• Title/Summary/Keyword: Linear Stability Theory

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Design of LQR controller for active suspension system of Partially Filled Tank Cars

  • Feizi, Mohammad Mahdi;Rezvani, Mohammad Ali
    • Structural Engineering and Mechanics
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    • v.49 no.3
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    • pp.329-353
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    • 2014
  • Increasing usage of tank cars and their intrinsic instability due to sloshing of contents have caused growing maintenance costs as well as more frequent hazards and defects like derailment and fatigue of bogies and axels. Therefore, varieties of passive solutions have been represented to improve dynamical parameters. In this task, assuming 22 degrees of freedom, dynamic analysis of partially filled tank car traveling on a curved track is investigated. In order to consider stochastic geometry of track; irregularities have been derived randomly by Mont Carlo method. More over the fluid tank model with 1 degree of freedom is also presented by equivalent mechanical approach in terms of pendulum. An active suspension system for described car is designed by using linear quadratic optimal control theory to decrease destructive effects of fluid sloshing. Eventually, the performance of the active suspension system has been compared with that of the passive one and a study is carried out on how active suspension may affect the dynamical parameters such as displacements and Nadal's derailment index.

A servo design method for MIMO Wiener systems with nonlinear uncertainty

  • Kim, Sang-Hoon;Kunimatsu, Sadaaki;Fujii, Takao
    • 제어로봇시스템학회:학술대회논문집
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    • 2005.06a
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    • pp.1960-1965
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    • 2005
  • This paper presents theory for stability analysis and design of a servo system for a MIMO Wiener system with nonlinear uncertainty. The Wiener system consists of a linear time-invariant system(LTI) in cascade with a static nonlinear part ${\psi}$(y) at the output. We assume that the uncertain static nonlinear part is sector bounded and decoupled. In this research, we treat the static nonlinear part as multiplicative uncertainty by dividing the nonlinear part ${\psi}$(y) into ${\phi}$(y) := ${\psi}$(y)-y and y, and then we reduce this stabilizing problem to a Lur'e problem. As a result, we show that the servo system with no steady state error for step references can be constructed for the Wiener system.

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Fuzzy Robust $H^{\infty}$ Controller Design for Discrete Uncertain Nonlinear Systems with Time Delays (시간지연을 가지는 비선형 불확실성 이산 시스템의 퍼지 견실 $H^{\infty}$ 제어기 설계)

  • 이형호;조상현이갑래박홍배
    • Proceedings of the IEEK Conference
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    • 1998.06a
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    • pp.227-230
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    • 1998
  • In this paper, we propose the design method of fuzzy robust H$\infty$ controller for the uncertain nonlinear discete-time systems with time delay. First, we represent a nonlinear plant with a modified T-S(Takagi-Sugeno) fuzzy model. Then design method utilizing the concept of PDC (parallel distributed compensation) is employed. For the modified T-S fuzzy model with uncertainty and delay, the sufficient condition of the quadratic stabilization with an H$\infty$ norm bound is presented in terms of Lyapunov stability theory and fuzzy robust H$\infty$ controller design method is given by LMI(linear matrix inequality) approach. Also an illustrative example is given to demonstrate the result of the proposed method.

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Lateral buckling of thin-walled members with openings considering shear lag

  • Wang, Quanfeng
    • Structural Engineering and Mechanics
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    • v.5 no.4
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    • pp.369-383
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    • 1997
  • The classical theory of thin-walled members is unable to reflect the shear lag phenomenon since it is based on the assumption of no shearing strains in the middle surface of the walls. In this paper, an energy equation for the lateral buckling of thin-walled members has been derived which includes the effects of torsion, warping and, especially, the shearing strains which reflect the shear lag phenomenon. A numerical analysis for the lateral buckling of thin-walled members with openings by using Galerkin's method of weighted residuals has been presented. The proposed numerical values and the predictions by experiment for the lateral buckling loads are to agree closely in the paper. The results from these comparisons show that the proposed method here is capable of predicting the lateral buckling of thin-walled members with openings. The fast convergence of the results indicates the numerical stability of the method. By the study, a very complex practical eigenvalue problem is transformed into a very simple one of solving only a linear equation with one variable.

Principle of Exchange of Stabilities in the Marangoni Convection System (Marangoni 대류계에서의 안정성 교환의 원리)

  • Kim, Min Chan
    • Korean Chemical Engineering Research
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    • v.47 no.2
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    • pp.262-265
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    • 2009
  • For the initially quiescent fluid layer, the principle of the exchange of stabilities for the Marangoni convection due to the impulsive temperature change is proven analytically. Under the linear stability theory, the temperature and vertical velocity disturbances are express as the liner combination of the orthogonal functions. It is shown that the growth rate of the temperature disturbance is the real function for all positive Marangoni numbers.

Design of Sliding Mode Fuzzy-Model-Based Controller Using Genetic Algorithms

  • Chang, Wook
    • Journal of the Korean Institute of Intelligent Systems
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    • v.11 no.7
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    • pp.615-620
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    • 2001
  • This paper addresses the design of sliding model fuzzy-model-based controller using genetic algorithms. In general, the construction of fuzzy logic controllers has difficulties for the lack of systematic design procedure. To release this difficulties, the sliding model fuzzy-model-based controllers was presented by authors. In this proposed method, the fuzzy model, which represents the local dynamic behavior of the given nonlinear system, is utilized to construct the controller. The overall controller consists of the local compensators which compensate the local dynamic linear model and the feed-forward controller which is designed via sliding mode control theory. Although, the stability and the performance is guaranteed by the proposed method, some design parameters have to be chosen by the designer manually. This problem can be solved by using genetic algorithms. The proposed method tunes the parameters of the controller, by which the reasonable accuracy and the control effort is achieved. The validity and the efficiency of the proposed method are verified through simulations.

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Real-Time Digital Fuzzy Control Systems considering Computing Time-Delay

  • Park, Chang-Woo;Shin, Hyun-Seok;Park, Mig-Non
    • Journal of the Korean Institute of Intelligent Systems
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    • v.10 no.5
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    • pp.423-431
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    • 2000
  • In this paper, the effect of computing time-delay in the real-time digital fuzzy control systems is investigated and the design methodology of a real-time digital fuzzy controller(DFC) to overcome the problems caused by it is presented. We propose the fuzzy feedback controller whose output is delayed with unit sampling period. The analysis and the design problem considering computing time-delay is very easy because the proposed controller is syncronized with the sampling time. The stabilization problem of the digital fuzzy control system is solved by the linear matrix inequality(LMI) theory. Convex optimization techniques are utilized to find the stable feedback gains and a common positive definite matrix P for the designed fuzzy control system Furthermore, we develop a real-time fuzzy control system for backing up a computer-simulated truck-trailer with the consideration of the computing time-delay. By using the proposed method, we design a DFC which guarantees the stability of the real time digital fuzzy control system in the presence of computing time-delay.

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Design of Power System Stability for Local Mode Using Eigen-Sensivity (지역모드 제동을 위한 고유치 감도와 PSS 설계)

  • Song, S.G.;Nam, H.K.;Shim, K.S.;Kim, Y.G.
    • Proceedings of the KIEE Conference
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    • 2001.05a
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    • pp.14-16
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    • 2001
  • The Eigen-Sensitivity theory at full system is used to supplement drawback of the existing PSS gain tuning methods in this paper. Hessenberg method is used to linear analysis. This proposed method is successfully tested on KEPCO 2003 off-peak power system to improve local mode. The designed PSS at 2003 off-peak system is installed in 2003 peak system to improve robustness.

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Neural-Net Based Nonlinear Adaptive Control for AUV

  • Li, Ji-Hong;Lee, Sang-Jeong;Lee, Pan-Mook
    • 제어로봇시스템학회:학술대회논문집
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    • 2001.10a
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    • pp.173.4-173
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    • 2001
  • This paper presents a stable nonlinear adaptive control for AUV(Autonomous Underwater Vehicle) by using neural network. AUV's dynamics are highly nonlinear, and their hydrodynamic coefficients vary with different operational conditions. In this paper, the nonlinear uncertainties of the AUV's dynamics are approximated by using LPNN(Linearly parameterized Neural Network). The presented controller is consist of three parallel terms; linear feedback control, sliding mode control, and adaptive control(LPNN). Lyapunov theory is used to guarantee the stability of tracking errors and neural network´s weights errors. Numerical simulations for nonlinear control of the AUV show the effectiveness of the proposed techniques.

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On learning control of robot manipulator including the bounded input torque (제한 입력을 고려한 로보트 매니플레이터의 학습제어에 관한 연구)

  • 성호진;조현찬;전홍태
    • 제어로봇시스템학회:학술대회논문집
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    • 1988.10a
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    • pp.58-62
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    • 1988
  • Recently many adaptive control schemes for the industrial robot manipulator have been developed. Especially, learning control utilizing the repetitive motion of robot and based on iterative signal synthesis attracts much interests. However, since most of these approaches excludes the boundness of the input torque supplied to the manipulator, its effectiveness may be limited and also the full dynamic capacity of the robot manipulator can not be utilized. To overcome the above-mentioned difficulties and meet the desired performance, we propose an approach which yields the effective learning control schemes in this paper. In this study, some stability conditions derived from applying the Lyapunov theory to the discrete linear time-varying dynamic system are established and also an optimization scheme considering the bounded input torque is introduced. These results are simulated on a digital computer using a three-joint revolute manipulator to show their effectiveness.

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