|
The environment of fresh fruits and vegetables fresh associated with a number of factors, such as temperature, humidity, gas content, etc, but the temperature and humidity is the most important thing affected the preservation of fresh fruits and vegetables. At present, however, China’s fruit and vegetable storage mainly based on cold storage, and control parameters mainly based on reducing the temperature, which resulting in the quality of fresh fruits and vegetables are affected and the impact of the economic benefits of fresh-keeping storehouse production. For the what above, in order to overcome the shortcomings of traditional fresh-keeping storehouse, such as dominated by cooling, Single control parameter, slow response and coupling with multiple parameters, that fuzzy PID temperature and humidity measure and control system based on DSP was design, which is high-precision temperature and humidity control system designed by way of combining fuzzy control techniques of Intelligent control systems with PID control of classical control system and to achieve high-precision temperature and humidity control.In this paper, the contents of following aspects were researched:First, the fresh status of the fresh-keeping storehouse was analyzed at home and abroad; Second, the working principle and overall design of temperature and humidity measure and control system of fresh-keeping storehouse were demonstrated, and composition and system structure of measure and control system were briefly introduced; Third, the hardware circuit designs of the entire control system were described in detail by way of demonstrated design proposal, mainly including the design of DSP main control core circuit, the design of temperature and humidity sensor, the design of A/D conversion circuit, the design of SPI-D/A conversion circuit, the design of power supply and reset circuit, the design of hardware simulation circuit combined DSP with JTAG, the design of clock oscillation circuit, the design of SCI-RS-232serial communication circuit, the design of communications interface circuits and the design of12864Graphic LCD driver circuit, etc; Fourth, in order to facilitate debugging and program modification, the software programs of measure and control system were designed with modularization, mainly including the design of DSP main program, the design of interface program and the design of fuzzy PID control program etc. Fifth, The system uses the C language and assembly language designed hardware and software for real-time emulation and debug.Paper’s findings as follows:One, the optimal design of fuzzy PID controller, fuzzy control rules by changing the table and adjust the PID parameters the system to adapt to different fruits and vegetables in different periods of storage temperature and humidity requirements.Two, that achieved the design of the entire control circuit system, and the design of software programming and interfaces programming, get the intended function.Three, Simulink simulation and DSP hardware debug results show that the system of high precision, the corresponding speed and cost savings, preservation of the library to meet the different requirements of temperature and humidity control.
|