A Fully Autonomous Bat-Like Terrestrial Robot

Researchers claim to have developed a fully autonomous bat-like terrestrial robot, named Robat, which uses echolocation for movement through a novel environment while mapping it based only on sound, according to a study published in PLOS Computational Biology by Itamar Eliakim of Tel Aviv University, and his colleagues.

Bats map novel environments while navigating through them by using echolocation- that is by emitting sound and extracting information from the echoes reflected from objects in their surroundings. Eliakim and colleagues developed a robot that uses a bat-like approach, emitting sound and analyzing the returning echoes to generate a map of space.

The robot, known as Robat, larger in size than most bats but does not have wings; it is based around an off-the-shelf four-wheeled robot. Robat produces ultrasonic chirps from a tiny speaker mounted above its front wheels. Robat has an ultrasonic speaker that functions like a bat mouth to produce frequency modulated chirps at a rate that bats do, and has two ultrasonic microphones that mimic ears.

When released into an obstacle course inside a large greenhouse containing plants and other objects, the robot was able to gracefully wheel through the environment without hitting anything.

Robat also mapped the 2D outline of the objects it encountered in real time, revealing obstacle-free paths that could be used on future journeys similar to how a natural bat would. It moved autonomously through this new outdoor environment and mapped it in real time using only sound. Robat delineates the borders of objects it encounters, and classifies them using an artificial neural network, thus creating a rich, accurate map of its environment while avoiding obstacles. For example, when reaching a dead end, the robot used its classification abilities to determine whether it was blocked by a wall or by a plant through which it could pass. Robat was also able to distinguish between plants and non-plants with 68% accuracy.

Robat however has to stop every half a meter for about 30 seconds to gather information. But the researchers say that with a few modifications—such as a speaker with a wider beam—Robat should be able to echolocate on the move. Once this is overcome and perfected by the Robat, it could become a particularly useful tool in helping with situations where visual systems usually struggle-for example in search and rescue operations in smoke-filled buildings or nocturnal operations—when bats are most active.

“To our best knowledge, our Robat is the first fully autonomous bat-like biologically plausible robot that moves through a novel environment while mapping it solely based on echo information – delineating the borders of objects and the free paths between them and recognizing their type,” Eliakim said. “We show the great potential of using sound for future robotic applications.”

Citation: A fully autonomous terrestrial bat-like acoustic robot. PLOS Computational Biology, 2018; 14 (9): e1006406 DOI: 10.1371/journal.pcbi.1006406 | https://journals.plos.org/ploscompbiol/article?id=10.1371/journal.pcbi.1006406