Research On Dynamic Modeling And Thrust Control For Mini-type AUV

As the cradle of life, ocean is not only endowed with precious water, but also flowswith plenty of mineral resources. It is the important material guarantee to enhance thedevelopment and utilization of ocean resources for the realization of the sustainablenational economic development. The technology of underwater vehicles has been the mostprinciple means in the exploration of ocean and one of the hot topics in the research areasof many countries. A new kind of underwater vehicles, mini-type autonomous underwatervehicle (AUV), has the virtues of extensive scope of activity, good maneuverability, strongsecurity, intelligence, etc. With the deepening of the development, AUV has been one ofthe important tools to accomplish the underwater tasks for its advantages.This thesis takes the small torpedo AUV as our research subject, and gives twocoordinate systems and the transformation matrix for the motion of AUV. Then thehorizontal and rotating equations of AUV are drawn from the analysis of the two types ofmotions. After that is the discussion of the hydrodynamic coefficients concerned whichhelps to get the six-degree-of-freedom (6DOF) equation of motion and the6DOF dynamicequations of motion taking the own characteristics of small AUV into consideration. Atlast, the system model of thrusters and mathematical model of the brushless DC motor aregiven out when the thruster is selected.On the basis of the dynamic model for small AUV and the model of numericalsimulation established according to the S-function model from Matlab/Simulink, thesimulation running is carried out. The relation between thrust and motion is studied fromtheoretical mechanics perspective to analyze the effect the thrust put on the motion. Thisthesis also establishes the CFX hydrodynamic model for AUV, discusses the influencefrom thrusters on hydrodynamic property, and verifies the dynamic model through thecomparison with the numeric simulation model. Besides, in this thesis the velocity control method of the brushless DC motor and the simulation model for the brushless DC motorand thruster are presented by the principle of motor control and the mathematical modelfor thruster to give the response curve of the motor rotating speed and moment.The control performance of the underwater vehicle thruster has a great effect on thesailing of the vehicle and the security of AUV. Traditional thrust control methods usuallyrelies on the measured thrust system model, which has many limitations and is frequentlyunable to get satisfying effect on thrust control. The immune feedback is a new controlmethod imitating the immune system to kill antigen without effect from the inaccuracy ofthrust system model. And it has a strong real time property and robust performance. Twokinds of thruster control system will be designed and established on the foundation of thephysical model for small AUV and thruster system model to effectively control the thrust.Matlab/Simulink and LabVIEW are used to set up the real-time control system ofthrust to discuss each parameter on the control effect, which helps to study theeffectiveness of the immune controller for the thrust control. It is found that the thrustcontrol effect of the immune controller is much better than that of the simplified thrustmodel controller under the same thrust instruction. The study of the environment effect onthe immune controller is carried out to see how it works applied to AUV. Compared withthe simplified model controller,the immune feedback method can control the thrust verywell,which shows that the immune control methods can be used to the thrust control andhave great significance to the maneuverability and the adaptive control.