Research On Control Strategy Of Key Environmental Factors Of Pleurotus Eryngii In Mycelium Growth Stage

Pleurotus eryngii is a kind of edible fungus that can eat and have medicinal effect,and it is popular with the masses and occupies a large market share,which has been widely cultivated in northwest China.The growth of mycelium directly affects the quality and yield of Pleurotus eryngii,and plays a decisive role in the entire cultivation process.The main factors affecting the mycelium growth include nutrient conditions and environmental conditions.This paper mainly studies the influence of environmental conditions on mycelial growth.According to literature analysis and single factor test results,the environmental factors are temperature,humidity and CO2 concentration,and their levels are determined as well.Orthogonal test is designed to analyze the influence of environmental factors on the growth of mycelium,and to find out the optimum environment combination.Response surfaces and contour plots of the growth time are drawn by BBD response surface methodology,the mathematical model is established and find the best response value.At the same time,according to the correlation analysis,the multivariate regression model of mycelium growth is established.Finally,the fuzzy PID controller is designed and a temperature control strategy is proposed to simulate the temperature.The research can get following results:(1)The orthogonal test results show that the optimal environment combination for the growth of mycelium is temperature 24-26℃.humidity 65-70%and CO2 concentration 2500-3500ppm.The order of influence is temperature>humidity>CO2 concentration.Both temperature and humidity have significant influence on mycelial growth,while CO2 concentration has only a general effect.Through the response surface analysis,the model of mycelium grown time and temperature and humidity is established.and through the derivation it is concluded that when the temperature of 25.48 ℃,66.8%humidity,CO2 concentration of 2665 PPM,the mycelium with shortest time is 30.1 days.(2)Correlation analysis shows that the temperature and humidity has a significant effect on mycelial growth,while CO2 concentration did not.Therefore the multivariate regression equation between the time and temperature and humidity is proposed.According to the law of energy conservation,the temperature and humidity transfer function model in the greenhouse consists of a first-order inertial link and a delay link.The parameters K、T、τwere calculated by the two-point method and the transfer functions were established.(3)The transfer function of the compensator is obtained by using the feedforward compensator to decouple the temperature and humidity.And respectively in the Simulink environment,former decoupling,fuzzy decoupling,and fuzzy PID decoupling model are simulated,the results show that feedforward decoupling compensator realizes the decoupling and eliminates the mutual influence between the temperature and humidity,It can be seen from the simulation curve and performance parameter table that under the fuzzy PID decoupling,the adjusting time is low,response speed is fast,system performance is stable,and the good control of temperature and humidity is realized.