Bat Ears Basis for new Robotic Sensing Technologies

Rolf Mueller, an assistant professor of mechanical engineering at Virginia Tech, thinks the geometry of bat ears may prove useful for self-contained, robotic flight systems.

When many people think of bats the image of blood-sucking vampires comes to mind. But for robotic researchers, those leathery fanged creatures may be just what’s needed to endow robots and other high-tech machinery with advanced sensing technology.

The sensory mechanics of echolocation

Why robotic researchers are batty about bats actually makes a lot of sense. Most species of bats around the world use a natural type of sonar called “echolocation” to navigate through night skies and find their prey. Intensive research into bats sensory mechanics have led researchers to discover solid evidence that the creatures can gather, store, and compute the auditory information swiftly. Mother Nature has endowed bats with remarkable ears specifically evolved to capture the tiniest sounds—even slight vibrations—in their environment.

Bat ear geometry also holds much promise for future adoptions by robotic sensory systems. Their ears can be swiveled and are almost multi-directional. Designed with ridges, flaps and irregular grooves, the inner ear baffles “scoop up” sound directing it to the brain where the information is processed.

A Virginia Tech article featuring Mueller’s research delved into some of the auditory science he’s discovered. He explained that bats transmit ultrasonic waves that ping off objects in their immediate environment much like the sonar echo returns that submarines use to navigate underwater. The returning echoes are bounced off the inner ear ridges, channels and flaps of bats’ ears creating certain patterns. This gives them an auditory, 3D map of their surroundings at any given moment during flight. They filter, differentiate, and process the information realtime at the speed of sound.  

Some species of bats also sport what are termed “noseleaves”—skin flaps that grow from their noses. Zoologists believe the noseleaves help sensitize bats to changing vibrations in the air. That aids in flight and helps to avoid collisions.

Bats and bots

Most robotic and autonomous systems today are engineered with a variety of sensors. Some have lasers or sonar, others 2D or 3D cameras. The sensing technology assists the machines determine its spatial environment, avoid objects, and augments programmed tasks.

Some military autonomous platforms incorporate radar into their sensor arrays. The radar employed does not augment “sidelobe” technology. Radar operators have believed that sidelobe capability is primarily a negative because ii tends to create noise in the signal and diminishes the accuracy of the echo.

But Mueller has found just the opposite may be true. Bats natural sidelobes incorporate secondary inner ear structures that point away from the highly sensitized auditory regions of the ear structure.Because of this, the sidelobes do not diminish the information but enhance it. It may even transform a 2D signal into a 3D sonic map.

If true, existing radar technology could be greatly improved.

Applying nature’s solutions to human technology is termed “biomimicry.” It is a research tool that many robotics engineers and artificial intelligence researchers have used successfully for decades.

Mastering the sensory skills of the bat may lead to the creation of a new generation of robots and autonomous systems with a greatly improved capacity to perceive and respond to their environments.