How tiny drones inspired by bats could save lives in dark and stormy
conditions
[October 31, 2025]
By HOLLY RAMER
WORCESTER, Mass. (AP) — Don't be fooled by the fog machine, spooky
lights and fake bats: the robotics lab at Worcester Polytechnic
Institute lab isn't hosting a Halloween party.
Instead, it’s a testing ground for tiny drones that can be deployed in
search and rescue missions even in dark, smoky or stormy conditions.
“We all know that when there’s an earthquake or a tsunami, the first
thing that goes down is power lines. A lot of times, it’s at night, and
you’re not going to wait until the next morning to go and rescue
survivors,” said Nitin Sanket, assistant professor of robotics
engineering. “So we started looking at nature. Is there a creature in
the world which can actually do this?”
Sanket and his students found their answer in bats and the winged
mammal's highly sophisticated ability to echolocate, or navigate via
reflected sound. With a National Science Foundation grant, they’re
developing small, inexpensive and energy-efficient aerial robots that
can be flown where and when current drones can’t operate.
Last month, emergency workers in Pakistan used drones to find people
stranded on rooftops by massive floods. In August, a rescue team used a
drone to find a California man who got trapped for two days behind a
waterfall. And in July, drones helped find a stable route to three mine
workers who spent more than 60 hours trapped underground in Canada.
But while drones are becoming more common in search and rescue, Sanket
and researchers elsewhere want to move beyond the manually operated
individual robots being used today. A key next step is developing aerial
robots that can be deployed in swarms and make their own decisions about
where to search, said Ryan Williams, an associate professor at Virginia
Tech.
“That type of deployment — autonomous drones — that is effectively nil,”
he said.
Williams tackled that problem with a recent project that involved
programming drones to choose search trajectories in coordination with
human searchers. Among other things, his team used historical data from
thousands of missing person cases to create a model predicting how
someone would behave if lost in the woods.
“And then we used that model to better localize our drones, to search in
locations with higher chances of finding someone,” he said.
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Colin Balfour, a sophomore studying robotics engineering, flies a
small drone at a simulated night flight at a laboratory at the
Worcester Polytechnic Institute, Monday, Oct. 20, 2025, in
Worcester, Mass. (AP Photo/Charles Krupa)
 At WPI, Sanket’s project addresses
other limitations of current drones, including their size and
perception capabilities.
“Current robots are big, bulky, expensive and cannot work in all
sorts of scenarios,” he said.
By contrast, his drone fits in the palm of his hand, is made mostly
from inexpensive hobby-grade materials and can operate in the dark.
A small ultrasonic sensor, not unlike those used in automatic
faucets in public restrooms, mimics bat behavior, sending out a
pulse of high-frequency sound and using the echo to detect obstacles
in its path.
During a recent demonstration, a student used a remote control to
launch the drone in a brightly lit room and then again after turning
off all but a faintly glowing red light. As it approached a clear,
Plexiglas wall, the drone repeatedly halted and backed away, even
with the lights off and with fog and fake snow swirling through the
air.
“Currently, search and rescue robots are mainly operational in broad
daylight,” Sanket said. “The problem is that search and rescues are
dull, dangerous and dirty jobs that happen a lot of times in
darkness.”
But development didn’t go completely smoothly. The researchers
realized that the noise of the bat robot’s propellers interfered
with the ultrasound, requiring 3D printed shells to minimize the
interference. They also used artificial intelligence to teach the
drone how to filter and interpret sound signals.
Still, there’s a long way to go to match bats, which can contract
and compress their muscles to listen only to certain echoes and can
detect something as small as a human hair from several meters away.
“Bats are amazing,” Sanket said. “We are nowhere close to what
nature has achieved. But the goal is that one day in the future, we
will be there and these will be useful for deployment in the wild.”
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