Research On Technology Of Dual Wavelength Fiber Biomimetic Acoustic Direction Finding

In recent years,the development of small intelligent unmanned equipment platforms such as drones and robots has put forward new demands for acoustic direction finding arrays,which require them to work reliably and accurately even when the equipment space size is limited.However,the accuracy of traditional array direction finding methods is limited by the array aperture.By introducing the binaural structure of the Omia brown fly,the signal delay can be effectively amplified,thereby improving the sensitivity of the delay to the direction angle of the sound source.Meanwhile,compared to traditional capacitive or piezoelectric microphones,extrinsic Fabry Perot Interferometer(EFPI)sensors have good electromagnetic interference resistance,and their equipment is simple,their structure is sturdy,and they can still work reliably in harsh environments.The purpose of this project is to solve the problem of effectively improving the accuracy of array direction finding under limited spatial dimensions,while enabling the equipment to work reliably under harsh conditions such as electromagnetic interference.The basic idea of the project is to first use the EFPI fiber optic sound pressure sensor structure,combined with a specific demodulation algorithm to recover the sound pressure signal.Then,using the biomimetic ear structure of the Ormia brown fly,a dual channel digital filtering network algorithm is implemented to amplify the received signal delay or phase difference of the array.Combined with the generalized cross correlation(GCC)delay estimation algorithm,the sound source direction angle is calculated.Firstly,an in-depth study was conducted on the F-P cavity interference mechanism of the EFPI fiber optic sound pressure sensor,and the interval transmission loss model was analyzed,providing a theoretical basis for the design of subsequent demodulation algorithms.At the same time,the amplification mechanism of the auditory coupling model of brown fly Omia and the time delay estimation orientation algorithm are simulated and analyzed,and the feasibility of the project is systematically demonstrated.Secondly,research is conducted on the dual wavelength phase demodulation algorithm based on ellipse fitting parameter estimation.Compared to the dual wavelength DC compensation algorithm,this method does not require measuring the initial F-P cavity length and can adapt to different optoelectronic measurement systems.It can achieve real-time parameter fitting for different interference signals.On this basis,combined with dual wavelength phase demodulation,the differential cross multiplication(DCM)algorithm is used to extract phase information from the sound signal and complete signal demodulation.Finally,replace the standard microphone with the F-P interferometric sensor as the array signal sensing unit,and build a complete experimental testing device for systematic experiments.During the experiment,the azimuth angle of the sound source was changed by rotating the angle table to obtain the signal delay at various angles.The amplification effect was verified by comparing the delay before and after coupling,and the GCC algorithm was used to estimate the amplified delay to verify that the coupling structure can improve the resolution of the delay to the azimuth angle.The experimental results indicate that the biomimetic coupling structure can significantly improve the accuracy of acoustic direction finding under small-scale conditions.