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Robust passive reconstruction of dynamic transfer function in dual-output systems.
Francesco Lanza di Scalea1, Simone Sternini1, Albert Y Liang1
1NDE & Structural Health Monitoring Laboratory, Department of Structural Engineering, University of California, San Diego, La Jolla, California 92093-0085, USA.
The Journal of the Acoustical Society of America
|March 3, 2018
Summary
This study introduces a novel method for estimating dynamic transfer functions in dual-output systems under unknown excitation and noise. The technique uses a specialized normalization approach for accurate system identification, crucial for structural health monitoring.
Area of Science:
- System Identification
- Signal Processing
- Structural Health Monitoring
Background:
- Estimating dynamic transfer functions is vital for understanding linear systems.
- Passive system identification often relies on ambient excitations, posing challenges due to unknown inputs and noise.
- Existing methods for single-input-single-output systems are well-established but not directly applicable to dual-output scenarios.
Purpose of the Study:
- To develop a robust method for estimating the dynamic transfer function between two outputs of a linear system.
- To address challenges posed by uncontrolled excitations and uncorrelated noise in dual-output systems.
- To provide a noise-robust transfer function estimation applicable to passive system identification and structural health monitoring.
Main Methods:
- Proposed an 'inter-segment' averaging method for the normalization factor in cross-power spectrum estimation.
- Combined this with classical 'intra-segment' averaging of the cross-power spectrum.
- Validated the method using synthetic and experimental data from ultrasonic rail inspection.
Main Results:
- The proposed normalization method effectively estimates the transfer function between two outputs.
- The method successfully mitigates the influence of unknown excitation spectra and uncorrelated output noise.
- Demonstrated accuracy in both simulated and real-world applications, including rail inspection.
Conclusions:
- The developed 'inter-segment' averaging technique provides a noise-robust solution for dual-output system transfer function estimation.
- This method enhances the reliability of passive system identification, particularly in structural health monitoring.
- The approach is validated and applicable to practical scenarios like ultrasonic rail inspection.
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