Browsing by Subject "Decentralized control"

Now showing 1 - 8 of 8

Open Access
Adaptive decentralized control of interconnected systems
(Watam Press, 2004) Sezer, M. E.; Altunel, H.
This paper presents a decentralized adaptive stabilization scheme for a class of interconnected systems using high-gain adaptive controllers. The nominal subsystems are assumed to satisfy some mild conditions required by standard adaptive control schemes, and the interconnections certain structural conditions. The decentralized controllers are high-gain dynamic systems operating on local outputs to generate local control inputs. Both continuous-time and sampled-data controllers are considered. The idea behind the design of continuous-time controllers is the small-gain theorem. The sampled-data controllers are discrete versions of the continuous-time controllers, where local sampling frequencies of the controllers also serve as their gains. The controllers are synchronized by a careful choice of their sampling frequencies. In order to guarantee closed-loop stability when the interconnection bounds are unknown, controller gains are increased, using simple centralized adaptation rule, to sufficiently high values as required by the strength of interconnections. The results are illustrated by a practical example.
Open Access
Analysis of a decentralized supply chain under partial cooperation
(2005) Güllü, R.; Van Houtum G. J.; Sargut F. Z.; Erkip, N.
In this article, we analyze a decentralized supply chain consisting of a supplier and two independent retailers. In each order cycle, retailers place their orders at the supplier to minimize inventory-related expected costs at the end of their respective response times. There are two types of lead times involved. At the end of the supplier lead time, retailers are given an opportunity to readjust their initial orders (without changing the total order size), so that both retailers can improve their expected costs at the end of respective retailer lead times (the time it takes for items to be shipped from the supplier to the retailers). Because of the possibility of cooperation at the end of supplier lead time, each retailer will consider the other's order-up-to level in making the ordering decision. Under mild conditions, we prove the existence of a unique Nash equilibrium for the retailer order-up-to levels, and show that they can be obtained by solving a set of newsboy-like equations. We also present computational analysis that provides valuable managerial insight for design and operation of decentralized systems under the possibility of partial cooperation.
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 simultaneous stabilization and reliable control using periodic feedback
(Elsevier BV, 1992) Ünyelioğlu, K. A.; Bülent Özgüler, A.; Khargonekar, P. P.
In this note we consider the simultaneous decentralized stabilization problem for linear, periodically time-varying, discrete time systems. We show that a finite number of periodically time-varying systems can be simultaneously stabilized by a periodically time-varying decentralized compensator if and only if each system admits a decentralized stabilizing compensator. The result is applicable in the design of reliable decentralized stabilizing compensators for interconnected systems. © 1992.
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
Global stabilization via local stabilizing actions
(Institute of Electrical and Electronics Engineers, 2006) Özgüler, A. B.
Stabilization of a linear, time-invariant system via stabilization of its main diagonal subsytems is the underlying problem in all diagonal dominance techniques for decentralized control. In these techniques as well as all Nyquist-based techniques, sufficient conditions are obtained under the assumption that the collection of the unstable poles of all diagonal subsystems is the same as the unstable poles of the overall system. We show that this assumption is by itself enough to construct a solution to the problem at least in cases where the diagonal subsystems have disjoint poles. © 2006 IEEE.
Open Access
Two-channel decentralized integral-action controller design
(IEEE, 2002) Gündeş, A. N.; Özgüler, A. B.
We propose a systematic controller design method that provides integral-action in linear time-invariant two-channel decentralized control systems. Each channel of the plant is single-input-single-output, with any number of poles at the origin but no other poles in the instability region. An explicit parametrization of all decentralized stabilizing controllers incorporating the integral-action requirement is provided for this special case of plants. The main result is a design methodology that constructs simple low-order controllers in the cascaded form of proportional-integral and first-order blocks.