Browsing by Subject "Unstable systems"

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    On feedback stabilization of neutral time delay systems with infinitely many unstable poles
    (Elsevier B.V., 2018) Gumussoy, S.; Özbay, Hitay
    It is shown that strictly proper neutral time delay systems having at least one asymptotic pole chain converging to a vertical line Re(s) = σ > 0 cannot be stabilized by a proper controller. A special coprime factorization can be obtained for such systems with infinitely many unstable poles, provided they are bi-proper (i.e. proper, but not strictly proper). From this factorization, stabilizing feedback controllers are obtained. Necessarily, all stabilizing controllers for this type of plants are also bi-proper.
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    On Smith predictor based controllers for plants with time delay and multiple unstable modes
    (Elsevier BV, 2022-12-31) Yeğin, Mustafa Oğuz; Özbay, Hitay
    This work proposes an extension of the Smith predictor to design stabilizing controllers for linear time-invariant (LTI) time-delay single-input single-output (SISO) systems with multiple unstable modes. The main contribution of this method is that it simplifies earlier predictor-based control designs for unstable plants. The predictor filters are designed by solving a Nevanlinna–Pick interpolation problem for optimal robust stability.
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    PID controller synthesis for a class of unstable MIMO plants with I/O delays
    (Elsevier BV, 2007-01) Gündeş, A. N.; Özbay, Hitay; Özgüler, A. B.
    Conditions are presented for closed-loop stabilizability of linear time-invariant (LTI) multi-input, multi-output (MIMO) plants with I/O delays (time delays in the input and/or output channels) using PID (Proportional + Integral + Derivative) controllers. We show that systems with at most two unstable poles can be stabilized by PID controllers provided a small gain condition is satisfied. For systems with only one unstable pole, this condition is equivalent to having sufficiently small delay-unstable pole product. Our method of synthesis of such controllers identify some free parameters that can be used to satisfy further design criteria than stability.
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    ItemOpen Access
    PID controller synthesis for a class of unstable MIMO plants with I/O delays
    (Elsevier, 2006-07) Gündeş, A. N.; Özbay, Hitay; Özgüler, A. Bülent
    Conditions are presented for closed-loop stabilizability of linear time-invariant (LTI) multi-input, multi-output (MIMO) plants with I/O delays (time delays in the input and/or output channels) using PID (Proportional + Integral + Derivative) controllers. We show that systems with at most two unstable poles can be stabilized by PID controllers provided a small gain condition is satisfied. For systems with only one unstable pole, this condition is equivalent to having sufficiently small delay-unstable pole product. Our method of synthesis of such controllers identify some free parameters that can be used to satisfy further design criteria than stability. Copyright © 2006 IFAC.
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    ItemOpen Access
    Resilient PI and PD controller designs for a class of unstable plants with I/O delay
    (Applied Mathematics Scientific Research Institute, 2007) Özbay, Hitay; Gündeş, A. N.
    In [8] we obtained stabilizing PID controllers for a class of MIMO unstable plants with time delays in the input and output channels (I/O delays). Using this approach, for plants with one unstable pole, we investigate resilient PI and PD controllers. Specifically, for PD controllers, optimal derivative action gain is determined to maximize the allowable controller gain interval. For PI controllers, optimal proportional gain is determined to maximize a lower bound of the largest allowable integral action gain
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    ItemOpen Access
    Resilient PI and PD controllers for a class of unstable MIMO plants with I/O delays
    (Elsevier, 2006-07) Özbay, Hitay; Gündeş, A. N.
    Recently (Gündeş et al., 2006) obtained stabilizing PID controllers for a class of MIMO unstable plants with time delays in the input and output channels (I/O delays). Using this approach, for plants with one unstable pole, we investigate resilient PI and PD controllers. Specifically, for PD controllers, optimal derivative action gain is determined to maximize a lower bound of the largest allowable controller gain. For PI controllers, optimal proportional gain is determined to maximize a lower bound of the largest allowable integral action gain. Copyright © 2006 IFAC.