Study Of High Precise Fuzzy Control Strategy And Application

Fuzzy controller is widely used by its merits, such as, simple structure, strong robust, no mathematics model of the controlled object, fast response etc. Whereas, the general fuzzy controller has some shortcoming also, for example, no high precision guaranteed, 'an adjusting dead range' etc. This paper studied the interpolation mechanism of a general fuzzy controller. From this point of view, two schemes were studied and modified to approach the practical response function. Finally, a simulation test, using the high precise fuzzy controller on the turbine regulating system and the continuous casting machinery mould controlled by hydraulic servo system, shows that the new schemes are feasible. The main contents are as follows:1. Point out the essential reason which effects the precise of the two inputs and one output fuzzy controller, through analyzes its interpolation mechanism, i.e. in the meanings of interpolation, the fuzzy set, which is the former of fuzzy inference, is just right the interpolative base function. The response function which gains from interpolating can sufficiency approach the practical response function depend on the distance of the membership's peak points.2. The internal relations between the two inputs and one output fuzzy controller and PD (PI), PID controller are revealed. A fuzzy controller is a piecewise quadratic surface passing the origin in the space, and the whole surface can approximate to a nonlinear regulation law. So the key to improve its precise is how to improve the interpolation precise near 'zero point'. Giving a proof the monotonicity of control rale is equal to the monotonicity of the control function.3. Bring forward a small error area to reduce steady-state error arithmetic and the flexible universe arithmetic. Making use of the principle of ITAE index minimum and evaluating compatibility of the fuzzy control rule optimizes its rales. Providing the value about the small error area is the 1/3~1/5 about the whole universe. The program of arithmetic was designed. The strictness of the contraction-expansion factor of flexible universe arithmetic was proved. Providing the range of exponent ofthe factor e is τ ∈(0.1,0.3).4. The simulating model about the turbine regulating system and the continuous casting machinery mould controlled by hydraulic servo system were built. Makes use of the high precise fuzzy controller, the ordinary fuzzy controller and PID controller to simulate. Adjusts the parameters of the high precise fuzzy controller and proves its perfect character.5. Point out some problems which should be solved in the future and some applications expectation in engineering about the high precise fuzzy control strategy.