathematical model is the basis of ROV motion control.In this paper,the kinematics and dynamics of ROV are analyzed,and the kinematics and dynamics models of ROV are established,and the degrees of freedom of the models are decoupled according to the control requirements.The ROV in this paper is equipped with six thrusters.The layout form of the propeller is designed,and the thrusters distribution model of the ROV is established.CFD method is used to solve the fluid damping coefficient in the mathematical model.In this paper,Fluent software was used for ROV fluid simulation,and MATLAB was used for data fitting of simulation results,which was substituted into the mathematical model for the controller design.Next,the motion control algorithm of ROV is studied.In this paper,the sliding mode variable structure control algorithm is applied to the automatic control function of ROV,and the saturation function is introduced to reduce the adverse effects caused by chattering phenomenon.At the same time,the classical PID and fuzzy PID two commonly used control algorithms for comparison,respectively designed three kinds of algorithms of the controller and the use of Simulink simulation analysis,finally compared the control effect.The simulation results show that the performance of sliding mode controller is better than that of classical PID controller and fuzzy PID controller.The program flow of the control system was designed,the implementation process of the sliding mode controller was written into C language code,and the bottom machine driver code was written based on the STM32 main control chip,so as to realize the ROV’s depth and angle stopping functions.Finally,the effectiveness of the control algorithm and the effectiveness of the code are verified by tests and experiments.The test and experiment in this paper is divided into three parts.Firstly,the effectiveness of the algorithm and the driver code is verified on the control board.Then,the semi-physical simulation system based on Unity3 D was used for repeated tests to verify the effect of the control algorithm.After debugging and inspection,ROV body underwater experiment is carried out.The above test results are sorted out and analyzed respectively and a conclusion is drawn.