Browsing by Subject "Neutral and retarded systems"
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Item Open Access Numerical computation and implementation of H-infinity controllers for retarded and neutral time delay systems(Bilkent University, 2017-11) Yeğin, Mustafa OğuzBeing the most commonly encountered systems in engineering applications, design of robustly stabilizing H∞ controller with maximum performance for timedelay linear time-invariant systems has been an attractive topic in control theory for many decades. A Matlab package called HINFCON is published in 1996. It applies an early solution to the problem, the so-called Toker-Özbay formula. It assumes that the coprime factorization is given, and computes the optimal performance level and the corresponding optimal controller through a manual iteration. The software introduced in this thesis, combines HINFCON with another Matlab package, YALTA, that is being used to do stability analysis for neutral/retarded systems, to perform coprime and inner-outer factorizations of the given infinite dimensional system. Additionally, an iterative algorithm for computation of optimal performance level automatically is implemented to prevent any manual computation. Finally, the Matlab command fitfrd is incorporated into the software that is used for approximation of the optimal controller to obtain a robustly stabilizing suboptimal finite dimensional controller. This thesis also introduces a new structure of the optimal controller which is more reliable and implementable on practical systems. Various examples are solved to compare the suboptimal controllers obtained by using the new structure with direct approximation of plant and optimal controller.Item Open Access Numerical computation of H∞ optimal controllers for time delay systems using YALTA(Elsevier B.V., 2016) Yeğin, M. O.; Özbay, HitayNumerical computation of H∞ controllers for time delay systems has been a challenge since 1980s. Even though significant techniques are developed to obtain direct optimal controllers, application of these methods may require manual computation depending on the plant. In this paper, an alternative computational technique is proposed for direct optimal controllers originally obtained by Toker and Özbay (1995). The new controller expression contains finite dimensional transfer functions and an infinite dimensional term, which is stable. Thus it is suitable for finite dimensional approximations and practical non-fragile implementations. In this method, in order to eliminate manual computation of the plant factorization for neutral and retarded delay systems YALTA (a tool developed at INRIA) is used. The new controller computation is implemented in Matlab, and it is illustrated on an example. © 2016