Coordination of sonar emitter and receiver dynamics inspired by bats

Abstract

Recent biomimetic sonar systems have started to mimic the mobility seen in the emission and reception baffles of bats (i.e., “noseleaves” and pinnae) in greater detail. Some of these efforts have included rigid rotations as well as non-rigid shape changes. Since some bat species are known to actuate their noseleaves during pulse emission and their two pinnae during pulse reception, it may be hypothesized that coordination between the dynamic behaviors of these baffle structures is important to system-level biosonar performance. However, it remains to be determined how the complicated rigid and non-rigid changes to the noseleaves and pinnae of bats are coordinated in the animals' biosonar behaviors. To shed some light on this dynamic system integration in bat biosonar, we have conducted experiments with a species of hipposiderid bat (Pratt's roundleaf bat, Hipposideros pratti) where at least 24 landmark points have been placed on the noseleaf and both pinnae in order to track the non-rigid shape changes in all these three structures simultaneously. A canonical correlation analysis has confirmed that the motions of the noseleaf and both pinnae are highly correlated with each other. Work to identify the nature of these relationships using techniques from nonlinear dynamics is currently underway.