| Broccoli is a popular corm vegetable,and China has the highest production in the world.Due to the rapid growth of the broccoli market,however,the adoption of mechanical production methods has become an essential requirement.Harvesting is a heavy workload in broccoli production.The broccoli harvesting in China is still done manually,and no harvester is adequate for the task.On the other hand,research on the mechanization of the harvesting of vegetables began rather late in China.There are still several flaws with the mechanized harvesting of broccoli and other corm vegetables,such as poor quality,inefficiency,and dependability.Targeting the present issues of low production efficiency,high labor costs,and heavy work in broccoli harvesting.The current study examines the method of mechanized harvesting broccoli based on actual needs and designs the prototype of a self-propelled broccoli harvester.In order to determine the mechanical qualities of broccoli stems,mechanical experiments were conducted to determine the stems’ mechanical properties,and a model was developed to describe the load failure characteristics of stems.A bionic cutter was designed using the morphological bionics approach to address the issue of the low cutting efficiency of thick broccoli stems.The cutting stem was simulated and tested.A high-efficiency and low-loss harvester for densely planted broccoli was developed based on these.This harvester provided theory and equipment for the mechanized harvesting of broccoli,which solved the problem of harvesting densely planted broccoli,and gave a reference for the mechanical harvesting of corm crops.The key content of the study is summarized as follows:(1)In order to reveal the biological traits and stem mechanical properties of the broccoli plant,the parameters such as plant height,number of leaves,the diameter of stems and heads were counted,and the structural characteristics and component content of stems were analyzed.The mechanical qualities of broccoli stems were found by testing them under different loads,such as tension,compression,shear,and bending.It was done in combination with how the stems broke when harvested.The mechanical model of the broccoli stem was established,and the failure process of the broccoli stem under load was simulated in ANSYS software.The deformation and failure characteristics of broccoli stems were discussed through physical experiments and simulation.(2)In order to solve the issue of inefficient cutting of broccoli stems,which was based on the morphological and mechanical features of broccoli stems,a cutter and a supporting cutting device were designed using the characteristics of a grasshopper’s incisor lobe.A regression equation has been formulated to describe the contour curve of the incisor lobe of a grasshopper based on microscopic imaging.Subsequently,the three bionic circular cutters have been designed.The ANSYS software was used to simulate the procedure of broccoli stem cutting,and the simulation process involved the assessment of the stem load and cutter operation.The parameters such as the cutting device’s forward speed,cutting edge angle and rotational speed were determined through the response surface methodology.The experiment involved analyzing the primary factors affecting cutting performance when cutting broccoli stems.Based on the results,the bionic cutter with the most effective cutting performance and the corresponding optimal operating parameters were identified.(3)This paper investigates the issue of inadequate machinery for broccoli harvesting and investigates the mechanized harvesting approach and harvester structure in accordance with the typical planting mode and field environment characteristics of broccoli.The mechanized harvesting of broccoli was realized by the operation process of cutting,conveying,and sorting.The design and analysis of the broccoli harvester encompassed various aspects,including the chassis walking mode,stem cutting mode,conveying lifting mode,and sorting operation mode.The mechanized broccoli harvesting was completed through the devices of self-propelled crawler chassis,double disc bionic cutting device,wavy conveying lifting device,and manual sorting.Theoretical analysis and computer simulation were used to determine each functional component’s structure and operating parameters.Subsequently,a broccoli harvesting machine prototype was trial developed and subjected to load-free testing.(4)This paper recommends a method for detecting the performance and efficiency of a broccoli harvester based on its design specifications and operational requirements.The functionality of the broccoli harvester was evaluated by conducting tests in an indoor environment.The tests involved measuring parameters such as the stem’s leakage rate,damage rate,and stubble height.In addition,the harvester’s performance was also evaluated in a field environment,and the result indicated that the broccoli leakage rate was 4.8%,the cutting pass rate was 81.6%,the conveying pass rate was 95.62%,the damage rate was 3.96%,and the total loss rate was 8.55% while these outcomes were consistent with expected results.The workload of a harvester consisting of a driver and two sorting operators was approximately twenty times greater than that of an individual worker.Therefore,the results of this study revealed that the mechanical characteristics and cutting mechanism of broccoli stems had been revealed and that the influencing factors and optimal operating parameters of bionic cutters cutting broccoli stems were examined via simulation and experiment.However,the proposed mechanized harvesting method and mechanical design scheme were based on mature broccoli’s plant traits and planting patterns.In contrast,the broccoli harvester’s performance was evaluated through indoor and field experiments.Furthermore,the current study concludes that the research conducted on the broccoli harvester and stem-cutting mechanism provides significant importance in achieving high efficiency and low loss harvesting of corm vegetables. |
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