A system identification technique using pseudo-wavelets

Sensitivity of regular wavelets to singularity has been used to detect a suddenly occurred structural damage and estimate its location in a large-scale structure. The usage of the approach is sometimes limited by a demand to the signal that the measurement data need to include the time period when the damage occurred. In this paper a concept of pseudo-wavelet is proposed based on shifting and scaling of conventional wavelets and a related pseudo-wavelet transform (PWT) is defined. A class of pseudo-wavelets is defined based on the frequency response function of the single degree of freedom mass-spring-dashpot system. A PWT-based system identification technique is developed to estimate the system parameters, mainly the natural frequencies and the damping ratios of the structure using vibration data. The approach can be applied for structural health monitoring. Change in system parameters using any two segments of response data may suggest occurrence of structural damages. The proposed approach is illustrated for single- and multiple-degree-of-freedom mass-spring-dashpot systems using simulated vibration response data. In all the case studies, the structural parameters are successfully estimated.