Aerospace & Defense Technology - May 2024 - 26

Tech Briefs
paths through uncertain regions, should
be added to the graph to cut down on
the overall travel time.
Selecting Shortcuts
By only selecting shortcuts that are likely
to be traversable, the algorithm keeps
the planning process from becoming
needlessly complicated.
" The quality of the motion plan is
dependent on the quality of graph. If
that graph doesn't have good paths in it,
then the algorithm can't give you a good
plan, " Veys explains.
After testing the algorithm in more
than 100 simulated experiments with
increasingly complex environments, the
researchers found that it could consistently
outperform baseline methods
that don't consider probabilities. They
also tested it using an aerial campus map
of MIT to show that it could be effective
in real-world, urban environments.
In the future, they want to enhance
the algorithm so it can work in more
than two dimensions, which could
enable its use for complicated robotic
manipulation problems. They are also
interested in studying the mismatch
between CTP graphs and the real-world
environments those graphs represent.
This research was performed by Yasmin
Veys, an Electrical Engineering and Computer
Science (EECS) Graduate Student for
the Massachusetts Institute of Technology
(Cambridge, MA). The research was funded,
in part, by the U.S. Army Research Labs.
For more information, download the
Technical Support Package (free white
paper) at mobilityengineeringtech.
com/tsp under the Electronics category.
New, Portable Antenna Could Help Restore Communication
After Disasters
Researchers from Stanford and the American University of Beirut have developed a lightweight,
portable antenna that can communicate with satellites and devices on the ground, making it easier
to coordinate rescue and relief efforts in disaster-prone areas.
Stanford University, Stanford, California
W
hen an earthquake, flood, or other
disaster strikes a region, existing
communication infrastructure such as cell
phone and radio towers are often damaged
or destroyed. Restoring emergency communications
as quickly as possible is vital
for coordinating rescue and relief efforts.
Researchers at Stanford University
and the American University of Beirut
(AUB) have developed a portable antenna
that could be quickly deployed in disaster-prone
areas or used to set up communications
in underdeveloped regions. The
antenna, described recently in Nature
Communications, packs down to a small
size and can easily shift between two configurations
to communicate either with
satellites or devices on the ground without
using additional power.
" The state-of-the-art solutions typically
employed in these areas are heavy,
metallic dishes. They're not easy to move
around, they require a lot of power to operate,
and they're not particularly cost-effective, "
said Maria Sakovsky, an Assistant
Professor of Aeronautics and Astronautics
at Stanford. " Our antenna is lightweight,
low-power, and can switch between two
operating states. It's able to do more with
as little as possible in these areas where
communications are lacking. "
Two Functions in One Antenna
The researchers developed the antenThe
bi-stable deployable quadrifilar helix antenna passively reconfigures its radiation characteristics in terms
of pattern and polarization. (Image: Stanford University Reconfigurable and Active Structures Lab)
26
mobilityengineeringtech.com
na with an approach typically used to
design devices that are being deployed in
space. Because of fuel and space limitations,
technology being sent into orbit
must be very lightweight and packaged
as small as possible. Once the items are
in orbit, they unfold into the proper
shape for use. The researchers wanted
their antenna to be similarly collapsible
and lightweight.
The antenna designed by Sakovsky
and her colleagues at AUB, including
Joseph Costantine, Youssef Tawk, and
Rosette Maria Bichara, is made of fiber
composites (a material often used in
satellites) and resembles a child's finger-trap
toy, with multiple strips of
material crossing in spirals. Just like any
helix-based antenna, conductive material
running through the antenna sends
out signals, but thanks to its unique
structure, the researchers can adjust the
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Aerospace & Defense Technology - May 2024

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