Franek, F., Kang, J., Uk, J., and Choi, S., "Localization of Transient Events in Dispersive Medium by Filter Bank Analysis," SAE Technical Paper 2017-01-1859, 2017.
Structure-born vibrations are often required to be localized in a complex structure, but in such dispersive medium, the vibration wave propagates with speed dependent on frequency. This property of solid materials causes an adverse effect for localization of vibrational events. The cause behind such phenomenon is that the propagating wave envelope changes its phase delay and amplitude in time and space as it travels in dispersive medium. This problem was previously approached by filtering a signal to focus on frequencies of the wave propagating with a similar speed, with improved accuracy of cross-correlation results. However, application of this technique has not been researched for localization of vibrational sources. In this work we take advantage of filtering prior to cross-correlation calculation while using multiple sensors to indicate an approximate location of vibration sources. We achieve this by pre-processing the acceleration by a frequency filter bank prior to a time of arrival algorithm. The theoretical feasibility of the proposed method is first tested over a computer simulation, where the dispersion phenomenon is introduced to the system. Then an experiment conducted on an actual car frame is performed. The results show accuracy in localization of transient vibration, also adding a statistical error indicator previously unavailable.