Guided Waves Direction of Arrival Estimation Based on Calibrated Multiresolution Wavelet Analysis

Damages produced by impacts can compromise structural integrity. Precise localization of the damage is fundamental to improve structural monitoring systems accuracy and reliability. A method based on the estimation of elastic waves Direction of Arrival (DoA) in plate-like structures by means of a DFT-Based Continuous Wavelet Transform (CWT) decomposition is proposed. To tackle the dispersive behaviour of guided waves, simultaneous multiband signal filtering in the Wavelet domain is performed. Subsequently, the cross-correlation method is applied to each computed scale to evaluate the Difference Time of Arrival (DToA). Finally, DoA is extracted applying an averaging procedure across scales to the arc-tangent of the ratio between the DToA among specific active areas of the sensors. This approach has been experimentally validated through measurements on an aluminum plate, after a calibration stage was performed