A New Closed-Form Solution for Acoustic Emission Source Location in the Presence of Outliers

Abstract

The accuracy of an acoustic emission (AE) source location is always corrupted by outliers due to the complexity of engineering practice. To this end, a preconditioned closed-form solution based on weight estimation (PCFWE) is proposed in this study. Firstly, nonlinear equations are linearized, and initial source coordinates are obtained by using equal weights. Residuals, which are calculated by source coordinates, are divided into three regions according to normal distribution. Secondly, the weight estimation is developed by establishing the relationship between residuals and weights. Outliers are filtered by the iteration between the weight estimation and source location. Subsequently, linear equations are reconstructed with the remaining measurements containing no outliers, while they are ill-conditioned. Finally, the preconditioning method is applied to weaken the ill condition of the reconstructed linear equations, so as to improve the location accuracy. This new method is verified by a pencil-lead break experiment. Tests results show that the location accuracy and stability of the new method are superior to traditional methods. In addition, outlier tolerance and the velocity sensibility of the new method are investigated by simulating tests.

A Closed-Form Method of Acoustic Emission Source Location for Velocity-Free System Using Complete TDOA Measurements

“…However, the linear system Equation (11) is always ill-conditioned, because the elements in the coefficient matrixes B and C differ by several orders of magnitude [ 18 ]. Furthermore, unreasonable sensor placement can also cause the linear dependence of certain equations and lead to the ill-condition.…”

“…With ceaseless research over several decades, numerous location methods based on TDOA measurements have been proposed to determine the position of an AE source [ 11 ]. Among them, the majority of these methods need to pre-measure the acoustic velocity of the media such as the Geiger-based method [ 12 , 13 ], simplex-based method [ 14 , 15 ], spherical interpolation method [ 16 ], and weighted least squares method [ 17 , 18 ]. These methods can achieve a good positioning result only when the acoustic velocity is accurate enough.…”

Structural Health Monitoring of Large Structures Using Acoustic Emission–Case Histories

“…In all AE applications, source location is essential and Zhou et al [16] proposed a new scheme for dealing with outliers, by introducing a preconditioned closed-form solution based on weight estimation. While this produced improvements, some real effects like damage-induced velocity variation still needs additional study, as noted by the authors.…”

A New Algebraic Solution for Acoustic Emission Source Localization without Premeasuring Wave Velocity

“…There are many traditional positioning methods, including Taylor-based methods [ 11 ], Inglada method [ 12 ], spherical-interpolation method [ 13 ], spherical-intersection method [ 14 ], and plane-intersection method [ 15 ]. The localization accuracy of these methods strongly depends upon the measurement precision of wave velocity [ 16 ]. However, it is very hard or impossible to determine the wave velocity exactly in real engineering practices due to the complex geological structures and dynamic variations in engineering environments.…”