International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 07 Issue: 09 | Sep 2020 www.irjet.net p-ISSN: 2395-0072
© 2020, IRJET | Impact Factor value: 7.529 | ISO 9001:2008 Certified Journal | Page 3911
A Man-Portable Hybrid Autonomous Underwater Vehicle for Antarctic
Exploration
A Cadena
1
, S Vera
2
1,2
Faculty of Systems and Telecomunicación, Universidad Estatal Península de Santa Elena (UPSE), La Libertad,
Ecuador
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Abstract - The present work describes the development of a
Hybrid Autonomous Underwater Vehicle (HAUV) called
“Spondylus” that combines the best characteristics of
Autonomous Underwater Vehicles (AUV) and Remotely
Operated Vehicle (ROV), good hydrodynamics and stability in
the water column to perform some tasks of a ROV like get
close-range images of specific objects and collect biological
samples from the sea floor. The HAUV design is focused on
portability for remote field deployments. The HAUV has got
Inertial Navigation System (INS), Computer Vision and
Artificial Intelligence algorithms implemented on FPGA and
ARM processor development boards. The routines are coded by
VHDL modules, assembler and C/C++ scripts running on a
Linux embedded System. HAUV Spondylus has been deployed
in Antarctica at the Ecuadorian Scientific Station Pedro
Vicente Maldonado, austral summer 2018-2019. Results from
laboratory and sea trials are shown.
Key Words: Autonomous Underwater Vehicle, Inertial
Navigation System, Computer Vision, Convolutional Neural
Networks, FPGA, System-on-Chip (SoC), Antarctica.
1. INTRODUCTION
Underwater exploration in Antarctica is a challenging task
due the extreme weather conditions and required logistic
support. Autonomous Underwater Vehicle (AUV) and
Remotely Operated Vehicle (ROV) have been used for
oceanographic, biological and geological applications at
polar environments [1], [2], [3], [4], [5]. One of the most
important fields of study in Antarctica is benthic ecosystems,
including their response of near-shore benthos to increasing
water temperatures due climate change. Usually scuba
divers are employed to get underwater photography and
samples of benthic communities on the sea bed [6]. Typically
the divers are deployed from small vessels or zodiac boats
(inflatable boat) [7]. Scuba divers have got some operational
limitations in Antarctica, diving time less than 30 min and
immersion depths up to 40 m in water temperature near to
0
o
C. Also there is the risk of suddenly changes of
meteorological conditions that could implies dealing with
winds of 60 knots at sea on a small vessel, compromising the
safety of de crew and the divers [8]. Unmanned Underwater
Vehicles (UUV), frequently ROV, are employed to sample
benthos without scuba divers operational constrains. The
vehicle is tethered, a live signal video is send from the
installed cameras in the ROV and an operator drives the
vehicle and decides with determined scientific criteria what
areas require close field imagery and what specimens must
be collected from the sea floor [9]. Explore deep-sea benthos
in Antarctica with ROV requires a large logistic support: an
oceanographic vessel with a five-ton winch for the umbilical
cable whose operational cost could be around USD 50000
per day [10]. At the South Shetlands Island, Antarctica most
of the scientific stations have got small vessels, zodiac boats
and easy-access to deep-sea waters, below 1000 m, but is not
possible to deploy large ROVs that can reach deeps more
than 1000 m from a zodiac boat. A more affordable
alternative are AUVs. They don’t depend on a physical
connection to the surface vessel and can carry out a mission
below the sea surface without human intervention. Man-
portable AUV has got a size less than 2 m and weighted
around 30-50 Kg. This kind of underwater vehicle can easily
be supported by zodiac boats [11], [12], [13]. However
perform the same mission of a ROV, taking close images of a
scientific site of interest and collect samples with a robotic
arm fully autonomously is a complex and computationally
costly task that rely on artificial intelligence, machine
learning and other adaptive techniques [14],[15]. Hybrid
Autonomous Underwater Vehicle (HAUV) combines the best
characteristic of ROV and AUV, high stability in the water
column and good hydrodynamics [16]. HAUV can hover in
the water column very precisely to get close images and
collect samples from the sea floor [17], [18].
Performing complex task in underwater environment
requires precise localization, attitude estimation and path
tracking for guidance and control. Global Navigation Satellite
System (GNSS) signals don’t propagate trough the sea water.
The main navigational aid for AUV is the Inertial Navigation
System (INS), commonly strapdown INS where the
gyroscope and accelerometers are rigidly mounted on the
vehicle frame [19]. The INS is complemented by other
sensors like sonar, pressure sensor, cameras and Doppler
velocity logs [20], [21]. All sources of information for the INS
are fused by Kalman Filter (KF) techniques to estimate the
velocity, position and orientation. KF usage implies high
computational costs using arithmetic floating point, matrix
calculations and real time operation [22]. Navigation very
close to the sea floor requires a Computer Vision (CV) system
to detect and identify obstacles [23]. The images could come
from optical cameras and acoustic devices like side-scan
sonar [24]. Usually SLAM algorithms are used for this kind of
underwater applications [25]. CV and INS can work together
to complement each other, updating navigation state vector
and generating 3D images [26], [27]. Real time underwater
object identification has a great research value for marine