E-Journal of Advanced Maintenance Vol.9-2 (2017) 126-131
Japan Society of Maintenology

Development of the Remote Decontamination Robot “MHI-MEISTeRⅡ”
for an Upper Floor of Reactor Building in Fukushima Daiichi NPP
Leona MORIKAWA1,*, Tatsuya HASHIMOTO1, Noriaki SHIMONABE 1, Masahiro
YANO1 , Hironori ONITSUKA1, and Jun FUJITA1
1

Mitsubishi Heavy Industries, LTD. ,16-5 Konan 2-chome, Minato-ku, Tokyo 108-8215, JapanABSTRACTIn Fukushima Daiichi nuclear power plant (NPP), the environment with high dose rate causes a serious problem.
The dose is especially high inside of the reactor building, so it is difficult for people to access there. Therefore,
many kind of work in this severe environment by the remote devices is required strongly. These works include
decontamination to reduce the environmental dose rate. MHI has implemented the development of
remote-operated robot, and we continue to struggle for settling the accident of Fukushima Daiichi NPP. This
article describes the actual performance of “MHI-MEISTeRⅡ” which was developed in 2015 to decontaminatefor an upper floor at Fukushima Daiichi NPP.
KEYWORDSARTICLE INFORMATION

robot, disaster response, manipulator, teleoperation,
Fukushima Daiichi NPP, decontamination

Article history:
Received 7 November 2016
Accepted 27 April 2017

1.

Introduction

After the accident of Fukushima Daiichi NPP, inside of the reactor building of Fukushima
Daiichi NPP is under high radiation area. Because of this high environmental dose, workers can’t
access the area and progress of settling accident is not grad. Therefore, it is necessary to lower theenvironmental dose and recover the area so that workers can access there by decontamination,
shielding, and removing contaminated equipment by using remote controlled robots.
In order to establish the remote decontamination technology, the decontamination project isplanned and promoted by initiative of Japanese government. In the decontamination project,decontamination target areas are divided into “lower area”, “high area”, and “upper floor”. Also theusing robots are different respectively, requirement tasks are same. The requirement tasks are asfollows.
・To access the areas by remote control
・To lower the environmental dose by using the decontamination tools
This article describes the remote controlled robot “MHI-MEISTeRⅡ” developed by Mitsubishi
Heavy Industries, LTD (MHI) as a decontamination device in the upper floor decontamination project.
In the upper floor decontamination project, MHI, Toshiba and Hitachi GE develop thedecontamination device respectively based on distinct method each other and construct an upper floor
decontamination system by combing each device. MHI-MEISTeRⅡ was developed as a part of thesystem. In addition, MHI developed MHI-MEISTeR Ⅱ to apply not only an upper floor
decontamination but various tasks such as follows.
・To move between floors by using stairs
・To operate various tasks(e.g. handling valves) in addition to decontamination by changing theend effectors*Corresponding author, E-mail: leona_morikawa@mhi.co.jp

ISSN-1883-9894/10 © 2010 – JSM and the authors. All rights reserved.

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L. Morikawa, et al./ Development of the Remote Decontamination Robot“MHI-MEISTeRⅡ” for an Upper Floor of Reactor Building in Fukushima Daiichi NPP

2.

MHI-MEISTeRⅡMHI has been developing the remote controlled robots which can operate in severe environments
where are difficult for people to access [1, 2]. By using these experiences, MHI developed double arm
remote controlled robot “MHI-MEISTeRⅡ”(Fig.1) which can meet a functional requirements that areindicated in 2.1 in order to realize the work performance described above.

Fig.1. MHI-MEISTeRⅡ

2.1. Functional requirement
The functional requirements of MHI-MEISTeRⅡ are as follows.
ⅰ) It is capable of decontaminating an upper floor
・It is capable of accessing reactor building upper floor ( 2 or 3 floor ) via an equipment hatchby using a lifting platform (e.g. It is capable of moving on slope with 15°angle and stepwith 50mm height)
・It is capable of decontaminating a floor and a wall (approximately 2 m height )・It is capable of working in cooperation with other upper floor decontamination devices when
the robot operates the above task
・It is capable of using and changing various decontamination tools
・It is capable of recovering the power supply and communication using buck up if they werelost
・It is capable of being operated by remote control by using equipped cameras and sensors indark place
・It is capable of being operated by remote control by using communication methods (wireor wireless)ⅱ) It is capable of having expansibility to operate various tasks(e.g. handling valves) in addition
to decontamination
・It is capable of changing various end effectors easily
・The accuracy of the manipulator’s end point position is less than ±5mm to operate varioustasks
・It is capable of going up and down stairs with a 40°angle and 200mm step127

L. Morikawa, et al./ Development of the Remote Decontamination Robot“MHI-MEISTeRⅡ” for an Upper Floor of Reactor Building in Fukushima Daiichi NPP

2.2. Specification
Table1 shows the specification of MHI-MEISTeRⅡ to realize the above functional requirement.
Table 1. Specification of MHI-MEISTeRⅡ

Items

Specifications

Size

L1,200mm x W740mm x H1,700mm

Weight500kg [approx.]

Moving mechanism

4-crawler drive

Traveling speed

1km/h [max.]

Communication method

Wire (300m) /WirelessPower source

Outside supply /Lithium-ion battery [max 4hours.]

Double 7-axis manipulators

The manipulators have the same number of joints as human andthe capacity for each manipulator to carry 25kg

Narrow space mode

It is capable of rotating with an external diameter of 850mm
This function is for passing through the Fukushima Daiichi NPP’sstairs landing

2.3. Characteristic function

As follows, we explain three important functions to decontaminate upper floor called“moving ability”, “operability”, and “manipulation ability”.
2.3.1. Moving ability
MHI-MEISTeRⅡ has various drive axes to move. The axes are four crawlers, one center ofgravity control axis and four titubation axes (Fig.3 left). MHI-MEISTeRⅡ can move on irregular
ground and stairs using these drive axes to adjust own center of gravity and position. For example, if
force is added to crawlers, titubation axis drives to reduce the force and crawlers follow the shape ofground automatically. In addition, if robot inclines to a horizontal direction, robot detects own
inclination by an internal angle sensor and keeps the own posture level automatically by standing thecrawler of leaning side by driving titubation axis (Fig.3 right). On the other hand, if robot inclines
sagittal direction, robot keeps the own posture level automatically by driving center of gravity
control axis.

Fig.3. Drive axes of MHI-MEISTeRⅡ

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L. Morikawa, et al./ Development of the Remote Decontamination Robot“MHI-MEISTeRⅡ” for an Upper Floor of Reactor Building in Fukushima Daiichi NPP

2.3.2. Operability
MHI-MEISTeRⅡ has two main PTZ cameras, eight fixed point cameras and various sensors
such as 3D-Lasor Range Finder, angle sensor, load sensor, and torque sensor. The operators are able
to understand the circumstances clearly through the virtual images received from the cameras of allangle. Using such functions, MHI-MEISTeRⅡ has realized high quality remote operability. Fig.4
shows the operation screen of MHI-MEISTeRⅡ.

Fig.4. Operation screen

2.3.3. Manipulation ability
MHI-MEISTeRⅡ has two 7-axis manipulators (weight capacity is 25kg) and they can perform
complex work in the narrow space and avoid the obstruction. MHI-MEISTeRⅡ decontaminates thetarget by linear sweeping like the blue line with the end point position of manipulator draws in Fig.5.
Our original control method has realized the reduction of complex operability due to the increase ofaxis. MHI-MEISTeRⅡ can operate various tasks by changing end effectors easily using toolchanger (Fig.5).

Fig.5. End effectors

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L. Morikawa, et al./ Development of the Remote Decontamination Robot“MHI-MEISTeRⅡ” for an Upper Floor of Reactor Building in Fukushima Daiichi NPP

3.

Functional test

In order to confirm that MHI-MEISTeRⅡ meets the functional requirements ⅰ), ⅱ), thefunctional tests were conducted. Table2 shows the test items and results of each functionalrequirement.
Table2. Test item and result

Functional
requirement

Criterion

Testresult

It is capable of moving on slope with 15°angle
and step with 50mm height✔

Series of upper floor
decontamination test

To pass through the area where is modeled after
the environment of Fukushima Daiichi NPP andoperate decontamination normally by remotecontrol with other trucks and blast
decontamination unit✔

Cooperation ability withincidental devices

To complete decontamination operation byremote control working in cooperation with
MHI-MEISTeRⅡ and others✔

Test itemMovegroundⅰ)

onirregularSafe performance of theIt is capable of recovering the power supply✔
event of failureand communication using buck up if they were lostⅱ)

Remote operability

Operators can operate the robot by remote control
using equipped cameras and sensors in dark place✔

Changing
thecommunication method

Operators can operate the robot by remote control
using communication methods(wire or wireless)✔

Tool changer ability

It is capable of changing various end effectors
using tool changer✔

Manipulator accuracy

The accuracy of the manipulator’s end point
position is less than ±5mm to operate various
tasks✔

Move on Stair

It is capable of going up and down stairs with a40°angle and 200mm step✔

The test of functional requirement ⅰ) includes the demonstration in connection with an upperfloor decontamination system. Fig.6 shows the upper floor decontamination system and Fig.7 shows
the upper floor decontamination state.

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L. Morikawa, et al./ Development of the Remote Decontamination Robot“MHI-MEISTeRⅡ” for an Upper Floor of Reactor Building in Fukushima Daiichi NPP

Fig.6. Upper floor decontamination system (blast system version)

Fig.7. Upper floor decontamination state

4. Conclusion
MHI developed MHI-MEISTeR Ⅱ and proved the usefulness of it by functional test ofMHI-MEISTeRⅡ and demonstrated with the upper floor decontamination system. In addition, we
got the likelihood of realization of the project. We continue to struggle for settling the accident ofFukushima Daiichi NPP with this robot and others.

Acknowledgement
The information of this report includes part of study results which MHI, as a member ofInternational Research Institute for Nuclear Decommissioning (IRID), carried out according to theSubsidy Enterprise of Agency of Natural Resources and Energy.

References[1] Jun Fujita, Ken Onishi: “The Development of Robot System “Super Giraffe” for Unmanned Operation onDisaster”, Journal of the Robotics Society of Japan Vol.32, No.2, pp.148-150, 2014[2] Mitsubishi Heavy Industries, Ltd. E-JAM Vol.5, No.4, NT62 “Remote Controlled Robot with expandablefeatures”

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