scholarly journals Modal control based on direct modal parameters estimation

2017 ◽  
Vol 24 (12) ◽  
pp. 2389-2399 ◽  
Author(s):  
Baptiste Chomette ◽  
Adrien Mamou-Mani
Keyword(s):  
Frequency Domain ◽  
Controller Design ◽  
State Space Model ◽  
Parameters Estimation ◽  
Modal Parameters ◽  
Rational Fraction ◽  
Modal Control ◽  
Identification Algorithm ◽  
Human Intervention ◽  
Rational Fraction Polynomial

Modal active control is based on a state model that requires the identification of modal parameters. This identification can typically be done through a rational fraction polynomial algorithm applied in the frequency domain. This method generates numerical problems when estimating high-order models, particularly when moving from the basis of orthogonal polynomials for the modal basis. This algorithm must therefore be applied independently on multiple frequency ranges with a low order for each range. In this case, the controller design cannot be automated and requires a lot of human intervention, especially to build the state space model. To address this issue, this paper presents the application of the direct modal parameters estimation (DMPE) algorithm for active modal control design. The identification algorithm is presented in a simplified version with only positive frequencies. Unlike other classical identification methods in the frequency domain, the DMPE algorithm provides a solution with a great numerical stability and allows estimating models with a higher order. Using this method, the design of the controller can be largely automated and requires a minimum of human intervention. After a theoretical presentation, the proposed method is experimentally validated by controlling the vibration modes of a suspended plate.

Comparison of Different Estimation Algorithms Used in the Experimental Determination of Modal Parameters

2015 ◽  
Vol 816 ◽  
pp. 412-415
Author(s):  
Róbert Huňady ◽  
Martin Hagara ◽  
Peter Pavelka
Keyword(s):  
Circular Cross Section ◽  
Extraction Methods ◽  
Modal Parameters ◽  
Rational Fraction ◽  
Polynomial Method ◽  
Laser Vibrometer ◽  
Estimation Algorithms ◽  
Freely Suspended ◽  
Rational Fraction Polynomial

The paper deals with the estimation of modal parameters and its main purpose is to compare differences in the values of natural frequencies and damping ratios, which were estimated using three different extraction methods: Rational Fraction Polynomial method, Complex Mode Indicator Function and Polyreference Time Domain Technique. These methods are well suited to the more general application to multi-FRF data, both of the SIMO and the MIMO types. The object of measurement was a freely suspended steel rod of circular cross section. The responses of the analyzed structure were measured by accelerometer and laser vibrometer. The results of these measurements are also discussed in the paper.

Prediction of random dynamic loads using second-order blind source identification algorithm

2020 ◽  
Vol 234 (9) ◽  
pp. 1720-1732
Author(s):  
You Jia ◽  
Zhichun Yang ◽  
Erqiang Liu ◽  
Yanhong Fan ◽  
Xuexia Yang
Keyword(s):  
Frequency Response ◽  
Frequency Domain ◽  
Source Identification ◽  
Second Order ◽  
Dynamic Loads ◽  
Modal Parameters ◽  
Frequency Domain Method ◽  
Identification Algorithm ◽  
Structural Dynamic ◽  
Comparison Results

Traditional load identification methods are based on the frequency response function matrix. However, in some cases, it is impossible to measure the frequency response functions directly, where only the measured structural dynamic response data are available. In this paper, a novel frequency domain method based on second-order blind source identification (SOBI) algorithm is proposed for identifying the random dynamic loads from some dynamic responses of limited test points. Firstly, the SOBI algorithm is applied to identify the modal parameters from the time histories of the measured displacement responses and then the modal loads are estimated by the identified modal parameters and modal responses in the modal space; finally, the random dynamic loads can be identified in the frequency domain. In order to control the error propagation, the theoretical formulas of the regularization process have been deduced, and the regularization parameters are selected by the generalized cross-validation method. A numerical simulation and an eight-storey spatial frame experimental model are studied to validate the proposed method; the comparison results show a good agreement between the identified random dynamic loads and the actually exerted loads.

Frequency Domain Structural System Identification by Observability Range Space Extraction

1996 ◽  
Vol 118 (2) ◽  
pp. 211-220 ◽  
Author(s):  
Ketao Liu ◽  
Robert N. Jacques ◽  
David W. Miller
Keyword(s):  
System Identification ◽  
Frequency Domain ◽  
Structural Control ◽  
Control Experiment ◽  
Space Shuttle ◽  
State Space Model ◽  
Identification Algorithm ◽  
Structural System ◽  
Range Space ◽  
Structural System Identification

This paper presents the Frequency Domain Observability Range Space Extraction (FORSE) identification algorithm. FORSE is a singular value decomposition based identification algorithm which constructs a state space model directly from frequency domain data. The concept of system identification by observability range space extraction was developed by generalizing the Q-Markov Covariance Equivalent Realization and Eigensystem Realization Algorithm. The numerical properties of FORSE are well behaved when applied to multi-variable and high dimensional structural systems. It can achieve high modeling accuracy by properly overparameterizing the system. The effectiveness of this algorithm for structural system identification is demonstrated using the MIT Middeck Active Control Experiment (MACE). MACE is an active structural control experiment to be conducted in the Space Shuttle middeck. Results of ground experiments using this algorithm will be discussed.

Improving the accuracy of SOD for modal parameters estimation of damped systems

2014 ◽  
Vol 226 (6) ◽  
pp. 1673-1687 ◽  
Author(s):  
Mousa Rezaee ◽  
Gholamreza Fattahi Yam
Keyword(s):  
Parameters Estimation ◽  
Modal Parameters ◽  
Damped Systems

Real-time vision-based modal parameters estimation at 10000 fps

2012 ◽  
Author(s):  
Hua Yang ◽  
Idaku Ishii ◽  
Takeshi Takaki
Keyword(s):  
Real Time ◽  
Parameters Estimation ◽  
Modal Parameters

Output-Only Analysis for Modal Parameters Estimation of an Elastically Scaled Ship

2008 ◽  
Vol 52 (01) ◽  
pp. 45-56
Author(s):  
Giuliano Coppotelli ◽  
Daniele Dessi ◽  
Riccardo Mariani ◽  
Marcello Rimondi
Keyword(s):  
Life Prediction ◽  
Structural Response ◽  
Random Excitation ◽  
Parameters Estimation ◽  
Elastic Response ◽  
Modal Parameters ◽  
Practical Application ◽  
Scaled Model ◽  
Output Only ◽  
Ship Speed

The study of the ship structural response assumes an increasing importance as soon as the structures, characterized by much more lightness, are designed and built for faster vessels. This requisite implies a greater flexibility of the structures themselves, the elastic response of which has to be evaluated with accuracy in order to predict the dynamic behavior. In the present paper, a methodology for the identification of the modal parameters from the measurement of only the responses of a vibrating structure has been developed and applied to an elastically scaled model. This output-only technique is successfully applied to the segmented model of a real ship towed in the INSEAN linear basin. The broadband random excitation, provided by the loads exerted by an irregular sea pattern, induces a stochastic response of the model, which is monitored with accelerometers. The obtained results not only outline the parametric dependence of the modal properties on the ship speed, but also suggest a possible practical application of this technique for on-board structural monitoring and fatigue-life prediction.

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