Key Technologies Of Directing And Positioning Precision Seeding Device For Large Cucurbitaceous Seeds

Precision seeder for plug seedling is the key equipment to industrial seedling-raising technique. Research upon the precision seeder started quite early both domestic and overseas and the precision sowing of seeds with regularly shape or pelleting shape have already achieved. However, as to large seed with big size and quality or not a sphere, like pumpkin and gourd, precision seeding cannot be realized by the ordinary seeder. In addition, the cotyledons of seedlings would affect the growth of each other for the shadow, thus usually sowing artificially in the angle of 45 ° was adopted which was slow and fatigue. Therefore, it is important to study on the development of directing and positioning precision seeding device for large seeds and nurturing standardize seedlings with a consistent cotyledon direction.The key technology of directing and positioning precision seeding device for large seeds lies in the separately supply of single seed and the realization of directional and positional sowing to the large seeds. Pumpkin seed was taken as a research object in this paper and study and design was taken to the single seeds supply device and directing and positioning precision seeding device on large seeds. Main contents and conclusions are as follows.(1) Overall scheme determination of directing and positioning precision seeding device for large seeds. First, through research in the factory-like seedling base and seeding method experiment on large seeds, a scheme of the adjustment direction and seeding mechanism that the long axis of seeds could keep in the direction of 45° and micropyle with the same direction locate in the center of the soil hole was realized. Second, according to the analysis of sowing process, overall plan of directing and positioning seeding method was established, including precision single seed supply device, directing precision seed metering device, plug transmission device and PLC control system. At last, scheme on the single seed supply and directing and positioning precision seeding which was important to the device were designed and the relevant functions and design specifications were defined.(2) The development of precision single seed supply device. Firstly, single seed supply device was designed, utilizing air cylinder driving device to select seed, negative pressure sucking seeds and positive pressure rowing seeds. Secondly, through parameter optimization test, the optimal parameter of key parts got determined. Test platform for single seed supply device was built after the installing of parts and the design of air circuit system. Finally, performance test was taken and the result of showed that the success rate of supply single seed to the device was 94.3% which met the requirement of single seed supply for directing and positioning seeding device.(3) The development of the directing and positioning seed metering device. Firstly, the judgment and controlling methods of large seeds direction based on machine vision was proposed utilizing the flattened oval shape of seeds; secondly, according to the seed direction information, a scheme of the adjustment direction and seeding mechanism that the long axis of seeds could keep in the direction of 45° and micropyle with the same direction locate in the center of the soil hole was realized. Finally, the 3D printing technology was used to produce models of the adjustment direction and seeding mechanism and Experimental research on the directing precision seed metering device for large seeds was made. According to results, the germination mouth of 94.7% seeds distributed at the circle with center at plug center and radius to 10 mm; over 95.9% seeds with an angle of deflection less than 15° which meet the requirement of directing and positioning precision seeding device for large seed.(4) Study on the integrated performance test of directing and positioning precision seeding device for large seeds. Based on the designed seeding process, precision single seed supply device and directing and positioning precision seeding device were installed on the sowing test platform, then gas line was connected, hardware circuit of control system got designed, control system programs being written and platforms was debugged. Combining with the large seed direction automatically recognition system based on PC, there were integrated performance tests for the directing and positioning precision seeding device about single seed supply and directing and positioning seeding process. Results showed that the directing and positioning success rate of this device was 91.6%; 93.8% germination mouth of seeds distributed in the circle with center at plug center and radius to 10 mm; over 94.1% seeds with an angle of deflection less than 15° which meet the requirement of directing and positioning precision seeding device for large seed.