MIMO Modal Parameters Identification in Frequency Domain

Modal Parameters identification in frequency domain using LSCF and LSFD algorithm for MIMO systems using fast implementation
738 Downloads
Updated 7 Dec 2020

View License

This tool allows to identify modal parameters, eigenfrequency, modal damping factor and modal residues using complex Frequency Response Function (FRF) of a MIMO system. The least-squares problem is solved using fast implementation of the normal equations based on fft to improve the efficiency of the algorithm.

The algorithm is based on

- the Linear Square Complex Frequency Estimator (LSCF) using discrete-time z-model to estimate eigenfrequency and modal damping.

- the Least-Squares Frequency-Domain estimator (LSFD) to estimate modal residues.

The choice of the identification order and the selection of the physical poles are assisted by a stabilization chart using frequency and damping convergence criteria. The stabilization chart can then be automatically interpreted.

The folder contains:

- A file example (file_example.m) based on a numerical 4 dofs system (omg.mat, FRF_tot.mat).

- the function time2frf.m allows to load time data (time, input, output) in .txt format and returns complex FRF and natural frequency vector.

- the function select_frf.m allows to select a part of the FRF in the specified frequency range.

- the function lscf.m estimates eigenfrequency and modal damping factor using a stabilization chart in a specified order range and computes identified FRF using discrete z-model.

- the function plotstabchart.m plot the stabilization chart

- the function select_stabchart.m allows to select physical stable poles in the stabilization chart.

- the function lsfd.m estimates complex residues and identified FRF using s-model.

Cite As

Baptiste Chomette (2024). MIMO Modal Parameters Identification in Frequency Domain (https://www.mathworks.com/matlabcentral/fileexchange/82380-mimo-modal-parameters-identification-in-frequency-domain), MATLAB Central File Exchange. Retrieved .

MATLAB Release Compatibility
Created with R2020b
Compatible with any release
Platform Compatibility
Windows macOS Linux

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!
Version Published Release Notes
1.0.5

New implementation in
- lscf: fast implementation of the normal equations based on fft to improve the efficiency of the algorithm
- lsfd: identification of modal residues using poles-residues form
- plotstabchart: plot the stabilization chart

1.0.4

improvement of lsfd function using scaled frequency to avoid poor conditioning

1.0.3

Corrections in lsfd and new file test based on a 4 dofs system with proportional damping.

1.0.2

corrections in lsfd

1.0.1

Correction of the lsfd function line 87: rntotCls = (Cls'*Cls) \ (Cls'*frf(:, ifrf)) ;

1.0.0