Utilization of Blind Source Separation Techniques for Modal Analysis

Swaminathan, Balakumar; Sharma, Balaji R.; Chauhan, Shashank

doi:10.1007/978-1-4419-9834-7_17

Cited by 9 publications

(10 citation statements)

References 6 publications

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“…One recent and elegant solution consists of viewing the modal expansion of a set of structural responses as a mixture of modal coordinates -the "source signals" -where the mode shapes fill the columns of a mixing matrix. Then, under quite mild assumptions concerning only the mutual independence of the sources, it is possible to identify all constituents of the mixture up to an arbitrary scaling of the mode shapes [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. In turn, standard single-degreeof-freedom techniques can be applied on the separated modal coordinates to identify the global modal parameters.…”

Section: Introductionmentioning

confidence: 99%

Least action criteria for blind separation of structural modes

Antoni

Chauhan

Monnier

et al. 2013

Mechanics & Industry

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-It was recently shown that blind source separation (BSS), as originally developed in the signal processing community, can be used in operational modal analysis to separate the responses of a structure into its individual modal contributions. This, in turn, allows the application of simple single-of-degreefreedom techniques to identify the modal parameters of interest. Several publications have recently attempted to give a posteriori physical interpretations to BSS -as initially developed in telecommunication signal processing -when applied to the field of structural dynamics. This paper proposes to follow the route the other way round. It shows that several separation criteria purposely dedicated to operational modal analysis can be deduced from general physical considerations. Three such examples are introduced, based on very different properties that uniquely characterise a structural mode. The first criterion, coined the "principle of shortest envelope", conjectures that the envelope of a modal response has, among all possible envelopes, the shortest length. That such a principle leads to the governing differential equation of a single-degree-of-freedom oscillator is proved from calculus of variation. The second criterion, coined the "principle of minimum spectral variance", conjectures that the frequency spectrum of a structural mode is maximally concentrated around its central frequency. Finally, the third criterion, coined the "principle of least spectral complexity", states that a structural mode has the lowest possible entropy in the frequency domain. All three criteria can be expressed in terms of a mixing matrix whose columns contain the unknown mode shapes. The recovery of the latter is then trivially achieved by minimising the criteria. Extensive simulations show that the proposed criteria lead to figures of merit very similar to those of the state-of-the-art, while at the same time providing physical insight that other algorithms issued form the signal processing community may dramatically lack. Key words:Operational modal analysis / blind source separation / least action principle / calculus of variation / structural dynamics Résumé -Principes de moindre action pour la séparation aveugle de modes. Des recherches récentes ont montré que certaines méthodes de séparation aveugle de sources, initialement développées pour les signaux de télécommunication, permettent de décomposer les réponses vibratoires d'une structure en ses différentes contributions modales. L'avantage qui s'ensuit pour l'analyse modale opérationnelle est une identification immédiate des paramètres modaux par application des techniques traditionnelles dédiées aux systèmesà un degré de liberté, et ceci sans connaissance des forces excitatrices appliquéesà la structure. L'approche est dite (( aveugle )), car elle ne nécessite aucune connaissance préalable des paramètres structuraux. Plusieurs publications ont récemment tenté de donner a posteriori une interprétation physique aux méthodes de séparation aveugle de sources, lors...

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Section: Introductionmentioning

confidence: 99%

Least action criteria for blind separation of structural modes

Antoni

Chauhan

Monnier

et al. 2013

Mechanics & Industry

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“…Coherently with the literature [44], SOBI technique does not perform equally well as FDD or TDD since it is suited for dealing with signals sources in which mode strengths are each other similar and excitation is stationary. For real scenarios, characterized by low SNR values, noise can deteriorate the performance of the SOBI approach, especially while considering that no prior preprocessing is required apart from whitening raw signals.…”

Section: Resultsmentioning

confidence: 99%

A Sensor Network with Embedded Data Processing and Data-to-Cloud Capabilities for Vibration-Based Real-Time SHM

et al. 2018

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This work describes a network of low power/low-cost microelectromechanical-(MEMS-) based three-axial acceleration sensors with local data processing and data-to-cloud capabilities. In particular, the developed sensor nodes are capable to acquire acceleration time series and extract their frequency spectrum peaks, which are autonomously sent through an ad hoc developed gateway device to an online database using a dedicated transfer protocol. The developed network minimizes the power consumption to monitor remotely and in real time the acceleration spectra peaks at each sensor node. An experimental setup in which a network of 5 sensor nodes is used to monitor a simply supported steel beam in free vibration conditions is considered to test the performance of the implemented circuitry. The total weight and energy consumption of the entire network are, respectively, less than 50 g and 300 mW in continuous monitoring conditions. Results show a very good agreement between the measured natural vibration frequencies of the beam and the theoretical values estimated according to the classical closed formula. As such, the proposed monitoring network can be considered ideal for the SHM of civil structures like long-span bridges.

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“…Utilizing this equation, the source signals were estimated using the mixing matrices produced by the JAD of each approach at the final (50th) lag. The accuracy of the source signal estimates was quantified using a normalized root-mean-square (NMSE) error as in Equation (30), where rms refers to the familiar root-mean-square calculation.…”

Section: Undamped Sinusoidsmentioning

confidence: 99%

“…Variants of the SOBI method have been developed in order to enhance the results for the identification of earthquake‐excited structures , underdetermined structural cases , and cases with narrow band excitation . Because of these continued advances, BSS has seen increasing viability and validity as an option for OMA . A summary of current state of BSS as related to OMA can be found in .…”

Section: Introductionmentioning

confidence: 99%

Increasing the efficiency and efficacy of second-order blind identification (SOBI) methods

Brewick

Smyth

2016

Struct. Control Health Monit.

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SUMMARYThis paper proposes a new technique to increase the efficiency and effectiveness of second-order blind identification (SOBI) methods by reducing the number of time-lagged covariance matrices required to produce highly accurate mixing matrix estimates. The technique is based on randomly selecting the time-lagged covariance matrices as opposed to choosing them sequentially, which takes advantage of a property of independence with regard to the selection of time-lagged covariance matrices, while simultaneously reducing the correlation between selected covariance matrices. The proposed randomized approach is first applied to undamped and damped sinusoids to demonstrate its effectiveness. The randomized method is then applied to a three-degree-of-freedom linear structure subjected to random excitation. Finally, the proposed method is incorporated into a modified version of the SOBI method and applied to perform identification of the UCLA Factor building from recorded earthquake responses. In each case, the performance of the randomized approach is compared with the traditional sequential selection of time-lagged covariance matrices, and the randomized approach consistently demonstrates superior performance both in terms of accuracy and efficiency. Additionally, the proposed randomized SOBI approach was easily inserted into the modified SOBI method demonstrating its malleability for SOBI variants and other blind source separation methods.

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Utilization of Blind Source Separation Techniques for Modal Analysis

Cited by 9 publications

References 6 publications

Least action criteria for blind separation of structural modes

Least action criteria for blind separation of structural modes

A Sensor Network with Embedded Data Processing and Data-to-Cloud Capabilities for Vibration-Based Real-Time SHM

Increasing the efficiency and efficacy of second-order blind identification (SOBI) methods

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