Research Of The Single-chip Microcomputer Control System In The Grain Drying Process

Grain drying processing is a important step in farming industry. Storing the food and seed must under safety moisture, so drying machine are used widely. But grain drying is a incompetent step in agricultural production of our country up to now. For drying process is influenced by many kinds of uncertain factors, traditional analog control system can't satisfied with requirement. Presently, measuring moisture depends on worker and control engine in drying process, So production is low-efficient and dried-grain's moisture isn't stability. The research aims at developing grain moisture measuring and close loop automatic control system which is matched with existing drier so as to raise the efficiency and quality of grain drying.In this paper, we designed economical and accurate measuring method of grain moisture. Measuring grain moisture quickly and accurately is key of automation control. Grain moisture can be indirectly measured by the concentric cylinder type of capacitance sensor, and using the temperature sensor realize temperature compensation by mathematical model. Automatic control system program design of grain dryer adopt assemble language, and ensure accuracy and stability of grain moisture by means of method of feedback control.In this paper, fuzzy control theory is applied to the automatic control system of grain drying. And designed fuzzy controller and control software. Classical control theory adopt difference equation and transfer function which demand analytic expressions of systematical knowledge of drying process and messages. However, grain drying process is complicated, changeful and nonlinear, so no suitable mathematical module can represent drying system. Control rules of fuzzy logic replace control methods of operator with fuzzy language variance so as to resolve dynamic characteristics and indeterminacy of control environment and satisfy the requirement of grain moisture content.Also in this paper, analyzing the features of high performance, high speed and stabilization of single-chip microcomputer in production-oriented control, using development technique of real-time operation system, and considering the demand of keeping grain drying quality, deceasing final cost and heightening productive rate, we designed production control system of grain dryer and programming module. Meanwhile, taking PC computer as upper monitoring and control system which based on visual programming language Visual Basic6.0 and has well operating environment. We bring forward real-time monitoring and control systematical thought, and carry out data dynamic showing and history data showing.The system has a favorable operating environment and friendly interface. It was easy to operate and it's performance is reliable.