The Auto-tuning PID Controller Of Under Water Propeller

Underwater propeller is the important power of AUV. Excellent control over it's speed can not only enhance the efficiency of AUV, but also reduce the energy consume and increase AUV's working time. We often control the DC timing system of propeller by the classical PID controller. PID controller is very simple and has good stability as well as dependability, so it is often used in those linear constant system. But it cann't bring us perfect control effect when it is used in complex nonlinear and time-varying system because PID parameter cann't adjust in real-time.The parameters' adjustment of the PID mainly depends on the human's experience and the object model, the result is normally dissatisfying. Fuzzy control which was outstanding in the field of the intelligent controller has already applied widely in industry production process, Fuzzy control do not need to know accurate mathematic model of object. But it is based on human thinking and producing experience and it applies language rule to describe controlling process and bases rule to modify the controlling arithmetic and parameter. The paper studies the methods of combing fuzzy control and PID control, achieves the best parameter tuning which only use the experience knowledge of manipulator and fuzzy control rule of expert, and use the fuzzy reasoning identifying the characteristic parameter of object on-line, changing control rule in time, needn't the identify the model.On the basis of this, work out a parameters' fuzzy auto-tuning PID controller. The firmware of the product based on the AT89S51 single chip microprocessor. It can accomplish data sampling parameters adjustment, LCD display. etc. The C51 language is used in the product's software designing. By the example of a under-water propeller's controller process simulation prove it have better effect and quality. It also has strong self-adaptation to the complex nonlinear, time-variety object. It can regulate the system in time when the object changes or something interfere the system.