Experiment design for improved frequency domain subspace system identification of continuous-time systems

Vakilzadeh, Majid Khorsand; Yaghoubi, Vahid; McKelvey, Tomas; Abrahamsson, Thomas; Ljung, Lennart

doi:10.1016/j.ifacol.2015.12.242

Cited by 20 publications

(11 citation statements)

References 7 publications

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“…A frequency range from 60 to 500 Hz was selected with 3000 frequency lines. The frequency lines were selected based on the improved frequency selection method [45] for system identification with N4SID [38].…”

Section: Rear Subframementioning

confidence: 99%

Model Updating of Multiple Nominally Identical Car Components

2020

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A method for estimation of rubber bushing stiffness parameters is presented. Four individual rubber bushings, mounted in a car rear subframe are considered. A traditional model of the bushing elements using a generalised spring model, known as a CBUSH element in Nastran, is compared to a geometrically more realistic approach where the bushing is modelled with solid elements and a linear elastic material model. Each bushing is mass loaded to better reveal the bushing's dynamic behaviour in a lower frequency range of interest. In an initial step, the overall subframe model is updated towards test data. In a second step, the bushing parameters are updated. Three nominally identical components are used to investigate the spread between the identified parameters. The model updating procedure is based on frequency responses and equalised damping. The undamped behaviour at frequencies below 300 Hz are considered. To quantify the parameter uncertainty, with respect to measurement noise for each individual, an uncertainty quantification procedure is proposed, using a linear-in-parameters surrogate model with bootstrapping.Experimental Techniques (2020) 44:391-407Publisher's Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

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Section: Rear Subframementioning

confidence: 99%

Model Updating of Multiple Nominally Identical Car Components

2020

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“…In addition, bilinear (Tustin) transformation causes frequency warping (distortions) at higher frequencies. To avoid this problem, we utilize the experimental design procedure of [25] by first pre-warping the input frequencies that will be used while designing the sum-of-cosines input.…”

Section: A Discretization Via Bilinear (Tustin) Transformmentioning

confidence: 99%

Frequency-Domain Subspace Identification of Linear Time-Periodic (LTP) Systems

Uyanik

Saranlı

Ankaralı

et al. 2019

IEEE Trans. Automat. Contr.

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This paper proposes a new methodology for subspace-based state-space identification for linear time-periodic (LTP) systems. Since LTP systems can be lifted to equivalent linear time-invariant (LTI) systems, we first lift input-output data from the unknown LTP system as if it was collected from an equivalent LTI system. Then, we use frequency-domain subspace identification methods to find an LTI system estimate. Subsequently, we propose a novel method to obtain a time-periodic realization for the estimated lifted LTI system by exploiting the specific parametric structure of Fourier series coefficients of the frequency-domain lifting method. Our method can be used to both obtain state-space estimates for unknown LTP systems as well as to obtain Floquet transforms for known LTP systems.

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“…The half-band width for a damped structural resonance at a certain frequency ω i can be expressed as ∆ω i = 2ξ i ω i where ξ i is the i:th relative modal damping. This is used in the calibration procedure, but in the EMA frequency lines were selected based on a more recent paper by Vakilzadeh et al [10] in which the authors advise in another selection strategy for improving the estimated state-space system with the N4SID method [11].…”

Section: Calibration Validation and Bootstrappingmentioning

confidence: 99%

“…Then the calibration data was gathered from an adaptive multisine test where 10 frequencies were sent to to the shaker simultaneously. The improved frequency selection [10] for system identification with N4SID [11] was used in a frequency range from 40 to 700 Hz with 8200 frequency lines for the multisine test.…”

Section: Experimental Modal Analysismentioning

confidence: 99%

“…Pretest planing has been performed with the expansion method of effective independence (EfI) [8] with an added gramian rejection step, described further in [9]. The three components were tested in a vibration-test with an improved frequency strategy [10] for subspace state-space system identification [11]. The FE model consists of a 556,758 degrees-of-freedom mesh and has been calibrated against all three components.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Calibration, Validation and Uncertainty Quantification of Nominally Identical Car Subframes

Gibanica

Abrahamsson

Olsson

2016

Model Validation and Uncertainty Quantification, Volume 3

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In this paper a finite element model, with over half a million degrees-of-freedom, of a car front subframe has been calibrated and validated against experimental MIMO data of several nominally identical components. The spread between the individual components has been investigated and is reported. Sensor positioning was performed with an extended effective independence method, using system gramians to reject sensors with redundant information. The Fisher information matrix was used in the identification of the most significant model calibration parameters. Validation of the calibrated model was performed to evaluated the difference between the nominal and calibrated model, and bootstrapping used to investigate the validity of the calibrated parameters. The parameter identification, calibration, validation and bootstrapping have been performed using the open-source MATLAB tool FEMcali.

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Experiment design for improved frequency domain subspace system identification of continuous-time systems

Cited by 20 publications

References 7 publications

Model Updating of Multiple Nominally Identical Car Components

Model Updating of Multiple Nominally Identical Car Components

Frequency-Domain Subspace Identification of Linear Time-Periodic (LTP) Systems

Calibration, Validation and Uncertainty Quantification of Nominally Identical Car Subframes

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