Design Of Air Conditioning Temperature Control System Based On Atmega128 Single Chip Microcomputer

With the coming of the information age, the number of communications room has exploded. As the main radiating equipment of communications room, the monitoring of the precision air conditioner has already been more and more valued and attracted by many businesses, In this paper, combined with the temperature & humidity environments characteristics of communication room and the functional requirement of the control system, the thesis has established a general the design scheme of precision air conditioner control system, and software and hardware introducing it in detail finally are designed, as well as the algorithm.The control system adopts the idea of hand board and the core board, two boards use Atmega128 micro-controller as the control core. Hand board is consist of the display module, the key module and the communication module, On the core board, there design the acquisition circuit for temperature & humidity data (through the temperature and humidity digital sensor DS18b20 and DHT11), the temperature control circuit based on SPI communication, the humidity control circuit based on micro-controller PWM function module, the fan control circuit and the communication module circuit. Introducing the system software design in detail, the focus is the control algorithm realization and the interrupt service. The functions of the control system including signal collecting, the moisture-adjusting device controlling, the temperature regulating device controlling, fan controlling, data calculating, data communicating and data displaying.According to the temperature environment of communications room, to make dynamic modeling for it. You can find that the room temperature is difficult to control because of its characteristics of non-linear, time-varying and complex lag. For the feature of the control object, this paper decided to adopt the method which combines variable universe fuzzy PID and Smith predictor, the Smith predictive compensator can eliminate the influence of the large delay. the method which combines the fuzzy control with PID can bypass the time-varying characteristic of the object, as an improvement of the fuzzy controller, through the expandable and shrinkable factor, the variable universe fuzzy control can constantly compress the basis of domain, under the condition of the original fuzzy control quantitative factor unchanged, it is equal to increase the control rules of fuzzy control, so it can obtain better control effect than the fuzzy control. Based on the simulation analysis of traditional PID-Smith, fuzzy PID-Smith and variable universe fuzzy PID-Smith, the results show that the variable universe fuzzy PID-Smith control has better dynamic and steady performance.