摘要
提出一种基于银膜的自准直外腔式光纤法布里-珀罗(EFPI)干涉仪声传感器阵列,用于中低频声信号的检测以及二维平面声源定位.传感器阵列由三个相同结构的EFPI组成,结构简单、制作简便.银膜的应用和准直器的引入提高了传感器的声压灵敏度,扩大了声源定位范围.实验结果表明:单个传感器声压灵敏度为185 mV/Pa,最小可探测声压为52.7 µPa/Hz1/2@500 Hz.在声源指向性实验中,声源设置在传感器正前方时,其声压灵敏度达到185 mV/Pa,声源设置在传感器侧面(90°,270°)时,其声压灵敏度衰减仅为4.5%.传感器阵列结合到达时间差技术,成功实现高精度的声源定位,系统的理论空间分辨率为0.71 cm,最大定位误差不超过2.8 cm,定位范围为200 cm×200 cm,具有成本低、实用性高等优点.
Abstract
Sound source localization is a pivotal research area within the field of acoustics,finding extensive applications in domains such as Unmanned Aerial Vehicle(UAV)navigation,intelligent traffic systems,medical imaging,and structural health monitoring.Traditional sound source localization methods typically rely on arrays of multiple microphones or sensor networks.Nevertheless,these conventional approaches are beset by challenges related to complex installation,intricate data processing,and poor resistance to interference.In recent years,there has been considerable attention directed towards the emerging field of optical fiber-based acoustic localization,within which most optical fiber-based detection systems have employed Fiber Bragg Grating(FBG)sensor arrays due to their wavelength-based multiplexing capabilities.However,FBG sensors exhibit limitations in sensitivity.In contrast,optical fiber Extrinsic Fabry-Perot Interferometer(EFPI)sensors,with their probe-like structure and advantages in terms of high sensitivity and structural simplicity,are better suited for sound source localization.In this research endeavor,we have introduced optical fiber collimators within EFPI sensor arrays to develop a self-collimating optical fiber-based EFPI acoustic sensor array.The primary objective is to augment the sound pressure sensitivity and detection range of the sensor array.The designed sensor array exhibits elevated acoustic sensitivity and an expanded spatial detection range,thus holding immense potential for applications in sound source localization and the detection of partial discharge phenomena.Firstly,the optical field distribution of a quarter-pitch-length gradient multimode optical fiber was verified using Rsoft software.Subsequently,an EFPI(Extrinsic Fabry-Perot Interferometer)acoustic sensor with a self-collimating optical fiber was designed.To assess whether the proposed sensor exhibits enhanced sensitivity to sound pressure,it was compared to an EFPI acoustic sensor without the self-collimating feature.Next,three EFPI acoustic sensors with identical structures and self-collimating optical fibers were fabricated for sound source localization experiments.Prior to conducting the localization experiments,the consistency of sound pressure sensitivity and sound source directionality among the three sensors with self-collimating optical fibers was verified.Subsequent to these preparations,time-delay signals were acquired using an intensity demodulation technique and recorded on an oscilloscope.The time-delay signals were processed using conventional cross-correlation algorithms to calculate the time delays between pairs of sensors.Finally,based on the geometric positions of the sensor array,an estimation of the approximate sound source location was determined.The experimental results show that the interference spectrum FSR of EFPI sensor with collimator is 5.25 nm,and the maximum fringe visibility is 14.96 dB.The EFPI sensor without a collimator has a FSR of 5.18 nm and a maximum fringe visibility of 9 dB.The FSR of them is almost the same,but the interference spectral intensity of the former is increased by about 6 dB.In addition,the EFPI spectral slopes were 6.5 dB/nm and 10.2 dB/nm,respectively,without and with collimators,and the spectral slope of the latter increased nearly twice as much as the former.In the response characteristic experiment for the single sensor,EFPI acoustic sensor with collimator is superior to EFPI acoustic sensor without collimator in sound pressure response waveform and sound pressure sensitivity test.EFPI acoustic sensor with collimator has sound pressure sensitivity of 185 mV/Pa.The minimum detectable sound pressure is 52.7 µPa/Hz1/2@500 Hz,and the signal-to-noise ratio reaches 62 dB.In the experiment of sound source directionality,the designed sensor showed good performance under different sound pressure directionality.When the sound source was placed directly in front of the sensor,its sound pressure sensitivity reached 185 mV/Pa.When the sound source was set on the side of the sensor(90°,270°),its sound pressure sensitivity could still reach 177 mV/Pa.This indicates the ability of the sensor array to achieve sound source localization within a wide-angle range.In the two-dimensional plane sound source location experiment,the signal delay in the time domain signal is extracted by the correlation algorithm,and the two-dimensional plane sound source location within the range of 200 cm×200 cm is finally realized.The theoretical spatial resolution is 0.71 cm,and the maximum positioning error of the system is no more than 2.8 cm.Finally,the performance comparison with other EFPI acoustic arrays shows that the system has the advantages of high sensitivity,low production cost,simple demodulation system and large detection range.
基金项目
重庆英才青年拔尖人才计划(cstc2021ycjh?bgzxm0128)
重庆英才创新领军人才计划(CSTC2021YCJH?BGZXM0287)
重庆市自然科学基金创新与发展联合基金(CSTB2023NSCQ?LZX0008)
重庆理工大学科研创新团队培育计划(2023TDZ002)
重庆理工大学研究生科研创新项目(gzlcx20223055)
NETL
NSTL
万方数据