A novel linear-correction localization method of acoustic emission source for velocity-free system.

To improve the noise immunity to time-difference-of-arrival (TDOA) measurements and reduce the influence of wave velocity measurement error on localization accuracy, a novel linear-correction localization method of acoustic emission (AE) source for velocity-free system based on the TDOA measurements is proposed in this paper. First, the linear equations with unknown wave velocity are constructed by introducing two intermediate variables, and they are solved for the unconstrained least square (LS) solution. Second, the weight matrix is obtained by estimating the equation residuals. Third, the weight matrix and quadratic constraint are imposed on LS estimate to construct the constrained weighted least square (CWLS) criterion. Finally, the linear correction technique is used to minimize the CWLS criterion and obtain the optimal estimate. The proposed method is verified by pencil-lead breaks experiment. The results show that the locating accuracy and stability of the proposed method are higher than those of the traditional methods. Furthermore, simulation tests prove that the proposed method holds the optimal positioning performance and can reach Cramér-Rao lower bound (CRLB) under different TDOA noise powers.