U.S. Fish and Wildlife Service Northeast Region

John Hallam: Batty about bats

When bats want to find their way around in the dark, they start by emitting a series of loud, ultrasonic sound pulses. Analysing how long it takes for the sound waves to return enables bats to construct a detailed map of their environment.

Reverse engineering this natural process — known as echolocation — and implementing it on a robotic platform was the goal of the recently completed ChiRoPing project, led by Professor John Hallam from the University of Southern Denmark, our guest on this edition of the EuroScientist podcast.

To achieve their goals, Hallam’s team spent two years investigating how insect gleaning and water-trawling bat species use echolocation to map their environment. As data rolled in from high-speed cameras and microphone arrays in the bat cages, scientists set to work with a set of plastic, model bat-ears, courtesy of a 3D printer.

The end result? A robotic bat-head with built-in echolocation capabilities; a new breed of robotic sonar sensor that could help robots of the future to build complex maps of their environment in scenarios where visual sensors don’t work.

Bats on tape

John Hallam: Soundfile Copyright The ChiRoPing Consortium, 2009.

This is a recording of a female N. leporinus hunting fish over a pond. The background sound is the noise of the jungle and insects and the bat sounds are the chirps. They tend to come in groups of 2-4. Initially, when the bat is searching, the chirps are quiet and infrequent. When she detects something interesting, her chirps are heard more frequently. Toward the end of the recording she hones in on a fish in the pond, and the chirps accelerate and become louder as she gets closer to the microphones. Note that all of this is scaled down by 10 times, so the actual chirps are 10 times higher in pitch (and inaudible to humans) while the behaviour takes 10 times less time.

Featured image credit: Public domain by the U.S. Fish and Wildlife Service Northeast Region

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Emmet Cole
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