Key Technologies Of Vibrating And Comb Brushing Harvesting For Lycium Barbarum L.

Currently,the price of the fruit remains high because Lycium barbarum L.(L.barbarum)is harvested manually,and the harvesting cost accounts for half of the total cost of production.With the increase of the planting area of L.barbarum,the problem of labor shortage for the fruit harvesting is becoming increasingly prominent.Various prototype harvesters have been previously designed for L.barbarum.In total,four types of L.barbarum harvesters have been proposed,i.e.,the vibrating,comb brushing,shearing,and air-flowing harvesters.Based on the field experiments,the vibrating harvester was the most efficient one,but it also caused the most damage.By contrast,the comb brushing harvester had the lowest efficiency and lowest damage.The shearing harvester was both inefficient and difficult to mechanize.Similarly,the air-flowing harvester had not overcome the problems relating to the air-flow stability and field passability.Combining methods to efficiently harvest L.barbarum have also been tried,taking the advantage of high efficiency of vibrating and low damage of comb brushing.A portable handheld vibrating and comb brushing harvester of L.barbarum was developed for the smallscale farmer planting mode of L.barbarum.Meanwhile,a self-propelled vibrating and comb brushing harvester of L.barbarum which could pass over plants was developed for the largescale manor planting mode of L.barbarum.In view of the research and development needs of vibrating and comb brushing harvesting method,six research contents were carried out to solve the above problems,i.e.,the biomechanical characteristics of L.barbarum,detecting the maturity in fresh L.barbarum fruit,simulations and experiments of detachments of L.barbarum,determination of impact bruises of ripe L.barbarum fruit,design and parameter optimization of vibrating and comb brushing harvester of L.barbarum,and parameter optimization of winnowing equipment for machine-harvested L.barbarum.This provides a theoretical basis for high efficiency and low damage harvesting of L.barbarum.The main research contents and conclusions are as follows.(1)The study on the biomechanical characteristics of L.barbarum consists of two parts.The modal analysis and experiment of a L.barbarum shrub was conducted by the establishment of three dimensional(3D)model,physical tests of the branches using the universal testing machine,establishment of the mechanics models,modal analysis using FEM simulation,modal experiment using acceleration sensors and an impact hammer,and field experiment verification.The determination of moisture of ripe L.barbarum fruit using NIRHSI was conducted by measuring the moisture change,nondestructive testing of moisture of ripe L.barbarum fruit using NIR-HSI,processing spectral data,and establishing the moisture prediction model.Field experiment results showed that the resonance of the shrub occurred when the resonance frequency was 2 Hz.In addition,the moisture of ripe L.barbarum fruit had a corresponding response to NIR-HSI.(2)The study on detecting the maturity in fresh L.barbarum fruit consists of three parts.Detecting maturity in fresh L.barbarum fruit using color information was conducted by the abnormal sample elimination using the Mahalanobis distance,extraction of nine components,image processing,establishing the maturity detection model,and field experiment verification.Detecting maturity in fresh L.barbarum fruit based on spectral characteristics was conducted using TOF,SRS,NIR-HSI,FL.The determination of sugar content of L.barbarum using NIRHSI was conducted by measuring the sugar content,nondestructive testing of sugar content using NIR-HSI,processing spectral data,and establishing the sugar content prediction model.Field experiment results showed that component R-G was conducive for the extraction of the area of the ripe fruit;component S was conducive for the extraction of the area of both the half-ripe fruit and unripe fruit.In addition,the accuracies of both the training set and prediction set were 100%.Besides,there were significant differences between different fruit at 846 nm.Furthermore,TOF of photons showed that there were also significant differences between different fruit at 4.6 ns.Moreover,there were significant differences among different fruit at the first four distances(1 mm,2 mm,3 mm,and 4 mm).Additionally,it could clearly distinguish the different fruit using PC3 based on NIR-HSI.What’s more,there were significant differences among different fruit based on FL.Lastly,the sugar content of ripe L.barbarum fruit had a corresponding response to NIR-HSI.(3)The simulations and experiments of detachments of L.barbarum was conducted by the reverse engineering modeling using the 3D scanner,physical tests using universal testing machines,establishing the mechanics models,detachment simulations based on FEM,and verification using field experiments.Field experiment results showed that the ripe fruit fractured first between the fruit and calyx,second between the stem and branch,and the stem fractured last.Mostly,the half-ripe fruit fractured first between the stem and branch,second between the fruit and calyx,and the stem fractured last.The unripe fruit fractured first between the stem and branch,second between the fruit and calyx,and the stem fractured last.The flower fractured first between the flower and calyx mostly,the stem fractured first in some cases,and it fractured first between the stem and branch least often.The leaves fractured between the leaf and branch.In addition,the detachment force between the fruit and calyx of ripe fruit was the lowest value of these forces.Therefore,only the ripe fruit was the first to detach from the calyx when harvesting.(4)The determination of impact bruises of ripe L.barbarum fruit was conducted by the reverse engineering,establishment of mechanics model,simulation of impact bruises of ripe L.barbarum fruit based on FEM explicit dynamics,analysis of variance(ANOVA)of field experiment results,response surface method(RSM)analysis of field experiment results,and field experiment verification.Field experiment results showed that the fruit could be clearly distinguished from the background when the ratio of the value of band 60(wavelength:1060.9900 nm)to the value of band 170(wavelength: 1426.1899 nm)was four.In addition,the bruise area of the fruit was clearly determined when the value of band 120(wavelength:1260.1899 nm)was less than 0.35.Besides,the optimized parameters were determined to be a drop height of 0.24 m,foam board as impact material,and an impact angle of 13.11°.Lastly,the bruise rate was 9.8%.(5)The study on the design and parameter optimization of vibrating and comb brushing harvester of L.barbarum consists of two parts.The design and parameter optimization of the portable handheld vibrating and comb brushing harvester of L.barbarum was conducted by the design of overall structure,analysis of operating principle,establishment of dynamics model,design of key systems,kinematics and dynamics simulation,performance experiment,ANOVA of field experiment results,RSM analysis of field experiment results,and field experiment verification.The design and parameter optimization of the self-propelled vibrating and comb brushing harvester of L.barbarum which could pass over plants was conducted by the physical tests using the universal testing machine,establishing the mechanical models,vibrating and comb brushing harvesting simulations based on FEM,parameter optimization experiments,ANOVA of field experiment results,RSM analysis of field experiment results,and field experiment verification.For the portable handheld vibrating and comb brushing harvester of L.barbarum,field experiment results showed that the best combination was that the revolving speed of comb brush was 64.52 r/min,the revolving speed of cam was 29.68r/min,and the style of comb brush was Ⅱ.In addition,the harvesting rate of ripe L.barbarum was 89.12%,the harvesting rate of unripe L.barbarum was 5.87%,and the damage rate of ripe L.barbarum was 6.24%.For the self-propelled vibrating and comb brushing harvester of L.barbarum which could pass over plants,field experiment results showed that the optimal parameters were a rotating speed of 180 r/min,using the silica gel,an amplitude of 15 mm.Lastly,the harvesting rate of ripe fruit was 85.8%,the harvesting rate of unripe fruit was 10.5%,and the damage rate of ripe fruit was 9.7%.(6)The parameter optimization of winnowing equipment for machine-harvested L.barbarum was conducted by the design of overall structure,analysis of operating principle,design of key systems,discrete element method(DEM)simulation of ripe fruit in the horizontal airflow,performance experiment of winnowing equipment,ANOVA of field experiment results,RSM analysis of field experiment results,and field experiment verification.Field experiment results showed that the optimal parameter combination was determined to be an airflow speed of 5.52 m/s,input conveyor speed of 0.50 m/s,and input-output conveyor distance of 265.04 mm.Lastly,the rate of impurity change and the clearance rate of ripe fruit were 89.74% and 8.71%,respectively.