Bio-Inspired Hydro-Acoustic Sensor for Sensing Directivity of Sound

Abstract

The aim of this research is to develop a biomimetic miniature underwater acoustic sensor for the measurement of the directivity of underwater sound. In contrast to a hydrophone array which detects direction by the arrival time of the sound waves this novel sensor is based on a mechanically coupled mechanism which amplifies the time delay by an order of two. In this research and design effort we develop a comprehensive mathematical model of the sensor in order to understand and optimize its performance characteristics. Fluid mass load and fluid-structure radiation are evaluated using both finite element analysis (FEA) and models obtained from the literature. It shows that the bio-inspired sensor can be designed to be directionally sensitive and operational at around up to 2 kHz within the current design limitation (2-D) and the micro range. This is because there is a tradeoff between the time delay amplification and the bandwidth of the sensor. This tradeoff and parametric study lead us to a design optimization of the sensor. For the design optimization, two independent optimization problems are solved: Amplification optimization of the time delay of the sensor and phase difference varying optimization with respect to the angle of incidence of the incoming sound. As an example, the results of the several different design optimizations are presented. Based on the design optimization, it is compared to the FEA simulation and shows a good agreement.