| Light and temperature are the most important environmental factors in greenhouse crop growth. In our country, especially in winter and spring of Northeast China, due to the effect of external weather factors, greenhouse structure and cover material, the light intensity inside the greenhouse cannot meet the requirement of crop growth, which has seriously restricted the yield and quality improvement of greenhouse vegetable. Therefore, adopting artificial light sources is an effective measure to improve the light environment in the process of crop growth. With the continuous development of LED technology and increasing maturity of the environmental control technology, the intelligent regulation of light environment has been realized. At present, regulation of light source can be designed according to crop demand in order to achieve timing and quantitative light supplement. But it cannot reflect the growth status of crops in real time with environmental changes, meanwhile it is difficult to achieve the purpose of on-line monitoring and control for optimal light environment of crop.Under the support of the National Natural Science Foundation of China, Natural Science Foundation of Liaoning Province funding,’Liaoyuanduoli’tomato planted greenhouse was taken as the research object, the key technology of the dynamic regulation of the light environment in the greenhouse facilities were studied, the main research contents are as follows:(1) Research of combination of LED light source and dynamic controlBased on the analyzing of optical property of LED, the appropriate type of LED was determined and the linear relationship between light intensity of LED and the current was verified in a certain range; Uniformity of the combined light source was analyzed by the special analysis software, suitable LED space, the array arrangement of the light source and heat dissipation way was determined. Thus an adjustable optical LED constant current driver power who can meet the LED light control requirements was designed, which realizes the dynamic regulation of voltage and current. Test results show that the composed source has the feature of adjustable light intensity, controllable light quality and flexible control etc.(2) The acquisition and detection system of light-temperature factors and chlorophyll fluorescence parametersThe work of sensor selection was completed, and the sampling and testing system based on ZigBee and GPRS communication technology was designed, which can collect and test environmental factors and chlorophyll fluorescence parameters. The communication protocol among the sensor data sampling module^ gateway nodes and remote data management center is programmed. μC/OSⅡ operating system and μC/GUI graphics support system was transplanted. Thus not only the detection and display of the environmental factors in the greenhouse was realized, but also the fluorescence parameters such as actual electron transfer rate, that is ETR, and actual quantum yield of PSII were transmitted to data management center by wireless mode, which reflects the condition of crop photosynthesis of the current environmental state in real time.(3) Research of intelligent control algorithm of the light environment in greenhouseTaking tomato seeding as experimental samples, the system collected fluorescence parameters of actual electron transfer rate ETR, which the temperature is 16,21,25,29, 31,35,37℃, and the light intensity is increased by 100μmol·m-2·s-1 from 100 to 1200 μmol·m-2·s-1. Median filter was adopted for error analysis and data processing. After this, the actual electron transfer rate model was established using the least square method, whose independent variables are temperature and light intensity. The fitting coefficient is 0.9886. Through the comparative analysis of genetic algorithm and the artificial fish swarm algorithm, the optimization of electron transfer rate at different temperatures was realized, and the optimal light intensity at specific temperature conditions was obtained in the whole temperature range. The research shows that compared with the genetic algorithm, the artificial fish swarm algorithm has faster convergence speed and better stability, and avoids the population degradation that occurred in genetic algorithm due to random selection and random mutation. Based on the analysis of artificial fish swarm algorithm, optimal target value of light intensity control model was established, and the good fitting effect was achieved between the temperature and the optimal light intensity, the fitting coefficient R2 is 0.9999.(4) Research of fluorescent parameters on-line detection and intelligent lighting system with LED as light sourceBased on the acquisition and detection system of multi environmental factors and chlorophyll fluorescence parameters, combined with the algorithm research and established mathematical model, the software of fluorescence on-line detection and intelligent lighting system with LED as light source was developed, which realizes the data storage、analysis and display of temperature、light intensity and chlorophyll fluorescence parameters. From the experiment process in the laboratory and greenhouse, it can be seen that the system can use the optimal light intensity which obtained by algorithm to realize the intelligent light on crops according to the change trend of temperature and light intensity, and through the feedback of the chlorophyll fluorescence parameters the exact value of the light can be detect and adjusted in real-time. It meets the light supplement of tomato. |
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