Design Of Fuzzy Self-turning PID Control Greenhouse Temperature Controller

Temperature Controller is a kind of device controlling temperature, it controls the end of central air-conditioning by the difference of the temperature the users need and the temperature set, so as to change the temperature to satisfy users. The three bases of modern information technology are information acquisition and controlling (as temperature controlling), information transmission (communication technology) and information processing (computer technology). Temperature controller belongs to the forefront of cutting-edge products of information technology, it is widely used in field of agricultural production, scientific research and lives of human-beings, the quantity of it have been increasing.From the development of the temperature control system, the main direction of development is micro-computer temperature control system device based on single- chip. To the temperature of greenhouse, there are many control method to be selected. The first is PID control method, it is simple and easily realized. It has the advantage to eliminate the steady-state error, but because of the conflict between quickness and the small overshoot, it can't meet control demand. The next is fuzzy method. It has the advantage of small overshoot, but it has huge steady-state error. The last one is fuzzy self-tuning PID control method whose parameters are adjusted by fuzzy control rules. It can get good result that it can make the regulating time short,the overshoot zero and the steady-state error very little can be obtained. Base on single-chip AT89C52, this paper research and designs a temperature controller to the green house. The paper explains the application and principle of temperature controller, introduces the hard design of detecting system based on single-chip AT89C52, and illustrates the way and algorithm by fuzzy self-tuning PID control method to achieve temperature control, display and alarm. Moreover, it still goes into analysis of the designing principles of hardware and software in the system in details.