Using bats as inspiration for sonar technology is anything but new. However, a group of engineers has honed in on a specific species (the Horseshoe bat) that could potentially improve existing sonar technology.
“Not all bats are equal when it comes to biosonar," said Rolf Müller, a Virginia Tech mechanical engineer. "Horseshoe bats hunt in very dense forests and they are able to navigate and capture prey without bumping into anything. In general, they are able to cope with difficult sonar sensing environments much better than we currently can."
Müller’s team studied the noses and ears of these bats in order to understand what makes their biosonar capabilities so advanced. To do so, the engineers relied on motion-capture technology used in Hollywood movies. They concluded that the Horseshoe bats are able to filter the frequency and direction of sounds by quickly deforming the shapes of their outer ears.
"They can switch between different ear configurations in only a tenth of a second – three times faster than a person can blink their eyes," explained Philip Caspers, a graduate student in Müller’s lab.
The Horseshoe bat also differs from others of its kind in how it emits ultrasound squeaks; it uses its nose rather than its mouth. Müller and his team came to the realization – with the help of laser-Doppler measurements that spot velocity – that the Horseshoe bat’s nose also deforms when it uses echolocation.
The team took inspiration from the species and developed a robotic sonar system that incorporates two receiving channels, along with one emitting channel. According to the group, its system can mimic motions in the bat’s ear and nose. The hope is that their device will consume less power and cut down the size of existing sonar technology, which can measure several meters.
"Instead of getting one huge signal and letting a supercomputer churn away at it, we want to focus on getting the right signal," Müller said.
The engineers recently presented a prototype of their sonar system at the May 2015 Meeting of the Acoustical Society of America (ASA) in Pittsburgh. For more information, visit the ASA’s website.