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Advances in Control Theory and Applications: Selected papers from TOK 2013
(Sage Publications Ltd, 2015) Hamamci, Serdar Ethem; Tan, Nusret; Efe, Mehmet Onder; Soylemez, Mehmet Turan
[Abstract Not Available]
An algorithm for stabilization of fractional-order time delay systems using fractional-order PID controllers
(Ieee-Inst Electrical Electronics Engineers Inc, 2007) Hamamci, Serdar Ethem
This technical note presents a solution to the problem of stabilizing a given fractional-order system with time delay using fractional-order (PID mu)-D-lambda controllers. It is based on determining a set of global stability regions in the (k(p), k(i), k(d)) -space corresponding to the fractional orders lambda and mu. in the range of (0, 2) and then choosing the biggest global stability region in this set. This method can be also used to find the set of stabilizing controllers that guarantees prespecified gain and phase margin requirements. The algorithm is simple and has reliable result which is illustrated by an example, and, hence, is practically useful in the analysis and design of fractional-order control systems.
Application and Modeling of a Novel 4D Memristive Chaotic System for Communication Systems
(Springer Birkhauser, 2020) Sahin, Muhammet Emin; Taskiran, Zehra Gulru Cam; Guler, Hasan; Hamamci, Serdar Ethem
In this paper, a new four-dimensional (4D) chaotic system which contains an active flux-controlled memristor characterized with a smooth continuous cubic nonlinearity is introduced. The objective is to obtain a 4D chaotic system which contains quadratic terms by using the memristor model which is designed as a new cubic emulator. A new chaotic circuit equation is obtained by using this emulator. The chaotic behavior of the system is observed both theoretically and graphically. The fundamental dynamics of the chaotic system are examined by using equilibrium points, phase portraits, Lyapunov exponents and bifurcation diagrams. The proportional-integral-derivative (PID) control design obtained using optimization algorithms is presented for memristor-based chaotic system. Firefly algorithm and genetic algorithm are used in PID control design for obtaining optimal PID controller gains that provides optimization between master and slave circuits. To verify system performance, this proposed PID-based chaotic circuit is used to communicate communication systems. Experimental results of this system are obtained and presented in real time.
Calculation of all stabilizing fractional-order PD controllers for integrating time delay systems
(Pergamon-Elsevier Science Ltd, 2010) Hamamci, Serdar Ethem; Koksal, Muhammet
In this paper, a simple and effective stabilization method for integrating time delay systems using fractional order PD controllers C(s) = k(p) k(d)s(mu) is proposed. The presented method is based on finding the stability regions according to the fractional orders of the derivative element in the range of (0, 2). These regions are computed by using three stability boundaries: Real Root Boundary (RRB), Complex Root Boundary (CRB) and Infinite Root Boundary (IRB). The method gives the explicit formulae corresponding to these boundaries in terms of fractional order PD controller (PD(mu) controller) parameters. Thus, the complete set of stabilizing controllers for an arbitrary integrating time delay system can be obtained. In order to demonstrate the effectiveness in solution accuracy and the simplicity of this method, two simulation studies are given. The simulation results indicate that the PD(mu) controllers can provide larger stability regions than the integer order PD controllers. (C) 2009 Elsevier Ltd. All rights reserved.
Design and Realization of a Hyperchaotic Memristive System for Communication System on FPGA
(Int Information & Engineering Technology Assoc, 2020) Sahin, Muhammet Emin; Guler, Hasan; Hamamci, Serdar Ethem
In this study, a memristor based hyperchaotic circuit is presented and implemented for communication systems on FPGA platform. Four dimensional hyperchaotic system, which contains active flux controlled memristor is designed by using a smooth continuous nonlinearity. Dynamical characteristics of designed hyperchaotic circuit are examined such as equilibrium points, chaotic attractors, Lyapunov exponents and bifurcation diagram. Furthermore, an electronic circuit model of hyperchaotic system has been modeled and results are submitted. Chaotic circuits are used in communication systems especially in secure communication due to their sensitive dependence on the initial conditions, not periodic, and having a spread spectrum. By using nonlinearity of memristor, the signals obtained from memristor based hyperchaotic system have been realized to analog and digital communication schemes on FPGA platform, which is suitable for re-programmable and reconfigurable systems. The success of memristor based hyperchaotic circuit with FPGA based communication is demonstrated by both simulation and experimental results.
Effects of Memristor on Oscillator and Regulator Circuits
(Aves, 2023) Gursul, Sevgi; Hamamci, Serdar Ethem
Many recent nanoscale studies have paved the way for obtaining suitable models for describing the nonlinear dynamics of memristive elements. Memristor, which is one of these elements and expresses the relationship between magnetic flux and electric charge, has had a wide application area since it has been modeled. In this study, oscillator and regulator circuits are designed as memristive, and these circuits are investigated with important parameters such as power consumption, operating speed, and regulation. Considering the Wien bridge oscillator and voltage regulator circuits as the working environment, the performance comparison is made by using the memristor circuit model instead of the standard resistor. The results obtained are interesting because they show the advantages of using memristor in both oscillator and regulator circuits in terms of power consumption, speed, and regulation properties.
A GRAPHICAL STABILITY ANALYSIS METHOD FOR CASCADE CONJUGATE ORDER SYSTEMS
(Amer Soc Mechanical Engineers, 2021) Cetintas, Gulten; Hamamci, Serdar Ethem
The theory and applications of complex fractional analysis have recently become a hot topic in the fields of mathematics and engineering. Therefore, studies on the complex order systems and their subset called the complex conjugate order systems began to appear in the control community. On the other hand, the concept of stability has always been an important issue, especially in the analysis and control of dynamical systems. In this paper, a graphical method for stability analysis of the complex conjugate order systems is presented. Since the proposed method is based on the Mikhailov stability criterion known from the stability theory of integer order systems, it is named the generalized modified Mikhailov stability criterion. This method gives stability information about the higher order complex conjugate order systems, i.e. cascade conjugate order systems, according to whether it encloses the origin in the complex plane or not. Three simulation examples for the cascade conjugate order systems are given to show the effectiveness and reliability of the method presented. The results are verified by the poles on the first sheet of Riemann surface and also time responses of the systems, which are calculated analytically in a very complex way.
IMPLEMENTATION of PID TYPE FUZZY LOGIC CONTROLLER WITH DIGITAL SIGNAL CONTROLLER
(Ieee, 2018) Ozguven, OmerulFaruk; Can, Mehmet Serhat; Hamamci, Serdar Ethem
In this study, the real-time application of the Fuzzy Logic-Proportional-Integral-Derivative (Fuzzy-PID) controller is performed. Product-Max operator is used in the design of Fuzzy Logic Controller (FLC). This FLC has Proportional-Derivative (PD) controller structure. An integrator was added to the designed FLC output and thus a Fuzzy-PID controller structure is obtained. For the real-time implementation of the controller, the dsPIC30F4010 digital signal controller (DSC) is preferred as the processor because it contains the necessary peripherals, has the required memory capacity and processor speed, low cost and easy to design. For the easily observe application result of the designed FLC, the speed of a brushed direct current electric motor (BDCM) driven by MOSFET is controlled using Pulse Width Modulation (PWM) produced by DSC. The Fuzzy-PID controller algorithm is written in C programming language. Edited C language program is compiled and generated operation codes (OP-CODE) is loaded into the DSC. In the study, the BDCM connected to a braking system driven by a shaft belt. So, for different parameters of the controller, the real time system output graphs of the BDCM in loaded, unloaded and varying speeds conditions is obtained and evaluated.
A New Chaotic System with Chaos Entanglement
(Ieee, 2015) Hamamci, Serdar Ethem; Gogebakan, Veysel; Isik, Ibrahim
In this paper, a new chaotic system is proposed by using chaos entanglement method. Chaos entanglement method is based on obtaining the new chaotic systems adding some nonlinear elements to sub-equations of a third order linear system. It is shown from analysis of the new system that it produces a rich chaotic behavior sequence. Furthermore, the proposed chaotic system is controlled by a simple constant controller and its chaotic behavior is converted to periodic or stable behaviours. The analysis results are confirmed by the figures.
Obtaining of Time Response from Frequency Response of Fractional Order Systems
(Ieee, 2015) Avsar, Selman Fatih; Hamamci, Serdar Ethem
In this paper, an approximation method for obtaining the unit step response of a fractional order system is presented. The method is based on using piecewise linear equivalence of real frequency response curve of the system. Simulation examples shows that this method gives successful unit step response results for the fractional order systems.
Performance Comparison of Various Memristor Emulators on a Phase Shifting Oscillator Circuit
(Ieee, 2020) Gursul, Sevgi; Hamamci, Serdar Ethem
An electrical element, which can take several resistance values between two different resistance values and remembers how much energy is given to it, is called as memristor. Circuits that consist of different electronic elements with the characteristics of the memristor are named by memristor emulator circuits. In this paper, four different memristor emulator circuits were used instead of one of the resistors that determine the frequency in the phase shifting oscillator circuit. Each memristor emulator and the same value resistance pairs are compared with each other and various results are obtained. Simulation results are quite encouraging to properly predict the appropriate configuration for power reduction.
PI and PID stabilization of neutral and retarded systems with time delay
(Tubitak Scientific & Technological Research Council Turkey, 2012) Hamamci, Serdar Ethem
Stabilization using fixed-order controllers is one of the key topics in control system design for the linear time-invariant (LTI) systems. In this paper, the stabilization of LTI neutral and retarded time-delay systems by means of PI and PID controllers is investigated in detail. The basic theme of the presented approach is to obtain a global stability region in the 2-dimensional (2-D) (k(p), k(i))-plane for the PI controller and in the 3-dimensional (3-D) (k(p), k(i), k(d))-space for the PID controllers. This region is formed by stability boundaries that are defined as the real root boundary, infinite root boundary, and complex root boundary. The 3-D global stability region for the PID case is made up of the set of 2-D stability regions that are obtained in the (k(p), k(i))-plane, (k(p), k(d))-plane, or (k(i), k(d))-plane by changing the other third parameter. To achieve this, the stability boundary locus approach is incorporated into the D-decomposition method. Thus, the complete set of stabilizing PI and PID controllers for the system is obtained. The simulation results indicate that the presented stabilization method is effective and practically useful in the analysis and control of the neutral and retarded time-delay systems.
Proportional-integral-derivative stabilization of complex conjugate-order systems
(Sage Publications Ltd, 2022) Cetintas, Gulten; Hamamci, Serdar Ethem
Proportional-integral-derivative (PID) stabilization is an important control design strategy that provides the designer with all PID controller set which results control system stability absolutely. In this way, the designer has a wide range of freedom to obtain the controller that meets the desired criteria. This process is particularly advantageous in situations where it is difficult to clearly define the design criteria at the beginning of the design or to make a balanced decision among the design criteria. The main objective of this paper is to present for the first time a PID stabilization method for complex conjugate-order systems, which is a new type of system for the control community and has been little studied on. The method is based on obtaining of stability/instability regions using the D-decomposition method in the controller parameter space graphically. These regions are formed by stability boundaries that are defined as real root, infinite root and complex root boundaries. The stability of the regions is determined using generalized modified Mikhailov stability criterion that is a powerful stability tool of the system theory. The simulation results indicate that the presented stabilization method is effective and practically useful in the analysis and control of the complex conjugate-order systems.
A Simple Graphical-Based Proportional-Integral-Derivative Tuning Method for Time-Delay Systems
(Aves, 2023) Cetintas, Gulten; Ozyetkin, Munevver Mine; Hamamci, Serdar Ethem
In this paper, a graphical-based proportional-integral-derivative (PID) tuning technique for time-delay systems is presented. The suggested tuning technique combines the stability boundary locus (SBL) method with the weighted geometrical center (WGC) concept. The plot of the stability region obtained by using real root boundary (RRB), infinite root boundary (IRB), and complex root boundary (CRB) in the parameter plane forms the basis of the proposed method. The tuning steps of the method can be expressed as follows. First, the stability region in (k(d), k(p)) -plane is obtained using the SBL for the fixed RRB line. Thus, the stability value range of the k(d) parameter is determined. Second, using these k(d) values, the entire set of stability regions in (k(p), k(i)) -plane is obtained. These regions constitute a three-dimensional global stability region in (k(p), k(i),k(d)) space. Finally, the WGC points of stability regions in each (k(p),k(i)) -plane are calculated. The center point having the best time domain performance among these WGC points is determined. This point gives the PID tuning parameters for the proposed method. The simulation results indicate that the presented tuning technique gives simple and reliable results and is useful in the stability analysis and the control of time-delay systems.
Stability region analysis in Smith predictor configurations using a PI controller
(Sage Publications Ltd, 2015) Deniz, Furkan Nur; Tan, Nusret; Hamamci, Serdar Ethem; Kaya, Ibrahim
This paper deals with the stabilization problem of Smith predictor structures using a PI controller. Stability regions that include all stabilizing parameters of a PI controller for the case of perfect matching between the plant and model and for mismatched case are obtained. The models of the plant are assumed to be FOPDT (first-order plus dead time) and SOPDT (second-order plus dead time) transfer functions. Thus, the aim of this study is to determine all stabilizing PI controllers for the Smith predictor scheme and to compare the stability regions obtained for perfectly matched and mismatched models. It is observed that the stability regions obtained for both cases are quite different and the stability regions for FOPDT and SOPDT models are broader than the stability region of the actual model. Furthermore, an approach is presented to find different models of an actual system using the stability region and it is shown that the stability region of these models can fit the stability region of actual system. A simulation example is provided to illustrate the results.
TRANSIENT RESPONSE CONTROL BY FRACTIONAL-ORDER PI CONTROLLERS
(Amer Soc Mechanical Engineers, 2012) Hamamci, Serdar Ethem; Obuz, Serhat
Consideration of the transient response is one of the key topics in control system design for time delay systems. In this paper, an efficient method to control the transient response of the first order plus time delay stable (FOPTD) systems using the fractional-order PI (PI lambda) controllers is presented. The main characterization of the method is first to construct the global stability region in the (k(p), k(i))-plane for any fixed value of). and then to obtain t(s), and M-p curves corresponding to special settling time and maximum overshoot values in this region. Finally, by intersection of these curves, the D-lambda-stability region in the k(p), k(i))-plane is found. Changing the value of lambda in the range of (0, 2), a set of D-lambda-stability regions is obtained. These regions involve the controller parameters providing the closed loop settling time and maximum overshoot specifications together in the acceptable values. Therefore, the designer can easily decide to the selection of suitable values of k(p), k(i) and lambda. The simulation results indicate that the presented transient response control method is effective and practically useful in the analysis and control of the stable FOPTD systems by means of fractional-order PI controllers.
Use of memristor-based chaotic circuits in AM-DCSK and FM-DCSK modulation
(Iop Publishing Ltd, 2023) Sahin, Muhammet Emin; Kolumban, Geza; Hamamci, Serdar Ethem; Guler, Hasan
In this paper, digital communications systems are built by taking advantage of hyperchaotic circuits implemented with an active flux-controlled memristor. The signals produced by these hyperchaotic circuits with rich chaotic dynamics obtained by replacing the nonlinear element with the memristor in the Chua circuit and the Wien bridge oscillator are used as carriers in digital communications systems. The dynamic behavior of memristor-based hyperchaotic circuits has a high degree of disorder. Therefore, they offer better system performance in many practical applications such as broadband signal generation, encryption and secure communications compared to the already used ordinary chaotic systems. To demonstrate the excellent system performance of memristor-based chaotic circuits, they are applied to two variants of differential chaos shift keying (DCSK) communications schemes. Both the Amplitude Modulated Differential Chaos Shift Keying (AM-DCSK) and Frequency-modulated differential chaos shift keying (FM-DCSK) have been considered. The Bit Error Rate (BER) performances of the proposed AM-DCSK and FM-DCSK systems are evaluated in an Additive White Gaussian Noise (AWGN) channel.

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