Research On Modeling And Simulation Of Motion Control Of An Autonomous Underwater Vehicle

Ocean is a fundamental composing part of life sustaining system and a precious treasure which can fulfill continual development. The design and utilization of underwater vehicle become more and more popular for the purpose of exploring ocean resources. The research in the area of underwater vehicles, especially autonomous underwater vehicle (AUV) becomes a study focus of researchers from many countries and great achievements have been made in this area. The study object of this thesis is an AUV like a fish torpedo and the research aim is to set up the mathematic model of it. The control simulation of AUV is done based on that mathematical model. The academic reference and guidance is presented for the following controller. The mathematical model of AUV is set up from the mathematical modeling method of the torpedo. The model is simplified by the theory of small perturbation and the control model of the depth and yaw angle is gotten. The correction of this model is tested compared with the computational result of the torpedo. Because the PID control methods are widely used recently, the simulation of motion control of the AUV is gotten by the PID control algorithm. It has been approved that that PID controller can accomplish the control task of the object. The optimal control simulation of this object is also discussed in this thesis. Though the satisfied result is gotten from the above two control methods, they are based on simplified model and the validity still needs to be approved by the experiments. Because fuzzy control is a control method that is not based on the mathematical model but based on the experience, it's appropriate to AUV control. Fuzzy control is introduced to the AUV motion control. The complicated logic computation theory is evaded in the process of controller design. The principle of adjusting fuzzy control decision table is gotten by the simple experience. Control decision tables of depth, steering and pitch are presented and the accuracy of this method is approved by the simulation results.It is must be stated that the conclusion of this thesis is just received by Matlab through computer. It still needs to be approved and some parameters of it also need to be modified by the later users.