The Study On Fuzzy Control Technique And Its Application For CC&AC Control Systems

Intelligent control is in the high class stage of the development of automatic control. It is the production crossed and integrated with control theory, system theory, information and artificial intelligence and other various subjects, for controlling those complicated systems that can't be controlled well using traditional methods, and provides effective theories and methods. Fuzzy control is the important constitute part of intelligence control. Fuzzy control is based on the knowledge of fuzzy mathematics, knownledge means of fuzzy language form and rules reasoning of fuzzy logic. Its constitute core is the intelligent fuzzy controller.The CC&AC systems are very huge; the respond speed is slow; the hysteresis is more serious. Most of the current CC&AC systems are still adopted the traditional control technique, PID control. The adaptability of PID control is not perfect with the work condition and environment changed. The control effect of PID is not good for the target with a big hysteresis. So it causes a lot of bad effects, such as: the extent of the processs variable is greatly beyond the setpoint; the time of adjustment is too long; the energy saving is not ideal. Therefore the fuzzy control technique is applied nto the CC&AC systems. It has important academic value and actual engineering application value, for improving the performance of CC&AC systems, energy saving, and pushing the application development of intelligent control technique.It is carried out based on the CC&AC system of Xi'an Jiaotong University Laboratorial Animal Center.The general sitiation of intelligent control and fuzzy control is introduced. The CC&AC system and its automatic control system are briefly told. Control program and human-machine interface are designed based on PLC. The application of fuzzy control theory is researched in the CC&AC temperature control system. First, the system structure of the fuzzy logic controller is designed, including the choice and regulating of the input and output variables. Second, according to the control target of the real AC system, considering about the knowledge and experiences of the experts, the control rules base is set up. Next, the fuzzy reasoning is done. Finally defuzzies and establishes the fuzzy control table. The algorithm of Fuzzy-PID control is also devised.The mathematic model for the CC&AC system of Xi'an Jiaotong University Laboratorial Animal Center is established in a particular situation and time. Designed fuzzy control algorithm and Fuzzy-PID control algorithm is simulated and validated.It is difficult to set up the accurate mathematic model for the real AC systems, because of the influence of situations, time and the other factors. In order to achieve the ideal control effects, the model reference fuzzy adaptive control is designed and simulated.