FLY-EAR INSPIRED MINIATURE SENSOR SYSTEM FOR TWO-DIMENSIONAL SOUND SOURCE LOCALIZATION

Abstract

A micro-scale sound localization sensor is developed and studied in this thesis to address the fundamental challenge of miniaturizing sound localization systems. When miniaturizing a microphone array, there is a critical size limitation at which the array will be unable to localize the sound source in a discernible manner. However, a solution to this dilemma came about when studying the hearing mechanisms of a particular fly, known as Ormia ochracea. Background research into the hearing mechanisms of the fly found that it can accurately locate a sound source even though its eardrums are separated by a distance of only 500 μm. The fly's exceptional directional hearing capability has been linked to a distinct mechanical coupling between its two eardrums, which helps amplify minute directional cues. Inspired by the remarkable hearing capabilities of the fly's micro-scale ear, researchers have sought to develop micro-scale sensors to mimic the fly's ear. One limitation of simply imitating the fly's ear is that the fly is only capable of localizing a sound source in one dimension. In this thesis work, the knowledge gained from understanding the fly ear mechanism is applied to achieve the goal of developing a micro-scale sound localization sensor capable of sound source localization in two dimensions. In this thesis, for the first time, micro-scale fly-ear inspired sensor devices employing three or four coupled membranes have been designed. Reduced-order models have been developed to achieve a fundamental understanding of the performance of each sensor design. Furthermore, a micro-scale sensor device incorporating three mechanically coupled membranes arranged in an equilateral triangular configuration has been successfully developed. Experimental study of the sensor device incorporated with a low coherence fiber optic interferometric detection system has suggested that the micro-scale fly-ear inspired sensor can achieve a much improved performance in terms of phase differences and directional sensitivities when compared to a similar sized microphone array constructed with separate microphones. In addition, localization techniques have been developed to best use the fly-ear inspired sound localization sensors. Future work is suggested to incorporate this sensor system with a fully autonomous robot to improve robot homing and navigation.