| Growing seedlings through trays is the main form of growing vegetable seedlings in our country.It has the advantages of saving time and industry,saving seeds and place for growing seedlings,convenient large-scale management and suitable for the mechanization operation.When the seedling is not sown to the seed,the seed is not germinated,and the seed is stunted,resulting in the lack of seedling holes.It is necessary to pick and replenish the holes of the missing seedling.After a period of cultivation,the substrate in the hole missing seedling should be removed and the good seedling should be taken out from the other hole and inserted into the current hole.This improves the quality of plate seedlings and conforms to the requirements of our refined agricultural development.However,the operation of picking seedling is still mainly manual operation with high intensity and low efficiency.It is great significance to study the automatic picking and repairing technology.In this paper,based on the previous research taking the tomato punctured seedling as the research object,the elimination scheme of punctured seedling and hole substrate was proposed.The main research contents and conclusions are as follows:(1)The overall scheme of substrate removal device was determined.The physical parameters of tomato seedlings at 10 d,15d,20 d and 25 d were measured in cooperative of Yang Ling Ji Yang fruit and vegetable.It was found that the substrate pot body showed loose and fragile characteristics by observing the seedling pot body.The picking stage of tomato seedlings was selected at the seedling age of 15-20 days.The main function and overall scheme of the substrate removal device are determined through investigation and analysis.This device includes the conveyor speed,the missing seedling detection system,the substrate removal system and the control system,to complete the task of the hole plate seedling conveying,the missing seedling detection and the substrate removal.Through the comparative and analysis of schemes of this system,the final scheme of the device was determined,and the working flow chart of the device was drawn according to the whole device.(2)Design and simulation optimization of air suction eliminator system.Based on the force analysis and negative pressure transport of matrix particles,the matrix removal transport system was designed.The suction port was designed according to the hole size and air transport characteristics.By analyzing the suction performance,the bottom length of the contraction tube of the suction port is 42 mm,the diameter of the round tube is 22～42 mm,and the height of the contraction tube is 30～50 mm.The optimization of the suction port was beneficial to reduce the pressure loss during operation by analyzing the pressure loss of pipeline.EDEM and Fluent software were used to carry out gas-solid coupling simulation tests for nine types.The results show that the maximum substrate particle mass volume ratio was similar in the same tube diameter,and the maximum particle mass volume ratio increases with the tube diameter increasing with the same tube height.The air suction port with a diameter of 30 mm and a height of 50 mm has the best performance in the substrate removal process of the whole air suction type missing seedling hole.(3)Design of missing seedling detection and control system.An image collection box was set up to collect the image of the plug seedling.The data of model training set was constructed by annotating and amplifying the image of the hole disc seedling.YOLOv4 network algorithm was used to obtain the specific location information of missing seedling hole.The test results showed that the average accuracy of the missing seedling hole detection model was 96.1%,the average accuracy of the tray and missing seedling detection was 95.3%and 96.8%,and the accuracy of the missing seedling location algorithm was 95.8%.Hardware selection and software design ware carried out for the control system of the missing seedling and substrate removal device,function modules of the control system ware analyzed,and the overall flow chart of the control system was drawn at last.(4)Trial production and test of substrate stripping device prototype.The substrate removal device prototype was built to carry out the parameter optimization test and machine verification test.The orthogonal experiment of substrate removal operation parameters was carried out by analyzing the experimental factors and parameter range affecting.The test results showed that the order of influence the test effect was the working pressure of the device,the moisture content of the seedling substrate,the suction time and the silicone pad.The optimal parameter combination was obtained as follows: moisture content of seedling substrate was 50%～55%,air regulation of vacuum generator in pneumatic circuit was 0.5MPa,suction time of single hole was 3 s,and there was silicone pad at suction port.Carry out the whole machine verification test of substrate removal device under the optimal parameters.The results showed that the success rate of missing seedling detection was more than 95%,the average substrate cleaning rate was more than 90%,and the working efficiency of the whole machine was 12holes/min.This meets the design requirements of substrate removal device。... |
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