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Citation: Guo, J.; Duan, J.; Yang, Z.;
Karkee, M. De-Handing Technologies
for Banana Postharvest
Operations—Updates and
Challenges. Agriculture 2022,12, 1821.
https://doi.org/10.3390/
agriculture12111821
Academic Editor: Wei Ji
Received: 4 October 2022
Accepted: 27 October 2022
Published: 1 November 2022
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4.0/).
agriculture
Review
De-Handing Technologies for Banana Postharvest
Operations—Updates and Challenges
Jie Guo 1,2,3,† , Jieli Duan 1, 2, *,† , Zhou Yang 1,2,4 and Manoj Karkee 3
1College of Engineering, South China Agricultural University, Guangzhou 510642, China
2Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou 510642, China
3The Center for Precision and Automated Agricultural Systems, Washington State University,
Prosser, WA 99350, USA
4School of Mechanical Engineering, Guangdong Ocean University, Zhanjiang 524088, China
*Correspondence: duanjieli@scau.edu.cn
† These authors contributed equally to this work and share first authorship.
Abstract:
Many aspects of the agricultural industry such a field crop planting and harvesting and
chemical application in fruit crops have been employing mechanization and automation solutions for
decades. However, the de-handing operation in banana postharvest operations is usually performed
manually. Mechanical or automated de-handing is a potential long-term solution to address labor
shortages and the associated high costs. Bananas are mainly grown in developing countries located
in tropical and subtropical regions, where the development of agricultural mechanization and
automation solutions started only recently and is progressing relatively slowly. In addition, large-
scale banana orchards are mainly distributed in hilly and mountainous areas, though there are also
some small-scale banana plantations in plain areas. The complex environment of banana orchards and
the aging farming population are other important factors that make it difficult to realize mechanized
operation of banana de-handing. In recent years, researchers have proposed advanced techniques that
may facilitate the development of mechanical de-handing systems. However, the successful adoption
of mechanical de-handing technology still faces many challenges. This paper systematically reviews
the existing research on de-handing technologies and component mechanisms. A comprehensive
evaluation is carried out from the perspectives of feasibility of the mechanism design, stability of
the model simulation and reliability of the prototype systems developed. The future challenges and
opportunities for designing and practically adopting mechanical de-handing equipment are also
summarized and discussed.
Keywords:
banana postharvest operations; de-handing; eye-hand synergy; mechanical solution;
operating cost; orchard crops
1. Introduction
Bananas are the largest fruit crop in terms of planting area and trade volume in the
world. Banana planting is mainly concentrated in developing countries in tropical and
subtropical regions such as China, Brazil, India, Ecuador and the Philippines [
1
,
2
] where it
provides one of the main sources of income for farmers [
3
]. The harvest and postharvest
operations in bananas primarily include field picking, ropeway transportation, de-handing,
cleaning and disinfecting, and packaging and distributing to grocery outlets (Figure 1).
With the development and advancement of mechanization, automation and intelligent
technologies, the production efficiency of banana farmers has been greatly improved.
Currently, various operations in banana postharvest operations have been mechanized to
varying degrees; however, the de-handing operation still relies on manual labor [4].
Agriculture 2022,12, 1821. https://doi.org/10.3390/agriculture12111821 https://www.mdpi.com/journal/agriculture
Agriculture 2022,12, 1821 2 of 21
Agriculture2022,12,xFORPEERREVIEW2of23
Figure1.Ageneralflowofbananaharvestandpostharvestoperations.
Withtherecentsocietalandeconomicchangesincludingurbanizationandwider
commercialactivitiesinurbanareas,youngandmiddle‐agedlaborersarerapidlyleaving
thefarmingcommunitiesinthecountrysideandenteringlargercities,whichleadstoag‐
ingoftheruralpopulationthuscreatingincreasinglyseriouschallengesforfarming.
Therefore,availabilityandcostofmanuallaborhasbecomethemostcriticalissueforba‐
nanafarmers,especiallyforthetime‐sensitiveandlabor‐intensiveoperations.Thereare
alsomultiplechallengesinretrainingworkerswithoperationalskillsandde‐handingex‐
perience.Toaddressthesechallengesandimprovelong‐termsustainabilityofthebanana
industry,mechanicalde‐handingoffersapotentialalternativetomanualde‐handing[5].
Bananaplantingismainlyconcentratedinhillyandmountainousareaswithuneventer‐
rainandsteepslopes,whicharenotconducivetopedestrianactivities.Inaddition,inor‐
dertoimprovereturnstofarmers,bananafarmershaveadopteddifferentplantingpat‐
ternsindifferentregions,asshowninFigure2.Inthecontextoftheintegrationofagri‐
culturalmachineryandagronomy/croparchitecture,thecomplexgeographicalenviron‐
mentanddiverseplantingpatternsinbananaorchardshaveposedadditionalchallenges
forthedesignandapplicationofde‐handingmachines.
Figure2.Bananaorchardsandtheirgrowingpatterns.(a)Appearanceofabananaorchardlocated
inahillymountainousarea,(b)Theinteriorviewofabananaplantationintheplains.
Figure 1. A general flow of banana harvest and postharvest operations.
With the recent societal and economic changes including urbanization and wider
commercial activities in urban areas, young and middle-aged laborers are rapidly leaving
the farming communities in the countryside and entering larger cities, which leads to aging
of the rural population thus creating increasingly serious challenges for farming. Therefore,
availability and cost of manual labor has become the most critical issue for banana farmers,
especially for the time-sensitive and labor-intensive operations. There are also multiple
challenges in retraining workers with operational skills and de-handing experience. To
address these challenges and improve long-term sustainability of the banana industry,
mechanical de-handing offers a potential alternative to manual de-handing [
5
]. Banana
planting is mainly concentrated in hilly and mountainous areas with uneven terrain and
steep slopes, which are not conducive to pedestrian activities. In addition, in order to
improve returns to farmers, banana farmers have adopted different planting patterns in
different regions, as shown in Figure 2. In the context of the integration of agricultural
machinery and agronomy/crop architecture, the complex geographical environment and
diverse planting patterns in banana orchards have posed additional challenges for the
design and application of de-handing machines.
Agriculture2022,12,xFORPEERREVIEW2of23
Figure1.Ageneralflowofbananaharvestandpostharvestoperations.
Withtherecentsocietalandeconomicchangesincludingurbanizationandwider
commercialactivitiesinurbanareas,youngandmiddle‐agedlaborersarerapidlyleaving
thefarmingcommunitiesinthecountrysideandenteringlargercities,whichleadstoag‐
ingoftheruralpopulationthuscreatingincreasinglyseriouschallengesforfarming.
Therefore,availabilityandcostofmanuallaborhasbecomethemostcriticalissueforba‐
nanafarmers,especiallyforthetime‐sensitiveandlabor‐intensiveoperations.Thereare
alsomultiplechallengesinretrainingworkerswithoperationalskillsandde‐handingex‐
perience.Toaddressthesechallengesandimprovelong‐termsustainabilityofthebanana
industry,mechanicalde‐handingoffersapotentialalternativetomanualde‐handing[5].
Bananaplantingismainlyconcentratedinhillyandmountainousareaswithuneventer‐
rainandsteepslopes,whicharenotconducivetopedestrianactivities.Inaddition,inor‐
dertoimprovereturnstofarmers,bananafarmershaveadopteddifferentplantingpat‐
ternsindifferentregions,asshowninFigure2.Inthecontextoftheintegrationofagri‐
culturalmachineryandagronomy/croparchitecture,thecomplexgeographicalenviron‐
mentanddiverseplantingpatternsinbananaorchardshaveposedadditionalchallenges
forthedesignandapplicationofde‐handingmachines.
Figure2.Bananaorchardsandtheirgrowingpatterns.(a)Appearanceofabananaorchardlocated
inahillymountainousarea,(b)Theinteriorviewofabananaplantationintheplains.
Figure 2.
Banana orchards and their growing patterns. (
a
) Appearance of a banana orchard located
in a hilly mountainous area, (b) The interior view of a banana plantation in the plains.
Agriculture 2022,12, 1821 3 of 21
The purpose of this paper is to present the latest literature on banana de-handing
machinery in order to assess the current situation and to find potential solutions to this
critical technical and scientific challenge. The organization of this paper is as follows:
in Section 2, an overview of de-handing methods including traditional manual work
patterns is provided. In addition, existing key mechanical de-handing techniques have
been reviewed. In Section 3, potential solutions to existing challenges are proposed in four
different aspects: the development of a visual perception system, the design of a cutting tool
with profiling function, the exploration of de-handing mechanisms and eye-hand synergy
and the evaluation of mechanical damage of banana hands after de-handing. Finally, in
Section 4, general conclusions of the review are summarized.
2. Overview of De-Handing Methods
2.1. Traditional De-Handing Methods and Challenges
Banana de-handing is the action of separating the banana hand (fruit) from the bunch
stalk (stalk). Traditionally, workers use a simple cutting tool to cut the node one by one
along the central axis of bunch stalk from the first hand to the last/end hand to complete
the task of de-handing whole banana bunches, as shown in Figure 3. A banana bunch has
complex morphological features. The banana hands grow and distribute nonlinearly in
both the axial and circumferential directions of the bunch stalk [
6
]. The overall quality of
the bunch is varied and the fruit is easily mechanically damaged.
Agriculture2022,12,xFORPEERREVIEW3of23
Thepurposeofthispaperistopresentthelatestliteratureonbananade‐handing
machineryinordertoassessthecurrentsituationandtofindpotentialsolutionstothis
criticaltechnicalandscientificchallenge.Theorganizationofthispaperisasfollows:in
Section2,anoverviewofde‐handingmethodsincludingtraditionalmanualworkpat‐
ternsisprovided.Inaddition,existingkeymechanicalde‐handingtechniqueshavebeen
reviewed.InSection3,potentialsolutionstoexistingchallengesareproposedinfourdif‐
ferentaspects:thedevelopmentofavisualperceptionsystem,thedesignofacuttingtool
withprofilingfunction,theexplorationofde‐handingmechanismsandeye‐handsynergy
andtheevaluationofmechanicaldamageofbananahandsafterde‐handing.Finally,in
Section4,generalconclusionsofthereviewaresummarized.
2.OverviewofDe‐HandingMethods
2.1.TraditionalDe‐HandingMethodsandChallenges
Bananade‐handingistheactionofseparatingthebananahand(fruit)fromthebunch
stalk(stalk).Traditionally,workersuseasimplecuttingtooltocutthenodeonebyone
alongthecentralaxisofbunchstalkfromthefirsthandtothelast/endhandtocomplete
thetaskofde‐handingwholebananabunches,asshowninFigure3.Abananabunchhas
complexmorphologicalfeatures.Thebananahandsgrowanddistributenonlinearlyin
boththeaxialandcircumferentialdirectionsofthebunchstalk[6].Theoverallqualityof
thebunchisvariedandthefruitiseasilymechanicallydamaged.
Figure3.Manualde‐handingmodeofbananabunchesusingasimplecuttingtool.
Manualde‐handingislabor‐intensiveandphysicallychallenging.Notonlydoesthe
de‐handingqualityvaryduetoworkers’skillsandexperience,butrepetitivemotionina
smalloperatingspacewillcausepotentialhazardstoworkers’healththatcannotbeig‐
nored[7].Inaddition,somede‐handedbananahandsdonotmeetthequalityrequire‐
mentsforfreshmarketconsumption,andthereforetheyareusuallysubjectedtosecond‐
arycutting,whichinevitablyincreasesthelaboruseandproductioncost.Thecurrent
manualde‐handingmode,therefore,hindersthesustainabilityofbananapostharvestop‐
erationandtheentireindustry.Thebananaindustryurgentlyneedstotransformfrom
thetraditionalde‐handingmode/techniquetoamodernmechanicalde‐handingopera‐
tion.
2.2.MechanicalDe‐Handing
Therehavebeensomeeffortsindevelopingmechanicalde‐handingtechniquesto
replacemanualwork.Inordertoeffectivelyconnectthecablewaytransportationandthe
cleaningofthebananahands,themechanicalde‐handingequipmentusuallyincludesthe
Figure 3. Manual de-handing mode of banana bunches using a simple cutting tool.
Manual de-handing is labor-intensive and physically challenging. Not only does the
de-handing quality vary due to workers’ skills and experience, but repetitive motion in
a small operating space will cause potential hazards to workers’ health that cannot be
ignored [
7
]. In addition, some de-handed banana hands do not meet the quality require-
ments for fresh market consumption, and therefore they are usually subjected to secondary
cutting, which inevitably increases the labor use and production cost. The current manual
de-handing mode, therefore, hinders the sustainability of banana postharvest operation and
the entire industry. The banana industry urgently needs to transform from the traditional
de-handing mode/technique to a modern mechanical de-handing operation.
2.2. Mechanical De-Handing
There have been some efforts in developing mechanical de-handing techniques to
replace manual work. In order to effectively connect the cableway transportation and the
cleaning of the banana hands, the mechanical de-handing equipment usually includes the
clamping mechanism of bunch stalk, the lifting mechanism for the bunch, the de-handing
Agriculture 2022,12, 1821 4 of 21
mechanism, the collection mechanism for banana hands and the crushing mechanism
for bunch stalk, as shown in Figure 4. Before working, the banana farmer places the de-
handing machine at the bottom of the ropeway, hangs the banana bunches picked from
orchards on the transportation ropeway and gradually approaches the de-handing machine.
The position of the bunch closest to the de-handing machine is slightly adjusted, so that
its central axis basically coincides with the center of the machine. Then the clamping
mechanism is adjusted to the top of bunch stalk, and the de-handing mechanism to the
first banana hand at the bottom of bunch stalk. Finally, the liftable legs of the de-handing
machine are adjusted to locate the flexible conveyor belt below the de-handing mechanism,
so as to complete the preparatory work for the de-handing operation.
Agriculture2022,12,xFORPEERREVIEW4of23
clampingmechanismofbunchstalk,theliftingmechanismforthebunch,thede‐handing
mechanism,thecollectionmechanismforbananahandsandthecrushingmechanismfor
bunchstalk,asshowninFigure4.Beforeworking,thebananafarmerplacesthede‐hand‐
ingmachineatthebottomoftheropeway,hangsthebananabunchespickedfromor‐
chardsonthetransportationropewayandgraduallyapproachesthede‐handingmachine.
Thepositionofthebunchclosesttothede‐handingmachineisslightlyadjusted,sothat
itscentralaxisbasicallycoincideswiththecenterofthemachine.Thentheclampingmech‐
anismisadjustedtothetopofbunchstalk,andthede‐handingmechanismtothefirst
bananahandatthebottomofbunchstalk.Finally,theliftablelegsofthede‐handingma‐
chineareadjustedtolocatetheflexibleconveyorbeltbelowthede‐handingmechanism,
soastocompletethepreparatoryworkforthede‐handingoperation.
Figure4.Schematicdiagramofmanualde‐handing[7](a);andvirtualprototypeofmechanicalde‐
handingsystems[8](b).
Whenthebananabuncheshangingonthetransportationropewayaretransported
fromlefttoright,theclampingmechanismclampsthebunchstalk,andthenthede‐hand‐
ingmechanismcompletesthecuttingoperationofthefirstbananahand.Intheprocessof
de‐handingfrombottomofthebunchtotop,thediameterofthebunchstalkgradually
increases,theprofilingcuttersofthede‐handingmechanismmoveradiallytoadapttothe
changingdiameterofthestalk,andthenthede‐handingiscomplet4dhandbyhandin
thebunch.Theremainingbunchstalksfallintothecuttingandpulverizingmechanismat
thebottomofthede‐handingmachineandarecutandpulverizedonthespot,whichis
convenientforthesubsequentunifiedoperationofreturningthestalkstothefield.After
thede‐handingworkisover,theflexibleconveyorbeltandthecollectionmechanismof
bananahandsareputaway,andthede‐handingmachineismovedtotheworkshopto
prepareforthenextjob.
Thede‐handingmechanismisanimportantpartofthede‐handingmachineanditis
thecoreofrealizingthebananade‐handingoperation.Sincethediametersandcurvatures
ofthesamebunchstalkwherebananahandsgrowaredifferent,theaboveparametersare
alsodifferentbetweendifferentbunchstalks.Therefore,self‐adaptiveprofilingperfor‐
manceofthecuttingtoolinthede‐handingmechanism,withregardstoabunchstalk
withirregulargeometricshapes,directlydeterminesthesuccessrateofde‐handingand
theincisionqualityofthebananahand,andalsoindirectlyaffectsthesmoothnessofthe
de‐handingoperationandthefruitqualityofthebananahand.Thechoppedbanana
handsandthefruitwithmechanicaldamagecannotbestoredandsoldforfreshmarket
consumption.Therefore,thispaperprovidesadetailedanalysisandevaluationoftheme‐
chanicalde‐handingcuttersandequipmentthathavebeenreportedsofar,andrecom‐
mendationsforfutureresearchwillbemadebasedonthefindingsofthesestudies.
2.2.1.CircumferentiallyRotatingMechanicalDe‐Handing
Figure 4.
Schematic diagram of manual de-handing [
7
] (
a
); and virtual prototype of mechanical
de-handing systems [8] (b).
When the banana bunches hanging on the transportation ropeway are transported
from left to right, the clamping mechanism clamps the bunch stalk, and then the de-handing
mechanism completes the cutting operation of the first banana hand. In the process of
de-handing from bottom of the bunch to top, the diameter of the bunch stalk gradually
increases, the profiling cutters of the de-handing mechanism move radially to adapt to the
changing diameter of the stalk, and then the de-handing is complet4d hand by hand in
the bunch. The remaining bunch stalks fall into the cutting and pulverizing mechanism at
the bottom of the de-handing machine and are cut and pulverized on the spot, which is
convenient for the subsequent unified operation of returning the stalks to the field. After
the de-handing work is over, the flexible conveyor belt and the collection mechanism of
banana hands are put away, and the de-handing machine is moved to the workshop to
prepare for the next job.
The de-handing mechanism is an important part of the de-handing machine and it is
the core of realizing the banana de-handing operation. Since the diameters and curvatures of
the same bunch stalk where banana hands grow are different, the above parameters are also
different between different bunch stalks. Therefore, self-adaptive profiling performance of
the cutting tool in the de-handing mechanism, with regards to a bunch stalk with irregular
geometric shapes, directly determines the success rate of de-handing and the incision
quality of the banana hand, and also indirectly affects the smoothness of the de-handing
operation and the fruit quality of the banana hand. The chopped banana hands and the
fruit with mechanical damage cannot be stored and sold for fresh market consumption.
Therefore, this paper provides a detailed analysis and evaluation of the mechanical de-
handing cutters and equipment that have been reported so far, and recommendations for
future research will be made based on the findings of these studies.
2.2.1. Circumferentially Rotating Mechanical De-Handing
The banana hands are distributed in the circumferential and axial directions on the
bunch stalk; the circumferential angles are different for different bunches and among
different banana hands on the same bunch [
6
]. Based on this hand configuration, mechanical
Agriculture 2022,12, 1821 5 of 21
de-handing methods have been investigated based on circumferential rotation along the
bunch stalk. It is noted that the performance of these de-handing mechanisms is assessed
based on how well the mechanism avoids cutting into the bunch stalks and banana hands,
and avoids damaging the banana fingers.
Referring to the working principle of aircraft engines in the aerospace field, Yang et al.
designed a banana de-handing cutter with an annular shape and a circle with variable
enveloping diameter, as shown in Figure 5[
9
]. This de-handing cutter included double-
edged cutting blade, annular knife holder, connector and an A-shaped tie rod mechanism.
The cutting blades are installed on the guide groove of the annular knife holder to form
an annular enveloping structure capable of wrapping the bunch stalk. The cutting blades
were staggered and each blade was divided into upper and lower parts, the upper part
a vertical blade body with double edges on the top, and the lower part an outwardly
inclined adjustment. Through the adjusting part, the annular enveloping structure can be
contracted inward or expanded outward, so as to realize the function of adaptively varying
the diameter. In addition, the distance between the annular knife holder and the central
axis can be changed by the swinging of the A-shaped tie rod mechanism, thereby ensuring
that the shape of the annular enveloping structure is circular or approximately circular.
The de-handing cutter can automatically adjust the diameter of the annular enveloping
structure according to the change of the diameter of bunch stalk, and can avoid missing
cutting nodes.
Agriculture2022,12,xFORPEERREVIEW5of23
Thebananahandsaredistributedinthecircumferentialandaxialdirectionsonthe
bunchstalk;thecircumferentialanglesaredifferentfordifferentbunchesandamongdif‐
ferentbananahandsonthesamebunch[6].Basedonthishandconfiguration,mechanical
de‐handingmethodshavebeeninvestigatedbasedoncircumferentialrotationalongthe
bunchstalk.Itisnotedthattheperformanceofthesede‐handingmechanismsisassessed
basedonhowwellthemechanismavoidscuttingintothebunchstalksandbananahands,
andavoidsdamagingthebananafingers.
Referringtotheworkingprincipleofaircraftenginesintheaerospacefield,Yanget
al.designedabananade‐handingcutterwithanannularshapeandacirclewithvariable
envelopingdiameter,asshowninFigure5[9].Thisde‐handingcutterincludeddouble‐
edgedcuttingblade,annularknifeholder,connectorandanA‐shapedtierodmechanism.
Thecuttingbladesareinstalledontheguidegrooveoftheannularknifeholdertoform
anannularenvelopingstructurecapableofwrappingthebunchstalk.Thecuttingblades
werestaggeredandeachbladewasdividedintoupperandlowerparts,theupperparta
verticalbladebodywithdoubleedgesonthetop,andthelowerpartanoutwardlyin‐
clinedadjustment.Throughtheadjustingpart,theannularenvelopingstructurecanbe
contractedinwardorexpandedoutward,soastorealizethefunctionofadaptivelyvary‐
ingthediameter.Inaddition,thedistancebetweentheannularknifeholderandthecen‐
tralaxiscanbechangedbytheswingingoftheA‐shapedtierodmechanism,therebyen‐
suringthattheshapeoftheannularenvelopingstructureiscircularorapproximatelycir‐
cular.Thede‐handingcuttercanautomaticallyadjustthediameteroftheannularenvel‐
opingstructureaccordingtothechangeofthediameterofbunchstalk,andcanavoid
missingcuttingnodes.
Figure5.Rotaryde‐handingcutterwithvariableenvelopingdiameter[9].(a)3Dmodel,(b)Front
view,(c)Bottomview,(d)Sideview.
Xuetal.designedacirculararcprofilingmechanismbasedontheworkingprinciple
oftheexpandablemechanism,andmanufacturedacircumferentiallyexpandablebanana
de‐handingplatformonthisbasis[10].Thecirculararcprofilingmechanismtheypro‐
posedwascomposedofupper,middleandlowerlayersofplaneslides.Theupperlayer
ofthemechanismwascomposedofanexpandablearc,arcsupportrodsanddriving
slides;themiddlelayerofthemechanismwascomposedoffixedslides,linearguides,
pushrodsandtransmissionrods;thelowerlayerwascomposedofadjustingslidesand
linearguides.Figure6showstheschematicdiagramofthearcprofilingmechanismand
thede‐handingplatform.Thisstudyshowedthatthede‐handingplatformhasgoodpro‐
filingaccuracy(>96.5%withintheprofilingrangeofthebunchstalk).Inaddition,thein‐
cisionqualityofthebananahandafterde‐handingisgreatlyimprovedcomparedwith
Figure 5.
Rotary de-handing cutter with variable enveloping diameter [
9
]. (
a
) 3D model, (
b
) Front
view, (c) Bottom view, (d) Side view.
Xu et al. designed a circular arc profiling mechanism based on the working principle
of the expandable mechanism, and manufactured a circumferentially expandable banana
de-handing platform on this basis [
10
]. The circular arc profiling mechanism they proposed
was composed of upper, middle and lower layers of plane slides. The upper layer of the
mechanism was composed of an expandable arc, arc support rods and driving slides; the
middle layer of the mechanism was composed of fixed slides, linear guides, push rods and
transmission rods; the lower layer was composed of adjusting slides and linear guides.
Figure 6shows the schematic diagram of the arc profiling mechanism and the de-handing
platform. This study showed that the de-handing platform has good profiling accuracy
(>96.5% within the profiling range of the bunch stalk). In addition, the incision quality of
the banana hand after de-handing is greatly improved compared with that of the manual
operations. This research is significant in guiding the de-handing operation of a single
banana hand. However, in commercial banana orchards, banana bunches are usually
required to be de-handed continuously throughout the whole bunch to achieve the desired
Agriculture 2022,12, 1821 6 of 21
throughput for practical adoption, which could be a direction for future advancement of
this technique.
Agriculture2022,12,xFORPEERREVIEW6of23
thatofthemanualoperations.Thisresearchissignificantinguidingthede‐handingop‐
erationofasinglebananahand.However,incommercialbananaorchards,banana
bunchesareusuallyrequiredtobede‐handedcontinuouslythroughoutthewholebunch
toachievethedesiredthroughputforpracticaladoption,whichcouldbeadirectionfor
futureadvancementofthistechnique.
Figure6.Designandapplicationofthecircumferentiallyexpandablede‐handingplatform.(a)Sche‐
maticdiagramoftheprofilingmechanism,(b)Prototypeofthede‐handingplatform,(c)Schematic
ofanindoorexperiment,(d)Incisionofbananahandswithdifferentprofilingradius.
Duanetal.alsodesignedade‐handingplatformwithself‐adaptivefunctionforthe
bananabunchstalk,whichprimarilyconsistsofacutterplate,slider,V‐shapedconnecting
rod,cuttingblade,Hook‐likehinge,motorandframe,asshowninFigure7[11].Through
therotationoftheHooke‐likehinge,thecutterplateandthecuttingbladeofthede‐hand‐
ingplatformcanrotatebyacorrespondingangleinspace,soastoadapttothechangein
thecurvatureofthebunchstalk.Sincetherotationangleiscontrolledbymotors,thepro‐
filingeffectismoreprecise.Inaddition,thecuttingbladecanadjustitsexpansionarea
accordingtothecircumferentialangleofthegrowthofthebananahand,soastocomplete
thecuttingoperationofbananahandswithdifferentcircumferentialangles.Thisfeature
ofthede‐handingmechanismsubstantiallyimprovedtheperformance,whichwasvalu‐
ableinaddressing:(i)thepoorprofilingeffectofexistingde‐handingmechanismsonthe
curvatureofbunchstalk;(ii)lowcuttingaccuracyofthecuttingbladeinthecircumferen‐
tialdirection.
Figure 6.
Design and application of the circumferentially expandable de-handing platform.
(a) Schemat
ic diagram of the profiling mechanism, (
b
) Prototype of the de-handing platform,
(c) Schematic of an indoor experiment, (d) Incision of banana hands with different profiling radius.
Duan et al. also designed a de-handing platform with self-adaptive function for the
banana bunch stalk, which primarily consists of a cutter plate, slider, V-shaped connecting
rod, cutting blade, Hook-like hinge, motor and frame, as shown in Figure 7[
11
]. Through
the rotation of the Hooke-like hinge, the cutter plate and the cutting blade of the de-handing
platform can rotate by a corresponding angle in space, so as to adapt to the change in the
curvature of the bunch stalk. Since the rotation angle is controlled by motors, the profiling
effect is more precise. In addition, the cutting blade can adjust its expansion area according
to the circumferential angle of the growth of the banana hand, so as to complete the
cutting operation of banana hands with different circumferential angles. This feature of the
de-handing mechanism substantially improved the performance, which was valuable in
addressing: (i) the poor profiling effect of existing de-handing mechanisms on the curvature
of bunch stalk; (ii) low cutting accuracy of the cutting blade in the circumferential direction.
2.2.2. Mechanical De-Handing with Axial Plunge-Cutting
In addition to the circumferentially rotating mechanisms discussed above (Section 2.2.1),
a number of studies have reported on the axial plunge-cutting mechanism for mechanical
de-handing along the bunch stalk. There is a big difference between the two mechanical
de-handing methods. The former realizes the de-handing operation of a single banana hand
according to the different circumferential angles of banana hands growing on the bunch stalk.
The research focuses on the circumferential profiling design of the cutting tool. The latter
is based on the characteristic that the banana hands are staggered along the axial direction
on the bunch stalk, and realizes the de-handing operation of all banana hands one by one
for the whole bunch. The research focuses on the self-adaptive performance of de-handing
equipment to changes in the curvature and diameter of the bunch stalk. Considering the
various requirements of the actual de-handing operation in banana orchards, we found that
the axial plunge-cutting mechanical de-handing method along the bunch stalk has more
potential for long-term development.
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Figure7.Schematicdiagramofde‐handingplatformthatcanadapttovariablediametersofbunch
stalk.(a)Virtualprototype,(b)Topview,(c)Leftview,(d)Axonometricviewofkeycomponents.
2.2.2.MechanicalDe‐HandingwithAxialPlunge‐Cutting
Inadditiontothecircumferentiallyrotatingmechanismsdiscussedabove(Subsec‐
tion2.2.1),anumberofstudieshavereportedontheaxialplunge‐cuttingmechanismfor
mechanicalde‐handingalongthebunchstalk.Thereisabigdifferencebetweenthetwo
mechanicalde‐handingmethods.Theformerrealizesthede‐handingoperationofasingle
bananahandaccordingtothedifferentcircumferentialanglesofbananahandsgrowing
onthebunchstalk.Theresearchfocusesonthecircumferentialprofilingdesignofthe
cuttingtool.Thelatterisbasedonthecharacteristicthatthebananahandsarestaggered
alongtheaxialdirectiononthebunchstalk,andrealizesthede‐handingoperationofall
bananahandsonebyoneforthewholebunch.Theresearchfocusesontheself‐adaptive
performanceofde‐handingequipmenttochangesinthecurvatureanddiameterofthe
bunchstalk.Consideringthevariousrequirementsoftheactualde‐handingoperationin
bananaorchards,wefoundthattheaxialplunge‐cuttingmechanicalde‐handingmethod
alongthebunchstalkhasmorepotentialforlong‐termdevelopment.
Yangetal.designedastalkdiameter‐adaptivede‐handingmechanismconsistingof
frames,motor,cutterplate,gearset,connectingrods,linearguides,L‐shapedslider,
springsandcuttingblades,asshowninFigure8[12].Thegearsetisinstalledunderthe
frameandconsistsofadrivinggearandacorrespondingmesh.Thelinearguidesare
arrangedonthecutterplateinacirculararraywiththecenterofthecutterplateasthe
centerofthecircle.Eachbladeholdercanmoveintheradialdirectionwiththevarying
diameterofthebunchstalk,soastoadjusttheexpansionareaoftheannularenvelope
andprofilethebunchstalk.Byintroducingthecrank‐slidermechanism,thesixcutting
bladesevenlydistributedaroundthecircumferencecanmovesynchronouslyintheradial
directionusingthegeardrive,whichprovidesareferenceforthedesignofthecutter,self‐
adaptingtothevaryingdiametersofthebunchstalk.
Figure 7.
Schematic diagram of de-handing platform that can adapt to variable diameters of bunch
stalk. (a) Virtual prototype, (b) Top view, (c) Left view, (d) Axonometric view of key components.
Yang et al. designed a stalk diameter-adaptive de-handing mechanism consisting of
frames, motor, cutter plate, gear set, connecting rods, linear guides, L-shaped slider, springs
and cutting blades, as shown in Figure 8[
12
]. The gear set is installed under the frame
and consists of a driving gear and a corresponding mesh. The linear guides are arranged
on the cutter plate in a circular array with the center of the cutter plate as the center of
the circle. Each blade holder can move in the radial direction with the varying diameter
of the bunch stalk, so as to adjust the expansion area of the annular envelope and profile
the bunch stalk. By introducing the crank-slider mechanism, the six cutting blades evenly
distributed around the circumference can move synchronously in the radial direction using
the gear drive, which provides a reference for the design of the cutter, self-adapting to the
varying diameters of the bunch stalk.
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Figure8.Ade‐handingmechanismthatcanadapttochangesinthediameterofbunchstalk.(a)
Axonometricview,(b)Frontview,(c)Topview,(d)Axonometricviewofkeycomponents.
Yangetal.designedanotherplunge‐cuttingde‐handingmechanismwithvariable
diameter,asshowninFigure9[13].Thismechanismprimarilyincludedcuttingblades,
cutterplate,synchronouscontrolmechanismforthemultiplecutters,aircylinderand
twistableannularhoop.Thecuttergroupsynchronizationcontrolmechanismisarrayed
onthecutterplatewiththecenterofthecutterplateasthecenter,andismainlycomposed
ofL‐shapedsupports,U‐shapedblocks,connectingrods,incompletegears,sliders,verti‐
calguidesandsprings.Duringthede‐handingprocess,theannularbladethatwrapsthe
bunchstalkmovesradiallyunderthedriveofthesynchronouscontrolmechanismofthe
cuttergroup.Onceahandisde‐handed,thebunchstalkatthecenterofthemechanismis
moveddownmanuallyormechanically,andtheexpansionareaoftheannularenvelope
isadjustedbythejointactionofthetorsionaldeformationofthetwistableannularhoop
andthedeformationmechanism,soastoachievethepurposeofself‐adaptingtothevar‐
yingdiametersofbunchstalks.
Figure9.Plunge‐cuttingde‐handingmechanismwithvariablediameter.(a)Sideview,(b)Front
view,(c)Topview,(d)Sideviewofkeycomponents.
Yangetal.proposedawire‐cuttingmechanismforde‐handingthatconsistedof,pri‐
marily,acutterplate,linearguide,L‐shapedslider,constantforcecoilspring,cutting
Figure 8. A de-handing mechanism that can adapt to changes in the diameter of bunch stalk. (a) Axonometric
view, (b) Front view, (c) Top view, (d) Axonometric view of key components.
Yang et al. designed another plunge-cutting de-handing mechanism with variable
diameter, as shown in Figure 9[
13
]. This mechanism primarily included cutting blades,
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cutter plate, synchronous control mechanism for the multiple cutters, air cylinder and
twistable annular hoop. The cutter group synchronization control mechanism is arrayed
on the cutter plate with the center of the cutter plate as the center, and is mainly composed
of L-shaped supports, U-shaped blocks, connecting rods, incomplete gears, sliders, vertical
guides and springs. During the de-handing process, the annular blade that wraps the
bunch stalk moves radially under the drive of the synchronous control mechanism of the
cutter group. Once a hand is de-handed, the bunch stalk at the center of the mechanism is
moved down manually or mechanically, and the expansion area of the annular envelope is
adjusted by the joint action of the torsional deformation of the twistable annular hoop and
the deformation mechanism, so as to achieve the purpose of self-adapting to the varying
diameters of bunch stalks.
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Figure8.Ade‐handingmechanismthatcanadapttochangesinthediameterofbunchstalk.(a)
Axonometricview,(b)Frontview,(c)Topview,(d)Axonometricviewofkeycomponents.
Yangetal.designedanotherplunge‐cuttingde‐handingmechanismwithvariable
diameter,asshowninFigure9[13].Thismechanismprimarilyincludedcuttingblades,
cutterplate,synchronouscontrolmechanismforthemultiplecutters,aircylinderand
twistableannularhoop.Thecuttergroupsynchronizationcontrolmechanismisarrayed
onthecutterplatewiththecenterofthecutterplateasthecenter,andismainlycomposed
ofL‐shapedsupports,U‐shapedblocks,connectingrods,incompletegears,sliders,verti‐
calguidesandsprings.Duringthede‐handingprocess,theannularbladethatwrapsthe
bunchstalkmovesradiallyunderthedriveofthesynchronouscontrolmechanismofthe
cuttergroup.Onceahandisde‐handed,thebunchstalkatthecenterofthemechanismis
moveddownmanuallyormechanically,andtheexpansionareaoftheannularenvelope
isadjustedbythejointactionofthetorsionaldeformationofthetwistableannularhoop
andthedeformationmechanism,soastoachievethepurposeofself‐adaptingtothevar‐
yingdiametersofbunchstalks.
Figure9.Plunge‐cuttingde‐handingmechanismwithvariablediameter.(a)Sideview,(b)Front
view,(c)Topview,(d)Sideviewofkeycomponents.
Yangetal.proposedawire‐cuttingmechanismforde‐handingthatconsistedof,pri‐
marily,acutterplate,linearguide,L‐shapedslider,constantforcecoilspring,cutting
Figure 9.
Plunge-cutting de-handing mechanism with variable diameter. (
a
) Side view, (
b
) Front
view, (c) Top view, (d) Side view of key components.
Yang et al. proposed a wire-cutting mechanism for de-handing that consisted of,
primarily, a cutter plate, linear guide, L-shaped slider, constant force coil spring, cutting
blade and retractor with metal wire (Figure 10) [
14
]. The retractor can be installed between
any two linear guides and fixed on the cutter plate, and it can quickly and automatically
retract or extend the wire. The cutting blades are connected in series by a metal wire.
The cutting blades and the metal wire form an annular envelope, and the metal wire
between adjacent blades is used for cutting. For a gradually increasing stalk diameter, the
L-shaped slider moves radially, and the length of the metal wire between the cutting blades
is elongated to adapt to the change of the diameter of bunch stalk. The cylinders installed
under the cutter plate provide power to move the cutter plate upward as a whole. The
metal wire in the retractor is tensioned at the moment when the blades cut the node, and
finally the blade and the metal wire complete the de-handing operation together. When the
whole bunch is completely de-handed, the bunch stalk is removed, the L-shaped slider is
reset under the action of the coil spring and the excess metal wire is automatically recovered
into the retractor. Using the method of combining the cutting blade and the metal wire,
the gap formed by the blade during the radial movement can be made up to ensure that
there is always a metal wire between the adjacent blades, so that the banana node will
not be missing. Retractors with balls and coil spring allow for rapid wire tensioning and
retraction, reducing blade recovery time and improving work efficiency. Therefore, this
mechanism minimizes or avoids issues such as short radial expansion stroke of the whole
blade, large cutting gap between adjacent blades and long recovery time of blades.
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bladeandretractorwithmetalwire(Figure10)[14].Theretractorcanbeinstalledbetween
anytwolinear