SUGISAKAMASANORI

Journal of Robotics, Networking and Artificial Life
Vol. 9(3); December (2022), pp. 209–215
ISSN (Online):2352-6386; ISSN (Print):2405-9021
https://alife-robotics.org/jrnal.html

Research Article

Design and Development of Ocean Debris Collecting Unmanned
Surface Vehicle and Performance Evaluation of Collecting
Device in Tank
Jonghyun Ahn1, Shunsuke Oda2, Shota Chikushi3, Takashi Sonoda4, Shinsuke Yasukawa2
1

Dept. of Intelligent Mechanical Engineering, Hiroshima Institute of Technology, 2-1-1 Miyake,Saeki-ku, Hiroshima, 731-5193, Japan
Dept. of Human Intelligence Systems, Kyushu Institute of Technology,2-4 Hibikino, Wakamatsu, Kitakyushu, Fukuoka, 808-0196, Japan
3
Dept. of Robotics, Kindai University, 1 Takaya Umenobe, Hiroshima, 739-2116, Japan
4
Dept. of Engineering, Nishinippon Institute of Technology, 2-11, Aratsu, Kanda-town, Miyako-gun, Fukuoka 800-0396, Japan
2ARTICLE INFO
Article History
Received 28 April 2022
Accepted 02 August 2022
Keywords
Ocean debris
Ocean cleaning robot
Marine robotics
USV design

ABSTRACTIn recent years, the oceans debris is increased because of human’s activity. Especially, the plasticdebris, such as plastic bottles, is not biodegradable, and therefore those are creating serious
environmental problems. The ocean debris collecting in the world is done through volunteer
activities. However, these activities require a lot of time and labor. In this research, we proposeda method of ocean debris collecting USV operation method. Also, we designed and developed a
USV (Unmanned Surface Vehicle) for the purpose of autonomous oceans debris collecting
mission and evaluated the developed ocean debris collecting device. In the development of USV,
electronic parts, which are to operate the mission autonomously, were selected. Then, eachelectronic part was placed inside the waterproof box according to the designed power andcommunication system diagram. In the development of oceans debris collecting device, we
designed a belt conveyor type device. A motor was selected to rotate the device and a decelerator,
which used the planetary gear mechanism, was designed. To evaluate the performance of thedeveloped ocean debris collecting device, we tested various types of plastic bottles in tankenvironment. As a result of the experiment, the developed USV collected various types of plastic
bottles with a 47.7% probability.
© 2022 The Author. Published by Sugisaka Masanori at ALife Robotics Corporation Ltd
This is an open access article distributed under the CC BY-NC 4.0 license(http://creativecommons.org/licenses/by-nc/4.0/)[4]. To reduce of these damages, many volunteers andworkers clean the coastal area [5], [6], [7]. However, thiscleanup method is required a lot of cost such as financial
cost, time, and manpower. Recently, marine robotics
system can be mentioned as a solution to this situationbecause the USV (Unmanned Surface Vehicle) can easily
approach ocean plastic debris and work over a large
ocean area for a long time [8], [9], [10].

1. Introduction
In recent years, the increase in ocean debris cause serious
problems such as damage to marine ecosystems, damage
to marine tourism industry, fisheries, and biodiversity
loss. Especially, the ocean plastic wastes, such as plastic
bottles, cannot be naturally decomposed, so it continues
to increase worldwide as ocean plastic debris [1], [2], [3],Corresponding author’s E-mail: j.ahn.h2@it-hiroshima.ac.jp : https://www.it-hiroshima.ac.jp/english/

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In this paper, we designed and developed a USV, whichis called MIROCA (Maritime Intelligence Robot for
Ocean Cleaning Assistance), to collect ocean plastic
debris autonomously. Also, we evaluated the developed
ocean debris collection performance by the experiment,
which employed various types of plastic bottles, in thetank environment.

design conditions of ocean debris collecting USV aredescribed below.
(i) Omnidirectional movement on the ocean surface(ii) Equipment of ocean debris collecting device(iii) Equipment of sensors and process unit forautomounts debris collecting mission
The designed ocean debris collecting USV, which
considered the design conditions, is shown in Fig.2, andtop and side view of designed ocean debris collecting
USV is shown in Fig.3.
As shown in Fig.2, the designed ocean debris collecting
USV is consists of collecting device, debris box, cameras,
wi-fi router, buoyancy and waterproof box.
As shown in Fig.3, the thrusters for omnidirectional
movement are diagonally mounted to consider design
condition (i), and the ocean debris collecting device isequipped on the front of USV for the design condition (ii).
Also, the waterproof box is mounted to arrange electronic
components such as sensors, battery and process unit todesign condition (iii).
The power and communication system diagram, which
include electronic components inside of the waterproofbox, is shown in Fig. 4.

2. Development of Ocean Debris Collecting USV
We propose a method to collect oceans debris using USVand UAV (Unmanned Aerial Vehicle) in Fig.1.
As shown in Fig.1, the proposed operation method iscomposed 6 steps. In the first step, the UAV patrols theset ocean area while take GPS data and ocean surface
images which include ocean debris. The UAV send GPS
data and ocean surface images to computer at USV basein the second step. In the third step, the computer uses thesent data to calculate information, such as the location,
type, size and number of the ocean debris, and then theinformation is sent to USV. The USV moves to the debris
location, and then USV collects the ocean debris in thefourth step. In the fifth step, the USV moves to next thedebris location and collects the ocean debris when thefourth step is completed. In the final step, when the USV
has collected all the ocean debris in the photographed
ocean area by UAV, it returns to the USV base.
We design and develop an USV which can operate thesesteps in Fig.1.

Fig. 2. Overview of designed ocean debris collecting USV

Fig. 1. The proposed ocean debris collecting operation method
using UAV and USV

2,1. Design condition and specifications of USV
The USV is necessary several condition to operate theproposed ocean debris collecting method in Fig.1. The

Fig. 3. Top and side view of designed ocean debris collecting
USV210As shown in Fig.4, 14.8[V] Li-ion battery is employed as
the main power source, and then DC 12[V] and DC 5[V]are transformed by the DC-to-DC converters. The
network cameras, which contain power source and Wi-Fi
communication board, are equipped as the front camera
and back camera. The IMU and GPS sensor arecommunicated using USB serial communication to thecomputer. The computer, which contain I/O port, is send
the PWM signal to motor drivers to operate the thrustersand ocean debris collecting device. The detail ofdesigned ocean debris collecting USV is shown in Table
1.
As shown in Table 1, the size of designed USV is 1.9[m]x 1.2[m] x 1.3[m], and the weight is 35[kg].
2.2 Development of ocean debris collecting device
The ocean debris collecting device, which is equipped on
the front of USV, was developed with the motif of a belt
Fig. 5. Overview of designed ocean debris collecting device

conveyor. The designed collecting device is shown in
Fig.5.
As shown in Fig.5, the designed collecting device iscomposed of brushes, belt and the decelerator with amotor. The brushes are carried ocean debris on the belt,
and then the belt is moved to the debris box. The
decelerator with a motor is necessary to rotate the belt
which is need high torque. Before the motor selection anddesign of the decelerator, we calculated the necessary
torque to operate the ocean debris collecting device. The
force toward driving direction of ocean debris collecting
device can be defined as follows:

Fig. 4. Overview of power and communication system
diagram for ocean debris collecting USV

𝐹 = 𝐹𝑏 +Table 1. Detail of designed ocean debris collecting USV
DetailValuesSize

1.9m×1.2m×1.3m

Weight35kg

Sensors

IMU, GPS, Camera×2

Computer

LattePanda alpha 864s

Equipment

Thruster×4, Wi-Fi Router, Collecting Device

Battery

14.8 V Li-ion battery𝑚𝑏∙ 𝑔 ∙ 𝜇 cos 𝛼 + 𝑚𝑤 (sin 𝛼 + 𝜇 cos 𝛼) (1)2where F is force toward driving direction, Fb is externalforce on the brushes by the fluid resistance, mb is mass ofbelt, g is gravitational acceleration, μ is coefficient offriction of belt, α is belt conveyor tilt angle and mw ismaximum collectable mass of ocean debris. In thedesigned collecting device, Fb was 8[N], mb was 3[kg], αwas 30[deg.], μ was 0.492, which is made by PLA [11],and mw was 10[kg], therefore the F was about 105[N].
The load torque for rotation of ocean debris collecting
device can be defined as follows:211𝜏𝐿 =𝐹∙𝐷∙𝑠
2 ∙ 𝜂𝑏 ∙ 𝑖(2)where τL is the load torque, D is diameter of gear, ηb isefficiency of belt mechanism and i is reduction ratio ofdesigned decelerator.
In the designed collecting device, D was 0.03[m], s wasfactor of safety, ηb was 0.7 and i was 10. As a result, theτL was about 0.45[Nm].
Therefore, we selected a motor, which can output morethan 0.45[Nm], and designed a decelerator to output theabout 1:10 reduction ratio.
The detail of selected a motor shown in Table 2.
As shown in Table 2, we select a BLDC motor which
output 0.5[Nm] as the maximum torque to rotate thedesigned ocean debris collecting device.
The designed decelerator to output about 1:10 reduction
ratio is shown in Fig. 6.
As shown in Fig.6, the designed decelerator employed
the planetary gear mechanism because it is compact andFig. 7. Overview of the ocean debris collecting USV

provide high power density in comparison to standard
parallel axis gear trains [12].
The reduction ratio of designed decelerator can bedefined as follows:

Table 2. Detail of selected a motor for collecting device
DetailValues

Operating voltage

6V ~ 20V

Maximum ampere

22A

Maximum torque

0.5Nm

RPM/V

490 RPM/V

𝑖=2𝑧𝑎∙ 𝜂𝑖𝑧𝑎 + 𝑧𝑐

(3)

where za is number of teeth of the sun gear, zc is numberof internal gear teeth and ηi is efficiency of decelerator.
In the designed decelerator, za was 12, zc was 42 and ηi
was 0.7. Therefore, the i was about 10. The developed
USV, which is mounted the developed ocean debris
collecting device, is shown in Fig. 7.
As shown in Fig.7, the ocean debris collecting device ismounted on the front side of USV. User can access toUSV inside the computer via the Wi-Fi router and whole
the electronic parts in the system diagram, which isshown in Fig.4, could be confirmed the operation. The
operation scene of collecting device, which is mounted
USV, is shown in Fig. 8.
The brushes on the belt are rotated by decelerator, and theplastic bottles on the surface are carried to colleting box
as shown in Fig. 8.

Fig. 6. Overview of the developed decelerator

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plastic bottle type, we employed 5 types of plastic bottles,
which have different amount, such as 350, 500, 750, 1000,1500 and 2000[ml]. For the condition of plastic bottle
attitude, we set 3 angle of plastic bottles such as 0, 45 and90 [deg.]. For the condition of amount of water inside,
Table 3. Experimental result of whole condition

Bottle type

InsideAngle

Collectingcondition[deg.]

rate [%]

05045409050060454090

100804560903005045309030080

45709050040453090

1008045709090060

45509010080

45509030030

455090

20

Empty
350ml
50% filled

Empty
500ml

Fig. 8. Operation scene of ocean debris collecting device

50% filled

3. Evaluation experiment of ocean debris
collecting device with USV
We experiment the developed ocean debris collecting
device with USV using the various size plastic bottles tocheck the collecting properties of device.
The detail of experiment is shown in Fig.9.
As shown in Fig. 9, the USV move toward a plastic bottle
while operating the collecting device. For the evaluation,
we set experimental condition about plastic bottle type,attitude and amount of water inside. For the condition ofEmpty
750ml
50% filled

Empty
1500ml
50% filled

Empty
2000ml
50% filled

Fig. 9. Detail of debris collecting experiment213

Acknowledgements

we set 2 amount such as empty and 50% filled. The
distance between USV and plastic bottle is 0.3[m] asshown in Fig.8. Each experimental condition wasreplicated 10 times. The experimental result is shown in
the table 3.
As the result in Table 3, the average collecting rates forwhole conditions was 47.7%. Also, collecting rates was
67% when the angle of plastic bottles was set 0[deg.]
which is horizontal position with the USV.

This research was supported by the 2021 University
Research Grant of the Satake Technology Foundation.
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6. Ocean Conservancy, “30th Anniversary International
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8. J. E. Manley, “Unmanned surface vehicles, 15 years ofdevelopment”, IEEE OCEANS 2008: Quebec, pp.1-4,2008.
9. Y. Chen et al., “Path Planning and Obstacle Avoiding ofthe USV Based on Improved ACO-APF Hybrid Algorithm
With Adaptive Early-Warning”, IEEE Access, vol. 9, pp.
40728-40742, 2021.
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Planning for Unmanned Surface Vehicles Using Deep
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4. Conclusion
In this paper, we designed and developed the ocean
debris collecting USV and the developed ocean debris
collecting device was evaluated using the plastic bottles
of various type in the tank environment.
The reason for the focus on plastic bottles is that it
accounted for the second largest number of ocean
garbage worldwide [6]. Then, the plastic debris arecaused the micro plastic problems [1], [2]. For this reason,
we have selected plastic bottles as the important collecttarget and experimented.
In the USV development part, we designed the power andcommunication system to enable autonomous operation.
In the ocean debris collecting device development part,
we designed the belt conveyor type device and thedecelerator of planetary gear mechanism to operate thedesigned ocean debris collecting device.
By the experiment, it has been confirmed that thedeveloped USV could collect the target with a simple
forward motion. As the results, the average collecting
rates for whole conditions was 47.7% and the averagecollecting rates was 67% when the angle of plastic bottles
was set 0[deg.] which is horizontal position with the USV.
Also, the average collecting rates was 74% when thebottle was empty, and the angle was set 0[deg.].
Therefore, to improve the collecting rate, it is necessary
to control the posture of USV and the debris. From theseexperimental results, it is expected that a strategy forautonomous collection of marine debris will be possible
as the future work.
For the ocean environment operation, self-localization,navigation during the influence of waves, such ascollection motion and obstacle avoidance, are required.
Also, we will modify the USV to collect various type ofdebris as the future work.
In the future, we will solve these problems and try to
make practical use of the USV for ocean debris collectingoperations.

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Prof. ShinsukeYasukawa
He received the Ph.D. degree inelectrical,
electronic,
andinformation engineering from
Osaka University, Japan, in
January 2017. Currently, he is an
Associate Professor of Dept. of
Human Intelligence Systems,
Kyushu In-stitute of Technology,
Japan. His research interests
include information processing in
biological sensory systems and their applications inrobotics.

Authors Introduction
Prof. Jonghyun Ahn
He is an Assistant Professor ofDept. of Intelligent MechanicalEngineering, in Hiroshima Instituteof Technology, Japan. He graduatedfrom the degree in underwater
robotics Kyushu Institute ofTechnology, in 2017. His researchinterests include marine robotics
system, intelligent sensing, andunderwater communication system.
Mr. Shunsuke Oda
He received his Bachelar's degreefrom theDept. of Intelligent
Mechanical Engineering, Hiroshima
Institute of Tech-nology, Japan in
2022. He is currently a Master's
course student in Kyushu Institute ofTechno-logy, Japan.

Prof. Shota Chikushi
He is received his Ph.D. from theKyushu Institute of Technology in2018. From 2018 to 2022, he was aproject assistant professor and anassistant professor at The Universityof Tokyo. Since 2022, he is a lecturer
at Kindai University. His researchinterests are field robotics andunmanned construction system. He
is a member of IEEE, RSJ and JSPE.
Prof. Takashi Sonoda
He is an Associate Professor ofDept. of Engineering, Nishinippon
Institute of Technology, Japan. His
research interests include theunderwater robotics system androbot manipulator system.

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