| Greenhouse planting can provide a good growing environment for cash crops and bring significant economic benefits.Therefore,it has developed into an important part of modern facility agriculture.However,the traditional greenhouse control system still has problems such as single control object and poor self-adaptability.Hence,it is urgent to design a greenhouse control system with good performance to realize the diversity and efficiency of greenhouse planting.This paper proposes an intelligent control strategy of multiple environmental variables according to the characteristics of greenhouse environmental factors such as multi-variable,delay and coupling.In order to verify the performance of the control system,an experimental platform is set up on the basis of software and hardware design.The main research contents are shown as follows:1.Based on the analysis of the research status of greenhouse control system and its intelligent control strategy at home and abroad,the main control requirements of greenhouse environmental factors were synthesized in this paper.After that,the controlled characteristics of the main control factors were emphatically analyzed.Moreover,the overall scheme design of greenhouse control system was completed based on single-chip microcomputer technology.2.The mechanism analysis and mathematical modeling were carried out for the temperature and humidity factors of the greenhouse control system.The PID and fuzzy PID controllers were designed based on the traditional PID control and fuzzy control methods,respectively.In addition,the temperature and humidity compensation relation was established by the polynomial data fitting method,and a temperature and humidity fuzzy PID-decoupling controller was designed.The MATLAB/Simulink simulation platform was used to build the overall simulation model of the control system,and the performance of the traditional PID,fuzzy PID and fuzzy PID-decoupling control were compared and analyzed.The results indicate that the fuzzy PID-decoupling control method has the characteristics of fast response and no overshot,which optimize the dynamic performance of the control system.3.The modules selection and the design of the hardware and software were completed based on the system overall design.The hardware part mainly includes: the selection of the STM32F103 Cx microcontroller,temperature and humidity sensor,soil moisture sensor,light intensity sensor,CO concentration sensor and main actuators,and the design of the key module,display module and other peripheral circuit.The software part mainly includes the programming and debugging of the control system main program,each environment factor control subroutine and its functional requirement program.4.The test platform of the small greenhouse control system was built based on the software and hardware design scheme of the control system.And the control function requirements were debugged.Inaddition,the environment factors of the control system were tested and the results are analyzed under different operating environments.The results show that the control accuracy of air temperature in the greenhouse is ±0.2℃,the control accuracy of air humidity is ±0.2%,and the control accuracy of soil humidity is ±3.0%.The measurement of light intensity and carbon monoxide concentration in different time periods has also reached good monitor effect,meet the design requirements of the greenhouse. |
PDF Full Text Request