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Paper No200000 - Comprehensive Automation for Specialty Crops

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					                                                                            An ASABE Meeting Presentation
                                                                            Paper Number: 10




               Novel Approaches to Passive Bin Filling for Apples

Brian Kliethermes
          Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213

Alexander Leslie
          Pennsylvania State University, 670 Old Harrisburg Road, Suite 204
          Gettysburg, PA 17325

Russel Rohrbaugh
          Pennsylvania State University, 670 Old Harrisburg Road, Suite 204
          Gettysburg, PA 17325

Jacob Koan
          Pennsylvania State University, 670 Old Harrisburg Road, Suite 204
          Gettysburg, PA 17325

Scott Wolford
          USDA-ARS Appalachian Fruit Research Station, 2217 Wiltshire Road, Appalachian Fruits
          RS, Kearneysville, WV, 25430-2771

Michael Glenn
          USDA-ARS Appalachian Fruit Research Station, 2217 Wiltshire Road, Appalachian Fruits
          RS, Kearneysville, WV, 25430-2771

Karen Lewis
          WSU Grant-Adams Area Extension,P.O. Box 37 – Courthouse, 35 C ST NW, Ephrata, WA
          98823

Tara Baugher
          Pennsylvania State University, 670 Old Harrisburg Road, Suite 204, Gettysburg, PA 17325

William Messner
          Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15217.

                                          Written for presentation at the
                                    2010 ASABE Annual International Meeting
The authors are solely responsible for the content of this technical presentation. The technical presentation does not necessarily reflect the
official position of the American Society of Agricultural and Biological Engineers (ASABE), and its printing and distribution does not
constitute an endorsement of views which may be expressed. Technical presentations are not subject to the formal peer review process by
ASABE editorial committees; therefore, they are not to be presented as refereed publications. Citation of this work should state that it is
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Mich.: ASABE. For information about securing permission to reprint or reproduce a technical presentation, please contact ASABE at
rutter@asabe.org or 269-429-0300 (2950 Niles Road, St. Joseph, MI 49085-9659 USA).
                                               Sponsored by ASABE
                                       David L. Lawrence Convention Center
                                             Pittsburgh, Pennsylvania
                                              June 20 – June 23, 2010
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Abstract. Bin filling remains among the most challenging operations of apple harvest. The current
standard practice is careful release of fruit from the bottom of a picking bag while sweeping the
across the top layer of apples already in the bin to distribute the fruit with minimal bruising. This
process is time consuming and still prone to damage the fruit. In this paper we describe two new
devices that show promise for increasing speed and reducing bruising in passive bin filling. The first
distribution is the "energy absorbing grate for apple distribution and bin filling" in which apples are
dumped through a network of elastic bands holding energy absorbing foam shapes. The vibration of
the elastic bands creates a fluidized bed effect that allows apples to pass through the device while
reducing their speed so that bruising is nearly eliminated. The second is the "pneumatic self-
adjusting bin filler," in which alternate inflation and deflation of adjacent cylindrical bladders causes
the device to climb up the rising pile of apples in the bin filler. The bladders also serve as to absorb
the energy of the falling apples. We will present the design process, the results of laboratory and field
tests, lessons learned, and future plans.
Keywords. Apple harvest, bin filling, energy absorbing materials.




The authors are solely responsible for the content of this technical presentation. The technical presentation does not necessarily reflect the
official position of the American Society of Agricultural and Biological Engineers (ASABE), and its printing and distribution does not
constitute an endorsement of views which may be expressed. Technical presentations are not subject to the formal peer review process by
ASABE editorial committees; therefore, they are not to be presented as refereed publications. Citation of this work should state that it is
from an ASABE meeting paper. EXAMPLE: Author's Last Name, Initials. 2010. Title of Presentation. ASABE Paper No. 10----. St. Joseph,
Mich.: ASABE. For information about securing permission to reprint or reproduce a technical presentation, please contact ASABE at
rutter@asabe.org or 269-429-0300 (2950 Niles Road, St. Joseph, MI 49085-9659 USA).
Introduction
Labor saving technologies such as full mechanization of harvest or less radical harvest assist
technology could greatly increase the efficiency of apple harvest. One major obstacle to any
technology for improving efficiency is the need to collect the fruit in a bulk container after it has
been removed from the tree without causing significant damage. The standard method of fruit
harvest involves having harvest employees fill a picking bag with fruit. Once the bag is full, they
carefully empty their bags into a bulk bin. There is potential for substantial economic and
ergonomic improvements if picking bags can be removed from the harvest process, and allow
for a more continuous process.
The problem lies in the physiology of an apple. Apples are much more fragile and sensitive to
bruising under fast loading (Baugher, 2006). If an apple is allowed to fall freely rather than
delicately lowered into a bin, it will have a considerable amount of kinetic energy when it either
hits the bottom of the bin or other apples. This kinetic energy must be absorbed by something.
Without any additional materials present, this energy will be absorbed during a very short period
of time in a relatively small area by either the falling apple itself, or the apples already in the bin.
If materials are present during the fall that can absorb this energy before the fruit reach the
bottom of the bin, bruising can be prevented.
We developed two new approaches for bin filling absorb enough energy of harvested fruit
dropped onto it to prevent bruising when the apple landed on a layer of apples or the hard
bottom of a bin. Either prototype would support the future development of a passive bin filling
device for use in orchards. Such a device would ideally be used in combination with other
harvest assist technology, primarily a harvest platform (Baugher et al., 2009). The first system is
a energy absorbing grate distributor design (Fig. 1). In this system, the kinetic energy of the
falling apples is absorbed by cubes (or other shapes) of energy absorbing foam or elastic cords
resting on top of or suspended from a frame. The second system that was modeled is a
pneumatic self-adjusting design (Fig. 7). The principle behind the design is to alternate the
inflation of two or more sets of flexible cylinders so that the device continually “steps” to stay on
top of apples in bin. The cylinders themselves absorb the energy of the dropping apples by
keeping the air pressure in the cylinders to a minimum. With these devices, ladders and picking
bags could be eliminated from the apple harvest, allowing workers to pick continuously from the
beginning to the end of a row.

Energy Absorbing Grate Bin Filler

Inspiration and Design
To eliminate reduce bruising it is necessary to absorb the energy of apples falling more than
one or two inches. Our first idea was dropping apples into a tank of water. However, we
quickly rejected this concept because (1) apple float, and after a few apples entered the tank,
apples would fall onto apples, (2) water is heavy and difficult to move around, and (3) we apples
would be more prone to contamination and spoilage. We briefly considered using another liquid
that was less dense than apples, such as vegetable oil, but this would still be difficult to
transport, and contamination was a concern.
These two ideas led to the idea of using a dry fluid-like medium as the energy absorber. Our
inspiration was the ball pits found in children’s playgrounds in which thousands of foam ball
serve to cushion the movements of children as the jump and wade through the pit. If the balls
are less dense than the apples, the apples would eventually move through the layers of balls,



                                                                                                        2
and the balls would remain on top of the pile of apples. However, some balls would
undoubtedly be trapped in the pile of apples, which would be a problem at the processing plant.
So, rather than dropping the apples onto a free layer of foam balls, we decided to suspend the
balls from rubber bands strung on a frame (Fig. 1). The rubber bands help create a fluidized bed
effect, because they vibrate as the apples hit them. A crank or motor raises and lowers the
frame.




                         Fig. 1. Energy absorbing grate bin filler concept.

Experiments
We tested six configurations of energy absorbing grates consisting of variations of three
different materials for their ability to passively handle apples without causing damage. The
experiment included four replications of six configurations. In each replication eight apples (of 2
¾ to 3 inch size) passed through that particular configuration. Trials were conducted with
Delicious, a variety with low susceptibility to bruising, and Golden Delicious, a variety with high
susceptibility to bruising.
We designed an apparatus that allowed the apples to free fall in a semi-random direction onto
the uppermost layer of energy absorbing material. Each type of material was arranged in a two-
foot square wooden frame. Fastened to a similar frame was a padded ramp at a 15° incline.
This ramp (Figure 2) was tapered with padded dividers at one end, which directed the apples in
each replicate in a random direction. A rack (Figure 3) allowed the square frames to be inserted
at any one of four positions with the ramp on top. The separation between the positions was 13
cm (5 in). The racks were placed every 13 cm from the bottom of the bin so that the materials
could be arranged in different configurations. For each experiment, the bottommost frame was
on the lowest rack and just above the bottom layer of apples, while the ramp was one rack
above the uppermost material.
The three energy absorbing materials were 6.3 cm (2.5 in) diameter hard foam balls strung on
elastic (rubber) bands, 7.6 cm (3 in) diameter soft foam balls strung on rubber bands, and
rubber bands alone. The rubber bands were stock materials ordinarily used for training apple
trees. The foam balls were purchased from toy departments.
The six configurations were as follows: one layer of 48 hard foam balls (Figure 4), one layer of
36 soft foam balls (Figure 5), one layer of each type of ball, two layers of rubber bands (Figure
6), one layer of each type of ball with one layer of rubber bands, and one layer of each type of



                                                                                                      3
ball with two layers of rubber bands. In the bottom of the testing apparatus was a single layer of
apples onto which the test apples fell after passing through the energy absorbing materials. A
control value for bruising was determined by allowing the apples to fall onto the layer of apples
without any of the energy absorbing materials present.




                      Figure 2. Padded ramp with one replicate of apples.



                        racks                                       ramp




                                                                    frame
                       stationary layer of apples                   s
                         Figure 3. Testing apparatus with multiple racks.
The apples were inspected for previous damage, and any bruises were circled with a permanent
marker to distinguish them from bruises resulting from the experiment. The apples were left at
room temperature for approximately one hour before the experiment. For each of the four
replicates, eight apples were placed in the ramp and allowed to drop all at once. If any apples


                                                                                                 4
stopped, the frames were shaken slightly until the apples passed to the bottom. The apples then
sat at room temperature overnight until they were inspected for bruising. The skin over the
damaged area was peeled back and the bruise diameter was measured. The apples were then
cut through the bruise and the bruise depth measured. Levels of downgrading due to bruising
were determined based on USDA Grades and Standards (Table 1).




                                  Figure 4. Hard foam balls.




                                   Figure 5. Soft foam balls.




                                   Figure 6. Rubber bands.
Table 2 shows the results the experiments including the percentage of downgraded fruit, mean
bruise width, and mean bruise volume. All combinations showed the ability to significantly
reduce bruising, but only the treatments that included rubber bands had 100% Extra Fancy


                                                                                               5
grade fruit. The data suggest that the elasticity of a rubber band is capable of absorbing the
energy of falling fruit. In each case, either a foam material fastened to rubber bands, or the
bands themselves gripped the apples long enough for the rubber bands to stretch out around
them. The rubber bands allowed the fruit to pass through one layer, and they immediately
snapped back to their original positions before additional fruit fell.
Table 1. Classification of bruise damage, based on USDA Grades and Standards.

              USDA fresh market
    Class                                Bruise specifications
              standard
      1       “Extra Fancy”              No bruising
      2       “Extra Fancy”              Bruise diameter ≤ 3.2 mm (1/8 in)
      3       “Extra Fancy”              Bruise diameter 3.2 mm (1/8 in) to 6.4 mm (¼ in)
                                         Bruise diameter 6.4mm (¼ in) to 12.7 mm (½ in) or
      4       “Extra Fancy”
                                         area of several bruises ≤ 127 mm2
      5       “Fancy”                    Bruise diameter 12.7 mm (½ in) to 19 mm (3/4 in)
      6       Downgraded                 Bruises larger than the tolerances in “Fancy”
      7       Downgraded                 Cuts or punctures of any size


Table 2. Effects of energy absorbing grates on apple bruising and USDA fresh market grade
(percentages based on % of total apples tested).
     Treatment         Downgraded to Downgraded to No. 1         Bruise width Bruise volume
                        Fancy Grade        or Utility Grade         (mm)          (mm3)
                             (%)                  (%)
    Hard foam balls                3                0                  1.1 bz            10.7 b
    Soft foam balls                3                0                  2.1 b             12.4 b
    1 layer each ball              3                0                  1.0 b             19.2 b
    type
    2 layers rubber                0                0                  1.3 b              8.2 b
    bands
    2 layers balls + 1             0                0                  0.6 b              3.6 b
    layer bands
    2 layers balls + 2             0                0                  1.6 b             43.9 b
    layers bands
    Control                       28                3                  7.1 a           195.1 a
z
 Means, within columns, followed by dissimilar letters are significantly different according to
Fisher’s protected least significant difference, P ≤ 0.05.

Pneumatic Self-Adjusting Bin Filler
A disadvantage of the energy absorbing grate is that manual intervention is required to keep it
at the proper height above the apples already in the bin or the bottom of the bin itself. Inspired



                                                                                                     6
by the idea of “stepping” over layers apples in the bin, we conceived pneumatic “feet” consisting
of bladders that alternate inflate and deflate (Fig. 7). The bladder material and the pressurize air
absorb the energy of the falling apples.




                         Fig. 7 pneumatic self-adjusting apple distributor

Experiments with Full Scale Bin Filler Prototypes
We constructed one full scale prototype of each bin filler. The energy absorbing grate (Figure 8)
used nylon bungee cords with a foam base pad. The energy absorbing grate bin filler contained
two layers of nylon bungee cords 9 mm (0.36 in) in diameter configured approximately at a
spacing of 3.75 cm (1.5 in). The drop height between the two layers of bungee cords was 7.5
cm (3 in) and the drop height to the foam mat was 9 cm (3.5 in).




              Fig. 8. Full scale prototype of energy absorbing grate with test ramp.


                                                                                                   7
The pneumatic self-adjusting bin filler contained two layers of 10 cm (4 in) plastic inflated
bladders (Fig. 9). The pressure in the upper bladder layer was slightly lower than the pressure in
the bottom bladder layer. This enabled the system to absorb the largest amount of energy
without causing apples to bounce upon impact.




                     Fig. 9. Pneumatic self-adjusting bin filler with test ramp.
The study included four replications of three drop height configurations—2.5, 5, and 10 cm (1, 2,
and 4 in), respectively. In each replication eight apples (of 2 ¾ to 3 inch size) passed through
each particular bin filler configuration. Trials were conducted with Golden Delicious, a variety
with high susceptibility to bruising. The testing apparatus was designed to allow the apples to
free fall in a semi-random direction onto the uppermost layer of energy absorbing material.
Additionally, one incomplete layer of red apples was placed on the bottom of the bin allowing
room for the test apples to distribute. The test apples were placed on a padded ramp at a 15°
incline with padded dividers to prevent bruising prior to departure from the ramp.
A control value for bruising was determined by allowing the apples to fall onto the incomplete
layer of apples without any of the energy absorbing materials present. For the singulation trials,
each apple was released individually from the ramp to completely isolate any initial bruising
from apple collisions between the end of the ramp and the bin filler.
The apples were inspected for previous damage, and any bruises were circled with a permanent
marker to distinguish them from bruises resulting from the experiment. The apples were left at
room temperature for approximately one hour before the experiment. For each of the four
replicates, eight apples were placed in the ramp and allowed to drop all at once. The apples
remained at room temperature overnight until they were inspected for bruising. The skin over
the damaged area was peeled back and the bruise diameter was measured. Then the apples
were cut through the bruise to measure the bruise depth. Levels of downgrading due to bruising
were determined based on USDA Grades and Standards (Table 1).
Table 3 and Fig.10 show the bruise measurements and corresponding levels of downgraded
fruit for all testing configurations. The trend lines for all trials showed as drop height increases
bruise volume increases nearly linearly. The energy absorbing grate reduced bruise volume at
all heights compared to the control. The pneumatic bin filler did not perform as well as the grate
since the fruit passed more slowly through the air filled bladders, allowing more opportunities for
fruit-to-fruit contact. An important finding (Figure 11) was that performance increases
significantly when fruit are singulated prior to entering the bin filler. The optimal bin filling



                                                                                                     8
configuration was a singulated fruit transfer system with a drop height of no more than 5 cm (2
in).




  Fig. 10. Trend lines comparing the performance of two full-scale bin filling prototypes across
                                      three drop heights.




                                                                                                   9
  Fig. 11. Bruise volume trend lines for the three best bin filling configurations with respective
                                    effects on USDA grades.
Table 3. Effects of full scale bin filler prototypes on apple bruising and USDA fresh market grade
(percentages based on % of total apples tested).
            Treatment              Downgraded to   Downgraded to No.     Bruise width   Bruise volume
                                                                                                3
                                    Fancy Grade     1 or Utility Grade      (mm)            (mm )
                                        (%)                (%)
  Energy absorbing grate
                                        0                  0                1.3 d          10.5 de
  prototype – 2.5 cm drop
  Energy absorbing grate
                                        3                  3                2.7 cd        22.5 cde
  prototype – 5 cm drop
  Energy absorbing grate
                                        0                  9               5.6 abc        62.8 cde
  prototype – 10 cm drop
  Pneumatic prototype – 2.5 cm
                                        6                  6                5.1 bc        57.8 cde
  drop
  Pneumatic prototype – 5 cm
                                        9                  13              6.0 abc        115.9 bc
  drop
  Pneumatic prototype – 10 cm
                                        18                 13              6.6 ab          182.7 b
  drop
  Energy absorbing
                                        0                  0                0.0 d           0.0 e
  grate/singulated – 2.5 cm drop
  Energy absorbing
                                        0                  0                0.3 d           4.6 e
  grate/singulated – 5 cm drop
  Energy absorbing
                                        9                  0                1.2 d          11.5 de
  grate/singulated – 10 cm drop




                                                                                                        10
    Pneumatic
    prototype/singulated – 2.5 cm             0                      0                  0.2 d               0.7 e
    drop
    Pneumatic
    prototype/singulated – 5 cm               3                      0                  0.6 d              2.4 de
    drop
    Pneumatic
    prototype/singulated – 10 cm              6                      0                  0.9 d              5.9 de
    drop
    Control – 2.5 cm drop                    13                      6                 5.5 abc           111.1 bcd
    Control – 5 cm drop                      24                     13                  8.7 ab            187.7 b
    Control – 10 cm drop                     34                     19                  9.0 a             289.6 a
z
 Means, within columns, followed by dissimilar letters are significantly different according to Fisher’s protected least
significant difference, P ≤ 0.05.

Conclusion
The scope of our harvesting research is to design a dry bin filling system that is capable of
handling apples within an acceptable level of bruising, and this paper presented initial work on
two passive concepts. Our experiments provided our team with insight into the required design
requirements to ultimately develop an in-field bin filling system. In particular, we quantified the
significance of maintaining fruit singulation throughout the entire harvesting process from
picking to transport to bin filling. Our future efforts will focus on integrating an apple transport
system with a bin filler design, so that singulation will be maintained from the moment an apple
is removed from a tree until placed in the bin. This strategy should result in a harvesting system
with improved productivity and reduced fruit damage.

Acknowledgements
The authors would like to acknowledge the valuable support of Jim Schupp and Terry Salada of
the Penn State Fruit Research and Extension Center, David Sherman of the Rogers
Corporation, Rice Fruit Company, and Bear Mountain Orchards. This project is supported by a
USDA Specialty Crop Research Initiative grant titled Comprehensive Automation for Specialty
Crops and the Washington Tree Fruit Research Commission.

References
Baugher, Tara. 2006. Why apples bruise. Fruit Times 25:1-2.
Baugher, T., J. Schupp, K. Lesser, R.M. Harsh, C. Seavert, K. Lewis, T. Auvil. 2009. Mobile
      platform increase orchard management efficiency and profitability. ACTA Horticulture
      824: 361-364.
Hyde, G.M., R.W. Bajema, J. Varith, and A.L. Baritelle. 2003. Increasing-height multiple-impact
      measurement of bruise threshold in fruits and vegetables. ACTA Horticulture 99: 409-
      410.




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