Research And Implementation Of Vibration Source Localization Based On TDOA Measurement

At present,the application of vibration source localization is very extensive,involving the microseismic monitoring,rock rupture,blasting position determination,pipeline crack localization and coal mine safety and other fields,if you can get the location information in advance,you may avoid these unexpected disasters,and reducing losses.Time difference of arrival method is a localization model based on time delay estimation,which is often used to determine the position of the target.The model has the characteristics of accurate positioning,and have a large number of applications in any engineering fields.In this paper,seismic signal as the object of study,to explore the problem of vibration source.This paper studies the characteristics of seismic signal,the preprocessing of signal and the estimation of time delay,the vibration source localization and its correction.The details are as follows:Due to the complex composition of the earth medium,we first process the seismic signals by empirical modal decomposition and Hilbert transform,and obtain different Hilbert spectra.Based on the Hilbert spectrum,the time-frequency and energy characteristics of the seismic signals are analyzed.The waveform and the spectrum of the signal,and then discuss the attenuation of the seismic signal.Some common wavelet basis functions and threshold estimation methods are compared,and then the background noise of the vibration signal is denoised by the wavelet threshold method.For the low SNR,the cross correlation method is difficult to extract the exact time delay estimation problem.The generalized cross correlation method of the maximum likelihood estimation window function is used to estimate the delay and verify the effectiveness of the method.For the classical Chan localization algorithm has poor results orientation,Newton optimization method of divergence leading to this algorithm failure,the paper presents a method of modifying the characteristic values of the ill conditioned matrix is positive definite,to improve the speed of iteration by introducing the step factor,so that each iteration along the descent direction and convergence as soon as possible.The experimental results show that the improved method can avoid the problem of the divergence of the initial value,and the performance of the algorithm is compared with the Chan algorithm and the method in this paper by RMSE.Completed the design of multi-sensor data acquisition system,including hardware acquisition and PC software design in two parts.The wave velocity of the test site is calculated,and several sets of source localization experiments are designed.The results of the positioning are discussed.Finally,the reason of the positioning deviation may be analyzed.