• Title, Summary, Keyword: Linear Time-Varying Sampled-Data Systems

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Variable Structure Controller for Linear Time-Varying Sampled-Data Systems with Disturbances (외란을 갖는 선형 시변 샘플링된 시스템에 대한 가변구조제어기)

  • Park Kang-Bak
    • The Transactions of the Korean Institute of Electrical Engineers D
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    • v.51 no.12
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    • pp.556-561
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    • 2002
  • In this paper, a discrete-time variable structure controller for linear time-varying sampled-data systems with disturbances is proposed. The proposed method guarantees that the system state if globally uniformly ultimately bounded (G.U.U.B), and the ultimate bound is shown to be the order of T, O(T), where T is a sampling period.

ROBUST $H_{\infty}$ FIR SAMPLED-DATA FILTERING

  • Ryu, Hee-Seob;Yoo, Kyung-Sang;Kwon, Oh-Kyu
    • 제어로봇시스템학회:학술대회논문집
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    • pp.521-521
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    • 2000
  • This paper investigates the problem of robust H$_{\infty}$ filter with FIR(Finite Impulse Response) structure for linear continuous time-varying systems with sampled-data measurements. It is assumed that the system is subject to real time-varying uncertainty which is represented by the state-space model having parameter uncertainty. The robust H$_{\infty}$ FIR filter is proposed for the continuous-time linear parameter uncertain systems. It is also derived from the equivalence relationship between the robust linear H$_{\infty}$ FIR filter and the robust linear H$_{\infty}$ filter with sampled-data measurements.

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H Sampled-Data Control of LPV Systems with Time-varying Delay (시변지연을 가지는 LPV시스템의 H 샘플데이타 제어)

  • Liu, Yajuan;Lee, Sangmoon
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.64 no.1
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    • pp.121-127
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    • 2015
  • This paper considers the problem of sampled-data control for continuous linear parameter varying (LPV) systems. It is assumed that the sampling periods are arbitrarily varying but bounded. Based on the input delay approach, the sampled-data control LPV system is transformed into a continuous time-delay LPV system. Some less conservative stabilization results represented by LMI (Linear Matrix Inequality) are obtained by using the Lyapunov-Krasovskii functional method and the reciprocally combination approach. The proposed method for the designed gain matrix should guarantee asymptotic stability and a specified level of performance on the closed-loop hybrid system. Numerical examples are presented to demonstrate the effectiveness and the improvement of the proposed method.

Robust $H_{\infty}$ FIR Sampled-Date Filtering for Uncertain Time-Varying Systems with Unknown Nonlinearity

  • Ryu, Hee-Seob;Byung-Moon;Kwon, Oh-Kyu
    • Transactions on Control, Automation and Systems Engineering
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    • v.3 no.2
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    • pp.83-88
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    • 2001
  • The robust linear H(sub)$\infty$ FIR filter, which guarantees a prescribed H(sub)$\infty$ performance, is designed for continuous time-varying systems with unknown cone-bounded nonlinearity. The infinite horizon filtering for time-varying systems is systems is investigated in therms of two Riccati equations by the finite moving horizon.

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Robust H$\infty$ FIR Filtering for Uncertain Time-Varying Sampled-Data Systems

  • Ryu, Hee-Seob;Kwon, Byung-Moon;Kwon, Oh-Kyu
    • Journal of KIEE
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    • v.11 no.1
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    • pp.21-26
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    • 2001
  • This paper considers the problem of robust H$\infty$ filter is derived by using the equivalence relationship between the FIR filter and the recursive filter, that would be guarantee a prescribed H$\infty$ performance in the continuous-time context, irrespective of the parameter uncertainty and unknown initial states.

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Improving a Digital Redesign for Time-Varying Trackers (시변 추종제어기를 위한 디지털 재설계의 개선)

  • Song, Hyun-Seok;Lee, Ho-Jae;Kim, Do-Wan
    • Journal of Institute of Control, Robotics and Systems
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    • v.17 no.4
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    • pp.289-294
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    • 2011
  • Digital redesign is yet another efficient tool to convert a pre-designed analog controller into a sampled-data one to maintain the analog closed-loop performance in the sense of state matching. A rising difficulty in developing a digital redesign technique for trackers with time-varying references is the unavailability of a closed-form discrete-time model of a system, even if it is linear time-invariant. A way to resolve this is to approximate the time-varying reference as a piecewise constant one, which deteriorates the state matching performance. Another remedy may be to decrease a sampling period, which however could numerically destabilize the optimization-based digital redesign condition. In this paper, we develop a digital redesign condition for time-varying trackers by approximating the time-varying reference through a triangular hold and by introducing delta-operated discrete-time models. It is shown that the digitally redesigned sampled-data tracker recovers the performance of the pre-designed analog tracker under a fast sampling limit. Simulation results on the formation flying of satellites convincingly show the effectiveness of the development.

Sampled-data Control for Lur'e Dynamical Systems (루에 동적 시스템을 위한 샘플데이타 제어)

  • Liu, Yajuan;Lee, Sangmoon
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.63 no.2
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    • pp.261-265
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    • 2014
  • This paper studies the problem of the sampled-data control for Lur'e system with nonlinearities. The nonlinearities are expressed as convex combinations of sector and slope bounds. It is assumed that the sampling periods are arbitrarily varying but bounded. By constructing a new augmented Lyapunov-Krasovskii functional which have an augmented quadratic form with states as well as the nonlinear function, the stabilizing sampled-data controller gains are obtained by solving a set of linear matrix inequalities. The effectiveness of the developed method is demonstrated by numerical simulations.

H filter design for offshore platforms via sampled-data measurements

  • Kazemy, Ali
    • Smart Structures and Systems
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    • v.21 no.2
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    • pp.187-194
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    • 2018
  • This paper focuses on the $H_{\infty}$ filter design problem for offshore steel jacket platforms. Its objective is to design a full-order state observer for offshore platforms in presence of unknown disturbances. To make the method more practical, it is assumed that the measured variables are available at discrete-time instants with time-varying sampling time intervals. By modelling the sampling intervals as a bounded time-varying delay, the estimation error system is expressed as a time-delay system. As a result, the addressed problem can be transformed to the problem of stability of dynamic error between the system and the state estimator. Then, based on the Lyapunov-Krasovskii Functional (LKF), a stability criterion is obtained in the form of Linear Matrix Inequalities (LMIs). According to the stability criterion, a sufficient condition on designing the state estimator gain is obtained. In the end, the proposed method is applied to an offshore platform to show its effectiveness.

Robust Discretization of LTI Systems with Polytopic Uncertainties and Aperiodic Sampling

  • Lee, Dong Hwan;Park, Jin Bae;Joo, Young Hoon
    • Journal of Electrical Engineering and Technology
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    • v.10 no.3
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    • pp.1255-1263
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    • 2015
  • In the previous work, the authors studied the problem of robust discretization of linear time-invariant systems with polytopic uncertainties, where linear matrix inequality (LMI) conditions were developed to find an approximate discrete-time (DT) model of a continuous-time (CT) system with uncertainties in polytopic domain. The system matrices of obtained DT model preserved the polytopic structures of the original CT system. In this paper, we extend the previous approach to solve the problem of robust discretization of polytopic uncertain systems with aperiodic sampling. In contrast with the previous work, the sampling period is assumed to be unknown, time-varying, but contained within a known interval. The solution procedures are presented in terms of unidimensional optimizations subject to LMI constraints which are numerically tractable via LMI solvers. Finally, an example is given to show the validity of the proposed techniques.