Study on Location Algorithms of Beamforming based on MVDR

Acoustic emission is an effective method of locating the rubbing fault. In order to solve the problem that satisfactory location accuracy is difficult to obtain because of the waveform distortion caused by signal propagation during the application of time delay estimation method in acoustic emission position estimation, beam-forming technique is applied to acoustic emission source location. Simulation studies have been made on the performance of near-field time-domain and frequency domain beam-forming in the location of rubbing acoustic emission source. The paper adopts the wideband signal minimum variance distortionless response (MVDR) location estimation method based on sub-band decomposition to avoid the problems of poor noise immunity and low resolution of traditional beam-forming. Decompose each group of array signals into a number of sub-band of equal length, conduct Fourier transformation on each sub-band to calculate the covariance matrix of each frequency component, get the two-dimensional joint distribution function of the MVDR output power of each sub-band with respect to the distance and azimuth angle, then synthesize the MVDR power of wideband signal, obtain the azimuth spectrum estimation of all frequency bands, and finally get the location of the acoustic source by the peak point. The experimental results show that this algorithm can accurately identify the rubbing fault location.