Autonomous Underwater Vehicle “BOSS-A”

Development Report:

Autonomous Underwater Vehicle “BOSS-A” for Acoustic andVisual Survey of Manganese Crusts
Yuya Nishida∗ , Kenji Nagahashi∗∗ , Takumi Sato∗∗ , Adrian Bodenmann∗∗ ,Blair Thornton∗∗ , Akira Asada∗∗ , and Tamaki Ura∗
∗ Kyushu Institute of Technology
2-4 Hibikino, Wakamatsu, Kitakyushu, Fukuoka 808-0196, Japan
E-mail: ynishida@lsse.kyutech.ac.jp∗∗ The University of Tokyo
4-6-1 Komaba, Meguro, Tokyo 153-8505, Japan[Received August 25, 2015; accepted December 8, 2015]

In order to effectively investigate the distribution andamount of cobalt-rich manganese crust (CRC), anautonomous underwater vehicle BOSS-A equippedwith visual and acoustic instruments were developed.
BOSS-A observes the seafloor along preset waypoints
at a constant speed and altitude. Detailed 3D seafloor
images can be obtained from the visual instrument,
which employs a sheet laser and a camera. In addition,an acoustic instrument measures the CRC thickness
beneath BOSS-A. The CRC at Katayama seamount
was surveyed in February. The results visually presented the state and distribution of the CRC in thissite and clarified the amount of the CRC. In the future, the authors will develop a more reliable thickness
measurement method.

1) A constant altitude of 1.5 to 2.0 m should be maintained during observation.
2) Acoustic waves from the thickness measurement device should be incident vertically on the seafloor.
3) Crust distribution in the horizontal direction should
be observed.
In this study, an autonomous underwater vehicle (AUV)
BOSS-A, was developed in 2013 to equip an acoustic instrument fulfilling above functions. Unlike the ROV, theAUV is untethered and thus can stably navigate regardlessof ship fluctuations [2]. Fig. 1 shows the external appearance of BOSS-A. This paper describes the functions andobservation methods of BOSS-A and reports CRC survey results for No.5 Takuyo and Katayama seamounts obtained using BOSS-A in 2015 (NT15-03 cruise).

Keywords: autonomous underwater vehicle (AUV),
manganese crust, 3D mapping

2. Overview of AUV BOSS-A
1. Introduction
The cobalt-rich manganese crust (CRC) that contains
more cobalt and platinum than other manganese crusts
is expected to be used as a mineral resource. However,
the accurate amount of CRC in marine environments has
not been determined because its distribution and thickness
vary with the marine environment. In order to investigate
the amount of CRC quantitatively, the authors have developed a thickness measurement device employing acoustic
waves [1]. Investigation of the CRC using this system on aremotely operated vehicle (ROV) of the JAMSTEC partly
clarified the amount of CRC in No.5 Takuyo seamount located south of Japan. However, it was difficult to maintainthe ROV at constant altitude because its cable was pulledwhen the ship moved and swung with the tides and waves.
Hence, the CRC thickness measurements were unsatisfactory.
In order to accurately and effectively examine theamount of CRC, the measurement device should meet thefollowing conditions.

A hovering type AUV BOSS-A (total length, 3.0 m;
weight, 580 kg; and depth limit, 3,000 m), has four
thrusters, and its maximum speed is 0.5 m/s. The AUV
measures the distance from an obstacle by front scanning sonar, and thus is capable of avoiding obstacles.
BOSS-A estimates self-location near the seafloor basedon the ground speed obtained by the Doppler velocitylog (DVL) and true bearing determined using a three-axis
fiber optic gyroscope (FOG). At altitudes where the DVLis unavailable, BOSS-A determines self-location by using acoustic positioning device from the ship. The AUV
automatically navigates along the preset waypoints andobserves the CRC. Observation devices on the BOSS-A
include a visual instrument for creating 3D seafloor images [3] and acoustic instrument for measuring the CRC
thickness. Images obtained by the visual instrument aredivided into reflection images of the sheet laser on the topand seafloor images of LED light on the bottom, as shownin Fig. 2. The relative distance between the AUV and theseafloor is geometrically calculated from the position on
the laser light in images, and the seafloor shapes are esti-

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Nishida, Y. et al.

Fig. 1. AUV BOSS-A.

Fig. 2. Observation method.

Fig. 3. 3D reconstruction of the seafloor of Katayama seamount.

mated based on its distance, the AUV’s self-location andattitude data. A 3D seafloor image is created by addingcolor data of the seafloor in pixel presented in the bottom
image to estimated seafloor topography. The acoustic instrument calculates the CRC thickness in millimeter byradiating acoustic waves with a narrow-beam width using
the parametric effect and measuring the time lag between
the acoustic waves reflecting on the seafloor surface andon the boundary surface of the bedrock. It is not necessary to frequently control the position and attitude ofthe BOSS-A because the direction of the acoustic probe
is controlled using a gimbal device so that the instrumenttransmits acoustic waves vertically to the seafloor. The
thickness of the rough CRC can be measured accurately
by separating the waves reflected from the seafloor surface and the boundary surface of the bedrock because theinstrument involves no side lobes or mechanical echoes.

3. Experimental Results
In order to study the exact distribution and amount ofCRC, a survey was conducted using BOSS-A in the water92

depth of 1350 to 1550 m in No.5 Takuyo and Katayama
seamount in February 2015 (NOT-03 cruise). BOSS-A
cruised underwater for 16.0 h and successfully observed
the seafloor for 4.5 h. Fig. 3 shows 3D seafloor images
for a 2 × 15 m area and the CRC thickness calculation
results based on the observation data obtained at a constant altitude of 2.0 m. Because our acoustic instrument
cannot accurately measure thickness of 15 mm or less,measurement values of 15 mm or less were indicated as
0. All the large black rocks in Fig. 3 are the CRC exposed on the seafloor surface. The color bars indicate
CRC thickness. The survey results show that the CRC
in Katayama seamount is not as massive as a bedrock andhas collapsed in some locations. The locations at a thickness of 50 mm or more are not on a black rock; they arelikely to be measured incorrectly. Hence, reflection waves
from the seafloor surface and the boundary layer cannot
be separated owing to noise. If these values are errors, thethickness at those location are 15–45 mm. These results
are highly valuable for understanding the CRC formation
process, enabling the use of the CRC as a mineral resourceand helping discover new CRC areas.

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Autonomous Underwater Vehicle “BOSS-A”

4. Conclusions
Name:

This paper describes the functions and observation
method of BOSS-A, an AUV that simultaneously performs 3D measurements and CRC thickness measurements, and reports the results of CRC survey performed inFebruary 2015. The results clarified the distribution andamount of CRC in Katayama seamount. However, thethickness measurement results included unreliable measurement values. Such unreliable measurement values
can probably be excluded or modified by comparing theseresults with the values obtained from the generated 3D
seafloor images because thick CRCs are more visible.
In the future, the authors will develop a reliable, accurate measurement method for CRC thickness by combining a visual instrument and an acoustic instrument. Inaddition, the CRC amount in No.5 Takuyo and Katayama
seamount as whole will be determined using the developed measurement method.

Kenji Nagahashi

Affiliation:
Researcher, Institute of Industrial Science, The
University of Tokyo

Address:
4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan

Brief Biographical History:
1993- Designer, Underwater & Defense System Engineering Department,
Mitsui Engineering & Shipbuilding Co., Ltd.
2012- Designer of Underwater Robot Technology (temporary assignment),
Institute of Industrial Science, The University of Tokyo

Main Works:• “Introduction to an AUV “r2D4” and its Kuroshima Knoll Survey
Mission,” MTS/IEEE TECHNO-OCEAN ’04, Nov. 2004.
• “Dives of AUV “r2D4” to Rift Valley of Central Indian Mid-OceanRidge System,” MTS/IEEE OCEANS 2007 – Europe, June 2007.

Membership in Academic Societies:• The Institute of Electrical and Electronics Engineers (IEEE) OceanicEngineering Society

References:[1] B. Thornton et al., “Instruments and Methods for Acoustic andVisual Survey of Manganese Crusts,” J. of Oceanic Engineering,
Vol.38, Issue 1, pp. 186-203, 2013.
[2] Y. Nishida et al., “Autonomous Underwater Vehicle Tuna-Sand for
Image Observation of the Seafloor at a Low Altitude,” J. of Robotics
and Mechatronics, Vol.24, No.6, pp. 519-521, 2014.
[3] A. Bodenmann et al., “3D mapping of the seafloor in color using a single camera: Benthic mapping based on video recordings
and laser profiling to generate colored 3D reconstructions of theseafloor,” Sea Technology, Vol.51, No.12, pp. 51-53, 2010.

Name:
Takumi Sato

Affiliation:
Ph.D. Student, Department of Ocean Technology, Policy and Environment, Graduate Schoolof Frontier Science, The University of Tokyo

Name:
Yuya Nishida

Affiliation:
Project Assistant Professor, Frontier Research
Academy for Young Researchers, Kyushu Institute of Technology

Address:
4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan

Brief Biographical History:
2011 Received Master’s degree of Environmentology from The Universityof Tokyo
2013- Entered Doctoral Course, Graduate School of Frontier Science, The
University of Tokyo

Main Works:
Address:
2-4 Hibikino, Wakamatsu, Kitakyushu, Tokyo 808-0196, Japan

Brief Biographical History:• B. Thornton, T. Takahashi, T. Sato, T. Sakka, A. Tamura, A. Matsumoto,T. Nozaki, T. Ohki, and K. Ohki, “Development of deep-sea laser-induced
breakdown spectrometer for in situ multi-element chemical analysis,”
Deep-Sea Research I, Vol.95, pp. 20-36, 2015.

2011- Researcher, Kyushu Institute of Technology
2012- Project Researcher, Institute of Industrial Science, The University ofTokyo
2015- Project Assistant Professor, Kyushu Institute of Technology

Main Works:• “Design Principle of High Power Joint Mechanism Possible to Walking
and Jumping Imitating Locust Leg Structure,” J. of Robotics andMechatronics, Vol.23, No.2, pp. 225-230, 2011.
• “Resource Investigation for Kichiji Rockfish by Autonomous
Underwater Vehicle in Kitami-Yamato Bank off Northern Japan,”
ROBOMECH J., Vol.1, Issue 2, pp. 1-6, 2014.

Membership in Academic Societies:• The Japan Society of Mechanical Engineers (JSME)• The Robotics Society of Japan (RSJ)• The Japanese Society of Fisheries Science

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Nishida, Y. et al.

Name:

Name:

Adrian Bodenmann

Akira Asada

Affiliation:

Affiliation:

Project Researcher, Thornton Laboratory, Institute of Industrial Science, The University ofTokyo

Director, Professor, Underwater Technology
Collaborative Research Center, Institute of Industrial Science, The University of Tokyo

Address:

Address:

4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan

4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan

Brief Biographical History:

Brief Biographical History:

2009 Received M.Sc. in Microtechnology from Ecole PolytechniqueFédérale de Lausanne (EPFL)
2009- Project Researcher, The University of Tokyo

1979- Joined Hydrographic and Oceanographic Department Japan CoastGuard
2000- Joined Institute of Industrial Science, The University of Tokyo

Main Works:

Main Works:• “3D Seafloor mapping with automated data analysis,” Sea Technology,Vol.53, No.10, pp. 41-46, Oct. 2012.

• M. Sato, M. Fujita, Y. Matsumoto, T. Ishikawa, H. Saito, M. Mochizuki,and A. Asada, “Displacement above the hypocenter of the 2011
Tohoku-Oki earthquake,” Science, Vol.332, No.6036, p. 1395, Jun. 2011.
• A. Asada and T. Yabuki, “Progress in the Long-term Seafloor Geodesy
on the Kumano Trough,” J. of Geography, Vol.110, No.4, pp. 529-543,
2001.

Membership in Academic Societies:
Name:Blair Thornton• The Marine Acoustics Society of Japan (MASJ)• The Japan Society for Marine Surveys and Technology (MST)

Affiliation:
Project Associate Professor, Institute of Industrial Science, The University of Tokyo

Name:
Tamaki Ura

Affiliation:

Address:

Professor, Director, Center for Socio-Robotic
Synthesis, Kyushu Institute of Technology

4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan

Brief Biographical History:
2006 Received Ph.D. in Ocean Engineering from The University ofSouthampton, UK
2006- JSPS Post-Doctoral Researcher, Institute of Industrial Science, The
University of Tokyo
2008- Project Research Associate, Institute of Industrial Science, The
University of Tokyo
2012- Project Associate Professor, Institute of Industrial Science, The
University of Tokyo

Main Works:• “Development of a Deep-Sea Laser Induced Breakdown Spectrometer
for In situ Multi-Element Chemical Analysis,” Deep-Sea Research I,Vol.95, pp. 20-36, 2015.
• “Continuous Measurement of Radionuclide Distribution Off Fukushima
Using a Towed Sea-Bed Gamma-ray Spectrometer,” Deep-Sea Research I,
Vol.79, pp. 10-19, 2013.
• “Instruments and Methods for Acoustic and Visual Survey of ManganeseCrusts,” IEEE J. of Oceanic Engineering, Vol.38, pp. 186-203, 2013.

Membership in Academic Societies:

Address:
2-4 Hibikino, Wakamatsu, Kita-Kyushu, Fukuoka 808-0196, Japan

Brief Biographical History:
1992-2013 Professor, Institute of Industrial Science, The University ofTokyo
2013- Professor, Kyushu Institute of Technology, The University of Tokyo

Main Works:• “r2D4”: cruising type autonomous underwater vehicle, 2003.
• “Tuna-Sand”: hovering type autonomous underwater vehicle, 2007.
• “ALBAC”: glider type autonomous underwater vehicle, 1992.

Membership in Academic Societies:• The Institute of Electrical and Electronics Engineers (IEEE)• The Robotics Society of Japan (RSJ)• The Institute of Electrical and Electronics Engineers (IEEE) Oceanic
Engineering Society (OES)

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