• Title/Summary/Keyword: system identification

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Modeling for M/C tools structure using system identification (System Identification을 이용한 공작기계구조물의 모델화에 관한 연구)

  • Hah, B.H.;Ro, S.H.;Kim, K.H.
    • Journal of the Korean Society for Precision Engineering
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    • v.10 no.1
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    • pp.142-146
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    • 1993
  • The vibrations of the main spindle of the M/C tools are most important in the consideration of the dymamic performance of the M/C tools. In order to resolve and predict the dynamic behaviour of the main syindle it is necessary to have the mathematical model of the system. The system identification is the procedure to provide us with the mathematical model of the procedure of the system identification of the main spindle of the M/C tools to predict the dynamic behaviour of the machine and further to have the basis for the design of M/C tools.

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Load and Mutual Inductance Identification Method for Series-Parallel Compensated IPT Systems

  • Chen, Long;Su, Yu-Gang;Zhao, Yu-Ming;Tang, Chun-Sen;Dai, Xin
    • Journal of Power Electronics
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    • v.17 no.6
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    • pp.1545-1552
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    • 2017
  • Identifying the load and mutual inductance is essential for improving the power transfer capability and power transfer efficiency of Inductive Power Transfer (IPT) systems. In this paper, a steady-state load and mutual inductance identification method focusing on series-parallel compensated IPT systems is proposed. The identification model is established according to the steady-state characteristics of the system. Furthermore, two sets of identification results are obtained, and then they are analyzed in detail to eliminate the untrue one. In addition, the identification method can be achieved without extra circuits so that it does not increase the complexity of the system or the control difficulty. Finally, the feasibility of the proposed method has been verified by simulation and experimental results.

Identification of nonlinear dynamical systems based on self-organized distributed networks (자율분산 신경망을 이용한 비선형 동적 시스템 식별)

  • 최종수;김형석;김성중;권오신;김종만
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.45 no.4
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    • pp.574-581
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    • 1996
  • The neural network approach has been shown to be a general scheme for nonlinear dynamical system identification. Unfortunately the error surface of a Multilayer Neural Networks(MNN) that widely used is often highly complex. This is a disadvantage and potential traps may exist in the identification procedure. The objective of this paper is to identify a nonlinear dynamical systems based on Self-Organized Distributed Networks (SODN). The learning with the SODN is fast and precise. Such properties are caused from the local learning mechanism. Each local network learns only data in a subregion. This paper also discusses neural network as identifier of nonlinear dynamical systems. The structure of nonlinear system identification employs series-parallel model. The identification procedure is based on a discrete-time formulation. Through extensive simulation, SODN is shown to be effective for identification of nonlinear dynamical systems. (author). 13 refs., 7 figs., 2 tabs.

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Output only system identification using complex wavelet modified second order blind identification method - A time-frequency domain approach

  • Huang, Chaojun;Nagarajaiah, Satish
    • Structural Engineering and Mechanics
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    • v.78 no.3
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    • pp.369-378
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    • 2021
  • This paper reviewed a few output-only system identification algorithms and identified the shortcomings of those popular blind source separation methods. To address the issues such as less sensors than the targeted modal modes (under-determinate problem), repeated natural frequencies as well as systems with complex mode shapes, this paper proposed a complex wavelet modified second order blind identification method (CWMSOBI) by transforming the time domain problem into time-frequency domain. The wavelet coefficients with different dominant frequencies can be used to address the under-determinate problem, while complex mode shapes are addressed by introducing the complex wavelet transformation. Numerical simulations with both high and low signal-to-noise ratios validate that CWMSOBI can overcome the above-mentioned issues while obtaining more accurate identified results than other blind identification methods.

On Identification of Discrete System Expressed by Network Model (네트워크형 이산 시스템의 동정에 관하여)

  • 석상문;강기중;이철영
    • Journal of Korean Port Research
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    • v.14 no.2
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    • pp.155-163
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    • 2000
  • A discrete system has interpreted by using the network model, and PERT network is one of these methods. For the purpose of analysing the real system, it is necessary to measure the parameter of the real system. And system identification problem is to assume the parameter of a real system when we get to know the system model, the input data and output data. System identification method has been only developed to a system of which a structure has expressed a differential equation or a polynomial expression. But it has been scarcely developed yet in that case of network model. The aim of this paper is to examine a changes when new system is introduced to the present system. The changes are as follows : how the present system will be changed, when the changes will be happened. In this paper, genetic algorithm is used to assume the parameter.

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HMM-based Music Identification System for Copyright Protection (저작권 보호를 위한 HMM기반의 음악 식별 시스템)

  • Kim, Hee-Dong;Kim, Do-Hyun;Kim, Ji-Hwan
    • Phonetics and Speech Sciences
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    • v.1 no.1
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    • pp.63-67
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    • 2009
  • In this paper, in order to protect music copyrights, we propose a music identification system which is scalable to the number of pieces of registered music and robust to signal-level variations of registered music. For its implementation, we define the new concepts of 'music word' and 'music phoneme' as recognition units to construct 'music acoustic models'. Then, with these concepts, we apply the HMM-based framework used in continuous speech recognition to identify the music. Each music file is transformed to a sequence of 39-dimensional vectors. This sequence of vectors is represented as ordered states with Gaussian mixtures. These ordered states are trained using Baum-Welch re-estimation method. Music files with a suspicious copyright are also transformed to a sequence of vectors. Then, the most probable music file is identified using Viterbi algorithm through the music identification network. We implemented a music identification system for 1,000 MP3 music files and tested this system with variations in terms of MP3 bit rate and music speed rate. Our proposed music identification system demonstrates robust performance to signal variations. In addition, scalability of this system is independent of the number of registered music files, since our system is based on HMM method.

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Identification and Robust $H_\infty$ Control of the Rotational/Translational Actuator System

  • Tavakoli Mahdi;Taghirad Hamid D.;Abrishamchian Mehdi
    • International Journal of Control, Automation, and Systems
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    • v.3 no.3
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    • pp.387-396
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    • 2005
  • The Rotational/Translational Actuator (RTAC) benchmark problem considers a fourth-order dynamical system involving the nonlinear interaction of a translational oscillator and an eccentric rotational proof mass. This problem has been posed to investigate the utility of a rotational actuator for stabilizing translational motion. In order to experimentally implement any of the model-based controllers proposed in the literature, the values of model parameters are required which are generally difficult to determine rigorously. In this paper, an approach to the least-squares estimation of the parameters of a system is formulated and practically applied to the RTAC system. On the other hand, this paper shows how to model a nonlinear system as a linear uncertain system via nonparametric system identification, in order to provide the information required for linear robust $H_\infty$ control design. This method is also applied to the RTAC system, which demonstrates severe nonlinearities, due to the coupling from the rotational motion to the translational motion. Experimental results confirm that this approach can effectively condense the whole nonlinearities, uncertainties, and disturbances within the system into a favorable perturbation block.

A Study on Practical PMM Test Technique for Ship Maneuverability Using System Identification Method (선박의 조종성능 추정에 있어서 시스템식별법을 이용한 PMM 시험 기법에 대한 연구)

  • 이태일;권순홍
    • Journal of Ocean Engineering and Technology
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    • v.16 no.6
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    • pp.25-31
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    • 2002
  • A system identification method is introduced to increase the prediction accuracy of a ship's maneuverability in PMM test, analysis. To improve the accuracy of linear hydrodynamic coefficients, the analysis techniques of pure sway and yaw tests are developed, and confirmed. In the analysis of sway tests, accuracy to linear hydrodynamic coefficients depends on the frequency of sway motion. To obtain nonlinear hydrodynamic coefficients for large drift angles, a combined yaw test is introduced. Using this system identification method, runs of PMM test can be reduced while retaining sufficient accuracy, compared to the Fourier integration method. Through the comparisons with sea trial results and the Fourier integration method, the accuracy and efficiency of the newly proposed system identification method, based on least square method, has been validated.

Damage Detection in Cracked Model Plate-Girder using Damage Index Method and System Identification Technique (손상지수법과 구조식별(SID) 기법을 통한 균열된 강판형 모형의 손상검색)

  • 백종훈;류연선;김정태;조현만
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.109-116
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    • 2001
  • An integrated damage identification system (IDIS) and system identification (SID) technique using modal information to detect damage in structures is presented. The objective is to detect damages in cracked model plate-girder without baseline modal parameters. The theory of damage localization and system identification is outlined. Experiments on a model plate-girder was described and a baseline model representing the experimental modal characteristics of the model plate-girder is updated using the system identification technique. Finally, damage inflicted in the model plate-girder is predicted using the IDIS software.

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Identification of vibration System With Stiffness and Damping Nonlinearity (비선형 강성 및 감쇠 특성을 갖는 진동 시스템의 규명)

  • 이병림;이재응
    • Journal of KSNVE
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    • v.10 no.1
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    • pp.144-152
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    • 2000
  • The identification of a nonlinear vibration system based on the time domain parametric model has been widely studied in recent years. In most of the studies, the NARMAX model has been used for the identification of a nonlinear system. However, the computational load for the identification with this model is quite heavy. In this paper, a new modeling procedure for nonlinear system identification in discrete time domain is proposed. The proposed model has less initial nonlinear terms than NARMAX model, and the terms in the proposed model are derived from physically meaningful way. The performance of the proposed method is evaluated through the simulation, and the result shows that the proposed model can identify the nonlinear characteristics of the vibration system very will less computational effort.

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