Browsing by Subject "Poles and zeros"

Now showing 1 - 9 of 9

Open Access
Decentralized blocking zeros and the decentralized strong stabilization problem
(IEEE, 1995) Ünyelioğlu, K. A.; Özgüler, A. B.; Özgüner, Ü.
This paper is concerned with a new system theoretic concept, decentralized blocking zeros, and its applications in the design of decentralized controllers for linear time-invariant finite-dimensional systems. The concept of decentralized blocking zeros is a generalization of its centralized counterpart to multichannel systems under decentralized control. Decentralized blocking zeros are defined as the common blocking zeros of the main diagonal transfer matrices and various complementary transfer matrices of a given plant. As an application of this concept, we consider the decentralized strong stabilization problem (DSSP) where the objective is to stabilize a plant using a stable decentralized controller. It is shown that a parity interlacing property should be satisfied among the real unstable poles and real unstable decentralized blocking zeros of the plant for the DSSP to be solvable. That parity interlacing property is also sufficient for the solution of the DSSP for a large class of plants satisfying a certain connectivity condition. The DSSP is exploited in the solution of a special decentralized simultaneous stabilization problem, called the decentralized concurrent stabilization problem (DCSP). Various applications of the DCSP in the design of controllers for large-scale systems are also discussed.
Open Access
Decentralized control and periodic feedback
(IEEE, 1994) Khargonekar P. P.; Özgüler, A. B.
The decentralized stabilization problem for linear, discretetime, periodically time-varying plants using periodic controllers is considered. The main tool used is the technique of lifting a periodic system to a time-invariant one via extensions of the input and output spaces. It is shown that a periodically time-varying system of fundamental period N can be stabilized by a decentralized periodic controller if and only if: 1) the system is stabilizable and detectable, and 2) the N-lifting of each complementary subsystem of identically zero input-output map is free of unstable input-output decoupling zeros. In the special case of N = 1, this yields and clarifies all the major existing results on decentralized stabilization of time-invariant plants by periodically time-varying controllers. © 1994 IEEE
Open Access
Decentralized strong stabilization problem
(IEEE, 1992-06) Özgüler, A. Bülent; Ünyelioğlu, Konur A.
In the decentralized strong stabilization problem for linear time-invariant finite-dimensional systems, the objective is to stabilize a given plant using a stable decentralized controller. A solvability condition for this problem is given in terms of a parity interlacing property which is to be satisfied among the real unstable poles and real unstable decentralized blocking zeros of the plant. The problem of synthesizing decentralized stabilizing controllers with minimum number of unstable poles is also solved.
Open Access
Fixed zeros of decentralized control systems
(IEEE, 2000) ÜÜnyelioglu, K. A.; Özgüner, Ü.; Özgüler, A. B.
This paper considers the notion of decentralized fixed zeros for linear, time-invariant, finite-dimensional systems. For an N-channel plant that is free of unstable decentralized fixed modes, an unstable decentralized fixed zero of Channel i (1 ≤ i ≤ N) is defined as an element of the closed right half-plane, which remains as a blocking zero of that channel under the application of every set of N - 1 controllers around the other channels, which make the resulting single-channel system stabilizable and detectable. This paper gives a complete characterization of unstable decentralized fixed zeros in terms of system-invariant zeros.
Open Access
Improving AWE accuracy using multipoint Pade approximation
(IEEE, 1994-05-06) Çelik, Mustafa; Ocali, Ogan; Tan, Mehmet Ali; Atalar, Abdullah
A new method is proposed for dominant pole-zero analysis of large linear circuits containing both lumped and distributed elements. This method is based on a multipoint Pade approximation. It finds a reduced order s-domain transfer function using a data set obtained by solving the circuit at only a few frequency points. The proposed method yields more accurate computation of transient and frequency responses with respect to the AWE-type techniques.
Open Access
Interframe differential vector coding of line spectrum frequencies
(IEEE, 1993-04) Erzin, Engin; Çetin, A. Enis
Line Spectrum Frequencies (LSF's) uniquely represent the Linear Predictive Coding (LPC) filter of a speech frame. In many vocoders LSF's are used to encode the LPC parameters. In this paper, an interframe differential coding scheme is presented for the LSF's. The LSF's of the current speech frame are predicted by using both the LSF's of the previous frame and some of the LSF's of the current frame. Then, the difference vector resulting from prediction is vector quantized.
Open Access
On algebraic properties of general proper decentralized systems
(Elsevier, 1993) Yu, R.; Sezer, M. E.; Gao, W.
The new concepts of the decentralized output feedback variable polynomial, the decentralized output feedback cycle index of general proper systems, and the geometric multiplicities of decentralized fixed modes are introduced. Their computational methods and some algebraic properties are presented. It is shown that the decentralized output feedback cycle index of a general proper system is equal to one when the system has no fixed modes or equal to the maximum of the geometric multiplicities of its decentralized fixed modes. It is also shown that almost all decentralized output feedback can be used to make the zeros of the decentralized variable polynomial distinct, and disjoint from any given finite set of points on the complex plane.
Open Access
Pole-zero computation in microwave circuits using multipoint Padé approximation
(Institute of Electrical and Electronics Engineers, 1995-01) Celik, M.; Ocali, O.; Tan, M. A.; Atalar, Abdullah
A new method is proposed for dominant pole- zero (or pole-residue) analysis of large linear microwave circuits containing both lumped and distributed elements. The method is based on a multipoint Padé approximation. It finds a reduced-order rational s-domain transfer function using a data set obtained by solving the circuit at only a few frequency points. We propose two techniques in order to obtain the coefficients of the transfer function from the data set. The proposed method provides a more efficient computation of both transient and frequency domain responses than conventional simulators and more accurate results than the techniques based on single-point Padé approximation such as asymptotic waveform evaluation.
Open Access
Stabilization and disturbance rejection for the wave equation
(Institute of Electrical and Electronics Engineers, 1998-01) Morgül, Ö.
We consider a system described by the one-dimensional linear wave equation in a bounded domain with appropriate boundary conditions. To stabilize the system, we propose a dynamic boundary controller applied at the free end of the system. The transfer function of the proposed controller is a proper rational function of the complex variable s and may contain a single pole at the origin and a pair of complex conjugate poles on the imaginary axis, provided that the residues corresponding to these poles are nonnegative; the rest of the transfer function is required to be a strictly positive real function. We then show that depending on the location of the pole on the imaginary axis, the closed-loop system is asymptotically stable. We also consider the case where the output of the controller is corrupted by a disturbance and show that it may be possible to attenuate the effect of the disturbance at the output if we choose the controller transfer function appropriately. We also present some numerical simulation results which support this argument.