Research On Sound Source Localization Method Based On The Principle Of Acoustic Valley Hall Phase Transformation Of Topological Insulator

In this thesis,an acoustic topological structure is designed based on the principle of valley Hall phase transition of phononic crystals.A new method of localization of sound source is proposed by using the boundary transmission effect of phononic crystals with two different valley Hall phases.The main contents are as follows:(1)First,it is verified that when the scatterer of the phononic crystal has at least double rotational symmetry,the bandgap characteristics of the phononic crystal can be adjusted by adjusting the rotation degree of freedom of the scatterer,especially the position and wideband of the band gap frequency.The intrinsic chirality of the phononic crystal and the center of the vortex are reversed with the change of the degree of freedom of rotation,that is,the valley Hall phase transition occurs,forming a stable Dirac cone.There is a unique boundary transmission phenomenon at the boundary of a phononic crystal with two different valley Hall phases.(2)On this basis,the acoustic topological structure with regular triangular scatterers and regular hexagonal phononic crystals with the same band gap characteristics and different valley Hall phases was designed.Through simulation and experiment,it is found that the acoustic topology is sensitive to the direction of incident sound waves in the forbidden band frequency.The sound pressure value of the sound wave passing through the acoustic topology decreases rapidly as the absolute value of the incident angle increases At 0 degrees,the outgoing sound pressure value is the largest.The frequency,initial phase,and pressure amplitude of the incident sound wave have no effect on this characteristic.This thesis derives the algorithm flow of sound source localization in two-dimensional space when two acoustic topologies are used simultaneously.And through the verification simulation,it is found that the positioning error of the sound source target is about 13%,which basically meets the calculation expectations.(3)Extend the sound source localization in 2D to 3D space,it is verified that the acoustic topology designed in this thesis maintains the sensitivity to the direction of incident sound waves in 3D space.It further deduces the algorithm flow of using three acoustic topologies that are not on the same plane to achieve sound source localization.Compared with the existing sound source localization methods,the method proposed in this paper to achieve the sound source localization using the boundary transmission characteristics of acoustic topological insulators has the advantages of simple algorithm,simple equipment,low calculation cost and good real-time performance.And the positioning direction of multiple sound sources needs further study.