Research And Development On Modeling And Control System Of An Autonomous Underwater Vehicle

As the ocean attracts great attention on resources and environmental issues aswell as scientific and military tasks, numerous worldwide research and developmentactivities have occurred in the area of autonomous underwater vehicles (AUVs) sincethe 1990s. As an important part of the projection of ocean measuring technology fieldof '863'plan-research, the thesis researches on a miniature, modular, preprogrammedAUV, and focuses on modeling and control system. The model of AUV is complexly nonlinear. Based on Newton-Euler's equations,the thesis deals with the derivation of a general six-degree dynamic model for anautonomous underwater vehicle. By using decoupling and method of smallperturbation , the general model is reasonably simplified. The system is separated intolightly interacting subsystems, and four autopilot controllers based on ProportionalIntegrating Differential (PID) techniques are designed for forward speed, steering,pitch and depth control. Results from simulation show robust performance andstability for the autopilot. According to the AUV's constitution, functions and tasks, The distributed andhybrid control architecture is studied in the thesis. Controller Area Net (CAN) is usedin the AUV firstly, and a hybrid and distributed control architecture is developed.Then the execution layer, which is the lowest but most fundamental and key one inthe control system for AUV, is generally planned and designed in detail. The designsinclude hardwares and softwares, as follows navigation control subsystem, executiontask subsystem, communication program, data processing program and executionprogram et al. The programs are based on C and assembly language. Because AUVneeds complete appliance and massive field experiments, a visual C++ program isdeveloped running in personal computer, which is convenient to tests andexperiments of AUV. To validate the modeling and the control system, many experiments have beendone in the laboratory of ocean engineering, and the results from experiments showthat the modeling and designs of control system are quite correct and feasible.