CAMBRIDGE, Mass., Jan. 25, 2021 /PRNewswire-PRWeb/
-- Detecting the presence of an unmanned underwater vehicle
(UUV) is usually achieved by intercepting the noise radiated by its
propeller. In a noisy harbor, this task is hindered because the
acoustic signature of a UUV and the noise in the local environment
often present too much signal complexity for current technologies
to process.
That may be about to change. Researchers at Draper, Massachusetts Institute of Technology (MIT) and Woods Hole Oceanographic Institute (WHOI)
have developed an acoustic remote sensing method for high-precision
propeller rotation and speed estimation of unmanned underwater
vehicles.
The new method is detailed in a study published in the Journal
of the Acoustical Society of America.
UUVs are marine platforms that are untethered and autonomous and
often used for a variety of applications, including national
security and ocean exploration. The robots selected for this study
belong to the smallest class of vehicles called micro-UUVs, which
have a diameter of six or fewer inches.
Detection, classification and tracking of ships are important
tasks for improving port security and the security of coastal and
offshore operations, explains Kristen
Railey, who led the study as a Draper Fellow. "However,
identifying UUV signatures and using those signatures to estimate a
UUV's speed for passive tracking is a relatively unexplored
research area in comparison to other marine vessels."
A state of the practice technique for identifying the presence
of ships is by analyzing passive acoustic data with the Detection
of Envelope Modulation on Noise (DEMON). The DEMON method, which
operates by filtering propeller noise, varies by vessel, and can be
challenged in a noisy and dynamic environment such as the shallow
waters of harbors.
In the study, the authors set out to isolate and characterize
motor noise, so they focused on brushless DC (BLDC) motors because
of their prevalence in UUV propulsion systems. They designed a
passive acoustic, high-precision method for estimating a
micro-UUV's propeller rotation frequency.
In field experiments, the new method outperformed the DEMON
algorithm. When boats passed by the UUV, the new method could
detect the motor noise, but the DEMON spectrum was dominated by the
interfering boats' propeller noise.
Quieter UUVs could have many benefits, the researchers explain
in their paper. "Understanding the origins of acoustic noise in
autonomous platforms can inform quieter UUV propulsion design to
avoid interference with onboard sensors and disturbance to marine
life. In the future, based on these findings, quieting techniques
for BLDC motors in UUVs can be compared and assessed."
While the current work is focused on micro-UUVs, the new method
can apply to other robotic platforms that are powered by
mass-manufactured BLDC motors. Brushless motors are found in
electric vehicles, hybrid vehicles, personal transporters and
electric aircraft.
Co-authors of the journal paper include Railey, a Ph.D.
candidate in mechanical and ocean engineering at Massachusetts Institute of Technology (MIT) / Woods Hole Oceanographic Institute (WHOI);
Henrik Schmidt, Railey's academic
advisor and a professor of mechanical and ocean engineering at
MIT; and Dino
DiBiaso, a computer scientist, systems engineer and
distinguished member of the technical staff at Draper.
Draper
At Draper, we believe exciting things happen when new
capabilities are imagined and created. Whether formulating a
concept and developing each component to achieve a field-ready
prototype or combining existing technologies in new ways, Draper
engineers apply multidisciplinary approaches that deliver new
capabilities to customers. As a not-for-profit engineering
innovation company, Draper focuses on the design, development and
deployment of advanced technological solutions for the world's most
challenging and important problems. We provide engineering
solutions directly to government, industry and academia, work on
teams as prime contractor or subcontractor, and participate as a
collaborator in consortia. We provide unbiased assessments of
technology or systems designed or recommended by other
organizations—custom designed, as well as
commercial-off-the-shelf.
http://www.draper.com
Media Contact
Dan Dent, Draper, 6174292883,
ddent@draper.com
SOURCE Draper