Engineers build compact ‘bats’ sonar for robots

Engineers at Virginia Tech in the United States have built a sonar system inspired by the horseshoe bat species for use in robots. The researchers believe that this will ultimately enable them to make a more efficient and smaller sonar.

A prototype of the system was presented Wednesday at the 169th meeting of the Acoustical Society of America. The final system should provide comparable precision to advanced professional sonar arrays, but at a fraction of the power consumption and significantly fewer parts. The system is based on the biological echolocation system of the horseshoe nose. The horseshoe bat is a family of bats that hunt in densely forested environments, requiring the animal to use very precise and fast echolocation.

The researchers do not take it overnight. Lead researcher Rolf Mueller has been researching bats and in particular the horseshoe nose for several years now, in order to eventually develop a good echolocation technology for robots. The horseshoe nose appears to have good echolocation, because the animal’s nose is almost twice as long as that of other bats. He’s using that nose to target echolocation signals. The animals use the frequency-specific properties of different pitches by modifying the physical properties of ears and nose. This change happens in tenths of a second, up to three times as fast as a person can blink.

By filming the animals and thus recording their movements with high-speed cameras, it was possible to closely follow how the bats change their ears. Laser doppler measurements that can measure speed have also made it possible to record how the animals deform their noses.

The system built by the engineers mimics the bat with a transmitter and two receiving channels for the sound. By mimicking some of the basic movements of the bat’s ears and nose, the robot can determine direction.

Philip Caspers/Virginia Tech