Research And Design Of Intelligent Temperature Measurement And Control System

Electric oven is a kind of non-linearity, time variability and time-lag object, it's difficult to establish the accurate mathematical model and obtain high control effect by classical PID controller. In this paper the advantages and disadvantages of PID control and fuzzy control is analyzed and the method of combining them together is presented. The fuzzy self-tuning PID control method, which involves fuzzy control rules, is employed to achieve real-time adjustments to the three parameters K P,K D,and K Iof the PID.Firstly, the development of intelligent temperature control system and the trend of virtual instrument technology are introduced. Then the mathematic model is established, the simulations of PID control,fuzzy control and fuzzy self-tuning PID control are done by MATLAB. The simulation results show that the controller based on fuzzy self-tuning PID control algorithm is the best one, because the regulating time is short, the overshoot and the steady-error is very little. It can meet the control demands and it's anti-interference ability is very strong. The designing method and realization of the system are discussed in detail. The MCU is the single-chip microprocessor AT89S52, K-type thermocouple is used as temperature sensor, and MAX6675 is used as A/D converter. When getting the input orders, MCU works out the control value and gives pulse signal to drive the performance unit which is composed of photoelectrical coupler MOC3061 and TRIACS BT136. Host computer collects the data through serial communication and uses a modular design approach. The display of the temperature and process of date are realized by LABVIEW.The result of the experiment shows that the intelligent temperature measurement and control system based on fuzzy self-tuning PID control algorithm is flexible, the system operates stably, reliably and control precision is effectively improved. The system combines the intelligent temperature control system with the virtual instrument. It is simple and has friendly interface.