On May 31, 2009, Air France flight 447 took off from Rio de
Janeiro, Brazil enroute to Paris, France. However, the Airbus A330 with 228 souls on
board was lost over the Atlantic Ocean (Wise, 2011). The cause of the crash was unknown, and
French aviation authorities were challenged to locate the accident site, in an
effort to recover the aircraft’s flight data recorders also known as the “black
boxes” (Wise, 2011). Oceanographic
experts were solicited for help to narrow the search pattern to a reasonable
area.
Three Remus 6000 unmanned maritime vehicles (UMVs) were tasked to
conduct the underwater search (Wise, 2011).
On April 3, 2011, the Airbus A330 wreckage was found by one of the Remus
6000 UMVs at a depth of 13,000 feet (Koberth-Baker, 2011). This discovery led
to the recovery of the flight data recorder and cockpit voice recorder, which
helped to answer questions for investigators and give closure to the families of
the deceased ("How statisticians found Air France Flight 447 two years after it
crashed into Atlantic," 2014).
The Remus 6000 is designed to operate autonomously in deep water,
down to almost 20,000 feet carrying a suite of sophisticated sensors ("Remus 6000 Deep Ocean,
large area search/survey”, n.d.). The
UMV uses acoustic navigation to survey the search area, and sensors to collect
and record data; the vehicle also has a high-resolution imaging system mounted
on its bottom to analyze areas of interest ("Remus 6000 Deep Ocean, large
area search/survey”, n.d.). Some general specifications for the REMUS 6000 are
as follows:
·
Diameter – 28 inches
·
Length – 12.6 feet
·
Weight – 1900 pounds
·
Max operating depth – 19,685 feet or 3.7
miles
·
Endurance – Up to 22 hours ("Remus
6000 Deep Ocean, large area search/survey”, n.d.).
Proprioceptive and exteroceptive sensors
contribute to the success of the Remus 6000. The proprioceptive sensors allow
the device to maintain heading and speed; all the data is obtained from within
the internal environment of the UMV (Clarks, 2011). The exteroceptive sensors get their input
from data collected from the UMVs external environment (Clark, 2011).
Proprioceptive sensors include:
1. Inertial Navigation Unit (INU):
This system consists of accelerometers and gyros which measure the UMVs surge,
sway, and heave. This data is used to
compute speed and distance.
2. Conductivity, Temperature, and
Depth Sensor (CTD): This sensor determines ocean water salinity, UMV depth, and
water temperature.
3. GPS/Iridium/Wi-Fi Antenna: This
one antenna serves three functions. When operating on the surface GPS location
can be determined, enables the UMV to call the control station with its
location, and connects to the control stations shipboard computer via a Wi-Fi
or iridium satellite connection ("Remus 6000 Deep Ocean, large area
search/survey”, n.d.).
Exteroceptive sensors include:
1. Acoustic Doppler Current
Profiler (ADCP): Pulses are bounced off the seafloor to calculate ground speed
and depth.
2. Pencil-Beam Sonar Collision
Avoidance System: Sound pulses are transmitted out in front of the UMV, these
pulses bounce off of any potential obstacles so the UMV can alter its path to
avoid an unwanted collision.
3. Dual-frequency Side-Scan Sonar:
Speakers and microphones are used to ping the seafloor with sound waves to map
a 2-dimensional image.
4. Custom Digital Camera with
Strobe Light: When the UMV is 10 meters above the seafloor, it is synced with a
strobe light to take digital photographs, which are tagged with position and
time.
5. Multibeam Profiling Sonar:
Sonar beams ping the seafloor to produce a 3-dimensional map.
6. Sub-Bottom Profiling Sonar: Sound beams are used to find objects
buried below the seafloor sediment ("Remus 6000 Deep Ocean, large area
search/survey”, n.d.).
One
modification that could be made to the REMUS 6000 to make it more successful in
maritime search and rescue operations is to outfit the UMV with the ability to
tow a smaller sized UMV that is tethered from the control station ship to the
wreckage site. As of now the Remus 6000
can only search and locate. As in the
crash of Air France flight 447, after the wreckage was discovered larger and
more capable UMVs had to be brought in to retrieve the wreckage (Wise,
2011). This smaller sized UMV could be
brought to the site by the REMUS 6000 whereupon it can stay indefinitely,
providing data and video to the control station. Additionally, the Remus 6000 could transmit
the data collected to the smaller sized UMV whereupon the data would be
transmitted to the control station via the tether to the ship, so it could
immediately be analyzed.
UMVs
coupled and integrated with Unmanned Aerial Systems (UAS) would increase the
effectiveness of maritime search and rescue operations. This idea of integrating different unmanned
platforms to work cooperatively in maritime search and rescue operations is not
new. Currently ICARUS, also known as
Integrated Components for Assisted Rescue and Unmanned Search operations is
exploring and creating a means for autonomous Unmanned Service Vehicles and UAS
to work as part of an integrated team in maritime related disasters ("ICARUS
Unmanned Maritime Search and Rescue System Demonstrated in Portugal | Unmanned
Systems Technology," 2015). ICARUS
is a shared network among unmanned systems devoted to detecting, locating, and
saving lives during times of disasters for accidents ("ICARUS Unmanned
Maritime Search and Rescue System Demonstrated in Portugal | Unmanned Systems
Technology," 2015). Integrating the
REMUS into the ICARUS plan will provide one more proven tool into maritime
search and rescue.
Unmanned
systems such as the REMUS 6000 have one distinct advantage over their manned
counterparts; the lack of the man. Manned
operators require space in which to operate the UMV, along with food, water,
and oxygen to name a few. The UMV has to
be larger to accommodate the operator and all of the necessary supplies, which
in turn can increase overall vehicle weight and operating costs. Underwater search operations can take many
months or in the case of Air France flight 447, two years. This is an exceptional amount of time to be
spent under the sea looking for evidence of a wreckage. This is dangerous work, and anytime risk to
human life can be mitigated it should.
Accidents can happen, even to those who are doing the searching and the
rescuing. At some point in maritime search
and rescue operations humans may be required to get involved because the
autonomous unmanned platforms cannot complete the task, but it should be out of
necessity.
The
effectiveness of the suite of sensors for both unmanned and manned systems in
theory is the same; a sensor is a sensor.
If an unmanned system and manned system are both the same size, then
most likely more sensors could be incorporated into the system occupying the
space that the operator formerly occupied.
If the same data is being collected by both systems with the same
sensors, and the mission can be performed autonomously, then it should.
References
Clark, C.
(2011). COS 495 - Lecture 7 Autonomous robot navigation [PowerPoint
Slides]. Retrieved from https://www.cs.princeton.edu/courses/archive/fall11/cos495/COS495-Lecture7-SensorCharacteristics.pdf
How statisticians found Air
France Flight 447 two years after it crashed into Atlantic. (2014, May 27).
Retrieved from https://www.technologyreview.com/s/527506/how-statisticians-found-air-france-flight-447-two-years-after-it-crashed-into-atlantic/
ICARUS
Unmanned Maritime Search and Rescue System Demonstrated in Portugal | Unmanned
Systems Technology. (2015, July 20). Retrieved from http://www.unmannedsystemstechnology.com/2015/07/icarus-unmanned-maritime-search-and-rescue-system-demonstrated-in-portugal/
Koberth-Baker, M. (2011, May
6). Air France 447: How scientists found a needle in a haystack / Boing Boing.
Retrieved from http://boingboing.net/2011/05/06/air-france-447-how-s.html
Remus 6000 Deep Ocean, large area
search/survey. (n.d.). Retrieved from https://www.whoi.edu/main/remus6000
Wise, J. (2011, December 6).
Air France 447 flight-data recorder transcript - what really happened aboard
Air France 447. Retrieved from http://www.popularmechanics.com/flight/a3115/what-really-happened-aboard-air-france-447-6611877/
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