Research On Motion Modeling And Control Strategy Of An Unmanned Underwater Vehicle

The research object set up the mathematic of this thesis is an UUV like a heavy torpedo and the research aim is to set up the mathematic model of it, The control strategy is researched based on that mathematical model, as preparative theory to control truly UUV.The mathematical model of UUV is established according to the mathematical modeling method of the torpedo, analyze the force acting on UUV and build the mathematical model of UUV. The model is simplified by the theory of small perturbation and divided into three groups.The PID control controller has been widely used, the simulation of motion control of the UUV is implemented base on the PID control strategy. It has been approved that that PID controller can accomplish the control aim of the UUV. PID controller is designed based on simplified model, so the validity still needs to be approved by the experiments in the future. Because the presence of model error of UUV, incertitude of parameters of hydrokinetics and the disturbance of seawater current, the control system should has adapt to incertitude of parameters. Expert PID controller has the advantage of simple and easily to be implemented, but it can adapt the incertitude of parameters, which enhance the system robust.Fuzzy control is a control method that is not based on the mathematical model but based on the experience, it is appropriate to UUV control which work in complex environment. We found that stabilization precision of Fuzzy control is not good and the PID control is good, so we combine Fuzzy control with PID control to use for UUV move 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 PID controller parameter are presented and the accuracy of this method is approved by the simulation results.