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The objective of this study was to review the research activity and developments on transplanting mechanisms for onion cultivation. The literature was reviewed for handheld, semi-automatic and automatic onion transplanting devices and their respective mechanisms used for onion transplantation. Handheld onion transplanter devices used a simple structure mechanism consisting of two jaws pivoted at the bottom of the seedling guide tube and can be open and close by pressing the hand lever. Finger type and plug type transplanting mechanism commonly used in semi-automatic onion transplanter. Semi-automatic onion transplanters are either walk behind or tractor driven and an operator need to concentrate on manual feeding of seedlings into the planting hoppers. Fully automatic onion transplanters consist of seedling picking and planting mechanisms. These automatic transplanting mechanisms involve a continuous process of seedling extraction from the growing medium cell tray and punching into the soil at required depth and planting interval respectively. Pin type and pushing bar type pickup mechanisms have developed to extract the onion seedlings automatically and place at pre-defined position. These mechanisms are comprise by grippers, manipulators, and end effectors. In recent studies, 4 bar and 5 bar seedlings pickup mechanisms were investigated to evaluate the motion trajectories and best possible combinations of the link bars. The wheel type, rotary type, and linkage type planting mechanisms have been developed to deposit the onion seedlings into the soil. Transplanting rate, efficiency, and accuracy of the automatic onion transplanting mechanism is significantly better than the handheld and semi-automatic onion transplanters.
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Copyright: © 2020 Korean Society of
Precision Agrculture
Precision Agriculture Science and Technology 2(4) December 2020
OPEN ACCESS
pISSN : 2672-0086
eISSN : 2713-5632
󽶅
Onion transplanting mechanisms: A review
Kamal Rasool1, Md Nafiul Islam1, Mohammod Ali1, Bo-Eun Jang1, Nadeem Ali Khan2, Milon
Chowdhury1, 2, Sun-Ok Chung1, 2*†, Haing-Ju Kwon3*†
󽶅󽶅󽶅󽶅 󽶋󽶅󽶅󽶋󽶅󽶅󽶅󽶋󽶅
󽶋󽶅󽶅󽶅
󽶅󽶅󽶅󽶅󽶋󽶅󽶅󽶋󽶅 󽶅󽶅󽶋󽶅󽶋󽶅
󽶅󽶅
󽶅󽶅󽶍󽶋󽶅󽶍󽶅󽶋󽶅󽶅󽶅
󽶅󽶏󽶅󽶍󽶍󽶐󽶅󽶍󽶍
󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅
Abstract
󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅 󽶅󽶅
󽶅󽶅󽶅󽶅󽶍󽶅󽶅󽶅󽶅󽶅󽶅󽶋󽶅
󽶌󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅
󽶅󽶅󽶅󽶍󽶅󽶅󽶅󽶅󽶅󽶅 󽶅󽶅
󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅
󽶅󽶅 󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶍󽶅󽶅󽶅󽶅󽶅󽶅
󽶅󽶅󽶅󽶅 󽶅󽶌󽶅󽶅 󽶍󽶅󽶌
󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅
󽶅󽶅󽶅󽶅󽶅 󽶅󽶅󽶅󽶅󽶅󽶍󽶅󽶅󽶅
󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶍󽶅󽶅󽶅
󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅
󽶅󽶅󽶅󽶅󽶅 󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅
󽶍󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅
󽶅󽶅 󽶅󽶅󽶅󽶅󽶅󽶌󽶅󽶍󽶅󽶅󽶅
󽶅󽶅󽶅󽶋󽶅󽶋󽶅󽶅󽶅󼵟󽶍󽶅󽶅󽶅󽶋󽶅󽶅󽶅󽶅󽶅󽶅
󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅
󽶅󽶅󽶅󽶅󽶅󽶍󽶅󽶅󽶅󽶋󽶅󽶅󽶋󽶅󽶅󽶅󽶅󽶅
󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶍󽶅󽶅
󽶋󽶅󼵢󽶋󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅󼵠󽶅
󽶅󽶅󽶅󽶅󽶅󽶌󽶅󽶅󽶍
Keywords: 󽶋󽶅󽶋󽶅󽶌󽶋󽶅󽶅󽶋󽶅󽶅
󽶋󽶅󽶅
The onion (
Allium cepa L
.) also known as the bulb onion is the most widely cultivated and
consumed vegetables across the globe. The onion cultivation area in the world was 2.4 million ha
in 1996 and it reached 4.9 million ha in 2016 and the changes in onion production was recorded 60
million tons in 1996 to 90 million tons in 2016 (Hanci, 2018). China is the largest onion producer in
󽶏󽶎󽶎󽶍󽶎󽶍󽶎󽶍
Accepted: 󽶅󽶋󽶅
Revised: 󽶅󽶋󽶅
Received: 󽶅󽶋󽶅
DOI:
Onion transplanting mechanisms: A review
Precision Agriculture Science and Technology 2(4) December 2020 196
the world with annual production is around 24 million tons. India produced 19 million tons of onion and comes second in the
yearly production. The demand of this vegetable is very high worldwide. Normally the onion seedling are raised in the cell tray
for the transplantation. Planting onion in a traditional way is very drudgery and non-efficient and require 185-260 man-hr/ha
(Kumar and Raheman, 2008). Onion is one of the crops with a lower mechanical work rate and higher labor input compared to
rice or other crops. In addition, the aging of rural workers has led to a decline in labor qualitative skill levels, while labor costs
for onion production are rising due to a lack of manpower. The manual transplanting of the vegetable seedling is a cumbersome
and laborious task for the famers when need to do on a large commercial scale. More time and money need to spend with non-
uniform outcomes of transplanting than the mechanized transplantation (Orzolek, 1996). The continuous increase in labor
costs for onion production leads to an increase in the price of onions in South Korea, resulting in lower price competitiveness
compared to foreign onions. In onion cultivation, the largest percentage of labor input is planting and harvesting, requiring a
large amount of labor of 26% each. Therefore, it is necessary to develop an automatic onion planting machine to reduce the
amount of labor input.
The transplanters are classified as semi-automatic and automatic (Park et al., 2004a). The automatic transplanter are able to
feed the seedling into the hopper of the planting device by mechanically designed self-propelled mechanisms whereas in semi-
automatic transplanters farmer manually supply the seedling to the planting device. Research and development of plug seedling
transplanter were started in 1980s. It was reported by Srivastava (2000) that mechanized cultivation of the vegetables can be
effective to increase the production as well as quality of the crop. In vegetable cultivation, mechanical transplanters are effective
to reduce the labor cost and increase the quality of the product by standardizing the row spacing, planting internal, planting
depth and on time transplantation of the seedlings. Min et al. (2014) stated that implantation of the seedling is simply dropping
the seedling in to the soil by a component of the transplanter called planting device. A 4-row onion automatic planting machine
(OPK-4-KR) developed by Kubota, South Korea, and a paper pot onion planting machine developed in India. (Kumar and
Raheman, 2011). Overall transplanting efficiency depends on the mechanism type of the planting device used for the
transplanter. These limitations in the transplanting efficiency occurred due to the non-vertical deposition of the seedling into the
soil and creation of wide transplanting hole diameter by some vegetable transplanter (Jo et al., 2018). The planting mechanisms
operate on a structure of linkages, which moves the planting hopper in a trajectory pattern that can be set to a constant rate of
motion. However, a few modifications to the linkages responsible for the trajectory may significantly improve the working
ability and efficiency of the transplanter by solving the problem of defective transplanting orientation.
The objective of this study was to review and classify the transplanting mechanisms utilized in different kind of onion
transplanters. The working principles and operational efficiencies of handheld low cost manually operated onion transplanting
mechanism, semi-automatic plug type onion transplanting mechanism and automatic onion seedling picking and planting
mechanism are discussed in this review article.
Onion transplanting mechanisms: A review
Precision Agriculture Science and Technology 2(4) December 2020 197
Classi󼵠cation of the onion transplanting mechanism
Fig. 1 shows the classification of onion transplanting mechanism based on the operational methods and mechanisms used in
onion transplanters. The handheld, semi-automatic and automatic onion transplanting devices have been commercially available
since last two decades. The handheld and the semi-automatic onion transplanting devices are cumbersome to utilize because,
the manual feeding of the seedlings in to the hopper depends on operation interval and expertise of the operator. The machine
vision was applied to extract the area of seedling perimeter, and a 98% success rate were obtained for automatic seedling
transplantation. (Jiang et al., 2009; Sun et al., 2010; Han et al., 2013; Tong et al., 2014).
The end effectors for seedling transplanter classified based on picking actions of the fingers, the clamp type Zhou et al. (2009)
and slide type (2015). The vertical position of clamp type end effector changes after clamping the seedling whereas, the slide
type end-effector dont change its vertical position during the seedling transportation. The pin type end effectors have difficulty
in releasing the seedling and slide type end effectors have grasping problems during the seeding transplanting process. Jiang et
al. (2017) designed an end effector with four needles could be driven by linear pneumatic cylinder. Therefore, the workability
of grasping and penetration of the needles into the substrate of the seedling pot could make possible simultaneously. 100%
results were obtained for total transplanting success rate whereas, less than 17% of seedling root damage rate were observed
with slightly cracked or 1/5 of substrate damage of root plugs. The designed model is convenient to adjust the verticality and
penetration depth for different vegetables and seedling tray.
Fig. 1.󽶅󽶅󽶅󽶅󽶅󽶍
Onion transplanting mechanisms: A review
Precision Agriculture Science and Technology 2(4) December 2020 198
Handheld onion transplanting
Jin (2013) invented a low cost handheld transplanter for onion seedling implantation into the soil. This device consisted of
hole punching mechanism at the lower end of the transplanter consisting on a pair of jaws which was able to penetrate through
the plastic mulch film and create a taper hole for onion seedling placement.
Moreover, a seedling guide mechanism moved downward to open the punching hopper and guide the seedling inside
the punched hole. To satisfy the vertical deposition state of the seedling an earthling mechanism used to cover the seedling
surroundings with soil. The required planting depth (2 cm) of the onion seedling was completely depending on the operator and
it was found random and result showed the errors. Nandede et al. (2017) developed a low cost two row vegetable transplanter
also suitable for the transplanting of onion plug seedling. The transplanting mechanism involve a simple jaws combined with
springs and hexagonal bolts, pivoted at the bottom of the seedling guide pipe. Table 1 shows the field performance comparison
of the handheld and manual transplanting of onion seedlings with or out without mulching. Field performance results such as
planting interval, planting efficiency, field capacity and transplanting rate were mentioned..
Fig. 2.󽶅󽶅󽶅󽶅󽶅󽶉󽶋󽶅󽶊󽶍
Table 1.󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅
Methods Planting interval
(cm)
E󽃣ciency
(%)
Field capacity
(ha/h)
Transplanting rate
(seedlings/min)
Manual transplanting on ridges 45×45 30 0.009 8
60×60 41 0.017
Manual transplanting on mulch 45×45 21 0.007 5
60×60 28 0.012
handheld transplanter on ridges 45×45 45 0.028 23
60×60 60 0.050
handheld transplanter on mulch 45×45 33 0.020 17
60×60 44 0.037
Onion transplanting mechanisms: A review
Precision Agriculture Science and Technology 2(4) December 2020 199
Single person required to punch the transplanter into the soil and pull the lever in upward direction, which is attached with
jaws mechanism by using a gauge wire to open the jaws inside the soil. An adjustable marker was attached by a holder to locate
the next planting position. Experiment was done for inter and intra row spacing on ridges and plastic much bed respectively.
The transplanting rate of 23 and 17 seedlings/min were obtained for raised bed and plastic mulch bed respectively.
Semi-automatic onion transplanting device
The semi-automated transplanter are not suitable for continuous operation for a long period of time due to the limited
operation speed as only one seedling is possible to feed manually at a time. In the case of the semi-automatic onion planting
machine developed by Joeun Agricultural Machinery, a person boards and manually transfers the seedlings as the seedling
transfer method. An 8-row semi-automatic onion transplanter (A5-1200) was developed by (Joeun Agricultural Machinery,
South Korea). Fig. 3 shows the riding type self-driven semi-automatic 8-row onion transplanter. The row to row distance for
above mentioned onion transplanter is 15cm. whereas, plant to plant distance is adjustable. In semi-automatic mechanism, there
is a possibility of miss feeding of the seedlings when the transplanting rate is higher (Khadatkar, 2018). The walk behind type
and riding type semi-automatic onion transplanters are commercially available.
The semiautomatic tractor driven onion transplanter generally comprised by a furrow opener, a seedling transferring or
conveying mechanism, a soil covering device, and a seedling delivery tube. It was judged that transplanting efficiency was
directly proportional to the speed of the operation. The 72.39% maximum transplanting efficiency was measured at 3.5 km/hr
operational working speed (Kumawat et al., 2020). A tractor driven semiautomatic transplanter was developed and evaluated for
different vegetables including onion and transplanting rate 60-80 seedlings/min was observed with row spacing of 30cm (Cráciun
and Balan, 2005).
Fig. 3.󽶅󽶅󽶅󽶌󽶅󽶅󽶅󽶉󽶌󽶋󽶅󽶅󽶅󽶋󽶅󽶅󽶊󽶍
Onion transplanting mechanisms: A review
Precision Agriculture Science and Technology 2(4) December 2020 200
Automatic onion transplanting mechanism
Automatic onion transplanting devices involve repeat process of seedling picking from the tray and planting it into the soil and
reduce the labour requirement for feeding the seedlings. Fig. 4 shows the schematic view of automatic seedling transplanting
mechanism. Automatic onion transplanting devices is a synchronized combination of automatic seedling pickup and planting
mechanism.
The self-propelled fully automated transplanting mechanism for onion seedlings permit the high speed planting operation and
effective for the elimination of laborious tasks because seedling fed and planted automatically by machine itself (Zhou et al.,
2014). In general, the automatic onion transplanting devices may be walk behind or riding type. Furthermore, the walk behind
type onion transplanter are self-propelled whereas the riding type are either self-propelled riding type or self-propelled tractor-
driven.
Automatic picking mechanisms
Pin type and pushing type automatic seedling pickup mechanism are used for the onion seedling extraction (Min et al., 2014).
Fig.5 shows the two different kind of plug seedling extraction methods which is picking and pushing the plug seedling from
the cell tray. The both pin type seedling picking and pushing type seedling extraction method used and suitable to meet the
required conditions for onion seedling transplantation. The Kubota onion planter OP4-KR selected pin type method to withdraw
the onion seedling from the cell tray and deliver it to the conveyor belt which is further synchronized with the rotary planting
hopper. The (Minoru, Japan) onion planter OPT-4 used pushing type method to pull out the onion seedling from the cell tray and
one seedlings carrying assembly transferred the seedling on the conveyor belt where seedling falls into rotary hopper to deposit
into the soil.
Fig. 4.󽶅󽶅󽶅󽶅󽶅󽶉󽶋󽶅󽶊󽶍
Onion transplanting mechanisms: A review
Precision Agriculture Science and Technology 2(4) December 2020 201
Pin type seedling extraction mechanism
Choi (2000) presented an automatic seedling pickup mechanism for plug seedlings showed in Fig. 6. This kind of seedling
pickup mechanism suitable for effective, accurate and efficient planting with less human intervention. General concept of this
kind of picking mechanism is to extract single seedling from the plug tray using pair of pins, then discharge at the required place
and come back its initial position.
Fig. 5.󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶏󽶅󽶉󽶊󽶅󽶅󽶅󽶅󽶅󽶉󽶊󽶅󽶅󽶅󽶅
󽶅󽶉󽶅󽶅󽶍󽶋󽶅󽶊󽶍
Fig. 6.󽶅󽶌󽶅󽶅󽶅󽶅󽶅󽶉󽶋󽶅󽶊󽶍
Onion transplanting mechanisms: A review
Precision Agriculture Science and Technology 2(4) December 2020 202
The onion seedling planting machines used in Japan and Korea have a small cell tray diameter of 18 mm or less. Rahul
et al. (2019) designed and developed a parallel robotic arm consisting of five revolute joint (5R) and two degree of freedom.
The developed mechanism was synchronized with mechanical, electronic, logic and program consideration to integrate the
automatic handling of the paper pot seedling for field operation. It was reported that a parallel robot arm was suggested to be
more suitable for high speed operation of picking and placing of the paper pot seedlings under a hostile environment. Forward
kinematic equations were synthesized to calculate the suitable lengths of linkage and the grippers for a specified working area
and depending on the known parameters, the input actuator link of appropriate combination was selected. The average estimated
time to complete one cycle of picking and placing of the seedling was 2.25 sec. Due to the implementation of linear trajectory
with parabolic blend a smooth positional repeatability, 2.1 and 3.4 mm in X and Y directions was obtained without any jerk
during the pick and drop cycle.
Pushing type seedling extraction mechanism
Min et al. (2014) investigated the performance of the onion transplanting mechanism consisting of pushing type onion
seedling extraction mechanism. A seedling pushing type mechanism developed to measure the extraction resistant of onion
seedlings. The ejection pin used in this study was consisted of pneumatic cylinder of 50 mm, a pin for pushing seedlings
of 80 mm, and pushing pin diameter varies from 4 mm to 8 mm. The seedling take-out resistance found to be increasing as
the diameter of the pushing pin increase. In addition, the extraction resistance and breakage rate of seedlings were analysed
according to the change in pin diameter and speed.
An automatic onion transplanting method described by Min et al. (1999) which consist of seedling-mounting, one step
downward movement then seedling-extraction and finally transferring the seedling into the hopper through free falling process.
It was suggested that weight of the root of the onion seedling is an important for safe transferring during the free fall process.
Fig. 7.󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶉󽶅󽶅󽶍󽶋󽶅󽶊󽶍
Onion transplanting mechanisms: A review
Precision Agriculture Science and Technology 2(4) December 2020 203
Automatic planting mechanisms
The planting device of the vegetable planter developed and distributed in Korea includes a wheel method, a rotary method,
a 4-section link method, and a 4-section link-cam method. A study was done by Min et al. (2015) involving the structural
and motion trace path trajectory analysis of four different vegetable transplanting mechanism for the development of onion
transplanter. These four mechanism were consisted of wheel type, rotary type, four bar link, and four bar link-cam type
transplanting mechanisms. Forward drag distance of the planting hopper was measured for each mechanism at zero relative
velocity. It was stated that four bar link-cam type mechanism produced the smallest drag distance of 9.89 mm when the row
spacing was 130 mm. Therefore, four bar link-cam type transplanting mechanism could meet the required needs and expected
to maximize the transplanting performance.
Wheel type transplanting mechanism
The wheel method is a method in which a number of planting openers are installed on the wheel to formally match the wheel
speed. And it is characterized by a uniform structure and simple structure even when the speed changes. However, the wheel-
type planting device has a disadvantage in that it is bulky and a plurality of planting openers must be mounted. For wheel
method, the planting opener would not be attracted because the end of the planting opener was fixed in the soil (Kim et al.,
2004).
Rotary hopper type transplanting mechanism
The rotary method is the planting device that is most often used for planting vegetables by drawing power through the
crankshaft and drawing the oval-shaped stop trajectory of the planting machine while the gear cases and planting machine
rotate. As for the rotary method.
Fig. 8.󽶅󽶅󽶅󽶅󽶅󽶉󽶅󽶅󽶍󽶋󽶅󽶊󽶍
Onion transplanting mechanisms: A review
Precision Agriculture Science and Technology 2(4) December 2020 204
Linkage-cam type transplanting mechanism
An onion transplanter consisting of a 4-bar cam type seedling planting mechanism was manufactured by Min et al. (2016)
with almost zero relative motion between hopper and forward speed of the device. Optimum operating condition was evaluated
and 100% success planting rate were obtained with plating efficiency of 50 seedling/min. Jo (2018) developed a study that
how to enhance the transplanting efficiency by positions analysis and selection of the appropriate lengths of the linkage
mechanism of planting device shown in figure. Validation comparison and analyzation were done between the actual and
simulated trajectories extracted by using the CCD (charged couple device) camera and Recurdyn 3D software respectively.
Performance evaluation experiment were conducted for both existing and improved planting devices. Average planting angle,
soil encroachment diameter and planting depth was improved by 4.96 mm, 11.30 mm, and 0.68 mm respectively.
Fig. 9.󽶅󽶅󽶅󽶅󽶅󽶅󽶉󽶅󽶅󽶍󽶋󽶅󽶊󽶍
Fig. 10.󽶅󽶅󽶅󽶅󽶅󽶅󽶋󽶅󽶅󽶅󽶅󽶅󽶅󽶉󽶋󽶅󽶊󽶍
Onion transplanting mechanisms: A review
Precision Agriculture Science and Technology 2(4) December 2020 205
Shao et al. (2019) developed a multifunctional vegetable transplanting machine with two kind of duckbill planter were
designed, diamond duckbill type and flat duckbill. The mechanism was composed of two crank arms and three connecting rods.
The both crank arms rotate counter clockwise with similar rotational speed around the fixed point respectively, as the result the
seedling were picked by the duckbill planter at predetermined position and move downward to plant the seedling into the soil.
Simulation were carried out at low, medium, and high speed of motion with corresponding values were set to be 0.5 km/h, 1.0
km/h and 1.5 km/h respectively. The planting frequency were determined 57, 72 and 88 seedlings/min respectively.
Fig. 11.󽶅󽶅󽶅󽶋󽶅󽶅󽶅󽶅󽶅󽶅󽶉󽶅󽶅󽶍󽶋󽶅󽶊󽶍
Table 2.󽶅󽶅󽶅󽶅󽶅󽶅󽶅󽶅󼵟󽶅󽶅󽶍
Type of mechanism Trajectory shape
Soil repulsion (mm)
for di󽃠erent planting interval
130 mm 140 mm 150 mm
Wheel type Cycloid curve 31.18 22.29 14.14
Rotary hopper type Elliptical curve 9.34 7.11 4.89
Linkage type Coupler curve 9.89 12.85 16.09
The study trends and findings in the field of onion transplanting mechanism briefly discussed in this review study. This study
elaborates the mechanisms used for onion transplantation over the past few decades. The low cost handheld onion transplanting
device are mostly used in under developed south Asian, central Asian and African countries. Single person can operate this
device with field efficiency and field capacity of 45-60% and 0.028-0.050 respectively. However, operator also requires a
rest pause of 4.5 minutes approximately during the transplanting operation. By using handheld device 34% time saving was
measured as compare to manual transplanting. The semi-automatic onion transplanters were developed and largely used in
USA, China, Japan, Korea, and India. These transplanters are mainly classified as self-driven and tractor driven type. But for
each type person has to board and manually feed the seedling to the planting hopper or conveying mechanism. Maximum
transplanting efficiency and working speed was calculated as 72.39% and 3.5 km/hr respectively. Whereas transplanting rate
of 70-80 seedlings/min can achieved using semi-automatic onion transplanter. Fully automatic onion transplanting mechanisms
possess the most convincing impact on the farmers and wide research is going on to improvise the performance. Most advanced
form of these transplanter is self-propelled riding type, consisting of mechanically extrusion of seedling from growing tray and
implanting into the soil.
Onion transplanting mechanisms: A review
Precision Agriculture Science and Technology 2(4) December 2020 206
Summary and Conclusions
Number of onion transplanter based on different operation mechanisms have been commercially available since last two
decades. Performance, transplanting efficiency, and accuracy of individual components as well as overall system has been
significantly improved. This review study provides the following useful information related to the mechanism used in the onion
transplantation.
1) Handheld onion transplanting device is a low cost manually operated mechanism suitable for small land holder farmers.
This transplanting mechanism involve a simple jaws pivoted at the bottom of the seedling guide mechanism and device
holder and jaws operation lever is attached at the top end of guide mechanism. Single person required to punch the
transplanter into the soil and pull the lever in upward direction, which is attached with jaws mechanism by using a gauge
wire to open the jaws inside the soil. Next planting position is also possible to locate using an adjustable marker. Based on
the literature, the handheld onion transplanting device is capable to transplant the 23 and 17 seedlings/min for raised bed
and plastic mulch bed respectively.
2) The semi-automatic onion transplanting devices are cumbersome to utilize because, the manual feeding of the seedlings
in to the hopper depends on operation interval and expertise of the operator. Semi-automatic walk behind type and tractor
operated type onion transplanter are commercially available worldwide. It requires manual feeding of the plug seedling by
a person who need to board on the transplanter. The semi-automatic onion transplanter used plug type, finger type, and cup
or bucket type metering mechanism for the onion seedling deposition into the soil. These type of transplanting device are
prone to miss feeding of seedling at higher transplanting rate.
3) The automatic onion transplanting devices are able to feed a row the seedlings to the conveyor mechanism where it further
fed into the hopper of the planting device by mechanically. 4 rows, 6 rows and 8 rows automatic onion transplanting
devices are available commercially. Depending on the number of rows and operational capacity these transplanters are
either walk behind type self-propelled or riding type self-propelled, and riding type tractor operated. Pin type and pushing
type seedling picking mechanism are used to extract a row of onion seedlings from the plug tray and end-effector assembly
used to transfer the seedlings on conveyor mechanism. Wheel type, rotary type and linkage type planting mechanism are
commonly used to deposit the onion seedlings into the soil. Performance evaluation of the automatic onion transplanting
mechanism is significantly better than the handheld and semi-automatic onion transplanters.
Acknowledgment
This research was supported by Korea Institute of Planning and Evaluation for Technology in Food, Agriculture and Forestry
(IPET) through (Project No. 2019300514), funded by Ministry of Agriculture, Food and Rural Affairs (MAFRA).
Onion transplanting mechanisms: A review
Precision Agriculture Science and Technology 2(4) December 2020 207
References
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󽶶󽶻󽶸󽶴󽶺󽶻󽶴󽶻󽶶
 󽶴󽶲󽶳󽶸
󽶶
󽶷󽶲󽶶󽶴󽶳󽶵󽶴󽶴󽶶
Onion transplanting mechanisms: A review
Precision Agriculture Science and Technology 2(4) December 2020 208
 󽶴󽶲󽶳󽶶
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 󽶳󽶻󽶻󽶻
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󽶳󽶲󽶲
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
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󽶳󽶸󽶸󽶳󽶲󽶷󽶲󽶳󽶶
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󽶶󽶸󽶸󽶶󽶹󽶹
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... At present, the essential part of a hole-punching transplanter is the hole-forming device, which primarily falls into two types in accordance with the hole-forming method, including the soil-extruding type and the soil-taking type [18,19,[21][22][23][24][25][26]. The Rain-flo semiautomatic hole-forming transplanter manufactured by Buckeye Tractor Co in the United States uses a hole-forming shovel distributed on the outer edge of the water wheel to form holes in the soil by forcing soil extrusion; then, the pot seedlings are directly put into the planting holes manually. ...
... The transplanting mechanisms of handheld, semi-automatic and automatic onion transplanters were previously summarized and analyzed and the wheel-type, rotary-type and linkage-type planting mechanisms were compared and analyzed. However, planting mechanisms adopt the rotary extrusion method to complete soil inserting, which results in large hole size and reduced soil porosity of the hole wall, thus having an effect on the perpendicularity of seedlings and air permeability in the formed holes [26]. Chen simulated and tested the hole-forming device of a buckwheat planter by applying discrete element software and multi-body dynamics software; the relevant parameters of the vital components (including duckbill and duckbill spring) were obtained and the bench test was performed to calculate the best spring wire diameter and rotational speed of seeding wheel. ...
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To address the problem whereby the size of the hole formed by the existing hole-forming device of hole-punching transplanters is significantly inconsistent with the theoretical size as it is impacted by the inserting and lifting methods, a scheme for eliminating the forward speed of the whole machine by the horizontal linear velocity of reverse rotation of the hole-forming mechanism is proposed to vertically insert and lift the hole-forming device in accordance with the working characteristics of hole-punching transplanting and the agronomic requirements of rapeseed transplanting. In addition, a novel type of reverse-rotating soil-taking-type hole-forming device for the pot seedling transplanting machine for rapeseed was developed. A test bench for the hole-forming device was set and its effectiveness was verified in the soil bin. It was found, from the test results, that, when the forward speed of the hole-forming device was between 0.25 m/s and 0.45 m/s, the average qualified rates of hole forming of the device were 95.2%, 94.0% and 93.3%, respectively; the average change rates of the hole size were 2.3%, 2.9% and 5.5%, respectively; and the average error between the theoretical value of effective depth and the experimental value was between 2.0% and 5.6%. The average angle between the hole-forming stage trajectory of the hole opener and the horizontal direction at different forward speeds was higher than 88.0°; the coefficient of variation was between 0.16% and 0.64%; the perpendicularity of the hole-forming operation was high; the change rates of soil porosity of the hole wall were between 8.2% and 9.3%; and the average soil heave degrees at the hole mouth after the completion of the hole-forming operation were 3.9%, 4.1% and 4.2%, respectively. The average soil stability rates of the hole wall were 91.9%, 91.2% and 91.0%, respectively. The different performances of the hole-forming device were confirmed to meet the requirements of rapeseed pot seedling transplanting. This study can provide a reference for the structural improvement and optimization of the hole-punching transplanter for rapeseed pot seedlings.
... For instance, onion production in Korea declined by 426,223 tons (26.7%) in 2020 compared to 2019 [4]. The primary causes of declining onion production are a scarcity of farm labor and the lack of mechanization in transplanting operations [5]. Mechanized onion transplanters are therefore required to solve issues in production and help both small landholders and older, more established farmers. ...
... For smooth meshing operation of the Machines 2021, 9, 183 6 of 17 spur gears, it is recommended that the gear contact ratio should be greater than 1.4 and less than 2 [25]. Gear contact ratio can be measured using Equation (5) [26], as below: ...
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The purpose of this study was to develop a kinematic model of a gear-driven rotary planting mechanism for a self-propelled onion transplanter. The kinematic model was simulated using a commercial mechanical design and a simulation software package, and was validated through an on-site performance test. Torque and acceleration sensors were installed with an input power shaft and hopper jaws, respectively. Through kinematic analysis and simulation, the appropriate length combinations for primary, connecting, and planting arm were determined as 90, 70, and 190 mm, respectively. The diameters of the driver, driven, and idler gears in the primary arm were 56, 48, and 28 mm, respectively. For the secondary link, the diameters of the driver, idler, and driven gears were 28, 28, and 56 mm, respectively. The length of the planting hopper was selected as 190 mm and remained constant during the kinematic analysis. The maximum magnitude of the velocity and acceleration of the planting mechanism were determined as 1032 mm/s and 6501 mm/s2, respectively. The power consumption was measured as 35.4 W at 60 rpm. The single- and double-unit assembly of the studied rotary planting mechanism can transplant 60 and 120 seedlings/min, respectively.
Conference Paper
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The lateral turning stability analysis of the self-propelled riding-type upland crop machinery is an important issue as the cultivation lands are usually uneven, and cause severe work-related injuries, even death. In this study, the lateral turning stability of a 12-kW self-propelled riding-type automatic onion transplanter was analyzed for ensuring the safety during transplanting operation. To evaluate turning stability, the center of gravity (CG) of the developed onion transplanter was determined theoretically. Then, a simulation was carried out to identify the lateral turning stability angles using the RecurDyn software, and the results were validated through tests. Rollover angles in the loaded and unloaded conditions were also checked. The statistical significance of the replications was determined by a one-way analysis of variance (ANOVA). According to the physical dimensions of the onion transplanter, the mathematical rollover angle was 34.5°. The average simulated rollover angles were 43.9°. Due to the symmetrical structure, a 4.5° turning difference was observed between the right and left side turning, and a 3° angle difference was occurred due to the variation of load conditions. The rollover angles fulfilled the ISO (International Organization for Standardization) standard. The findings of this study would be helpful for the manufacturers to ensure operator safety during the upland crop machinery operation in uneven and sloped lands.
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A 15 hp mini tractor operated 4-row automatic onion transplanter was developed to transplant onion seedlings raised in hexagonal shaped (honeycomb) paper pot chain of length 800 mm, width 180 mm and depth 40 mm. A total of 128 seedlings were raised in this paper pot chain. The onion transplanter was developed to transplant 4- rows of onion seedlings at a time with a spacing of 10 cm between each row. It consisted of a furrow opener, a covering device, conveying belt and cutting units, a seedling delivery tube for each of the four rows and two ridgers for making two ridges each of 40 cm wide at the top. Belt-type conveying unit was employed for the movement of the paper pots. On the conveyor, paper pot chain was put and it conveyed the same to the furrow opener through the seedling delivery tubes after singulation using two types of cutting units i.e. three rotary cutters and a vertical blade. The rotary cutters were used to tear the paper pot chain lengthwise along the rows whereas one vertical blade was used to cut the paper pot chain perpendicular to the rows so that seedlings were singulated and one seedling was available for each seedling delivery tube at a time. Rotary cutters were powered by ground drive wheel whereas vertical blade was powered by a 12V 600 W DC motor using the tractor battery. The developed automatic onion transplanter was tested in the field with alluvial soil (M. C. 20.3% db) at an average forward speed of 3.0 km/h. The average row to row spacing, plant to plant spacing and depth of placement were found to be 8.12 cm, 20.3 cm, and 2.99 cm, respectively. The average effective field capacity of the developed transplanter for transplanting onion seedlings was found to be 0.071 ha/h with a field efficiency of 71.25 % and average missing index and multiple index was found to be 33% and 18.77%, respectively. Keywords – Onion transplanter; Hexagonal shaped paper pot chain; Conveying unit; Rotary cutters; Vertical blade; Field efficiency; Missing index and Multiple index
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Vegetable transplanting is a labourious and time consuming field operation when performed manually. The semi-automatic vegetable transplanters are cumbersome to operate due to limitations on manual feeding rates of seedlings which vary with respect to work duration and skill of the operator. Automation in the field of vegetable transplanters has provided opportunities for savings in labour and time required for transplanting operation in open field and controlled environmental structures, i.e. shade nets or polyhouse. The advent and recent advances in transplanting technologies suggest ample scope of working on automated seedling pickup and drop mechanisms using robotics. Use of seedling pickup mechanism in automatic transplanters can repeatedly extract single seedling automatically from the seedling pro-tray with the help of a pair of pins or forks and drop at predefined location. In general, these systems comprise either a machine vision system or end-effector mechanism for extracting the seedling; gripper and a manipulator; indexing drum-type seedling removal device with ejector; or a pick-up system, feeding system and a planting system. Such automated systems have helped ease the transplanting operation and efficient planting of seedlings by maintaining the accuracy, precision and effectiveness in planting seedlings with minimum human intervention. This study highlights the research gaps and developments in smart transplanting technologies used in the field of vegetable cultivation.
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The onion belongs to Allium section cepa, which consists of twelve species, most of which are used as the vegetable, spices, or medicinal plants. A region of especially high species diversity occurs in Turkey and in the Irano-Turanian floristic region. In this review, changes in the world's and Turkey's onion cultivation areas, production quantities, and yields were examined for last 21 years. Also, monthly producer prices were examined for covering the period 2007-2016. The values of Turkey were compared with Republic of Korea having highest yield, and China having highest quantities. In the conclusion section, it has tried to explain the causes of price fluctuations in the light of findings.
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A low cost manually operated two row vegetable transplanter was developed for transplanting of plug type vegetable seedlings on ridges and mulch beds. It consisted of frame, seedling tray holder, hand lever, frame support rod, jaw assembly, seedling feeding pipe, handle, gauge wire, marker holder and marker. The developed transplanter was evaluated for inter and intra-row spacings of 45×45 cm and 60×60 cm. Manual transplanting on ridges (MTR) and on plastic mulch beds (MTP) were compared with manually operated transplanter on ridges (MOTR) and on plastic mulch beds (MOTP). The transplanting rate of vegetable seedlings using single labour was found to be 8, 5, 23 and 17 seedlings min-1 for MTR, MTP, MOTR and MOTP, respectively. Forward speed ranged from 0.15 to 0.41 km/h for entire range of spacing and type of transplanting selected. Similarly, field efficiency was found to be 30 and 41% (MTR), 21 and 28% (MTP), 45 and 60% (MOTR), 33 and 44% (MOTP) for spacing of 45×45 and 60×60 cm, respectively. Similarly, cost of operation (Rs/ha) was found to be 2571 and 1416; 3770 and 2121; 884 and 497 and 1200 and 675 Rs/ha, respectively. Difference in heart rate, cardiac cost and maximum oxygen consumption rate was worked out to be 33 beats/min, 203703/ha (20.37 beats/m 2) and 2.9109 l/min. Moreover rest pause during the operation was worked out to be 4.5 minute. The time saving over manual transplanting is 34% and 32% in MOTR and MOTP, respectively.
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Automatic transplanters have been very important in greenhouses since the popularization of seedling nurseries. End-effector development is a key technology for transplanting plug seedlings. Most existing end-effectors have problems with holding root plugs or releasing plugs. An efficient end-effector driven by a linear pneumatic cylinder was designed in this study, which could hold root plugs firmly and release plugs easily. This end-effector with four needles could clamp the plug simultaneously while the needles penetrate into the substrate. The depth and verticality of the needles could be adjusted conveniently for different seedling trays. The effectiveness of this end-effector was tested by a combinational trial examining three seedling nursery factors (the moisture content of the substrate, substrate bulk density and the volume proportion of substrate ingredients). Results showed that the total transplanting success rate for the end-effector was 100%, and the root plug harm rate was below 17%. A force measure system with tension and pressure transducers was installed on the designed end-effector. The adhesive force FL between the root plug and the cell of seedling trays and the extrusion force FK on the root plug were measured and analyzed. The results showed that all three variable factors and their interactions had significant effects on the extrusion force. Each factor had a significant effect on adhesive force. Additionally, it was found that the end-effector did not perform very well when the value of FK/FL was beyond the range of 5.99~8.67. This could provide a scientific basis for end-effector application in transplanting.
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This paper presents a complete mechatronic approach in designing and developing a robotic arm for handling paper pot seedlings in a transplanter for the purpose of inclusion of automation and possible reduction of heavy mechanical components in pot seedling transplanters by utilizing microcontrollers and embedded systems. The robot arm developed was of two degrees of freedom (DOF), five revolute joints (5R) with parallel arm structure using 3D printed parts, commercially available embedded microcontrollers and sensors. The gripper which was connected to the parallel robot arm performed pick and place operations at a desired path. For achieving the preferred maximum and minimum reach of the gripper, a suitable method for synthesizing the link length has been discussed. A complete logical technique to program microcontrollers was developed which enabled smooth actuation of both the independent input links simultaneously. Parabolic blends were utilized at the beginning and at the end of the robot input joint trajectory for minimizing dynamic vibrations during continuous operation. The developed robot arm was flexible to change the number of pickup points in a row, pickup and drop co-ordinates within the workspace envelope. Finally, the robot arm was tested and evaluated for picking and placing 15 numbers (4 replications, 60 runs) of actual paper pots filled with vermicompost, soil and sand. Each pot weighed approximately 80 g with a moisture content of approximately 5%. The robot arm took 2.1 to 2.4 s to pick and drop a pot seedling from a distance of 116.6 mm with a maximum power consumption of 20.47 W. Experimental results showed that no pots were missed in picking and dropping, no visual cracks and damage appeared on the pots. The repeatability of the robot arm was 2.1 mm in X-axis and 3.4 mm in Y-axis.
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In China, low degree of automation seriously affects the working efficiency and quality in vegetable transplanting. As one of the most important vegetables in China even in the world, tomato was taken as the research object in this study. An automatic single-row transplanting device was designed, based on the statistical analysis of the physical and mechanical properties of tomato seedlings of a typical variety. Based on the technology of mechatronics, the device integrated the functions of transporting seedling tray, automatic seedling extraction and mechanical planting. The kinematics orthogonality solution combined with the dynamic sequence solution method was used to optimize and analyze the kinematic parameters of the automatic seeding mechanism, and the “sickle” trajectory was obtained. According to the position and movement requirement for taking and dropping seedling, the mechanical conditions and the working parameters of key execution parts were obtained by using analytic drawing method to analyze the mechanical condition of seedling collecting mechanism. The transplanting experiment was conducted at room temperature of 25°C, and the age and moisture content of the seedlings were 40 d and 55%, respectively. The results showed that the highest success rate was 92.59%, and the lowest rate of leakage was 23.13%, when the transplanting frequency was 60 plants/min. The lowest success rate was 77.78%, and the highest rate of leakage was 38.75%, when transplanting frequency was 120 plants/min. When the transplanting frequency is between 60-90 plants/min, the device can meet the requirement of high speed transplanting for potted vegetable seedling. © 2018, Chinese Society of Agricultural Engineering. All rights reserved.