Research On Control Unit Based On Fuzzy Control In Bin Drying Machine

The grain drying machine is the hardware of the grain drying. The mechanization of gain drying has become the bottleneck of the mechanization of whole grain production process in China. Although experts proposed the idea of bin drying machine which tallies with our actual situation, and carried out a lot of researches. But it is not widespread for our people because of its operating principle and structure. Therefore, the research of the bin drying machine has become a task which brooks no delay.On the basis of the research of on-line determination of grain water content suitable for bin drying machine by Mr. Dong, an electronic control unit for bin drying machine is developed in this paper. With complex nonlinear, changing with the time, multi-variable of bin drying machine control system, fuzzy control theory without mathematical precise model was applied to design a variable parameter fuzzy-PID controller, this variable parameter fuzzy-PID controller can modify the parameter of K_P T_i T_d of the variable parameter fuzzy-PID control algorithm. By this algorithm, the bin drying machine control unit was designed.The control unit takes the temperature of hot air as control value, and the humidity of grain is looked as aim value. The altering trend of air temperature can be obtained by measuring the humidity signals of grain. The signals from MCU were transmitted to the step motor driver. The size of the heater valve can be changed by the step motor. Therefore, the control of grain temperature is come true by changing the temperature of hot air.The core of this paper was the designing of the variable parameter fuzzy-PID controller, the designing of the circuits diagram by mean of Protel software and the software programmed by Keil C51 software. In the course of developing the hardware system, on the basis of analyzing function of hardware circuit, choosing AT89C52 MCU as the core of the controller hardware, designing the filter and amplifier circuit, sample and hold circuit, watchdog circuit, Analog-to-Digital conversion circuit, out port control circuit and step motor driving circuit, display circuit, etc. In the course of developing the software system, structure and modular design method was adopted in the principle of reliability and practice. Finishing every module interruptive subprogram by Keil C51 software. Finally, the anti-interference of both hardware and software were designed by considering the scene of working.