Research On CO₂ Monitoring System Facing Greenhouse Environment

In the process of agricultural production,greenhouse as a new crop planting technology,reducing the natural environment affected by crop planting,targeted adjustment of production environment is conducive to the increase of crops.Among them,carbon dioxide as a raw material for photosynthesis,timely and accurate detection of greenhouse CO₂ concentration and effective regulation of greenhouse CO₂ concentration of greenhouse crops and increase production of great significance.Currently,the method for detecting CO₂ concentration in greenhouse has the advantages of wide measuring range,low cost and long-term stability.Due to the complexity of the greenhouse environment,the control of greenhouse CO₂concentration is affected by such factors as illumination,temperature and humidity,air exchange rate,crop photosynthesis rate and crop respiration rate.In this paper,fuzzy PID intelligent control technology is introduced into greenhouse CO₂concentration control.PID control parameters,so as to precisely control the greenhouse CO₂ concentration.In this thesis,the principle of CO₂ detection for solid electrolyte sensor is first presented.Then the fuzzy PID intelligent control algorithm is studied.The fuzzy PID intelligent control algorithm is designed and simulated by LabVIEW software.Then,to optimize the algorithm parameters and reduce the verification cost,The basic law uses LabVIEW software and MathScript modules to establish a greenhouse CO₂concentration model.On this basis,the software and hardware design of CO 2detection node is given and the host computer software of the monitoring system is designed.Through the CO₂ gas experiment,one by one test the monitoring system of the technical indicators.CO₂ sensor detection range is 300⁵000ppm,the relative error of the measured values?between-6.0%⁸.7%;400ppm and 1000ppm two gas concentrations,The stability of the CO₂ test node test,measuring longer than 8 hours,at 400 ppm,the sensor fluctuations of less than 2.5%at 1000 ppm,the sensor fluctuations of less than 1.5%;run the monitoring system in the greenhouse The CO₂concentration is actually measured and controlled and fluctuates within±40 ppm after steady state.Through experiments conducted to verify the monitoring system can effectively monitor greenhouse CO₂ concentration.The main innovations of this thesis are as follows:1.To improve the greenhouse CO₂ detection node moisture-proof design to adapt to the greenhouse high humidity environment.2.The introduction of fuzzy PID intelligent control technology in the greenhouse CO₂control system,the CO₂ concentration in the greenhouse under complex conditions,and the design of greenhouse CO₂ concentration model for simulation.