| Light is an indispensable factor in plant growth, because of the covering material, dust, structural effects and shading and so on, facility lighting cannot meet the crop requirements, which seriously affects the crop yield and quality. Artificial fill light technology can effectively improve the light environments of facility plant growth, and it has become an important means of light environmental control. Currently, there are problems like non-matching light quality and low regulation accuracy in the light environmental control system which result in low crop light absorption and large energy consumption. Therefore, aiming at the real needs of crop light environmental system, based on WSN, this paper takes CC2530 as core processor, red blue light and deep red LED array as dimming light source and designs greenhouse dimming light monitor terminal, which can provide decision-making basis and dimming means for accurate light environmental algorithm.The main research content and conclusions are as follows:(1) Propose the overall design of light environment regulation, take the wireless sensor network as architecture and ZigBee2007 wireless network as transmission protocol, design the greenhouse dimming light monitor terminal and control terminal; the former is for real-time information monitoring and uploading of greenhouse environment and the later is to realize accurate dynamic regulation of environmental light.(2) Considering the effect of light, temperature and CO2 concentration on photosynthesis, use CC2530 as core processor and design the dimming system monitor terminal to complete the monitoring of the above three factors, then upload the monitoring data routing node and coordinator node to the information management system, which can provide real-time data for the upper optimal regulation algorithm, and lay the foundation for precise regulation of light environment.In the design of light source, crop selectivity theory of light absorption and fluorescence decay kinetics of fast component principles are taken full account; the dark red 700 nm light LED is added to the original center of band- 680 nm and 450 nm red and blue LED array, which forms a double optical gain efficiency, and can effectively inhibit the red drop phenomenon, increase the quantum production capacity substantially and improve the photosynthetic efficiency of about 20%.(4) Design the PT4115 LED based dimming light source driving circuit; according to the optimal dimming intensity target issued by the upper terminal information management system, the dimming terminal calculates the corresponding PWM-control signals and make hardware-generated error correction, which can research the precise regulation of different light qualities for different amounts of light; the experiment shows that the error is within 6%.(5) Taking the eggplants as research subjects and making comparative analysis of the effects of fill light from three different light source, the following are the conclusions: under the same conditions, the photosynthetic rate of eggplant seedlings is the fastest in red and blue + dark red light source, followed by red and blue light in which the crop growth is the slowest; taking eggplant as subject to test the yield and quality, the results show that the deployment area of the first ripe eggplant yield relatively increases 82.37%, and the total amount of amino acids and vitamin C increase 20.03% 30.26% respectively.In summary, the design of greenhouse dimming system based on LED has the advantages as low energy consumption, high control precision and good application and has important theoretical and practical significance in conducting precise regulation of greenhouse light environment. Also, this research results have some certain reference for the further study on environmental light regulation. |
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