Study And Design On The Temperature And Humidity Of Multivariable Control System Based On Fuzzy Control Technolog

With the constant pursuit of the life’s quality.people gradually focus on the pursuit of the fancy new things especially fresh fruits and vegetables. People’s needs have greatly promoted the development of the greenhouse industry. By using fuzzy control algorithm control of temperature and humidity in the greenhouse are studied in this paper, according to the influence of temperature and humidity. The greenhouse environment is a complex multivariable system with the characteristics of large inertia, nonlinear and time delay, so it is difficult to use traditional mathematical model to control the greenhouse environment,Besides the nonlinear data is converted to linear which will cause the distortion and affect the crop growth. In this paper,Fuzzy control is used to precisely control the temperature and humidity. Fuzzy control has strong robustness and it is not like traditional control which need to establish mathematical models so it is very suitable for nonlinear systems, such as greenhouse control.The greenhouse control system is designed for two parts which are the upper machine and the lower machine:VB is used to design the greenhouse’s monitoring and control software in PC. The strategy of distributed control system is used to design the lower machine and the chip of STM32F103VC is used to design fuzzy control module, signal acquisition module, execution mechanism module and wireless communication module of ZigBee. The fuzzy algorithm has good control effect through the comparison between the PID and fuzzy algorithm, which is simulated in Matlab software.In this paper, the control chip uses ARM microcontroller, with strong performance and lower cost. This paper adopts distributed control system which has the advantages of simple structure and convenient maintenance and expansion. Wireless communication of ZigBee has reduced the field wiring. The combination of monitoring software in the upper machine and LCD display in lower machine is facilitate to observe the greenhouse’s condition. The fuzzy algorithm has characteristics of adjusting short time and strong stability, which promotes the greenhouse control system to guarantee the healthy growth of crops.