Tez No	İndirme	Tez Künye	Durumu
523363		Self-optimization systems design based on sliding mode control / Yazar:AHMET ÇAKANEL Danışman: Prof. VADIM I. UTKIN Yer Bilgisi: The Ohio State University / Yurtdışı Enstitü Konu:Bilgisayar Mühendisliği Bilimleri-Bilgisayar ve Kontrol = Computer Engineering and Computer Science and Control ; Elektrik ve Elektronik Mühendisliği = Electrical and Electronics Engineering Dizin:	Onaylandı Doktora İngilizce 2017 125 s.
The objective of control systems is to maintain desired output with the best attainable eciency, in which such performance of many modern technologies is enhanced via minimizing or maximizing some state variables. Optimization problems are occasionally handled under the condition such that extremum value, local plant gain and required inputs are unknown. Sliding Mode Control (SMC) theory was developed for the plants operate under uncertainty conditions and it exhibits high accuracy, low sensitivity with respect to parameter variations and disturbances. SMC comply with self optimization application requires controlling without gradient evaluation or measurement. This is non-conventional control-system problem, cause gradient takes part of the local gain and it can change sign. In the thesis, searching algorithm is designed with monotonously decreasing or increasing function which is tracked by the output of a plant until the extremum point is reached. Along with developed design principle, aforementioned system behavior in the vicinity of extremum is investigated through deeper analyses, cause the local gain of the plant tends to zero and SMC inherently suers from the presence of high frequency oscillations, so called chattering. This scope is considered as the theoretical part of the thesis and it is complemented with comparison of other developed methodologies apply gradient vector evaluation. Generalization of the proposed method is demonstrated for multidimensional optimization. Beyond theoretical part, three self-optimization problems are under consideration, which are frequency control of DC/AC inverters implemented on induction motors, output maximization of Underground Coal Gasication (UCG) power plants and capability enhancement of a three-dimensional particle tracking system by integration of an electrically focus-tunable lens. The objective of minimizing the switching-frequency of DC/AC inverters with desired width of hysteresis results in decreasing heat losses in the power converter. Moreover, decreasing the width of hysteresis loop with remaining the level of admissible frequency will increase the accuracy of inverters. Gasication of coal deep below the earth surface, known as the Underground Coal Gasication (UCG) process, is very sensitive to the ow rate of oxidants. However, the most critical factor is the steam to oxygen ratio in the input ow rate. Sliding modes based static self-optimization is applied to the UCG process which takes into consideration the inlet pressure of the UCG reactor, adjusts the steam to oxygen ratio such that the reactor output, which is the caloric value of the product gases, is maximized. The simulation results are presented for the validated UCG model to emphasize eectiveness of the algorithm. SMC self-optimization model is used for tracking an axillary moving microscopic particle of electrically focus tunable lens. Using lenses mounted on mechanical actuators are not ecient against limited movement range, slower response times and vibrations in the system. These drawbacks are often handled by using mathematical models to estimate the state feedbacks before designing the control system. However, the SM the self-optimizing design does not require state feedback information and works by optimizing an output function of the system. The control system is then successfully simulated.