SUGISAKAMASANORI

Journal of Robotics, Networking and Artificial Life
Vol. 9(1); June (2022), pp. 66–71
ISSN (Online): 2352-6386; ISSN (Print): 2405-9021
https://alife-robotics.org/jrnal.html

Research Article

Development of Small-size Jellyfish Removal ROV and its
Evaluation of Removal Motion Performance in Tank
Jonghyun Ahn1, Hiroyuki Yokota2, Shinsuke Yasukawa2

Dept. of Intelligent Mechanical Engineering, Hiroshima Institute of Technology, 2-1-1 Miyake, Saeki, Hiroshima,731-5193, Japan
Dept. of Human Intelligence Systems, Kyushu Institute of Technology, 2-4 Hibikino, Wakamatsu, Kitakyushu, Fukuoka, 808-0196, Japan

1
2

ARTIC LE INFO
Article History
Received 25 November 2021
Accepted 17 March 2022

Keywords

robot design
ocean engineering i
ROVjellyfish removal work

ABSTRACTIn recent years, increase in the number of jellyfish causes damage in the fishery and tourism
industries. Currently, most of the jellyfish removal work is carried out by workers. However, thisconventional removal work is required a lot of time and manpower. In this paper, we proposed amethod for removal work of jellyfish using an underwater robot. Also, we introduced developed
ROV type underwater robot, which is called JENOS (Jellyfish Extermination Nifty-robot for
Ocean Sustentation), and its removal motion performance. The ROV was developed inconsideration of the attitude control during the removal operation. Because, the attitude, such as
surge and pitch, of ROV became unstable when performing jellyfish removal work. To solve thisproblem, we equipped 8 thrusters to improve attitude stability during the jellyfish removal work.
As results, surge acceleration was reduced about 30.0%, and pitch angle velocity was reduced
about 25.8%, and the jellyfish sample was chopped within 25 seconds.
© 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/).

However, this method is required a lot of cost such as
financial cost, time, and manpower. Furthermore, thenumber of fishery workers in Japan decreases in recent
years by various factors such as change industry6.
Recently, underwater robotics can be mentioned as asolution to this situation. Because small-size underwater
robots can work over a large area for a long time, and low
cost compare with divers.
In this paper, we designed and developed a ROV(Remotely Operated Vehicle) for jellyfish removal work,
which is called JENOS (Jellyfish Extermination Niftyrobot for Ocean Sustentation) and designed to evaluate
jellyfish removal motion performance of ROV in tank.

1. Introduction
In recent years, the massive increase in the number ofjellyfish causes ocean environment damage such as
decrease in biodiversity. Also, the number of jellyfish
increases across Asia, it damages the fisheries, power
generation and tourism industries1,2. It is supposed thatthese causes are overfishing of fishery resources, changes
in coastal topography due to global warming, andeutrophication3. In Japan, the aurelia, which is small andpoisonous jellyfish, damages to human activities such as
fisheries and tourism industries. Furthermore, they gather
at the water intakes of power plants, and clog theintakes4,5. Therefore, jellyfish removal work is carriedout to reduce such damage by fishery workers or experts.
Conventionally, jellyfish removal work is used fishingnets. The workers catch jellyfish using fishing nets, andthen caught jellyfish is cut up by the electronical tools.

2. Development of Jellyfish Removal ROV
2.1. Proposed jellyfish removal work using ROV
The proposed jellyfish removal work using the ROV
was operated on the small size fishing boat. The detail of

Corresponding author’s E-mail: j.ahn.h2@it-hiroshima.ac.jp, yokota.hiroyuki247@mail.kyutech.jp, s-yasukawa@brain.kyutech.ac.jp
https://www.it-hiroshima.ac.jp/english, https://www.kyutech.ac.jp/english

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enough to be drop and return on the boat by 2 people.

proposed jellyfish removal ROV operation is illustrated
in Fig.1.

Thruster3(1)
LED1
Thruster2

(5)

Hull

Thruster1(2)(4)

Thruster4
Tether cable
Depth sensor(3)
Jellyfish removal device

Thruster5
Thruster6
Thruster7
LED2
Thruster8

Fig. 2 Overview of designed the ROV for jellyfish removal
work

Fig. 1 Overview of the proposed jellyfish removal ROV
operation method

Because the minimum number of people requires to work

The proposed operation in Fig.1, the ROV have 5 steps,
which detailed below, to remove jellyfish in the sea area.
(1) The ROV and operator are carried using a boat to thefield where is number of jellyfish is increasing. Then,the ROV is dropped to the sea area.
(2) The ROV is controlled by operator on the boat tosearch jellyfish under water. If a jellyfish is found,
the ROV approaches to the jellyfish.
(3) The jellyfish removal device, which is mounted to
ROV, sucks the jellyfish with water. Then thejellyfish was cut by the blade of removal device.
(4) The ROV is controlled to search other jellyfish in thesame sea area.
(5) When the removal work in the target sea area
finished, the ROV is returned on the boat. Then,
operator try to same works in the other sea area.
We develop a ROV which can operate these steps in
Fig.1.

Table 1 Specifications of developed to ROV
Dimensions
Dry weight
Maximum depth
Actuator
Battery
Sensors
Umbilical Cable
Equipment
Angle of view

0.65 x 0.52 x 0.47 [m](L x W x H)
17[kg]
10[m]Thruster x 8,
Micro servo motor x 2
Lithium-ion battery
USB camera,
IMU,
Depth sensor
100[m] length,
7.6 [mm] diameter
LED x 2,
Jellyfish removal device
Voltmeter
Pan110[deg], Tilt120[deg]on a boat is 2 for the safety.
The purpose of the design concept (ii) is to ensure that
if a problem occurs during the operation, such as a poorconnection or dead battery related to the internal system
of ROV, it can be recovered and repaired quickly.
Underwater environment is dark and makes it difficult
to recognize objects. Therefore, like the design concept(iii), the ROV is necessary to light source and wideviewing angle.
In the Fig.1, we proposed an operation method, which
is sucked the jellyfish and cutting them. However, in thisway, the posture of the ROV tends to be unstable becauseof the suction device applies the force to ROV. Therefore,
the ROV is necessary to high positional stability forjellyfish removal work in the design concept (iv). The
designed ROV, which is considered the design concept(i) ~ (iv), is shown in Fig.2 and the ROV specifications
is shown in Table 1. As shown in Fig.2, the ROV includes

2.2. Design concept and specifications of ROV
The ROV is necessary several condition to operate theproposed jellyfish removal work on the small size boat.
The design concept of ROV, which is considered todevelop, is described below.
(i)
Small size and light weight(ii)
High maintainability(iii)
Wide viewing angle and high recognition rate(iv)
High positional stability
We proposed a ROV operation method, which can be
carried out with a few workers compared to conventional
method, in the Fig.1. Therefore, the design concept of
ROV, which can perform (1) ~ (5), is required. For thedesign concept (i), size and weight must be designed easy67

a hull, which is composed camera dome and acrylic
cylinder, thrusters, LEDs and jellyfish removal device.

interface board. Also, DC 5[V], which is employed to
14.8[V] 18[Ah]Li-ion battery
VoltmeterPower
distributor
DC/DC
5[V] 3[A]USB hub

Fig. 3 Inside design of the hull of developed ROV

Fan

14.8V
5V

Tether interface board
LED x 2Motor driver
for thruster x 8

Thruster x 8

Motor driverfor removal device

Jellyfish
removal device

USB server
CameraMicro servo motor x 2

Arduino Uno

Depth sensor

Arduino Mega

IMU

Fig. 4 Overview of ROV power supply system

Each device was equipped using aluminum frames to
ROV. The ROV was designed 0.65 x 0.52 x 0.47[m] and17[kg] because of design concept (i) for the drop andreturn work. This size and weight were made possible theremoval operation using the ROV by 2 grown mans on
the boat. The ROV hull inside was designed as a module
for design concept (ii). The inside design of hull is shown
Fig.3.
As shown in Fig.3, the control units such as Arduino,
battery, motor drivers, sensors are placed on hull inside.
This is the single module part, which designed to beeasily inserted into and removed from the hull, by slide
mechanism. The camera system was composed by acamera, 2 LEDs and 2 micro servo motors to satisfy
design concept (iii). The camera system could move to
pan and tilt angle. Also, the LEDs, which has a maximum
brightness of 1,500 lumens, were equipped.
The ROV has low positional stability during jellyfish
removal work because the center of rotation of ROV andjellyfish removal device are mounted at a distance asshown in Fig.2. Therefore, the force from jellyfish
removal device occurred to surge direction and pitch
angle. This force made the ROV posture unstable, and it
is made difficult to jellyfish removal work. To satisfy
design concept (iv), the ROV was mounted 8 thrusters,
which are maximum output of 5.25 [kgf] at 16 [V]. We
placed 4 thrusters in the surge and sway directions, andother 4 thrusters are placed in the heave direction asshown in Fig.2 for high positional stability of the ROV.

sensors and processing units, is converted by DC/DC
converter, and that is employed to supply power to USB
server, camera, Arduino Uno and Mega.
The communication system of ROV is illustrated in
Fig.5.
As shown in Fig.4, the ROV communication system is
employed various communication formats such as
ethernet or USB serial. The computer on the boat isconnected to ROV by ethernet cable via tether interface
and then the ethernet signal is converted to USB serial by
USB server. The USB hub, which connects to Arduino
Mega and Uno, is connected to USB server. Arduino
Mega controls the thrusters, which include the jellyfish
removal device, LEDs and get the IMU data. The PWM
signal is employed for the thruster and LED control. The
PWM signal, which output to Arduino Mega, has 1100 to1900 [micro sec.] range. Arduino Uno controls micro
servo motors for camera movement and get the depth
sensor data.
Boat

Ethernet

ComputerTether interface
LAN cable reelROV

USB serial
PWM
BLDC motor
control signal
I2C

Tether interface board

Camera2.3. Design of power and communication system

Jellyfish removal
deviceUSB server

Micro servo motor x 2

The power source of the ROV was employed a lithiumion battery which is 14.8[V], 18[Ah]. The designed
power system is shown in Fig.4.
The battery is supplied DC 14.8 [V] to electronic parts
as shown in Fig.4. DC 14.8[V] is employed to supply
power to fan, voltmeter, LEDs, motor drivers and tether

Motor driverfor removal device

USB hub

Arduino Uno

Motor driver
for thruster x 8

Arduino Mega

Depth sensor

Thruster x 8

LED x 2

IMU

Fig. 5 Overview of ROV communication system

683.1. Evaluation of removal motion control
The removal motion of ROV was performed using
jellyfish removal device which mounted on downside of
the ROV. Therefore, when was used the jellyfish removal
device, the pitch angle rotates as the ROV moves forward.
To solve this problem, we stabilized the posture by using
other thrusters mounted on the ROV. In this experiment,
the thrust of the removal device was set to 1.44 [kgf]. The
control results are shown in Fig.7, and the scene ofexperiment is illustrated in Fig.8.

Fig. 6 Overview of jellyfish removal device
Table 2 Specification of jellyfish removal device
Dimensions
0.46 x 0.15 [m] (L x W)
Dry weight2[kg]ActuatorThruster(T200)
Suction port
100[mm]diameterWire mesh size
15 x 15[mm]ThrustUp to 4.07 [kgf] at 16 [V]2.4. Jellyfish removal device
We propose jellyfish a removal method using suction
device, which mounted on ROV, in Fig. 1. The jellyfish
removal device, which can be possible the proposed
ROV operation method, is illustrated in Fig.6 and thespecifications is shown in Table2.
The jellyfish removal device is composed of a thruster,
wire mesh, acrylic cylinder, and frames as shown in Fig.5.
When the thruster rotates, the jellyfish was sucked in andcut off by the wire mesh and blade of thruster. In the
proposed jellyfish removal ROV operation method, we
didn't collect cut jellyfish pieces because the pieces areused as food for marine organisms in marine ecosystem.
The wire mesh was made of stainless steel and the meshsize is 15 [mm] x 15 [mm]. It also served to crush
jellyfish and to protect hard objects other than jellyfish,
such as large rocks and shells, from the thruster.

Fig. 7 Experiment results of ROV motion control by IMU

3. Evaluation experiment of developed ROV
We experimented using developed ROV to evaluate
removal motion performance. The stability of removal
motion of ROV was evaluated by first experiment, andsuction performance of the jellyfish removal device was
evaluated by second experiment.
For the motion stability, the jellyfish removal motion of
ROV was evaluated with acceleration data and angularvelocity data from equipped IMU.
For suction performance of jellyfish removal device, thedevice was evaluated with the jellyfish sample removal
time and the flow velocity.

Fig. 8 Scene of the ROV control of jellyfish removal motion(a) ~ (b) in the Fig.7 represents acceleration of surge,
sway, and heave direction. And (d) ~ (f) in the Fig.7 are69

shown angular velocity of roll, pitch, yaw angle. The
dashed lines represent acceleration and angular velocity
during removal motion without control of other thrusters,
and the solid lines represent acceleration and angularvelocity during removal motion with control of otherthrusters. Also, each data is measured by IMU which ismounted the ROV.
Fig.7 (a) in the dashed line, the ROV can confirm thatthe acceleration is applied in the surge direction during
removal motion and its maximum acceleration of thesurge direction was 2.27[m/s2]. Fig.7 (a) in the solid line
represents the surge acceleration which is reduced by
mounted thrusters on ROV. As a control result, theacceleration of surge direction is about 30.0% reduced.
Fig.7 (b) and (c) are shown acceleration of sway andheave direction, and there was little acceleration in those
direction.
Fig.7 (d) and (f) are shown angular velocity of roll, yaw
angle, and there was little angular velocity in those
direction. However, Fig.7 (e) in the dashed line is shownhigh angular velocity and its maximum angular velocityof the pitch angle was 17.76[deg/s]. Fig.7 (e) in the solidline represents the angular velocity which is reduced by
mounted thrusters on ROV. As a control result, theangular velocity of pitch angle is about 25.8% reduced.
We can verify in Fig. 8 that the acceleration and angularvelocity are highly reduced. In Fig. 8, a marker is
attached to the lower center of the ROV, and the
movement of the marker was observed during theremoval motion. As a result of observation, it was
confirmed that the removal motion of ROV is highly
stabilized.

Fig. 9 Scene of jellyfish removal device experiment
Table 4 Experiment result of performance ofjellyfish removal device using jellyfish samples
Type
A
B
C

We experimented to evaluate the flow velocity of thejellyfish removal device. In this experiment, the 3 typesof truncated cone shape jellyfish samples, whichUsedamountofTable 3 Detail of jellyfish samples
A
B

C

Water
[ml]

200

300

400

Gelatin
[g]

5

10

15

199843387733503702

Volume [mm3]

0.60
3.22

0.56
9.57

0.53
24.75

Number of collected sample
pieces

121

157

259

Average volume of collected
sample pieces [mm3]

2443

2300

2504

composed of water and gelatin, was employed. The detailof 3 types of truncated cone shape jellyfish samples isshown in Table 3.
Each jellyfish sample in Table 3 is made using 200, 300,
400 [ml] of water, 5, 10, 15[g] of gelatin, 1, 2, 3[g] of red
food coloring.
In the experiment, the sample was dropped in front of
the jellyfish removal device and then sucked to measure
the flow velocity. Using an underwater camera, thejellyfish samples were recorded at 120 frames and theflow velocity was measured. The force output by thethruster which was mounted jellyfish removal device was
1.44 [kgf]. The scene of device evaluation is shown in
Fig.9, and the experiment result is shown in Table 4.
As shown in Fig.9, each jellyfish sample is chopped byremoval device. In Table 4, the measured flow velocity
when sucks the samples are 0.60[m/s], 0.56[m/s] and0.53[m/s]. Also, we collected chopped pieces of jellyfish
sample to evaluate jellyfish removal performance bypieces size. As a result, we collected 537 chopped pieces,

3.2. Evaluation of jellyfish removal device

Tape

Flow velocity [m/s]Sample removal time [s]70and those average volume were 2443, 2300 and 2504
[mm3].
4.

5.

Conclusion

In this paper, we designed and developed a ROV forjellyfish removal work, and then the ROV motion control
to jellyfish removal and performance of jellyfish removal
device were evaluated. The design concept of ROV wasshown in (i) ~ (iv), and a ROV was developed thatsatisfies those concepts.
In the evaluation of removal motion control, maximum
acceleration of surge direction was 2.27[m/s2], andmaximum angular velocity of pitch angle was
17.76[deg/s] by the thruster which is mounted jellyfish
removal device without other thruster control. By theequipped with control system, the acceleration of surge
direction was reduced about 30.0[%], and angularvelocity of pitch angle was reduced about 25.8[%].
The removal device was shown enough performance toremove the jellyfish. Especially type C jellyfish sample,
which has 503702 [mm3] volume, was chopped until
2504 [mm3] volume. This result was about 0.5% of theoriginal volume, therefore it was sufficient to remove
jellyfish.
There are many issues to be solved for the operation in
the oceans, such as automatic recognition of jellyfish andimprovement of attitude control capability such as
hovering control of the ROV. In the future, we will solvethese problems and try to make practical use of the ROV
for small jellyfish removal operations.

6.

Authors Introduction
Prof. Jonghyun Ahn
He is an Assistant Professor of
Department of Intelligent Mechanical Engineering, in Hiroshima
Institute of Technology, Japan. He
graduated from the degree in underwater robotics Kyushu Institute ofTechnology, in 2017. His researchinterests include underwater imaging system, intelligent sensing, and underwatercommunication system.
Mr. Hiroyuki Yokota
He received his Bachelar's degreefrom the Department of Intelligent Mechanical Engineering,
Hiroshima
Institute of Technology, Japan in 2022. He iscurrently a Master's course student
in Kyushu Institute of Technology, Japan.

References
1.

2.

3.
4.

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Prof. ShinsukeYasukawa
He received the Ph.D. degree inelectrical, electronic, and information engineering from Osaka
University, Japan, in January 2017.
Currently, he is an Associate Professor of Department of HumanIntelligence Systems, Kyushu Institute of Technology, Japan. His
research interests include information processing in biological sensory systems and theirapplications in robotics.

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