Structure Analysis And Application Research Of New Fuzzy PID Controllers

Since 1990's, the mathematic expression of the fuzzy controller has received increasing attention, theoretically discussed a series of fundamentaity issue, such as the nature characteristic fuzzy con-troller, and compared with the conventional controller. Analyzing the design parameters of the fuzzy controller influence to them-selves control performance became to the research focuses in the field of fuzzy control.Because the early fuzzy PD and fuzzy PI fuzzy controllers exist the flaws the new PID fuzzy controllers continuously proposed, to unify with the structure analysis and the stability analysis became to a new task of the application research of the fuzzy controller.Although the design method of the fuzzy controller is rather mature and has been obtained a large number of applications in practice, but the tuning methods of fuzzy controller are very small and have disadvantageous.To this situation, this paper has done the following work:1. Analyzed the structure of the conventional PID controller and design a new two-dimensional fuzzy PID controller, namely fuzzy PI+fuzzy ID. Through the structure analysis of the fuzzy PI+ fuzzy ID fuzzy controller, initialization to the relationship between the coefficients KP, KI,KD of the conventional PID controller and that of the fuzzy PI+fuzzy ID fuzzy controller, and this fuzzy PI+ fuzzy ID fuzzy controller essentially to a non-linear PID controller. The fuzzy PID controller with high precision, the process is simple, the calculation is small, and the structure and algorithm are simple and easy realization.The simulation results show that the PID fuzzy controller is of practicality, effectiveness and superiority.2. Designed another a new two-dimensional fuzzy PID con-troller, namely fuzzy PD+fuzzy ID. According to the graphic solution analysis of fuzzy rules, it proposed the control structure of the input variables (error and the rate of change of error) and the output variable of this fuzzy ID controller, and determined the fuzzy control rule of the two controllers is similarity. Through to a detailed structural analysis to the above-mentioned PID fuzzy con-troller, and the formula of the system working range of the con-troller, it can be obtained that this fuzzy controller has similar structure with the conventional PID, and essentially indicated to a non-linear PID controller. The simulation results show that the PID fuzzy controller is of practicality, effectiveness and superiority.3. Conducts the detailed theoretical study to the parameters of the FLC, has defined:(1) the value L for inputs and outputs of the FLC is the absolute value of the reference signal r(kt). (2) The out-put scaling coefficients Gu of the FLC isβtimes of the max of among the parameters KP, KI, KD of the conventional PID controllers. (3) Based on the above two conditions, we established the relationship between the inputs scaling coefficients GP, GI, GD of the FLC and the parameters KP, KI, KD of the conventional PID controllers.4. To deeply research the gain and phase margin method, and give the corresponding theoretical analysis and the simulation con-trast analysis, we can propose a parameters tuning method of the fuzzy controller based on gain and phase margin. The parameter tuning formula of fuzzy PID controller given by has been different to the literatures. The simulation results show that this method can effectively solve to the fuzzy controller parameter tuning.5. The Pulse Number Modulation (PNM) used to heat in micro-wave netting kiln is put forward, and the PNM method is designed to control the heating process of the microwave netting kiln with the characteristic caused by multi-input, multi-output and close coupling. The fuzzy controller is a new two-dimension PID fuzzy controller, namely fuzzy PD+fuzzy ID. The optimum control cycle of the PNM method is determined through the simulation experi-ments, whose results show that the control method is feasible.