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Research on Automatic Transplanting Technology and Device for Vegetable Plug Seedling

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Tutor: LiShuJun;LiDong
School: China Agricultural University
Course: Agricultural Mechanization Engineering
Keywords: Vegetable plug seedlings,seedlings pick-up mechanism,Mathematical models,Seedlin
CLC: S223.9
Type: PhD thesis
Year:  2014
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Transplanting technique has lots of advantages at vegetable cultivation, such as enhance the high and stable yield, and improving the land utilization rate. Automatic transplanter is a most important trends at vegetable transplanting technology, which can promote work efficiency, reduce human-dependent seedlings feeding labor intensity and increase economic benefit. The object of this research were to aim at the key technology and equipment of tomato plug seedlings transplanting, experimental investigate the mechanical properties of plug seedlings, theoretical study and simulation the plug seedlings pick-up mechanism, develop and verify an automatic recognition picking vegetable plug seedlings system. Conclusion was as follows,1. The tomato seedlings at40days period were investigated through compressive capacity, creep strain and pullout force testing s base on the factors of morphological characteristics, physical dynamics, and pullout strength. The results showed the best tomato seedlings for the picking seedlings machinery was FNZ substrates (peat/perlite was2:1by volume) at55%moisture content, meanwhile the compressible displacement of seedling pot was13.45mm. When substrates at55%moisture content, the creep strain of seedling pots was pretty small after5N pressure sustaining2s, and the influence of clamping relaxation properties could be neglected while quickly mechanical picking plug seedling. The pullout force was2N-3N, and little affected by experimental factors.2. A woodpecker type trajectory of picking seedlings was invention, and a theory model of the five-rod fixed axis gear train combined type plug seedlings pick-up mechanism, which can meet the requirements of picking seedlings trajectory. Then, the computer aided analysis and optimization software of the theory model was developed based on software VB.NET, and the influence law of seedlings pick-up trajectory and mechanism vibration affected by the model parameters was obtained. The optimal parameters combination was l1=29mm, l2=90mm,l3=93mm,l4=42mm,l5=180mm, l6=126mm, xD=74mm,.yD=27mm, ¦Á10=169¡ã,¾Á40=319¡ã,¦È1=165¡ã,¦È2=90¡ã. Simulated analysis of the mechanism3-D model by software Inventor at the optimal parameters combination showed that the height of seedlings pick-up trajectory was239.7mm, the length of seedlings pick-up trajectory in pot was31.2mm, the angle between seedlings pick-up trajectory in pot and seedlings pot surface was almost vertical. So the correctness of the theory model was verified, and the conditions of the good operation performance of seedlings pick-up mechanism was obtained that the picking seedlings frequency was60strains per minute to90strains per minute.3. An automatic recognition picking plug seedlings system was developed which consisted of five-rod fixed axis gear train combined type plug seedlings pick-up mechanism, seedlings feed mechanism, identification sensor of plug seedlings and control system. The seedlings pick-up mechanism parameters were based on theoretical model, using two fingers picking seedlings, and the amount of compression for holding seedlings pot was8mm, the angle of two fingers on plug seedlings pick-up mechanism for clamping seedlings pot was16.4¡ã, the holding force was4.21N, the picking force was5.31N. The plug seedlings could be alternately intermittently fed vertically and horizontally by seedlings feed mechanism. The system was based on background suppression reflected photoelectric sensor and PLC program control to continuously automatically recognizing, picking and feeding the plug seedlings. The system could recognize seedlings stem, and the recognition position was15mm height of seedlings stem, the recognition distance was35mm between the seedlings stem. During the process of feeding seedlings, the identification sensor conducted recognizing plug seedlings in trays. The highest frequency of picking seedlings of the system was90strains per minute.4. To verify the work performance of the automatic system, a test device of automatic transplanting vegetable plug seedlings was built. The verify experiment result showed that the automatic recognition picking plug seedlings system could automatic, accurate and high efficient recognize the seedling in tray that satisfy recognition picking plug seedlings requirements. When the transplanting frequency were60strains per minute and90strains per minute, the success rate of the seedlings pick-up were92.59%and87.41%respectively, and the decreased leakage transplanting rate was about12%compare to the transplanter without the automatically picking seedlings control system. The success rate of seedlings pick-up was92.59%as the transplanting frequency at sixty strains per minute, and87.41%as the transplanting frequency at ninety strains per minute. The leakage transplanting rate with automatically recognition picking seedlings control system was12%lower than without the automatically recognition picking seedlings control system.
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