Research And Application Of Double Let Water Tank Control System Based On Fuzzy PID

Liquid level is an important parameter in process control, therefore, its effect on production should not be ignored. Water tank level control is a major problem in liquid level control, which is common in the industrial process, representative typical and practical. Liquid level control often encounter big delay for time-varying and nonlinear complex system. For such a complex system and the conventional PID control with fixed parameters, it is difficult to guarantee system to adapt to change in the parameters of the control system and the working conditions change. The liquid level always have larger fluctuation, which can not get ideal effect, however, fuzzy control can overcome this. Fuzzy control is based on the artificial experience, which doesn't need to know accurate mathematical model of controlled object, using language variables to describe the system characteristics, and on the basis of system dynamic information and the fuzzy control rules of reasoning to obtain appropriate amount of control, which is not sensitive to parameter variation and the characteristics of strong robustness, however, the control precision is not very ideal. In order to effectively improve the control precision of the liquid level process and the combination of fuzzy control and PID control, how to design a fuzzy PID controller is the main content of this article research.First of all, with double let water tank as the controlled object, tank liquid level for the controlled quantity, electromagnetic valve as the actuator, the level of single circuit control system is built with the liquid level cascade control system. The mathematical model of controlled object is analyzed, using the experimental modeling method to calculate the transfer function of the model.Secondly, according to the mathematical model of the object and accused of process feature design level cascade control system, a dynamic simulation technology for single loop control system and the performance of the cascade PID control system are analyzed and design of the controller.Finally, in order to improve the dynamic response performance of the system, fuzzy PID controller is designed with the help of a data acquisition module and OPC software, realizing the fuzzy PID cascade control of liquid level through the Simulink technology.