| China ’ s garlic planting area accounts for about 75% of the world.At present,it is still mainly artificial planting,with the agronomic requirements of ‘ shoot tip upward and vertical planting ’.Due to the irregular shape and large size difference of garlic seeds,the orientation of garlic seeds is a difficult problem for garlic planting mechanization.At present,mechanical orientation only plays a role in garlic varieties with longer bud tip and lower center of gravity.For general vari eties such as Jinxiang garlic,the directional effect is not good,which directly affects the subsequent vertical planting.Image recognition technology can effectively solve the general garlic seed orientation problem,but the recognition environment requires high,it is difficult to combine with garlic planting machine.At present,it is in the stage of image recognition garlic bud tip algorithm research or bench test.Air-suction seed metering device has small damage to seeds,strong adaptability,and continuous and stable operation.It can be combined with image recognition and orientation technology to achieve continuous single-seed directional seed metering,but further experimental research is needed to make it practical.In this paper,an experimental study was carried out on the air-suction metering device of garlic,which was convenient for the application of image recognition and orientation technology.The structure and working parameters were optimized,and the performance was improved,so that the image recognition and orientation technology was applied to the garlic planting machine to solve the problem of low mechanized vertical planting rate of general garlic varieties.In order to facilitate the application of image recognition and orientatio n technology,provide application conditions for rapid image recognition of garlic sprout tip and control of orientation technology,and combine with image recognition and control technology to achieve single-grain directional seed metering,the garlic airsuction seed metering device studied in this paper should have two functions of single-grain seed metering and preliminary orientation.In this paper,Jinxiang garlic with large planting amount was selected as the experimental research object.According t o the thickness size,the garlic seeds were divided into three levels of A,B and C from small to large.The single-grain rate,double-grain rate and hole rate were used as the performance indexes of single-grain seed metering,and the orientation rate was used as the preliminary orientation performance index to conduct experimental research on the two performances.Aiming at the problem of unfavorable accumulation of garlic seeds,a stirrer was designed to push garlic seeds to the suction hole without affecting the initial orientation and image recognition.According to the suspension characteristics of garlic,the wind power system was designed to meet the test requirements.Single-seed metering performance test with single-seed rate,hole rate,double-seed rate as the index,garlic seed size,suction hole diameter,negative pressure in the air chamber,seed plate speed,seed amount in the seed chamber,stirring height,stirring tooth blade number of experimental factors,single factor experimental study wa s carried out to determine the optimal value or range of each factor.The quadratic rotation orthogonal combination test with three factors and five levels was carried out with the rotational speed of seed-metering plate,negative pressure of air chamber and seed quantity in seed chamber as experimental factors.The results showed that the main factors affecting the single seed rate of the seed-metering device were the negative pressure of air chamber,the interaction between negative pressure of air chambe r and rotational speed of seed-metering plate,the rotational speed of seed-metering plate,seed quantity in seed chamber,and the interaction between rotational speed of seed-metering plate and seed quantity in seed chamber.The optimal structure and work ing parameters were seed quantity in seed chamber 143.2mm,rotational speed 7.2r/min,negative pressure of air chamber 12.3k Pa,stirring height 22 mm,stirring tooth blade 8,and suction hole diameter 11 mm.At this time,the single grain rate was 97.53%.The preliminary orientation performance was experimentally studied under the above parameters.Firstly,the angle range after orientation was taken as the experimental factor,and the vertical ratio falling into the lower device was taken as the index.The index to measure the qualified preliminary orientation was determined as the angle range of-50°～50° between the length direction of garlic seeds after orientation and the tangential direction of the trajectory.In view of different sizes of garlic,the single factor experiment was carried out with the position of internal and external directional needle as the experimental factor.The results showed that when the sizes of A,B and C garlic were 12～15mm,15～18mm and 18～21mm respectively,the distance from the position of internal and external directional needle to the center of the seed plate was 133 mm,162 mm,132mm,167 mm,130mm and 170 mm respectively,the initial orientation rates were 91.45%,92.58% and 92.62% respectively.Solidworks was used to model the air chamber of the seed metering device,and ANSYS CFX was imported to process the model.The simulation experiment was carried out with the thickness of seeding plate,the shape of suction hole and the position of suction pipe as the factors.Through the analysis of the gas chamber and suction hole cloud images,it can be obtained that when the thickness of seeding plate is 8 mm,the angle of suction hole is 70°,and the position of suction pipe α is 80°,the flow field in the gas chamber is uniform,and the negative pressure effect is the best.In this study,the seed metering and preliminary directional performance of the metering device were analyzed and tested,and the flow field of the air chamber was simulated.The optimal structure and working parameters were determined,which met the application requirements of image recognition orientation technology in garlic planting machine,and realized the mechanized vertical planting of general garlic varieties. |
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