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Identification and characterization of galloping of Tsuruga test line based on multi-channel modal analysis of field data

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JOURNAL OF WIND ENGINEERING AND INDUSTRIAL AERODYNAMICS 2003年第7期91卷 903-924页

作者： Gurung, CB Yamaguchi, H Yukino, T Saitama Univ Dept Civil & Environm Engn Urawa Saitama Japan Kansai Elect Power Co Inc Tech Res Ctr Amagasaki Hyogo Japan

In spite of several signal processing and system identification techniques, discussion on field-observed galloping of overhead transmission lines is still based on primitive form of field data such as time series, Lissajous diagrams and power spectra. Any form of large amplitude vibration in ice storms is defined as galloping and an attempt has seldom made in identifying whether such vibrations are self-excited modal responses. In doing so, there are always possibilities of misinterpreting gust response as galloping. In this study, a method of multi-channel modal analysis consisting of random decrement method (RDM) and eigensystem realization algorithm (ERA) is proposed to identify galloping, which is self-excited modal response based on a typical field-monitored data of wind-induced vibration of the Tsuruga Test line. RDM was used to transform the field data into non-forced response component, which is similar to free vibration response, and ERA was used to extract modal parameters from the non-forced components. Based on these modal parameters, galloping events were identified, and characteristics of galloping such as coupled translational and rotational motions, and nature of full span vibration, oscillation envelopes and influence of geometry of the line section to its occurrence are discussed. Result of analysis has confirmed well-known mechanism of bundle conductor galloping, which is galloping of bundle transmission lines involves significant coupling of vertical and torsional motions. As for the characteristics of bundle conductor galloping, the most likely galloping mode in deadend span is found as first asymmetric mode and large amplitude of galloping occurs when torsion is in-phase with vertical velocity. Furthermore, it is found that deadend span line section is more prone to galloping than semi-suspension span line section. Finally, performance of proposed method was tested by introducing usual buffeting analysis, and it is confirmed that it has immense

关键词： transmission line field data galloping gust response random decrement method eigensystem realization algorithm buffeting analysis modal analysis motion-induced force

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A study of damping errors in correlation-driven stochastic realizations using short data sets

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PROBABILISTIC ENGINEERING MECHANICS 2003年第1期18卷 61-77页

作者： Pridham, BA Wilson, JC McMaster Univ Dept Civil Engn Hamilton ON L8S 4L7 Canada

A numerical study, motivated by applications in structural engineering, is conducted to investigate the effects of using short data sets for the identification of system damping in correlation-driven stochastic realizations. Sets of single-degree-of-freedom systems are excited with white noise and the eigensystem realization algorithm, with the aid of the modal confidence factor, is employed for the identification scheme. The study reveals information regarding the effects of sample size and Hankel matrix dimension on the resulting estimates of system damping. Results illustrate that significant bias is associated with using short data sets in a correlation-driven framework;in particular errors are seen to increase for high frequency, high-damping systems. Some of this error can be attributed to the inclusion of problematic regions of the correlation function in addition to leakage from the correlation estimation. (C) 2003 Elsevier Science Ltd. All rights reserved.

关键词： eigensystem realization algorithm system identification Hankel matrix structural dynamics damping data correlations modal confidence factor earthquake engineering

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Structural identification using inverse system dynamics

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 2000年第5期23卷 819-825页

作者： Kammer, DC Steltzner, AD Univ Wisconsin Dept Engn Phys Madison WI 53706 USA

A time-domain technique is presented that uses inverse structural dynamics to identify physical characteristics of a structure that can subsequently be used for damage detection. The term inverse refers to the roles of input and output being reversed from the usual forward system structural dynamics problem. If sensors such as accelerometers are placed at the external input locations, modal parameters corresponding to structural motion with the sensor locations fixed can be identified. One of the main advantages of this approach is that it only requires measured response data, This characteristic makes the approach applicable in cases where the input forces cannot be measured.

关键词： Sensors Structural Dynamics Accelerometer eigensystem realization algorithm Elastic Structure Single Input Single Output System Sandia National Laboratories Singular Value Decomposition International Space Station Frequency Response Functions

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System identification in the presence of completely unknown periodic disturbances

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 2000年第2期23卷 251-259页

作者： Goodzeit, NE Phan, MQ Princeton Univ Dept Mech & Aerosp Engn Princeton NJ 08544 USA

A system identification method to extract the disturbance-free dynamics and the disturbance effect correctly despite the presence of unknown periodic disturbances is presented. The disturbance frequencies and waveforms can be completely unknown and arbitrary Only measurements of the excitation input and the disturbance-contaminated response are used for identification. Initially, the disturbances are modeled implicitly. When the order of an assumed input-output model exceeds a certain minimum value, the disturbance information is completely absorbed in the identified model coefficients. A special interaction matrix explains the mechanism by which information about the system and the disturbances are intertwined and more importantly, how they can be separated uniquely and exactly for later use in identification and control. From the identified information a feedforward controller can be developed to reject the unwanted disturbances without requiring the measurement of a separate disturbance-correlated signal. The multi-input multi-output formulation is first derived in the deterministic setting for which the system and disturbance identification is exact. Extensions to handle noise-contaminated data are also provided. Experimental results illustrate the method on a flexible structure. A companion paper addresses the problem where the disturbance effect is modeled explicitly.

关键词： System Identification Lightly Damped Structures Trusses eigensystem realization algorithm Singular Value Decomposition Neural Networks Feedback Control Accelerometer White Noise

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On-line version of the eigensystem realization algorithm using data correlations

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 1997年第1期20卷 137-142页

作者： Cooper, JE University of Manchester Manchester M13 9PL England United Kingdom

An on-line (recursive) version of the eigensystem realization algorithm using data correlations is developed based on the QR decomposition. The method can be used to estimate a theoretically unbiased minimum-order realization from decay response data. The proposed method is an improvement on other on-line time domain identification techniques in that the minimum-order realization permits overspecification of the mathematical model, removing simultaneously the problems of a priori model order selection and possible computational difficulties with identified spurious modes. Time varying modal parameters can also be tracked through the use of a forgetting factor to weight the most recent points. The method is demonstrated on a number of simulated data sets corrupted with measurement noise.

关键词： eigensystem realization algorithm Data Correlation Damping Ratio Single Input Single Output Mathematical Models

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Dynamic system characterization via Eigenvalue orbits

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 1999年第3期22卷 447-454页

作者： Marczyk, J Rodellar, J Barbat, AH Tech Univ Catalonia Sch Civil Engn Dept Struct Mech Barcelona Spain Tech Univ Catalonia Sch Civil Engn Dept Appl Math 3 Barcelona Spain

A new model-free approach for the description of general dynamical systems with unknown structure, order, and excitation is introduced. The approach is based on the new concept of eigenvalue orbit, The eigenorbits are obtained by building an associated linear time-variant system through a matrix that relates the output measurements in a moving horizon window and viewing the trajectories of its time-varying eigenvalues. How the eigenorbits may be computed from the measurements and used for the characterization of the original system is shown. The basic properties of the eigenorbits are presented via a series of theorems for the case of a discrete-time, linear time-invariant system. A set of examples are included to illustrate these properties for more general classes of systems and to suggest some practical issues that can be drawn from the orbits.

关键词： Eigenvalues Linear Time Invariant Mathematical Models eigensystem realization algorithm Singular Value Decomposition Aspect Ratio Four Degree of Freedom Orbit Determination Dissipative System Neural Networks

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Time-domain identification of low-order models for flexible structures

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 1999年第6期22卷 908-909页

作者： Bauer, RJ Hughes, PC Dalhousie Univ Halifax NS B3J 1Z1 Canada Univ Toronto Inst Aerosp Studies Toronto ON M3H 5T6 Canada

Consideration is given to a novel approach to system identification that applies cubic smoothing splines to the system Markov parameters calculated by Observer Kalman Filter Identification. Applying this smoothing procedure early in the identification process allows models that are both low order and accurate to be directly identified. Experiments with Daisy, a flexible spacecraft emulator, demonstrate significant computational savings and numerical robustness by avoiding the model overspecification and reduction process. (AIAA)

关键词： Flexible Structures eigensystem realization algorithm Model Order Reduction Reaction Wheels Control System Design Space Structures Satellites Yaw

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Independent analysis of the space station node modal test data

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 1999年第1期22卷 22-27页

作者： Pappa, RS NASA Struct Dynam Branch Struct Div Langley Res Ctr Hampton VA 23681 USA

With complex structures, comparison of independently derived sets of experimental modal parameters is an excellent way to increase confidence in the results. Modal identification results are presented using the eigensystem realization algorithm on frequency response functions from the modal test of the space station resource node. The resource node is the first U.S.-built structure for the International Space Station. The modal test was conducted by the NASA Marshall Space Flight Center in January 1997 for The Boeing Company, who designed and built the node. The calculated parameters are compared with independent results obtained by the test team using commercial software. There was excellent correlation of mode shapes between the two sets of results for the first 21 vibration modes of the structure up to 35 Hz. From 35 to 50 Hz, about 60% of 25 additional modes had excellent correlation. Natural frequencies and damping factors of most modes agreed within 0.1 Hz and 0.2%, respectively.

关键词： Space Stations eigensystem realization algorithm Functional Cargo Block NASA Marshall Space Flight Center Frequency Response Functions Boeing Accelerometer Shuttle Payloads Pressurized Mating Adapter Multiple Input Multiple Output

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Do all linear flexible structures have convergent second-order observers?

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 1999年第6期22卷 905-908页

作者： Balas, MJ Univ Colorado Dept Aerosp Engn Sci Boulder CO 80309 USA

It is shown that all linear flexible structures have second-order observers with arbitrary rates of convergence. However, the most natural definition of such an observer does not work, and it is necessary to accept an... 详细信息

关键词： Flexible Structures eigensystem realization algorithm Model Order Reduction Reaction Wheels Control System Design Space Structures Satellites Yaw

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Extracting second-order systems from state-space representations

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AIAA JOURNAL 1999年第1期37卷 132-135页

作者： Friswell, MI Univ Coll Swansea Dept Mech Engn Swansea SA2 8PP W Glam Wales Aston Univ Sch Engn Birmingham B4 7ET W Midlands England

Provides a simple method to generate the transformation of second-order systems from state-space representation. Presentation of the equation motion; Transformation to second-order form; Conclusions.

关键词： State Space Representation State Space Systems Structural Dynamics Stiffness Matrices Second Order Differential Equations eigensystem realization algorithm Boundary Layer Separation Lagrange Multipliers Three Degrees of Freedom Energy Conservation

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