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Effect of Shaking Amplitude and Capturing Height on Mechanical Harvesting of Fresh Market Apples
6th IFAC Conference on Sensing, Control and Automation for 6th IFAC 6th IFAC Conference Conference on on Sensing, Sensing, Control Control and and Automation Automation for for Agriculture 6th IFAC Conference on Sensing, Control and Automation for Agriculture Agriculture December 4-6, 2019. Sydney, Australia Available online at www.sciencedirect.com December 4-6, 2019. 2019. Sydney, Sydney, Australia Agriculture 6th IFAC Conference on Sensing, Control and Automation for December 4-6, Australia December Agriculture4-6, 2019. Sydney, Australia December 4-6, 2019. Sydney, Australia
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IFAC PapersOnLine 52-30 (2019) 306–311 Effect of Shaking Amplitude and Capturing Height on Mechanical Harvesting of Effect of Shaking Amplitude and Capturing Height on Mechanical Harvesting of Fresh Market Apples Effect of Shaking Amplitude and Capturing Height on Mechanical Harvesting of Fresh Market Apples Effect of Shaking Amplitude and Capturing Height on Mechanical Harvesting of Fresh Market Apples FreshLong Market Han Fu*, Jieli Duan**, Manoj Karkee***, He****,Apples Hongmei Xia*, Jun Li*, Qin Zhang***
Han Han Fu*, Fu*, Jieli Jieli Duan**, Duan**, Manoj Manoj Karkee***, Karkee***, Long Long He****, He****, Hongmei Hongmei Xia*, Xia*, Jun Jun Li*, Li*, Qin Qin Zhang*** Zhang*** Han Fu*, Jieli Duan**, Manoj Karkee***, Long He****, Hongmei Xia*, Jun Li*, Qin Zhang*** * College Engineering, South China Hongmei Agricultural University. Han Fu*, Jieli Duan**, Manoj of Karkee***, Long He****, Xia*, Jun Li*, Qin Zhang*** ** College College of of Engineering, Engineering, South South China China Agricultural Agricultural University. University. * College of Engineering, South China Agricultural University. ** Engineering Fundamental Teaching and Training Center, South China Agricultural University ** Teaching and Training Center, South Agricultural ** Engineering Engineering Fundamental Fundamental Teaching andSouth Training Center, South China China Agricultural University University *Precision College ofand Engineering, China Agricultural University. ** *** Engineering Fundamental Teaching and Training Center, SouthWashington China Agricultural University Center for Automated Agricultural Systems, State University *** Center for Precision and Automated Agricultural Systems, Washington State University *** Center for Precision and Automated Agricultural Systems, Washington State University ** Engineering Fundamental Teaching and Training Center, South China Agricultural University ***of Center for Precision and Automated Agricultural Systems, Washington State University ****Department Agricultural and Biological Engineering, Fruit Research and Extension Center, Pennsylvania State ****Department of of Agricultural Agricultural and and Biological Biological Engineering, Engineering, Fruit Fruit Research Research and and Extension Extension Center, Center, Pennsylvania Pennsylvania State State ****Department University *** Center for Precision and Automated Agricultural Systems, Washington State University ****Department of Agricultural and Biological Engineering, Fruit Research and Extension Center, Pennsylvania State University University Jieli Duan (Tel:+86-020-85286120; [email protected]); ****Department Corresponding of Agricultural author: and Biological Engineering, Fruit Research and Extension Center, Pennsylvania State University Corresponding author: author: Jieli Jieli Duan Duan (Tel:+86-020-85286120; (Tel:+86-020-85286120; [email protected]); [email protected]); Corresponding University Co-corresponding Karkee (Tel: +01-509-786-9208; [email protected]) Corresponding author: Manoj Jieli Duan (Tel:+86-020-85286120; [email protected]); Co-corresponding author: author: Manoj Manoj Karkee Karkee (Tel: (Tel: +01-509-786-9208; +01-509-786-9208; [email protected]) [email protected]) Co-corresponding Corresponding author: Jieli Duan (Tel:+86-020-85286120; [email protected]); Co-corresponding author: Manoj Karkee (Tel: +01-509-786-9208; [email protected]) Co-corresponding author: Manoj Karkee (Tel: +01-509-786-9208; [email protected]) Abstract: This study evaluated the effect of shaking amplitude and capturing height on mechanical Abstract: This This study study evaluated evaluated the the effect effect of of shaking shaking amplitude amplitude and and capturing capturing height height on on mechanical mechanical Abstract: harvesting of fresh market apples in trellis trained trees. A linear-forced limb shaker with adjustable Abstract: This study evaluated the effect of shaking amplitude and capturing height on mechanical harvesting of fresh market apples in trellis trained trees. A linear-forced limb shaker with adjustable harvesting of freshand market appleswas in designed trellis trained trees. A linear-forced limb shaker with adjustable shaking amplitude frequency and fabricated. Shaking amplitudes of 20, 25, 30, 35 and harvesting of fresh market apples in trellis trained trees. A linear-forced limb shaker with adjustable Abstract: This study of shaking amplitude and capturing shaking amplitude and evaluated frequency the was effect designed and fabricated. fabricated. Shaking amplitudesheight of 20, 20, on 25,mechanical 30, 35 35 and and shaking amplitude and frequency was designed and Shaking amplitudes of 25, 30, 40 mm were accessible. A catcher filled with 50 mm thickness of peanut foam underneath a piece of shaking amplitude and frequency was designed and fabricated. Shaking amplitudes of 20, 25, 30, 35 and harvesting of fresh market apples in trellis trained trees. A linear-forced limb shaker with adjustable 40 mm were accessible. A catcher filled with 50 mm thickness of peanut foam underneath a piece of 40 mmwas were accessible. Ashaker catcherand filled with 50mounted mm thickness of peanut foam underneath aintegrated piece of cotton developed. The the catcher on a movable lifting platform were shaking amplitude and The frequency was designed and fabricated. amplitudes of 20,were 25, 30, 35 and 40 mmwas were accessible. Ashaker catcher filled with 50 mm thickness of peanut foam underneath aintegrated piece of cotton was developed. The shaker and the catcher catcher mounted on aaShaking movable lifting platform were integrated cotton developed. and the mounted on movable lifting platform into a shake-and-catch harvesting system. The approximate middle ofpeanut a targeted limb waswere selected as the 40 mm were accessible. A catcher filled with 50 mm thickness of foam underneath a piece of cotton was developed. The shaker and the catcher mounted on a movable lifting platform integrated into aa shake-and-catch shake-and-catch harvesting harvesting system. system. The The approximate approximate middle middle of of aa targeted targeted limb limb was was selected selected as as the the into shaking point and detached fruits were captured underneath the targeted section. The overall cotton was developed. The shaker and the catcher mounted on a movable lifting platform were integrated into a shake-and-catch harvesting system. The approximate middle of a targeted limb was selected as the shaking point point and and detached detached fruits fruits were were captured captured underneath underneath the the targeted targeted section. section. The The overall overall shaking combinations of five levels of shaking amplitude and two levels of capturing height were tested foroverall ‘Pink into a shake-and-catch harvesting system. Thecaptured approximate middle ofthe a targeted limb wastested selected as the shaking pointof detached fruits were underneath targeted section. Thefor combinations of and five levels levels of shaking shaking amplitude and two levels of capturing height were ‘Pink combinations five of amplitude and two levels of capturing height were tested for ‘Pink Lady’ apple trees trellis trained in a vertical fruiting wall architecture. Shaking frequency with 20 Hz and shaking point and detached fruits were captured underneath the targeted section. The overall combinations of five levels of shaking amplitude and two levels of capturing height were tested for ‘Pink Lady’ apple trees trellis trained in a vertical fruiting wall architecture. Shaking frequency with 20 Hz and Lady’ apple trellisused trained in tests. a vertical wall architecture. Shaking frequency with 20 Hzwere and duration withtrees 5 s were in all Fruitfruiting removal efficiency and fruit quality (USDA standard) combinations of levels of amplitude andwall two levels of capturing height were tested Lady’ apple trellis trained in tests. a vertical architecture. Shaking frequency with 20forHz‘Pink and duration withtrees 5 ssfive were used inshaking all tests. Fruitfruiting removal efficiency and fruit quality (USDA standard) were duration with 5 were used in all Fruit removal efficiency and fruit quality (USDA standard) were adopted to evaluate theused quality oftests. the harvesting system. Statistical analysis shows thatwith fruit20removal duration with 5 s were in all Fruit removal efficiency and fruit quality (USDA standard) were Lady’ apple trees trellis trained in a vertical fruiting wall architecture. Shaking frequency Hz and adopted to evaluate the quality of the harvesting system. Statistical analysis shows that fruit removal adopted towas evaluate the quality of thewith harvesting system. Statistical analysisrange; showsthethat fruit removal efficiency significantly improved increase ofefficiency amplitude at afruit certain capturing height adopted to evaluate theused quality oftests. thewith harvesting system. Statistical analysis shows that fruit removal duration with 5 s were in all Fruit removal and quality (USDA standard) were efficiency was significantly improved increase of amplitude at a certain range; the capturing height efficiency wasaffected significantly improved with increase of amplitude at aThe certain range; the capturing height significantly the percentage ofharvesting Extra Fancy grade fruit. results indicated that shaking adopted towas evaluate the of thewith system. Statistical analysis shows fruit efficiency significantly improved increase of amplitude at aThe certain range; thethat capturing height significantly affected thequality percentage of Extra Extra Fancy grade fruit. The results indicated that removal shaking significantly affected the percentage of Fancy grade fruit. results indicated that shaking amplitude with ~30 mm is sufficient to remove majority of fruits in the tested variety; capturing fruits efficiency was significantly improved with increase of amplitude at a certain range; the capturing significantly affected the percentage of Extra Fancy grade fruit. The results indicated that shaking amplitude with with ~30 ~30 mm mm is is sufficient sufficient to to remove remove majority majority of of fruits in the tested variety; capturingheight fruits amplitude fruits inExtra the tested variety; capturing fruits that are much closer to the targeted limb is promising to obtain more Fancy grade fruit. significantly affected the percentage Extra Fancy grade fruit.inExtra The indicated that shaking amplitude with ~30 to mm sufficient toofis majority of fruits the results tested capturing fruits that are much much closer to theistargeted targeted limb isremove promising to obtain obtain more Extra Fancy variety; grade fruit. that are closer the limb promising to more Fancy grade fruit. amplitude with ~30 mm is sufficient to remove majority of fruits in the tested variety; capturing that are much closer to the targeted limb is promising to obtain more Extra Fancy grade fruit. © 2019, IFACtree (International Federation of Automatic Hosting by Elsevier Ltd. All rights reserved. fruits Keywords: fruit; shaker; catcher; mechanicalControl) harvesting; removal efficiency; fruit quality. Keywords: treecloser fruit;to shaker; catcher; mechanical harvesting; removal efficiency; fruit quality. that are much the targeted limb is promising to obtainremoval more Extra Fancyfruit gradequality. fruit. Keywords: tree fruit; shaker; catcher; mechanical harvesting; efficiency; Keywords: tree fruit; shaker; catcher; mechanical harvesting; removal efficiency; fruit quality. Keywords: tree fruit; shaker; catcher; mechanical harvesting; removal efficiency; fruit quality. not been achieved for fresh market due to the low removal 1. INTRODUCTION not been been achieved achieved for for fresh fresh market market due due to to the the low low removal removal not efficiency and severe fruit damage (Zhang al., low 2016;removal Zhang 1. INTRODUCTION 1. INTRODUCTION not been achieved forfruit fresh market due toet the efficiency and severe fruit damage (Zhang et al., 2016; Zhang efficiency and severe damage (Zhang et al., 2016; Zhang 1. INTRODUCTION et al., 2018). World of fresh market apples produced 83.1 million tons efficiency not been achieved forfruit fresh market due toet the and severe damage (Zhang al., low 2016;removal Zhang et al., 2018). et al., 2018). World of fresh market apples produced 83.1 million tons 1. 2017. INTRODUCTION World of fresh market apples produced 83.1 million (FAOSTAT, 2017) in Currently, these fresh applestons are efficiency and severe (Zhang harvesting et al., 2016; mainly Zhang et al., 2018). World of fresh market apples produced 83.1 million tons Previous studies on fruit fruitdamage mechanical (FAOSTAT, 2017) in Currently, these fresh apples are (FAOSTAT, 2017)which in 2017. 2017. Currently, these fresh (He apples are picked manually, needs a huge of labour et al., Previous studies on fruit mechanical harvesting mainly et al., 2018). Previous studies on fruit mechanical harvesting mainly (FAOSTAT, 2017) in 2017. Currently, these fresh apples are World of fresh market apples 83.1 million onstudies shakingonthefruit tree trunk/bough obtain high fruit picked manually, which needs aaproduced huge labour (He al., picked In manually, which needs huge of ofwage labour (He et ettons al., focused mechanical to harvesting mainly 2019). recent ten the of labour focused on on shaking shaking the the tree tree trunk/bough trunk/bough to obtain high high fruit focused to obtain fruit picked manually, which needs aaverage huge these ofwage labour (He et use al., Previous (FAOSTAT, 2017) inyears, 2017. Currently, fresh apples are removal efficiency (Pellerin et al., 1982; Peterson and 2019). In In recent ten years, the average of labour labour use 2019). recent ten years, the average wage of use Previous studies on fruit mechanical harvesting mainly focused on shaking the tree trunk/bough to obtain high fruit increased over 30% (USDA-NASS, 2019). The decreasing removal efficiency (Pellerin et al., 1982; Peterson and efficiency (Pellerin et al.,fruits 1982; Peterson and picked manually, which needs huge2019). ofwage labour (He et use al., removal 2019). In recent30% ten years, the aaverage of labour Wolford, 2003). However, massive falling in a very increased over 30% (USDA-NASS, 2019). The decreasing increased over (USDA-NASS, The decreasing removal efficiency (Pellerin et al., 1982; Peterson and focused on shaking the tree trunk/bough to obtain high fruit availability of skilled labor and increasing cost has threatened Wolford, 2003). However, massive fruits falling in a very 2003). massive offruits falling a very 2019). In over recent ten years, the increasing average wage of labour use Wolford, increased 30% (USDA-NASS, 2019). decreasing short timeefficiency causedHowever, a (Pellerin large number contacts of in apple-toavailability of skilled skilled labor and increasing costThe has threatened availability of labor and cost has threatened massive falling a very removal et al., 1982; Peterson and the sustainability of apple industry (Zhang andThe Karkee, 2016). Wolford, short time time2003). causedHowever, a large large number number offruits contacts of inapple-toapple-toshort caused a of contacts of increased over 30% (USDA-NASS, 2019). decreasing availability of skilled labor and increasing cost has threatened apple and apple-to-branch (Peterson, 2005), resulting in the sustainability sustainability of of apple apple industry industry (Zhang (Zhang and and Karkee, Karkee, 2016). 2016). Wolford, the short time caused a large number of contacts of apple-to2003). However, massive fruits falling in a very The technological innovations need to be carried out to apple and apple-to-branch (Peterson, 2005), resulting in apple and apple-to-branch (Peterson, 2005), resulting in availability of skilled labor and increasing cost has threatened the sustainability of apple industry (Zhang and Karkee, 2016). excessive fruit damage. To reduce damage, some researcher The technological innovations need to be carried out to The technological innovations need to be carried out to apple short time caused a large number of contacts ofresearcher apple-toandfruit apple-to-branch (Peterson, 2005), resulting in reduce the dependence on manual labor. excessive fruit damage. To reduce damage, some researcher excessive damage. To reduce damage, some the sustainability of innovations apple industry (Zhang andcarried Karkee,out 2016). The technological need to be to designed a single capturing frame with major branch shaking reduce the on labor. reduce the dependence dependence on manual manual labor. apple andafruit apple-to-branch (Peterson, 2005), resulting in excessive damage. To frame reduce damage, some researcher designed single capturing frame with major branch shaking single capturing with major branch shaking reduce the dependence on manual labor. The technological innovations need to be carried out to designed for trellisaafruit trained trees To (Peterson and Wolford, 2003), and Mechanical harvesting is one of the most commonly excessive damage. reduce damage, some researcher designed single capturing frame with major branch shaking for trellis trellis trained trained trees trees (Peterson (Peterson and and Wolford, Wolford, 2003), 2003), and and for Mechanical harvesting is one of most reduce the dependence labor. Mechanical harvesting ismanual one crops. of the the most commonly commonly developed capturing frame used for inserting investigated method forontree Vibratory or shaking some designed a trained singlemulti-tier capturing frame with major branch shaking for trellis trees (Peterson and Wolford, 2003), and Mechanical harvesting is fruit one crops. of the most commonly some developed multi-tier capturing frame used for inserting some developed multi-tier capturing frame used for inserting investigated method for tree fruit Vibratory or shaking investigated is method for treeused fruit crops. Vibratory or shaking canopy for conventional trees (Millier et al., 1973). Today, harvesting a widely approach in mechanical trellis trees (Peterson and Wolford, 2003), and some developed multi-tier capturing frame used for inserting investigated method for tree fruit Vibratory or shaking for canopy fortrained conventional trees (Millier et al., 1973). Today, Mechanical harvesting is used one crops. of the most commonly canopy for conventional (Millier et the al., 1973). Today, harvesting is is widely used approach in mechanical mechanical harvesting aa applies widely approach in apple orchards are plantedtrees increasingly in simple, narrow, harvesting, which kinetic energy to fruit branches to canopy for conventional trees (Millier et the al., 1973). Today, some developed multi-tier capturing frame used for inserting apple orchards are planted increasingly in simple, narrow, investigated method for tree fruit crops. Vibratory or shaking harvesting is a widely used approach in mechanical orchards are planted increasingly the simple, narrow, harvesting, which which applies applies kinetic kinetic energy energy to to fruit fruit branches branches to to apple harvesting, accessible, productive (SNAP) treein canopy architectures generate detaching force fruit-stem system (Erdoğan et al., orchards are plantedtrees increasingly the narrow, canopy for and conventional (Millier et al.,simple, 1973). Today, accessible, and productive (SNAP) treein canopy architectures harvesting is a applies widelyfor used approach in mechanical harvesting, which kinetic energy to fruit branches to apple accessible, and productive (SNAP) tree canopy architectures generate detaching detaching force for fruit-stem system (Erdoğan et al., al., generate force for fruit-stem system (Erdoğan et (i.e., vertical fruiting wall), which creates an opportunity for 2003). Research on shake-and-catch harvesting for tree fruit accessible, and productive (SNAP) tree canopy architectures apple orchards are planted increasingly in the simple, narrow, (i.e., vertical fruiting wall), which creates an opportunity for harvesting, which applies kinetic energy to fruit branches to generate detaching force for fruit-stem system (Erdoğan et al., (i.e., vertical fruiting wall), which creates an opportunity for 2003). Research Research on on shake-and-catch shake-and-catch harvesting harvesting for for tree tree fruit fruit shaking limb and capturing fruits closely to the targeted limb 2003). crops such as apples (Peterson et al., harvesting 1999; He(Erdoğan et al., 2018), accessible, and productive tree canopy architectures (i.e., vertical fruiting wall),(SNAP) whichclosely creates anthe opportunity for shaking limb and capturing fruits closely to the targeted limb generate detaching force for fruit-stem system et al., 2003). Research on shake-and-catch for tree fruit shaking limb and capturing fruits to targeted limb crops such as apples (Peterson et al., 1999; He et al., 2018), crops such as apples (Peterson al., 1999; et al., 2018), 2015). This type to of tree architecture cherries (Zhou eton al.,shake-and-catch 2014), andet (Liu He et al., 2018) has (De (i.e.,Kleine vertical fruiting wall), which creates anthe opportunity for shaking limband andKarkee, capturing fruits closely targeted limb (De Kleine and Karkee, 2015). This type of of tree architecture 2003).such Research foral., tree fruit crops as apples (Peterson etcitrus al., harvesting 1999; He et 2018), (De Kleine and Karkee, 2015). This type tree architecture cherries (Zhou et al., 2014), and citrus (Liu et al., 2018) has cherries (Zhou et al., 2014), and citrus (Liu et al., 2018) has was friendly for shake-and-catch harvesting (He et al., 2017b, been conducting for decades. It has been succeeded for nuts, shaking limb and capturing fruits closely to the targeted limb (De Kleine and Karkee, 2015). This type of tree architecture cherries (Zhou et al., 2014), and citrus (Liu et al., 2018) has was friendly friendly for for shake-and-catch shake-and-catch harvesting harvesting (He (He et et al., al., 2017b, 2017b, crops conducting such as apples (PetersonIt al.,been 1999; He et al.,for was been for decades. succeeded nuts, been conducting forcrops decades. It ethas has been succeeded for2018), nuts, 2018, 2019; and Ma et al., 2018). berries and other targeted primarily for processing (De friendly Kleine 2015). This type of(He treeetarchitecture was for Karkee, shake-and-catch harvesting al., 2017b, been conducting for decades. It has been succeeded for nuts, 2018, 2019; Ma et al., 2018). cherries (Zhou et al., 2014), and citrus (Liu et al., 2018) has 2018, 2019; Ma et al., 2018). berries and other crops targeted primarily for processing berries (Chen and other crops targeted primarily for success processing market et al., 2011). However, commercial has 2018, for et shake-and-catch harvesting (He et al., 2017b, 2019; Ma al., 2018). berries and other targeted for success processing been conducting forcrops decades. It has primarily been succeeded for nuts, market (Chen et al., al., 2011). However, commercial has was friendly market (Chen et 2011). However, commercial success has berries and other for success processing market (Chen et al.,crops 2011).targeted However,primarily commercial has 2018, 2019; Ma et al., 2018). Copyright © 2019 2405-8963 © 2019, IFAC (International Federation of Automatic market (Chen et IFAC al., 2011). However, commercial successControl) has 306 Copyright © 2019 2019 IFAC 306Hosting by Elsevier Ltd. All rights reserved. Copyright © IFAC 306 Peer review under responsibility of International Federation of Automatic Control. Copyright © 2019 IFAC 306 10.1016/j.ifacol.2019.12.553 Copyright © 2019 IFAC 306
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The fruit removal force and fruit quality are primarily determined by shaking frequency, amplitude, and duration (Loghavi and Mohseni, 2007; Zhou et al., 2013, 2014). The capturing height determines the impact of fruit onto the catching surface and thus affects the fruit quality. The effect of shaking frequency and duration on mechanical harvesting of fresh market apples in the vertical fruiting wall architecture had been investigated (He et al., 2017b, 2019). The objectives of this study were (1) to develop a localized shake-and-catch harvesting system; and (2) to evaluate the performance in terms of fruit removal efficiency and quality with different shaking amplitudes, capturing heights and their interaction in a commercial apple orchard.
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was filled with 50 mm thickness of peanut foam underneath a piece of cotton. The peanut foam was used to reduce the impact and prevent fruits from rolling to minimze fruit bruising on the catching surface. The shaker and catcher were mounted on a mobile lifting platform to integrate a localized harvesting system (Fig. 3).
2. MATERIALS AND METHODS Fig. 2. Prototype of a linear-forced limb shaker with adjustable shaking amplitude and frequency.
2.1 Concept of the Localized Shake-and-catch Harvesting Vertical fruiting wall (Fig. 1) is a typical architecture of modern apple orchard, in which the trees are trained into horizontal tiers using trellis wires. Those horizontally growing limbs reduces the overlapping and crossing of branches in conventional trees and thus has better machine accessibility. To achieve desired fruit quality level with mechanical harvesting, the concept of localized shake-andcatch harvesting that shaking limb and capturing detached fruits closely to the targeted limb was proposed by our team.
Fig. 3. General view of the prototype of the localized shakeand-catch harvesting system. 2.3 Tested Orchard and Experiment Design To evaluate the developed shake-and-catch harvesting system (Fig. 3), a series of field tests ware conducted in a commerial ‘Pink Lady’ apple orchard near Othello, Washington, during the 2015 grower-identified apple harvest season. The trees in this orchard were trained to a vertical fruiting wall architecture (Fig. 1), in which seven horizontal tiers of limbs were trained using seven trellis wires. For the uniformity of the tree architecture, limbs at different tiers could be viewed as similar. For each tier, two limbs trained to trellis wire grows oppositely along the tree row. Trees grow in a relatively flat terrain with dimension of inter-row x intra-row spacing of 4.0 m x 1.5 m. The overall height of the trees was about 4 m and each tier was about 0.5 m. To simplify the experimental process, only limbs from 2nd to 4th tier were used in this study. The mean with standard deviation of the test limbs is 10.4 ± 2.3 mm in diameter. The tests were conducted in the morning to avoid the high temperature on fruit removal and post-removal fruit quality.
Fig. 1. A vertical fruiting wall apple orchard. 2.2 Development of a Localized Shake and Catch Harvesting System A linear-forced limb shaker with adjustable shaking frequency and amplitude was designed and fabricated for (Fig. 2). The shaker mainly consisted of a frame, flywheel, crank, connecting rod and U-shaped hook head. A slidercrank mechansim with variable crank length was used to generate an oscillating motion at the desired amplitudes. A cardan universal joint was used for this connection to provide enough spatial flexibility for the rod. The shaker was powered by a DC motor (7200, AMETEK, Inc, Berwyn, Pennsylvania, U.S.) with corresponding speed controller. Shaking amplitudes of 20, 25, 30, 35 and 40 mm were accessible by manually connecting the crank to various points located at radial distances of 10, 12.5, 15, 17.5, and 20 mm. A catcher with dimension of 1000 mm length x 600 mm width x 150 mm height was developed using a cardboard and
Preliminary tests suggested that the apples could detach from branches with the shaking amplitudes of 20, 25, 30, 40 and 45 mm. Due to available space limit between two adjacent tiers, the capturing heights close to the targeted limb were tested two levels of 108 and 370 mm. This experiments evaluated the overall treatment combinations of the five 307
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levels of shaking amplitude and two levels of capturing height on mechanical harvesting. Total sixty with six limbs for each were randomly selected for the ten treatment combinations in this study. Previous study (He et al., 2017b) showed that most of the fruits could be removed from limb and reserved good quality with a shaking frequency of 20 Hz and a duration of 5 s. The same treatment was adopted in this study. The shaking points generally focused on the approximate middle of the targeted limbs. Each targeted limb composed a localized harvesting section, as shown in Fig. 4. One localized section was selected to harvest at a time, and the catcher was placed underneath the targeted section. The next section was tested only after the apple fruits were manually picked out of the catching surface. The harvesting system was manually moved from one section to another.
Where ηc is the fruit collection efficiency (%); Nc is the number of fruit collected by the catcher. Fruit recovery efficiency indicates the collected fruit with respect to the overall fruits on a test section, which could be calculated by multiplying the fruit removal efficiency and fruit collection efficiency, as shown in Equation (3).
η= ηr ⋅ ηc o Where ηo is the fruit recovery efficiency (%). Fruit Quality Assessment
After tests, the harvested fruits were carefully transported to the laboratory for quality assessment. It was completed after 24 h of storage in room temperature of ~22℃. According to USDA fresh market standard, fruit quality was categorized into different grades as illustrated in Table 1 (Peterson et al., 2010). In the standard, fruit quality is classified into three major categories: Extra Fancy, Fancy, and Downgrade. The percentage of each category was defined by Equation (4). The percentage of Fresh-marketable fruit is the sum of those in Extra Fancy and Fancy categories.
ηd =
Bruise Specifications [mm for diameters (D) or mm2 for total areas (A)] 1 Extra Fancy No injury 2 Extra Fancy D ≤ 3.2 Extra Fancy 3 3.2 < D ≤ 6.4 Extra Fancy 6.4 < D ≤ 12.7 or A ≤ 4 127 12.7 < D ≤ 19.0 or 127 < 5 Fancy A ≤ 285 6 Downgrade D > 19.0 or A > 285 Cuts or punctures of any 7 Downgrade size The diameter of bruise was measured using a vernier caliper under a fluorescent. If there are several bruises on an apple, the total area of the bruises was calculated. Since bruise is generally elliptical (Bollen et al., 1999), the bruise area is calculated by Equation (5). No. Assigned to Class
2.4 Harvesting Performance Fruit Removal and Collection Efficiency Fruit removal efficiency was defined as the percentage of the number of fruit mechanically harvested based on the total number of fruit growing on a test limb. It was determined by Equation (1). (1)
Where ηr is the fruit removal efficiency (%); Nr is the number of fruit mechanically harvested; N is the total number of fruit growing on the test limb. Some detached fruits may drop out of the catching frame. A fruit collection efficiency was defined as the percentage of fruit collected by the catcher based on the total number of fruit removed by the shaker from the test limb. It was given by Equation (2).
N ηc = c x 100 Nr
(4)
Table 1. USDA standard and class for fresh market apples
The numbers of harvested fruit and collected fruit were counted. The fruit removal efficiency, collection efficiency, and fruit quality were analyzed using ANOVA (Duncan’s method) at a significant level of 0.05 in SPSS 17.0 software.
Nr x 100 N
Nd x 100 N
Where ηd is the percentage of harvested fruit in a fruit quality category (%); Nd is the number of fruit in a quality category; N is the total number of harvested fruit in a test.
Fig. 4. Schematic of the localized harvesting section. The tree limbs are trellis trained into horizontally growing.
ηr =
(3)
USDA Standard
A=
π 4
ab
(5)
Where A is the bruise area; a is the major diameter of the bruise; b is the minor diameter of the bruise.
(2)
3. RESULTS AND DISCUSSION 308
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Fig. 6 shows the fruit quality when each level of shaking amplitude was taken as one sample. As shown in this figure, shaking amplitude had an effect on percentage of Extra Fancy grade fruit. The percentages of fruit at Extra Fancy level were 81%, 73%, 70%, 69% and 70%, respectively for the five shaking amplitudes. The corresponding percentages of Fresh-marketable grade fruit were 93%, 92%, 82%, 85% and 90%. When we inspect the Downgrade percentage, the corresponding values were 8%, 8%, 17%, 16% and 10%. There was about 9% more fruit in the Downgrade level when shaking with 30 mm amplitude compared to 20 mm amplitude. Although the shaking amplitude did not generate significant difference in terms of percentage of each of the three major fruit quality grades, the percentage of Extra Fancy grade fruit had negatively relation with corresponding fruit removal efficiency.
3.1 Fruit Removal Efficiency and Collection Efficiency Since no fruits dropped out of the catching frame, it is no necessary to discuss the collection efficiency. Fruit recovery efficiency thus depends on the fruit removal efficiency. The removal efficiency was calculated from the field data using Equation (1). Since the capturing height has no relation with fruit detaching, each level of shaking amplitude was taken as one sample. Fig. 5 shows the fruit removal efficiency under different shaking amplitudes with respect to individual sections. As shown in this figure, the average of fruit removal efficiency was 70%, 80% and 94% respectively with shaking amplitude of 20 mm, 25 mm and 30 mm. The removal efficiency was significantly increased among the three shaking amplitudes. The best value of fruit removal efficiency was similar to that obtained in previous study at the similar treatments (He et al., 2017b). The unremoved fruits normally hang on the long thin twigs and the observation was the same with previous study (He et al., 2017a, 2019).
Fig. 6. Fruit quality in different grades under different levels of shaking amplitudes with respect to individual sections. Treatments ‘A1’, ‘A2’, ‘A3’, ‘A4’ and ‘A5’ respectively represent shaking amplitudes of 20, 25, 30, 35 and 40 mm. Statistical analysis was only done within the same grade of fruit quality.
Fig. 5. Fruit removal efficiency under different levels of shaking amplitude with respect to individual sections. Treatments ‘A1’, ‘A2’, ‘A3’, ‘A4’ and ‘A5’ respectively represent shaking amplitudes of 20, 25, 30, 35 and 40 mm.
Fig. 7 shows the fruit quality with respect to individual sections when each level of capturing height was taken as one sample. The percentages of Extra Fancy quality grade fruit were 78% and 66% respectively for the low and high capturing patterns. Relatively high percentage of Extra Fancy quality grade fruit was obtained when capturing fruits was much closer to the targeted limb. However, this situation was reverse for percentages of Fancy quality grade fruit. The percentages of each of the two quality grades have significant differences. In terms of Downgrade grade, the percentages were 9% and 14% respectively for the low and high level of capturing patterns and there was about 5% less fruit when capturing fruit was much closer to the targeted limb. However, the capturing height didn’t significantly affect the percentage of Downgrade grade fruit between the two levels of height. In other words, the capturing height didn’t generate significant differences for the percentage of Freshmarketable quality grade fruit. The higher capturing height means higher impact energy, which would result in larger percentage of Fancy or Downgrade grade fruit (Fu et al., 2016, 2017). Therefore, to obtain higher grade of fruit quality, capturing fruit at a much closer positon to targeted limb could be recommended for the shake-and-catch harvesting system.
Fig. 5 also shows that fruit removal efficiency slightly decreased when shaking amplitude continued increasing, although no significant difference was found among the three treatments. While the fruit detached force is proportional to the amplitude, the targeted limb was constrained by the trained trellis wire that limited the deformation of the targeted limb. In addition, the larger deformation of the targeted limb not only causes itself more easily to injury but also generates larger resistance to the shaker, which could reversely lower the performance of the shaker. Therefore, these results indicate that the suitable shaking amplitude should be around 30 mm for the special ‘Pink Lady’ apple cultivar with vertical fruiting wall architecture in terms of fruit removal efficiency. 3.2 Fruit Quality Assessment After field tests, those apples were carefully transported to the laboratory for fruit quality assessment according to USDA fresh market standard. We respectively evaluated the effect of shaking amplitude, capturing height and their interaction on fruit quality.
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the view of fruit removal efficiency, the suitable shaking amplitude should be around 30 mm. In terms of fruit quality, the patterns of the percentage of Extra Fancy grade fruit had negatively relation on the corresponding fruit removal efficiency, although no significant differences of the percentage of Extra Fancy grade fruit were found among the five shaking patterns. If the shaker could gradually increase its amplitude automatically, both high fruit efficiency and good fruit quality may be achieved. In addition, capturing fruits much closer to the targeted limb decreased the strength of impact of the fruits to the catching surface or other fruits on the surface. Compared to our previous study (He et al., 2017b), we found that 94% of fruit could still maintain fresh market grade without rolling and bounce buffers used in previous handheld shake-and-catch harvesting system. There was only 0.7% difference for the percentage of Extra Fancy grade fruit between previous and current studies. The comparison of the two studies indicate that the two buffers may not function primarily on maintaining fresh market quality grade and new strategy for reducing fruit damage may need to be reconsidered. Besides, the shaking was manually controlled and the errors was inevitable for each test. The fruits on the catching surface had to be manually transferred to a collector one by one, which reduced the harvesting efficiency. Modification of the harvesting system with timing controlling and fruits automated transferring will be considered in our future study.
Fig. 7. Fruit quality under different capturing patterns with respect to individual sections. Treatments ‘Low’ and ‘High’ respectively represent two levels of capturing height close to the targeted limb. Statistical analysis was only done within the same grade of fruit quality. Fig. 8 shows the fruit quality when each combination between shaking amplitude and capturing height was taken as sample. The figure shows that the combination has a significant effect on percentages of fruit in the Extra Fancy quality grade. The percentages of fruit at Extra Fancy grade were 84%, 78%, 81%, 64%, 73%, 68%, 78%, 60%, 75% and 63% under shaking patterns of ‘A1-L’, ‘A1-H’, ‘A2-L’, ‘A2H’, ‘A3-L’, ‘A3-H’, ‘A4-L’, ‘A4-H’, ‘A5-L’ and ‘A5-H’, respectively. The corresponding percentages of Freshmarketable quality fruit were 93%, 94%, 94%, 89%, 82%, 84%, 90%, 79%, 94%, and 85%. Significant differences of the percentage of the Extra Fancy grade fruit only exist in the two combination treatments of ‘A1-L’ and ‘A4-H’. When we look into the Downgrade percentage, the corresponding values were 7%, 6%, 6%, 11%, 18%, 16%, 10%, 21%, 6% and 15%. There was about 15% more fruit in the Downgrade level at shaking pattern of ‘A4-H’ compared to ‘A1-H’ or ‘A2-L’.
4. CONCLUSIONS This study developed a localized shake-and-catch harvesting system for trellis trained apple trees and investigated the effect of shaking amplitude and capturing height on mechanical harvesting. A series of field harvesting tests were conducted on a vertical fruiting wall tree architecture of ‘Pink Lady’ apples. Fruit removal efficiency and fruit quality according to USDA fresh market standard were used to evaluate the harvesting system. A few conclusions were summarized as follows: 1.
Fruit removal efficiency was significantly improved with the increase of shaking amplitude at a certain range for such apple trees. Relative high fruit removal efficiency of 94% was achieved with a shaking amplitude of 30 mm. 2. The capturing height significantly affected fruit quality in terms of percentage of Extra Fancy grade fruit. To obtain higher percentage of Extra Fancy grade fruit, capturing fruit at a much closer position to the targeted limb was recommended for the localized shake-andcatch harvesting system. 3. The percentage of Extra Fancy quality grade fruit had negatively relation on corresponding fruit removal efficiency. The harvesting system achieved an Extra Fancy quality grade fruit of 84% and Fresh-marketable quality grade fruit of 94%. This study showed a very promising mechanical harvesting solution for such apple trees with expected fruit quality. In future study, the effect of new shaking patterns of the combination of amplitude, frequency and duration on mechanical harvesting will be considered.
Fig. 8 Fruit quality under different treatment combinations between shaking amplitude and capturing height with respect to individual sections. Statistical analysis was only done within the same grade of fruit quality. According to the results, the increase of shaking amplitude in a certain range significantly improved the fruit removal efficiency. The relatively high removal efficiency with 94% was obtained for the test variety ‘Pink Lady’ at the shaking amplitude of 30 mm. The value was just less 1% compared to that obtained in our previous study with a 32 mm shaking amplitude (He et al., 2017b). When the shaking amplitude was increased further, we observed that shaker’s performance was lowered and intermittent vibration occurred. If things continue this way, the shaker’s life cycle will be reduced and the potential damage to targeted limb will be increased. From 310
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Loghavi, M., and Mohseni, S. (2007). The effects of shaking frequency and amplitude on detachment of lime fruit. Iran Agricultural Research, 24(1.2), 27-38. Ma, S., Karkee, M., Fu, H., Sun, D., and Zhang, Q. (2018). Evaluation of shake-and-catch mechanism in mechanical harvesting of apples. Transactions of the ASABE, 61(4), 1257-1263. Millier, W. F., Rehkugler, G. E., Pellerin, R. A., Throop, J. A., and Bradley, R. B. (1973). Tree fruit harvester with insertable multilevel catching system. Transactions of the ASAE, 16(5), 844-850. Pellerin, R. A., Millier, W. F., Throop, J. A., Lakso, A. N., and Carpenter, S. G. (1982). Apple harvesting with a double impact trunk shaker. Transactions of the ASAE, 25(6), 1567-1574. Peterson, D. L., Bennedsen, B. S., Anger, W. C., and Wolford, S. D. (1999). A systems approach to robotic bulk harvesting of apples. Transactions of the ASAE, 42(4), 871. Peterson, D. L. and Wolford, S. D. (2003). Fresh–market quality tree fruit harvester part II: apples. Applied engineering in agriculture, 19(5), 545. Peterson, D. L. (2005). Harvest mechanization progress and prospects for fresh market quality deciduous tree fruits. HortTechnology, 15(1), 72-75. Peterson, D. L., Tabb, A. L., Baugher, T. A., Lewis, K., & Glenn, D. M. (2010). Dry bin filler for apples. Applied Engineering in agriculture, 26(4), 541. USDA-NASS. 2019. Farm Labor. Available on: https://usda.library.cornell.edu/concern/publications/x92 0fw89s?locale=en&page=2#release-items. Access on: 7/13/2019. Zhang, Z., Heinemann, P. H., Liu, J., Baugher, T. A., and Schupp, J. R. (2016). The development of mechanical apple harvesting technology: A review. Transactions of the ASABE, 59(5), 1165-1180. Zhang, Q. and Karkee, M. (2016). Fully automated tree fruit harvesting. Resource magazine, 23(6): 16-17. Zhang, X., He, L., Majeed, Y., Whiting, M. D., Karkee, M., and Zhang, Q. (2018). A precision pruning strategy for improving efficiency of vibratory mechanical harvesting of apples. Transactions of the ASABE, 61(5): 1565-1576. Zhou, J., He, L., Zhang, Q., Du, X., Chen, D., and Karkee, M. (2013). Evaluation of the influence of shaking frequency and duration in mechanical harvesting of sweet cherry. Applied engineering in agriculture, 29(5), 607-612. Zhou, J., He, L., Zhang, Q., and Karkee, M. (2014). Effect of excitation position of a handheld shaker on fruit removal efficiency and damage in mechanical harvesting of sweet cherry. Biosystems engineering, 25, 36-44.
This research was supported partially by Natural Science Foundation of China (Grant No. 51905179), Research and Development Plan in Key Areas of Guangdong Province (2019B020223002), Science and Technology Planning Project of Guangdong Province (2018A070717019), USDA’s Hatch and Multistate Project Funds (1005756 and 1001246), USDA National Institutes for Food and Agriculture competitive grant (1005200), Agricultural Science and Technology Achievements promotion of Guangdong Province (2018LM2162), Washington State University (WSU) Agricultural Research Center (ARC). Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the authors and do not necessarily reflect the view of the USDA, WSU or SCAU. REFERENCES Bollen, A. F., Nguyen, H. X., and Rue, B. D. (1999). Comparison of methods for estimating the bruise volume of apples. Journal of agricultural engineering research, 74(4), 325-330. Chen D., Du X., Wang S., Zhang Q. (2011). Mechanism of vibratory fruit harvest and review of current advance. Transactions of the CSAE, 27(8): 195-200. De Kleine, M. E. and Karkee, M. (2015). A semi-automated harvesting prototype for shaking fruit tree limbs. Transactions of the ASABE, 58(6), 1461-1470. Erdoǧan, D., Güner, M., Dursun, E., and Gezer, I. (2003). Mechanical harvesting of apricots. Biosystems engineering, 85(1), 19-28. FAOSTAT. Crops. http://www.fao.org/faostat/en/#data/QC. Access on: 10/12/2019. Fu, H., He, L., Ma, S., Karkee, M., Chen, D., Zhang, Q., and Wang, S. (2016). Bruise responses of apple-to-apple impact. IFAC-PapersOnLine, 49(16), 347-352. Fu, H., He, L., Ma, S., Karkee, M., Chen, D., Zhang, Q., and Wang, S. (2017). ‘Jazz’ apple impact bruise responses to different cushioning materials. Transactions of the ASABE, 60(2), 327-336. He, L., Fu, H., Karkee, M., and Zhang, Q. (2017a). Effect of fruit location on apple detachment with mechanical shaking. Biosystems engineering, 157, 63-71. He, L., Fu, H., Sun, D., Karkee, M., and Zhang, Q. (2017b). Shake-and-catch harvesting for fresh market apples in trellis-trained trees. Transactions of the ASABE, 60(2), 353-360. He, L., Fu, H., Xia, H., Karkee, M., Zhang, Q., and Whiting, M. (2018). Evaluation of a localized shake-and-catch harvesting system for fresh market apples. Agricultural engineering international: CIGR journal, 19(4), 36-44. He, L., Zhang, X., Ye, Y., Karkee, M., and Zhang, Q. (2019). Effect of shaking location and duration on mechanical harvesting of fresh market apples. Applied engineering in agriculture, 35(2), 175-183. Liu, T. H., Luo, G., Ehsani, R., Toudeshki, A., Zou, X. J., and Wang, H. J. (2018). Simulation study on the effects of tine-shaking frequency and penetrating depth on fruit detachment for citrus canopy-shaker harvesting. Computers and electronics in agriculture, 148, 54-62. 311
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IFAC PapersOnLine 52-30 (2019) 306–311 Effect of Shaking Amplitude and Capturing Height on Mechanical Harvesting of Effect of Shaking Amplitude and Capturing Height on Mechanical Harvesting of Fresh Market Apples Effect of Shaking Amplitude and Capturing Height on Mechanical Harvesting of Fresh Market Apples Effect of Shaking Amplitude and Capturing Height on Mechanical Harvesting of Fresh Market Apples FreshLong Market Han Fu*, Jieli Duan**, Manoj Karkee***, He****,Apples Hongmei Xia*, Jun Li*, Qin Zhang***
Han Han Fu*, Fu*, Jieli Jieli Duan**, Duan**, Manoj Manoj Karkee***, Karkee***, Long Long He****, He****, Hongmei Hongmei Xia*, Xia*, Jun Jun Li*, Li*, Qin Qin Zhang*** Zhang*** Han Fu*, Jieli Duan**, Manoj Karkee***, Long He****, Hongmei Xia*, Jun Li*, Qin Zhang*** * College Engineering, South China Hongmei Agricultural University. Han Fu*, Jieli Duan**, Manoj of Karkee***, Long He****, Xia*, Jun Li*, Qin Zhang*** ** College College of of Engineering, Engineering, South South China China Agricultural Agricultural University. University. * College of Engineering, South China Agricultural University. ** Engineering Fundamental Teaching and Training Center, South China Agricultural University ** Teaching and Training Center, South Agricultural ** Engineering Engineering Fundamental Fundamental Teaching andSouth Training Center, South China China Agricultural University University *Precision College ofand Engineering, China Agricultural University. ** *** Engineering Fundamental Teaching and Training Center, SouthWashington China Agricultural University Center for Automated Agricultural Systems, State University *** Center for Precision and Automated Agricultural Systems, Washington State University *** Center for Precision and Automated Agricultural Systems, Washington State University ** Engineering Fundamental Teaching and Training Center, South China Agricultural University ***of Center for Precision and Automated Agricultural Systems, Washington State University ****Department Agricultural and Biological Engineering, Fruit Research and Extension Center, Pennsylvania State ****Department of of Agricultural Agricultural and and Biological Biological Engineering, Engineering, Fruit Fruit Research Research and and Extension Extension Center, Center, Pennsylvania Pennsylvania State State ****Department University *** Center for Precision and Automated Agricultural Systems, Washington State University ****Department of Agricultural and Biological Engineering, Fruit Research and Extension Center, Pennsylvania State University University Jieli Duan (Tel:+86-020-85286120; [email protected]); ****Department Corresponding of Agricultural author: and Biological Engineering, Fruit Research and Extension Center, Pennsylvania State University Corresponding author: author: Jieli Jieli Duan Duan (Tel:+86-020-85286120; (Tel:+86-020-85286120; [email protected]); [email protected]); Corresponding University Co-corresponding Karkee (Tel: +01-509-786-9208; [email protected]) Corresponding author: Manoj Jieli Duan (Tel:+86-020-85286120; [email protected]); Co-corresponding author: author: Manoj Manoj Karkee Karkee (Tel: (Tel: +01-509-786-9208; +01-509-786-9208; [email protected]) [email protected]) Co-corresponding Corresponding author: Jieli Duan (Tel:+86-020-85286120; [email protected]); Co-corresponding author: Manoj Karkee (Tel: +01-509-786-9208; [email protected]) Co-corresponding author: Manoj Karkee (Tel: +01-509-786-9208; [email protected]) Abstract: This study evaluated the effect of shaking amplitude and capturing height on mechanical Abstract: This This study study evaluated evaluated the the effect effect of of shaking shaking amplitude amplitude and and capturing capturing height height on on mechanical mechanical Abstract: harvesting of fresh market apples in trellis trained trees. A linear-forced limb shaker with adjustable Abstract: This study evaluated the effect of shaking amplitude and capturing height on mechanical harvesting of fresh market apples in trellis trained trees. A linear-forced limb shaker with adjustable harvesting of freshand market appleswas in designed trellis trained trees. A linear-forced limb shaker with adjustable shaking amplitude frequency and fabricated. Shaking amplitudes of 20, 25, 30, 35 and harvesting of fresh market apples in trellis trained trees. A linear-forced limb shaker with adjustable Abstract: This study of shaking amplitude and capturing shaking amplitude and evaluated frequency the was effect designed and fabricated. fabricated. Shaking amplitudesheight of 20, 20, on 25,mechanical 30, 35 35 and and shaking amplitude and frequency was designed and Shaking amplitudes of 25, 30, 40 mm were accessible. A catcher filled with 50 mm thickness of peanut foam underneath a piece of shaking amplitude and frequency was designed and fabricated. Shaking amplitudes of 20, 25, 30, 35 and harvesting of fresh market apples in trellis trained trees. A linear-forced limb shaker with adjustable 40 mm were accessible. A catcher filled with 50 mm thickness of peanut foam underneath a piece of 40 mmwas were accessible. Ashaker catcherand filled with 50mounted mm thickness of peanut foam underneath aintegrated piece of cotton developed. The the catcher on a movable lifting platform were shaking amplitude and The frequency was designed and fabricated. amplitudes of 20,were 25, 30, 35 and 40 mmwas were accessible. Ashaker catcher filled with 50 mm thickness of peanut foam underneath aintegrated piece of cotton was developed. The shaker and the catcher catcher mounted on aaShaking movable lifting platform were integrated cotton developed. and the mounted on movable lifting platform into a shake-and-catch harvesting system. The approximate middle ofpeanut a targeted limb waswere selected as the 40 mm were accessible. A catcher filled with 50 mm thickness of foam underneath a piece of cotton was developed. The shaker and the catcher mounted on a movable lifting platform integrated into aa shake-and-catch shake-and-catch harvesting harvesting system. system. The The approximate approximate middle middle of of aa targeted targeted limb limb was was selected selected as as the the into shaking point and detached fruits were captured underneath the targeted section. The overall cotton was developed. The shaker and the catcher mounted on a movable lifting platform were integrated into a shake-and-catch harvesting system. The approximate middle of a targeted limb was selected as the shaking point point and and detached detached fruits fruits were were captured captured underneath underneath the the targeted targeted section. section. The The overall overall shaking combinations of five levels of shaking amplitude and two levels of capturing height were tested foroverall ‘Pink into a shake-and-catch harvesting system. Thecaptured approximate middle ofthe a targeted limb wastested selected as the shaking pointof detached fruits were underneath targeted section. Thefor combinations of and five levels levels of shaking shaking amplitude and two levels of capturing height were ‘Pink combinations five of amplitude and two levels of capturing height were tested for ‘Pink Lady’ apple trees trellis trained in a vertical fruiting wall architecture. Shaking frequency with 20 Hz and shaking point and detached fruits were captured underneath the targeted section. The overall combinations of five levels of shaking amplitude and two levels of capturing height were tested for ‘Pink Lady’ apple trees trellis trained in a vertical fruiting wall architecture. Shaking frequency with 20 Hz and Lady’ apple trellisused trained in tests. a vertical wall architecture. Shaking frequency with 20 Hzwere and duration withtrees 5 s were in all Fruitfruiting removal efficiency and fruit quality (USDA standard) combinations of levels of amplitude andwall two levels of capturing height were tested Lady’ apple trellis trained in tests. a vertical architecture. Shaking frequency with 20forHz‘Pink and duration withtrees 5 ssfive were used inshaking all tests. Fruitfruiting removal efficiency and fruit quality (USDA standard) were duration with 5 were used in all Fruit removal efficiency and fruit quality (USDA standard) were adopted to evaluate theused quality oftests. the harvesting system. Statistical analysis shows thatwith fruit20removal duration with 5 s were in all Fruit removal efficiency and fruit quality (USDA standard) were Lady’ apple trees trellis trained in a vertical fruiting wall architecture. Shaking frequency Hz and adopted to evaluate the quality of the harvesting system. Statistical analysis shows that fruit removal adopted towas evaluate the quality of thewith harvesting system. Statistical analysisrange; showsthethat fruit removal efficiency significantly improved increase ofefficiency amplitude at afruit certain capturing height adopted to evaluate theused quality oftests. thewith harvesting system. Statistical analysis shows that fruit removal duration with 5 s were in all Fruit removal and quality (USDA standard) were efficiency was significantly improved increase of amplitude at a certain range; the capturing height efficiency wasaffected significantly improved with increase of amplitude at aThe certain range; the capturing height significantly the percentage ofharvesting Extra Fancy grade fruit. results indicated that shaking adopted towas evaluate the of thewith system. Statistical analysis shows fruit efficiency significantly improved increase of amplitude at aThe certain range; thethat capturing height significantly affected thequality percentage of Extra Extra Fancy grade fruit. The results indicated that removal shaking significantly affected the percentage of Fancy grade fruit. results indicated that shaking amplitude with ~30 mm is sufficient to remove majority of fruits in the tested variety; capturing fruits efficiency was significantly improved with increase of amplitude at a certain range; the capturing significantly affected the percentage of Extra Fancy grade fruit. The results indicated that shaking amplitude with with ~30 ~30 mm mm is is sufficient sufficient to to remove remove majority majority of of fruits in the tested variety; capturingheight fruits amplitude fruits inExtra the tested variety; capturing fruits that are much closer to the targeted limb is promising to obtain more Fancy grade fruit. significantly affected the percentage Extra Fancy grade fruit.inExtra The indicated that shaking amplitude with ~30 to mm sufficient toofis majority of fruits the results tested capturing fruits that are much much closer to theistargeted targeted limb isremove promising to obtain obtain more Extra Fancy variety; grade fruit. that are closer the limb promising to more Fancy grade fruit. amplitude with ~30 mm is sufficient to remove majority of fruits in the tested variety; capturing that are much closer to the targeted limb is promising to obtain more Extra Fancy grade fruit. © 2019, IFACtree (International Federation of Automatic Hosting by Elsevier Ltd. All rights reserved. fruits Keywords: fruit; shaker; catcher; mechanicalControl) harvesting; removal efficiency; fruit quality. Keywords: treecloser fruit;to shaker; catcher; mechanical harvesting; removal efficiency; fruit quality. that are much the targeted limb is promising to obtainremoval more Extra Fancyfruit gradequality. fruit. Keywords: tree fruit; shaker; catcher; mechanical harvesting; efficiency; Keywords: tree fruit; shaker; catcher; mechanical harvesting; removal efficiency; fruit quality. Keywords: tree fruit; shaker; catcher; mechanical harvesting; removal efficiency; fruit quality. not been achieved for fresh market due to the low removal 1. INTRODUCTION not been been achieved achieved for for fresh fresh market market due due to to the the low low removal removal not efficiency and severe fruit damage (Zhang al., low 2016;removal Zhang 1. INTRODUCTION 1. INTRODUCTION not been achieved forfruit fresh market due toet the efficiency and severe fruit damage (Zhang et al., 2016; Zhang efficiency and severe damage (Zhang et al., 2016; Zhang 1. INTRODUCTION et al., 2018). World of fresh market apples produced 83.1 million tons efficiency not been achieved forfruit fresh market due toet the and severe damage (Zhang al., low 2016;removal Zhang et al., 2018). et al., 2018). World of fresh market apples produced 83.1 million tons 1. 2017. INTRODUCTION World of fresh market apples produced 83.1 million (FAOSTAT, 2017) in Currently, these fresh applestons are efficiency and severe (Zhang harvesting et al., 2016; mainly Zhang et al., 2018). World of fresh market apples produced 83.1 million tons Previous studies on fruit fruitdamage mechanical (FAOSTAT, 2017) in Currently, these fresh apples are (FAOSTAT, 2017)which in 2017. 2017. Currently, these fresh (He apples are picked manually, needs a huge of labour et al., Previous studies on fruit mechanical harvesting mainly et al., 2018). Previous studies on fruit mechanical harvesting mainly (FAOSTAT, 2017) in 2017. Currently, these fresh apples are World of fresh market apples 83.1 million onstudies shakingonthefruit tree trunk/bough obtain high fruit picked manually, which needs aaproduced huge labour (He al., picked In manually, which needs huge of ofwage labour (He et ettons al., focused mechanical to harvesting mainly 2019). recent ten the of labour focused on on shaking shaking the the tree tree trunk/bough trunk/bough to obtain high high fruit focused to obtain fruit picked manually, which needs aaverage huge these ofwage labour (He et use al., Previous (FAOSTAT, 2017) inyears, 2017. Currently, fresh apples are removal efficiency (Pellerin et al., 1982; Peterson and 2019). In In recent ten years, the average of labour labour use 2019). recent ten years, the average wage of use Previous studies on fruit mechanical harvesting mainly focused on shaking the tree trunk/bough to obtain high fruit increased over 30% (USDA-NASS, 2019). The decreasing removal efficiency (Pellerin et al., 1982; Peterson and efficiency (Pellerin et al.,fruits 1982; Peterson and picked manually, which needs huge2019). ofwage labour (He et use al., removal 2019). In recent30% ten years, the aaverage of labour Wolford, 2003). However, massive falling in a very increased over 30% (USDA-NASS, 2019). The decreasing increased over (USDA-NASS, The decreasing removal efficiency (Pellerin et al., 1982; Peterson and focused on shaking the tree trunk/bough to obtain high fruit availability of skilled labor and increasing cost has threatened Wolford, 2003). However, massive fruits falling in a very 2003). massive offruits falling a very 2019). In over recent ten years, the increasing average wage of labour use Wolford, increased 30% (USDA-NASS, 2019). decreasing short timeefficiency causedHowever, a (Pellerin large number contacts of in apple-toavailability of skilled skilled labor and increasing costThe has threatened availability of labor and cost has threatened massive falling a very removal et al., 1982; Peterson and the sustainability of apple industry (Zhang andThe Karkee, 2016). Wolford, short time time2003). causedHowever, a large large number number offruits contacts of inapple-toapple-toshort caused a of contacts of increased over 30% (USDA-NASS, 2019). decreasing availability of skilled labor and increasing cost has threatened apple and apple-to-branch (Peterson, 2005), resulting in the sustainability sustainability of of apple apple industry industry (Zhang (Zhang and and Karkee, Karkee, 2016). 2016). Wolford, the short time caused a large number of contacts of apple-to2003). However, massive fruits falling in a very The technological innovations need to be carried out to apple and apple-to-branch (Peterson, 2005), resulting in apple and apple-to-branch (Peterson, 2005), resulting in availability of skilled labor and increasing cost has threatened the sustainability of apple industry (Zhang and Karkee, 2016). excessive fruit damage. To reduce damage, some researcher The technological innovations need to be carried out to The technological innovations need to be carried out to apple short time caused a large number of contacts ofresearcher apple-toandfruit apple-to-branch (Peterson, 2005), resulting in reduce the dependence on manual labor. excessive fruit damage. To reduce damage, some researcher excessive damage. To reduce damage, some the sustainability of innovations apple industry (Zhang andcarried Karkee,out 2016). The technological need to be to designed a single capturing frame with major branch shaking reduce the on labor. reduce the dependence dependence on manual manual labor. apple andafruit apple-to-branch (Peterson, 2005), resulting in excessive damage. To frame reduce damage, some researcher designed single capturing frame with major branch shaking single capturing with major branch shaking reduce the dependence on manual labor. The technological innovations need to be carried out to designed for trellisaafruit trained trees To (Peterson and Wolford, 2003), and Mechanical harvesting is one of the most commonly excessive damage. reduce damage, some researcher designed single capturing frame with major branch shaking for trellis trellis trained trained trees trees (Peterson (Peterson and and Wolford, Wolford, 2003), 2003), and and for Mechanical harvesting is one of most reduce the dependence labor. Mechanical harvesting ismanual one crops. of the the most commonly commonly developed capturing frame used for inserting investigated method forontree Vibratory or shaking some designed a trained singlemulti-tier capturing frame with major branch shaking for trellis trees (Peterson and Wolford, 2003), and Mechanical harvesting is fruit one crops. of the most commonly some developed multi-tier capturing frame used for inserting some developed multi-tier capturing frame used for inserting investigated method for tree fruit Vibratory or shaking investigated is method for treeused fruit crops. Vibratory or shaking canopy for conventional trees (Millier et al., 1973). Today, harvesting a widely approach in mechanical trellis trees (Peterson and Wolford, 2003), and some developed multi-tier capturing frame used for inserting investigated method for tree fruit Vibratory or shaking for canopy fortrained conventional trees (Millier et al., 1973). Today, Mechanical harvesting is used one crops. of the most commonly canopy for conventional (Millier et the al., 1973). Today, harvesting is is widely used approach in mechanical mechanical harvesting aa applies widely approach in apple orchards are plantedtrees increasingly in simple, narrow, harvesting, which kinetic energy to fruit branches to canopy for conventional trees (Millier et the al., 1973). Today, some developed multi-tier capturing frame used for inserting apple orchards are planted increasingly in simple, narrow, investigated method for tree fruit crops. Vibratory or shaking harvesting is a widely used approach in mechanical orchards are planted increasingly the simple, narrow, harvesting, which which applies applies kinetic kinetic energy energy to to fruit fruit branches branches to to apple harvesting, accessible, productive (SNAP) treein canopy architectures generate detaching force fruit-stem system (Erdoğan et al., orchards are plantedtrees increasingly the narrow, canopy for and conventional (Millier et al.,simple, 1973). Today, accessible, and productive (SNAP) treein canopy architectures harvesting is a applies widelyfor used approach in mechanical harvesting, which kinetic energy to fruit branches to apple accessible, and productive (SNAP) tree canopy architectures generate detaching detaching force for fruit-stem system (Erdoğan et al., al., generate force for fruit-stem system (Erdoğan et (i.e., vertical fruiting wall), which creates an opportunity for 2003). Research on shake-and-catch harvesting for tree fruit accessible, and productive (SNAP) tree canopy architectures apple orchards are planted increasingly in the simple, narrow, (i.e., vertical fruiting wall), which creates an opportunity for harvesting, which applies kinetic energy to fruit branches to generate detaching force for fruit-stem system (Erdoğan et al., (i.e., vertical fruiting wall), which creates an opportunity for 2003). Research Research on on shake-and-catch shake-and-catch harvesting harvesting for for tree tree fruit fruit shaking limb and capturing fruits closely to the targeted limb 2003). crops such as apples (Peterson et al., harvesting 1999; He(Erdoğan et al., 2018), accessible, and productive tree canopy architectures (i.e., vertical fruiting wall),(SNAP) whichclosely creates anthe opportunity for shaking limb and capturing fruits closely to the targeted limb generate detaching force for fruit-stem system et al., 2003). Research on shake-and-catch for tree fruit shaking limb and capturing fruits to targeted limb crops such as apples (Peterson et al., 1999; He et al., 2018), crops such as apples (Peterson al., 1999; et al., 2018), 2015). This type to of tree architecture cherries (Zhou eton al.,shake-and-catch 2014), andet (Liu He et al., 2018) has (De (i.e.,Kleine vertical fruiting wall), which creates anthe opportunity for shaking limband andKarkee, capturing fruits closely targeted limb (De Kleine and Karkee, 2015). This type of of tree architecture 2003).such Research foral., tree fruit crops as apples (Peterson etcitrus al., harvesting 1999; He et 2018), (De Kleine and Karkee, 2015). This type tree architecture cherries (Zhou et al., 2014), and citrus (Liu et al., 2018) has cherries (Zhou et al., 2014), and citrus (Liu et al., 2018) has was friendly for shake-and-catch harvesting (He et al., 2017b, been conducting for decades. It has been succeeded for nuts, shaking limb and capturing fruits closely to the targeted limb (De Kleine and Karkee, 2015). This type of tree architecture cherries (Zhou et al., 2014), and citrus (Liu et al., 2018) has was friendly friendly for for shake-and-catch shake-and-catch harvesting harvesting (He (He et et al., al., 2017b, 2017b, crops conducting such as apples (PetersonIt al.,been 1999; He et al.,for was been for decades. succeeded nuts, been conducting forcrops decades. It ethas has been succeeded for2018), nuts, 2018, 2019; and Ma et al., 2018). berries and other targeted primarily for processing (De friendly Kleine 2015). This type of(He treeetarchitecture was for Karkee, shake-and-catch harvesting al., 2017b, been conducting for decades. It has been succeeded for nuts, 2018, 2019; Ma et al., 2018). cherries (Zhou et al., 2014), and citrus (Liu et al., 2018) has 2018, 2019; Ma et al., 2018). berries and other crops targeted primarily for processing berries (Chen and other crops targeted primarily for success processing market et al., 2011). However, commercial has 2018, for et shake-and-catch harvesting (He et al., 2017b, 2019; Ma al., 2018). berries and other targeted for success processing been conducting forcrops decades. It has primarily been succeeded for nuts, market (Chen et al., al., 2011). However, commercial has was friendly market (Chen et 2011). However, commercial success has berries and other for success processing market (Chen et al.,crops 2011).targeted However,primarily commercial has 2018, 2019; Ma et al., 2018). Copyright © 2019 2405-8963 © 2019, IFAC (International Federation of Automatic market (Chen et IFAC al., 2011). However, commercial successControl) has 306 Copyright © 2019 2019 IFAC 306Hosting by Elsevier Ltd. All rights reserved. Copyright © IFAC 306 Peer review under responsibility of International Federation of Automatic Control. Copyright © 2019 IFAC 306 10.1016/j.ifacol.2019.12.553 Copyright © 2019 IFAC 306
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The fruit removal force and fruit quality are primarily determined by shaking frequency, amplitude, and duration (Loghavi and Mohseni, 2007; Zhou et al., 2013, 2014). The capturing height determines the impact of fruit onto the catching surface and thus affects the fruit quality. The effect of shaking frequency and duration on mechanical harvesting of fresh market apples in the vertical fruiting wall architecture had been investigated (He et al., 2017b, 2019). The objectives of this study were (1) to develop a localized shake-and-catch harvesting system; and (2) to evaluate the performance in terms of fruit removal efficiency and quality with different shaking amplitudes, capturing heights and their interaction in a commercial apple orchard.
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was filled with 50 mm thickness of peanut foam underneath a piece of cotton. The peanut foam was used to reduce the impact and prevent fruits from rolling to minimze fruit bruising on the catching surface. The shaker and catcher were mounted on a mobile lifting platform to integrate a localized harvesting system (Fig. 3).
2. MATERIALS AND METHODS Fig. 2. Prototype of a linear-forced limb shaker with adjustable shaking amplitude and frequency.
2.1 Concept of the Localized Shake-and-catch Harvesting Vertical fruiting wall (Fig. 1) is a typical architecture of modern apple orchard, in which the trees are trained into horizontal tiers using trellis wires. Those horizontally growing limbs reduces the overlapping and crossing of branches in conventional trees and thus has better machine accessibility. To achieve desired fruit quality level with mechanical harvesting, the concept of localized shake-andcatch harvesting that shaking limb and capturing detached fruits closely to the targeted limb was proposed by our team.
Fig. 3. General view of the prototype of the localized shakeand-catch harvesting system. 2.3 Tested Orchard and Experiment Design To evaluate the developed shake-and-catch harvesting system (Fig. 3), a series of field tests ware conducted in a commerial ‘Pink Lady’ apple orchard near Othello, Washington, during the 2015 grower-identified apple harvest season. The trees in this orchard were trained to a vertical fruiting wall architecture (Fig. 1), in which seven horizontal tiers of limbs were trained using seven trellis wires. For the uniformity of the tree architecture, limbs at different tiers could be viewed as similar. For each tier, two limbs trained to trellis wire grows oppositely along the tree row. Trees grow in a relatively flat terrain with dimension of inter-row x intra-row spacing of 4.0 m x 1.5 m. The overall height of the trees was about 4 m and each tier was about 0.5 m. To simplify the experimental process, only limbs from 2nd to 4th tier were used in this study. The mean with standard deviation of the test limbs is 10.4 ± 2.3 mm in diameter. The tests were conducted in the morning to avoid the high temperature on fruit removal and post-removal fruit quality.
Fig. 1. A vertical fruiting wall apple orchard. 2.2 Development of a Localized Shake and Catch Harvesting System A linear-forced limb shaker with adjustable shaking frequency and amplitude was designed and fabricated for (Fig. 2). The shaker mainly consisted of a frame, flywheel, crank, connecting rod and U-shaped hook head. A slidercrank mechansim with variable crank length was used to generate an oscillating motion at the desired amplitudes. A cardan universal joint was used for this connection to provide enough spatial flexibility for the rod. The shaker was powered by a DC motor (7200, AMETEK, Inc, Berwyn, Pennsylvania, U.S.) with corresponding speed controller. Shaking amplitudes of 20, 25, 30, 35 and 40 mm were accessible by manually connecting the crank to various points located at radial distances of 10, 12.5, 15, 17.5, and 20 mm. A catcher with dimension of 1000 mm length x 600 mm width x 150 mm height was developed using a cardboard and
Preliminary tests suggested that the apples could detach from branches with the shaking amplitudes of 20, 25, 30, 40 and 45 mm. Due to available space limit between two adjacent tiers, the capturing heights close to the targeted limb were tested two levels of 108 and 370 mm. This experiments evaluated the overall treatment combinations of the five 307
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levels of shaking amplitude and two levels of capturing height on mechanical harvesting. Total sixty with six limbs for each were randomly selected for the ten treatment combinations in this study. Previous study (He et al., 2017b) showed that most of the fruits could be removed from limb and reserved good quality with a shaking frequency of 20 Hz and a duration of 5 s. The same treatment was adopted in this study. The shaking points generally focused on the approximate middle of the targeted limbs. Each targeted limb composed a localized harvesting section, as shown in Fig. 4. One localized section was selected to harvest at a time, and the catcher was placed underneath the targeted section. The next section was tested only after the apple fruits were manually picked out of the catching surface. The harvesting system was manually moved from one section to another.
Where ηc is the fruit collection efficiency (%); Nc is the number of fruit collected by the catcher. Fruit recovery efficiency indicates the collected fruit with respect to the overall fruits on a test section, which could be calculated by multiplying the fruit removal efficiency and fruit collection efficiency, as shown in Equation (3).
η= ηr ⋅ ηc o Where ηo is the fruit recovery efficiency (%). Fruit Quality Assessment
After tests, the harvested fruits were carefully transported to the laboratory for quality assessment. It was completed after 24 h of storage in room temperature of ~22℃. According to USDA fresh market standard, fruit quality was categorized into different grades as illustrated in Table 1 (Peterson et al., 2010). In the standard, fruit quality is classified into three major categories: Extra Fancy, Fancy, and Downgrade. The percentage of each category was defined by Equation (4). The percentage of Fresh-marketable fruit is the sum of those in Extra Fancy and Fancy categories.
ηd =
Bruise Specifications [mm for diameters (D) or mm2 for total areas (A)] 1 Extra Fancy No injury 2 Extra Fancy D ≤ 3.2 Extra Fancy 3 3.2 < D ≤ 6.4 Extra Fancy 6.4 < D ≤ 12.7 or A ≤ 4 127 12.7 < D ≤ 19.0 or 127 < 5 Fancy A ≤ 285 6 Downgrade D > 19.0 or A > 285 Cuts or punctures of any 7 Downgrade size The diameter of bruise was measured using a vernier caliper under a fluorescent. If there are several bruises on an apple, the total area of the bruises was calculated. Since bruise is generally elliptical (Bollen et al., 1999), the bruise area is calculated by Equation (5). No. Assigned to Class
2.4 Harvesting Performance Fruit Removal and Collection Efficiency Fruit removal efficiency was defined as the percentage of the number of fruit mechanically harvested based on the total number of fruit growing on a test limb. It was determined by Equation (1). (1)
Where ηr is the fruit removal efficiency (%); Nr is the number of fruit mechanically harvested; N is the total number of fruit growing on the test limb. Some detached fruits may drop out of the catching frame. A fruit collection efficiency was defined as the percentage of fruit collected by the catcher based on the total number of fruit removed by the shaker from the test limb. It was given by Equation (2).
N ηc = c x 100 Nr
(4)
Table 1. USDA standard and class for fresh market apples
The numbers of harvested fruit and collected fruit were counted. The fruit removal efficiency, collection efficiency, and fruit quality were analyzed using ANOVA (Duncan’s method) at a significant level of 0.05 in SPSS 17.0 software.
Nr x 100 N
Nd x 100 N
Where ηd is the percentage of harvested fruit in a fruit quality category (%); Nd is the number of fruit in a quality category; N is the total number of harvested fruit in a test.
Fig. 4. Schematic of the localized harvesting section. The tree limbs are trellis trained into horizontally growing.
ηr =
(3)
USDA Standard
A=
π 4
ab
(5)
Where A is the bruise area; a is the major diameter of the bruise; b is the minor diameter of the bruise.
(2)
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Fig. 6 shows the fruit quality when each level of shaking amplitude was taken as one sample. As shown in this figure, shaking amplitude had an effect on percentage of Extra Fancy grade fruit. The percentages of fruit at Extra Fancy level were 81%, 73%, 70%, 69% and 70%, respectively for the five shaking amplitudes. The corresponding percentages of Fresh-marketable grade fruit were 93%, 92%, 82%, 85% and 90%. When we inspect the Downgrade percentage, the corresponding values were 8%, 8%, 17%, 16% and 10%. There was about 9% more fruit in the Downgrade level when shaking with 30 mm amplitude compared to 20 mm amplitude. Although the shaking amplitude did not generate significant difference in terms of percentage of each of the three major fruit quality grades, the percentage of Extra Fancy grade fruit had negatively relation with corresponding fruit removal efficiency.
3.1 Fruit Removal Efficiency and Collection Efficiency Since no fruits dropped out of the catching frame, it is no necessary to discuss the collection efficiency. Fruit recovery efficiency thus depends on the fruit removal efficiency. The removal efficiency was calculated from the field data using Equation (1). Since the capturing height has no relation with fruit detaching, each level of shaking amplitude was taken as one sample. Fig. 5 shows the fruit removal efficiency under different shaking amplitudes with respect to individual sections. As shown in this figure, the average of fruit removal efficiency was 70%, 80% and 94% respectively with shaking amplitude of 20 mm, 25 mm and 30 mm. The removal efficiency was significantly increased among the three shaking amplitudes. The best value of fruit removal efficiency was similar to that obtained in previous study at the similar treatments (He et al., 2017b). The unremoved fruits normally hang on the long thin twigs and the observation was the same with previous study (He et al., 2017a, 2019).
Fig. 6. Fruit quality in different grades under different levels of shaking amplitudes with respect to individual sections. Treatments ‘A1’, ‘A2’, ‘A3’, ‘A4’ and ‘A5’ respectively represent shaking amplitudes of 20, 25, 30, 35 and 40 mm. Statistical analysis was only done within the same grade of fruit quality.
Fig. 5. Fruit removal efficiency under different levels of shaking amplitude with respect to individual sections. Treatments ‘A1’, ‘A2’, ‘A3’, ‘A4’ and ‘A5’ respectively represent shaking amplitudes of 20, 25, 30, 35 and 40 mm.
Fig. 7 shows the fruit quality with respect to individual sections when each level of capturing height was taken as one sample. The percentages of Extra Fancy quality grade fruit were 78% and 66% respectively for the low and high capturing patterns. Relatively high percentage of Extra Fancy quality grade fruit was obtained when capturing fruits was much closer to the targeted limb. However, this situation was reverse for percentages of Fancy quality grade fruit. The percentages of each of the two quality grades have significant differences. In terms of Downgrade grade, the percentages were 9% and 14% respectively for the low and high level of capturing patterns and there was about 5% less fruit when capturing fruit was much closer to the targeted limb. However, the capturing height didn’t significantly affect the percentage of Downgrade grade fruit between the two levels of height. In other words, the capturing height didn’t generate significant differences for the percentage of Freshmarketable quality grade fruit. The higher capturing height means higher impact energy, which would result in larger percentage of Fancy or Downgrade grade fruit (Fu et al., 2016, 2017). Therefore, to obtain higher grade of fruit quality, capturing fruit at a much closer positon to targeted limb could be recommended for the shake-and-catch harvesting system.
Fig. 5 also shows that fruit removal efficiency slightly decreased when shaking amplitude continued increasing, although no significant difference was found among the three treatments. While the fruit detached force is proportional to the amplitude, the targeted limb was constrained by the trained trellis wire that limited the deformation of the targeted limb. In addition, the larger deformation of the targeted limb not only causes itself more easily to injury but also generates larger resistance to the shaker, which could reversely lower the performance of the shaker. Therefore, these results indicate that the suitable shaking amplitude should be around 30 mm for the special ‘Pink Lady’ apple cultivar with vertical fruiting wall architecture in terms of fruit removal efficiency. 3.2 Fruit Quality Assessment After field tests, those apples were carefully transported to the laboratory for fruit quality assessment according to USDA fresh market standard. We respectively evaluated the effect of shaking amplitude, capturing height and their interaction on fruit quality.
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the view of fruit removal efficiency, the suitable shaking amplitude should be around 30 mm. In terms of fruit quality, the patterns of the percentage of Extra Fancy grade fruit had negatively relation on the corresponding fruit removal efficiency, although no significant differences of the percentage of Extra Fancy grade fruit were found among the five shaking patterns. If the shaker could gradually increase its amplitude automatically, both high fruit efficiency and good fruit quality may be achieved. In addition, capturing fruits much closer to the targeted limb decreased the strength of impact of the fruits to the catching surface or other fruits on the surface. Compared to our previous study (He et al., 2017b), we found that 94% of fruit could still maintain fresh market grade without rolling and bounce buffers used in previous handheld shake-and-catch harvesting system. There was only 0.7% difference for the percentage of Extra Fancy grade fruit between previous and current studies. The comparison of the two studies indicate that the two buffers may not function primarily on maintaining fresh market quality grade and new strategy for reducing fruit damage may need to be reconsidered. Besides, the shaking was manually controlled and the errors was inevitable for each test. The fruits on the catching surface had to be manually transferred to a collector one by one, which reduced the harvesting efficiency. Modification of the harvesting system with timing controlling and fruits automated transferring will be considered in our future study.
Fig. 7. Fruit quality under different capturing patterns with respect to individual sections. Treatments ‘Low’ and ‘High’ respectively represent two levels of capturing height close to the targeted limb. Statistical analysis was only done within the same grade of fruit quality. Fig. 8 shows the fruit quality when each combination between shaking amplitude and capturing height was taken as sample. The figure shows that the combination has a significant effect on percentages of fruit in the Extra Fancy quality grade. The percentages of fruit at Extra Fancy grade were 84%, 78%, 81%, 64%, 73%, 68%, 78%, 60%, 75% and 63% under shaking patterns of ‘A1-L’, ‘A1-H’, ‘A2-L’, ‘A2H’, ‘A3-L’, ‘A3-H’, ‘A4-L’, ‘A4-H’, ‘A5-L’ and ‘A5-H’, respectively. The corresponding percentages of Freshmarketable quality fruit were 93%, 94%, 94%, 89%, 82%, 84%, 90%, 79%, 94%, and 85%. Significant differences of the percentage of the Extra Fancy grade fruit only exist in the two combination treatments of ‘A1-L’ and ‘A4-H’. When we look into the Downgrade percentage, the corresponding values were 7%, 6%, 6%, 11%, 18%, 16%, 10%, 21%, 6% and 15%. There was about 15% more fruit in the Downgrade level at shaking pattern of ‘A4-H’ compared to ‘A1-H’ or ‘A2-L’.
4. CONCLUSIONS This study developed a localized shake-and-catch harvesting system for trellis trained apple trees and investigated the effect of shaking amplitude and capturing height on mechanical harvesting. A series of field harvesting tests were conducted on a vertical fruiting wall tree architecture of ‘Pink Lady’ apples. Fruit removal efficiency and fruit quality according to USDA fresh market standard were used to evaluate the harvesting system. A few conclusions were summarized as follows: 1.
Fruit removal efficiency was significantly improved with the increase of shaking amplitude at a certain range for such apple trees. Relative high fruit removal efficiency of 94% was achieved with a shaking amplitude of 30 mm. 2. The capturing height significantly affected fruit quality in terms of percentage of Extra Fancy grade fruit. To obtain higher percentage of Extra Fancy grade fruit, capturing fruit at a much closer position to the targeted limb was recommended for the localized shake-andcatch harvesting system. 3. The percentage of Extra Fancy quality grade fruit had negatively relation on corresponding fruit removal efficiency. The harvesting system achieved an Extra Fancy quality grade fruit of 84% and Fresh-marketable quality grade fruit of 94%. This study showed a very promising mechanical harvesting solution for such apple trees with expected fruit quality. In future study, the effect of new shaking patterns of the combination of amplitude, frequency and duration on mechanical harvesting will be considered.
Fig. 8 Fruit quality under different treatment combinations between shaking amplitude and capturing height with respect to individual sections. Statistical analysis was only done within the same grade of fruit quality. According to the results, the increase of shaking amplitude in a certain range significantly improved the fruit removal efficiency. The relatively high removal efficiency with 94% was obtained for the test variety ‘Pink Lady’ at the shaking amplitude of 30 mm. The value was just less 1% compared to that obtained in our previous study with a 32 mm shaking amplitude (He et al., 2017b). When the shaking amplitude was increased further, we observed that shaker’s performance was lowered and intermittent vibration occurred. If things continue this way, the shaker’s life cycle will be reduced and the potential damage to targeted limb will be increased. From 310
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This research was supported partially by Natural Science Foundation of China (Grant No. 51905179), Research and Development Plan in Key Areas of Guangdong Province (2019B020223002), Science and Technology Planning Project of Guangdong Province (2018A070717019), USDA’s Hatch and Multistate Project Funds (1005756 and 1001246), USDA National Institutes for Food and Agriculture competitive grant (1005200), Agricultural Science and Technology Achievements promotion of Guangdong Province (2018LM2162), Washington State University (WSU) Agricultural Research Center (ARC). Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the authors and do not necessarily reflect the view of the USDA, WSU or SCAU. REFERENCES Bollen, A. F., Nguyen, H. X., and Rue, B. D. (1999). Comparison of methods for estimating the bruise volume of apples. Journal of agricultural engineering research, 74(4), 325-330. Chen D., Du X., Wang S., Zhang Q. (2011). Mechanism of vibratory fruit harvest and review of current advance. Transactions of the CSAE, 27(8): 195-200. De Kleine, M. E. and Karkee, M. (2015). A semi-automated harvesting prototype for shaking fruit tree limbs. Transactions of the ASABE, 58(6), 1461-1470. Erdoǧan, D., Güner, M., Dursun, E., and Gezer, I. (2003). Mechanical harvesting of apricots. Biosystems engineering, 85(1), 19-28. FAOSTAT. Crops. http://www.fao.org/faostat/en/#data/QC. Access on: 10/12/2019. Fu, H., He, L., Ma, S., Karkee, M., Chen, D., Zhang, Q., and Wang, S. (2016). Bruise responses of apple-to-apple impact. IFAC-PapersOnLine, 49(16), 347-352. Fu, H., He, L., Ma, S., Karkee, M., Chen, D., Zhang, Q., and Wang, S. (2017). ‘Jazz’ apple impact bruise responses to different cushioning materials. Transactions of the ASABE, 60(2), 327-336. He, L., Fu, H., Karkee, M., and Zhang, Q. (2017a). Effect of fruit location on apple detachment with mechanical shaking. Biosystems engineering, 157, 63-71. He, L., Fu, H., Sun, D., Karkee, M., and Zhang, Q. (2017b). Shake-and-catch harvesting for fresh market apples in trellis-trained trees. Transactions of the ASABE, 60(2), 353-360. He, L., Fu, H., Xia, H., Karkee, M., Zhang, Q., and Whiting, M. (2018). Evaluation of a localized shake-and-catch harvesting system for fresh market apples. Agricultural engineering international: CIGR journal, 19(4), 36-44. He, L., Zhang, X., Ye, Y., Karkee, M., and Zhang, Q. (2019). Effect of shaking location and duration on mechanical harvesting of fresh market apples. Applied engineering in agriculture, 35(2), 175-183. Liu, T. H., Luo, G., Ehsani, R., Toudeshki, A., Zou, X. J., and Wang, H. J. (2018). Simulation study on the effects of tine-shaking frequency and penetrating depth on fruit detachment for citrus canopy-shaker harvesting. Computers and electronics in agriculture, 148, 54-62. 311