‘Robat’ Uses Sound to Navigate and Map a Novel Environment

On that day, men shall fling away, To the flying foxes and the bats, The idols of silver And the idols of gold Which they made for worshiping. Isaiah 2:20 (The Israel Bible™)

Bats are mysterious mammals with the God-given, amazing abilities to hang upside down, fly and locate and identify objects and prey – and they navigate by echolocation, a type of biological sonar.

It was an 18th-century Italian scientist named Lazzaro Spallanzani who –after performing a series of complicated experiments – reached the conclusion that when bats fly at night, they rely on some sense besides vision, It took other scientists to realize later that the other sense, below human range, was hearing. The bat makes sounds that bounce off objects and inform the flying mammal where they are located.

The growing use of autonomous robots around the world stresses the need for new sensory approaches to facilitate tasks such as avoiding obstacles, recognizing objects and planning itineraries.

Now, a fully autonomous bat-like Israeli robot – named Robat – has been developed by Tel Aviv University scientists to use echolocation to move through a novel environment while mapping it solely based on sound. The work led by Prof. Itamar Eliakim of the mechanical engineering department and his team has just been published in the respected journal PLOS Computational Biology.

Autonomous robots can be used in cleaning homes, treating wastewater without human intervention, delivering goods and services such as mowing grass, vacuuming floors or cleaning swimming pools – and even in spaceflight.

Most modern factory robots are “autonomous” within the strict limits of their direct environment but they don’t have the ability to collect information about their surroundings, work for a long time without human intervention or avoid situations that could be dangerous to people, itself or property. They also should be able to take care of themselves.

Bats use echolocation to map novel environments while simultaneously navigating through them by emitting sound and extracting information from the echoes reflected from objects in their surroundings. Many theoretical frameworks have been proposed to explain how bats routinely solve one of the most challenging problems in robotics, but few attempts have been made to build an actual robot that mimics their abilities.

Many theoretical frameworks have been suggested to explain how bats accomplish these feats, but few attempts have been made to build an actual robot that mimics their abilities.

Unlike most previous efforts to apply sonar in robotics, Eliakim and colleagues developed a robot that uses a biological bat-like approach.

Robat has an ultrasonic speaker that mimics the bat’s mouth, producing frequency modulated chirps at a rate typically used by the dark mammals, as well as two ultrasonic microphones that mimic ears. It moved autonomously through a novel outdoor environment and mapped it in real time using only sound.

Robat picks up 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, Eliakim said. “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.”

To the best of his team’s knowledge, 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.”

The resulting terrestrial robot classifies objects in the environment by using an artificial neural-network to create a rich map of its environment. Robat, using complicated mathematical algorithms, relies on a single ultrasonic speaker and two ultrasonic microphones that serve as artificial ears.

“Many animals are able of mapping a new environment even while moving through it for the first time,” explained the Tel Aviv University scientists in their article. Bats can do this by emitting sound and extracting information from the echoes reflected from objects in their surroundings. In this study, we mimicked this ability by developing a robot that emits sound like a bat and analyzes the returning echoes to generate a map of space.

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