Application Of The Theory Of Fuzzy Control In Time-Delay System

The time-delay system is a kind of system that is often seen in industrial production. Because of its time-delay action to the output of control value, the control value can't be reflected on the controlled object timely. Therefore, some control properties of the control system become worse in terms of super-regulating value, the steady-state error and stability. Although the experts of control system have made research on it for many years, no effective methods for the control of the time-delay system are found. Therefore, it is commonly acknowledged as a system difficult to control.Fuzzy control is characterized by its method with which, according to the theory of fuzzy sets, control rule can be summarized from man's control experience. As an important and effective method in intelligent control, the fuzzy control explored new path for the research on the methods of controlling the time-delay system.Generally speaking, to select membership function, confirm control rule, carry out fuzzy inference and calculate the data in control table are indispensable so that the fuzzy control theory can be applied to the time-delay system and gain good results. And then, iterative design and modification should be made on the base of proper simulative model. Later, long-term debugging and modification are carried out on the control spot. At last, the structure of the controller is made certain. The preceding process often needs a long-time circle. During the course of developing fuzzy controller, to enhance the developing efficiency, shorten the developing circle, and reduce the repetitive labour in designing, debugging and the application of real-time control, we design a package for developing and simulating fuzzy controller and a real-time package for fuzzy control. The former is based on MATLAB and the latter, coordinating with the former, is based on DOS.MATLAB is a sort of application software for numerical calculation and graph process. It owns not only high capability of calculation, but also special advanced language of its own which is used for the design of application program. What is more important, the fuzzy logic toolboxes contained in MATLAB can be used to design and analyse the fuzzy controller. And the simulating tool (Simulink) can be used to carry out dynamic system simulation. That is why FCDP chooses MATLAB as development tool. It adopts modularized techniques of programming and makes full use of and enriches the toolboxes and functions that MATLAB has possessed. In this way, FCDP meets the demands of the design of fuzzy controller. These demandsare as follows: 1) The fuzzy controller is designed with the method of orienting structure graph. The intuitionistic process of design is convenient to construct different control models and to set and modify parameters; 2) The user can conveniently confirm the input and output of the fuzzy controller, select membership function, modify control rules, accomplish fuzzy inference and defuzzy; 3) The user can carry out dynamic simulation and find quickly the curve and data output by simulation. It makes the analysis on fuzzy controller easily; 4) Fuzzy control table should be created in time so that it can be applied to real-time control.The response of real-time control should be prompt and the control should be stable. According to the two demands, with the structured method of programming, RTFCP is designed in a menu form in C language, which is based on DOS platform. It can conveniently call the fuzzy control table for real-time control, which is generated in FCBP. It is able to type and display control data. The simple cooperation fits in with the control of fixed value time-delay system.In the real-time control system constructed by PC, data pick-up board MS-1214A that has been commercialized is selected to be the circuit for data pick-up and control value output. The anti-interference of the system is important in the design. The adoption of the technique of signal isolation can enhance effectively the anti-interference ability of hardw...