Research On Crawler Self-propelled Cabbage Harvesting Equipment And Development Of Its Weighing System

Cabbage is a kind of headed vegetable,which is widely planted in China.At present,cabbage harvesting mainly depends on manual works with increasingly negative benefits,which are labor-intensive,high-cost and low-efficiency.It is practical to develop mechanized harvesting technology to solve this problem.This paper takes the cabbages in Zhejiang Province as the objectives.Based on the research of cabbage mechanical properties,a crawler self-propelled cabbage harvesting prototype was designed and manufactured according to virtual prototyping technology and field tests.A agronomy standard was proposed to meet the mechanized cabbage harvesting system,and a dynamic weighing system was also developed for this cabbage harvester.The main research contents and results are displayed as below:(1)Research on the mechanical properties of cabbage.The main morphological parameters of the very common cabbage varieties in Zhejiang Province were measured.The statistic results showed that different cabbage varieties and individuals differ in morphological characteristics.The cutting position experiments,orthogonal cutting experiments and cutting splitting experiments of the cabbage root were conducted based on the chemical analytic instruments and the universal testing machine.The results showed that the main chemical composition influencing cutting forces is the crude fiber.Both of the maximum and average cutting force are linear with the crude fiber content,and their R~2 are 0.9491 and 0.9756 respectively.The results also revealed the diameters ranging from 30 to 35 mm as the best cutting region.The cutting experimental results suggested that single point support mode,sliding cutting mode,downward inclining mode and low cutting speed could be applied to design the cutting mechanism.To reduce the cutting splitting failure under single point support mode,cutting at diameter of 32 mm with including angle of 30° and cutting speed of 300 mm/min were also suggested.(2)Design,analysis and assembly of the crawler self-propelled cabbage harvester.Based on the research of cabbage mechanical properties,different walking ways of the power chassis,picking ways,lifting ways,cutting ways and leaf-separating ways were compared,and the processing flow of mechanized harvesting cabbage and the overall scheme of the harvester were finally determined.Based on 3D software and FEA software,the picking mechanism made of picking shovels and a reel,the lift mechanism made of dual-transverse lifting belts and serration-type lifting chains,the dual-disc cutting mechanism,the roller-type leaf separator,and the hydraulic system were detailed.A crawler self-propelled cabbage harvesting prototype was finally manufactured,assembled,debugged and improved.This harvester can finish the cabbage harvesting process of picking,lifting,root-cutting,leaf-separating,and collecting,which proved the feasibility of the design proposal.(3)Field tests and improvements of the crawler self-propelled cabbage harvester.A testing method was proposed to judge the field working performance of cabbage harvester.6 times field tests were conducted,leading to the improvements of the key parts of the prototype,including picking shovels,sink-avoiding board,dual-transverse lifting belts,serration-type lifting chains,and root-cutting mechanism.The field testing report showed that the harvester is suitable for harvesting the cabbage with diameter of 15?25 cm,the productivity is 0.21 hm~2/h,the picking rate is 97.4%,the qualified cutting rate is 89.8%,the qualified leaf-separating rate is 88.2%,and the harvesting loss is 4.8%.(4)The research on agronomy standard suitable for cabbage mechanized harvesting.After investigating the traditional cabbage planting mode,an agronomy standard for planting cabbage was proposed.According to the comparative field tests in experimental and traditional fields with different cabbage varieties,the results showed that the picking rate in experimental fields was improved by 5.6%compared to traditional field tests.In addition,the accurate cutting rate was improved by 3.3%and the working loss was reduced by 6.4%.When the harvester was harvesting the pointed-head cabbage of Chunfeng,the picking rate was 8.3%higher than that of harvesting the round-head cabbage of Lanzhoubao,but the qualified cutting rate and the accurate cutting rate were reduced by 6.0%and 8.9%respectively.However,there was little difference in working loss.The results demonstrated that the agronomy standard can benefit the field working performance of cabbage harvester.(5)Development of dynamic weighing system for the cabbage harvester.On the purpose of developing cabbage yield monitoring system,a weighing system based on dynamic weighing technology for this crawler self-propelled cabbage harvester was developed,including the mechanical part and data acquisition part based on Lab VIEW.The system was designed,manufactured,debugged,and its valid weighing data were extracted.The lab experimental results showed that when conveying speed was set as 0.1 m/s,0.2 m/s and 0.3 m/s,the coefficients of determination R~2,between the measured data and the actual data were 0.9918,0.9874 and 0.9845 respectively.The results revealed the dynamic weighing system had a good accuracy and stability.The developed crawler self-propelled cabbage harvesting prototype is powered by hydraulic system with a sound structure.The field tests demonstrated that the harvester already has the ability to harvest cabbages.The proposed agronomy standard suitable for mechanized cabbage harvesting can improve the working performance of cabbage harvester.The developed dynamic weighing system is the basis of developing the cabbage yield monitoring system.The researches above can provide the therotical and research basis for China and help harvest cabbage in a mechanized,automatic and intelligent way in the future.