Serdar Ethem Hamamci

Bio: Serdar Ethem Hamamci is an academic researcher from İnönü University. The author has contributed to research in topics: PID controller & Control theory. The author has an hindex of 11, co-authored 30 publications receiving 874 citations.

An Algorithm for Stabilization of Fractional-Order Time Delay Systems Using Fractional-Order PID Controllers

Abstract: This technical note presents a solution to the problem of stabilizing a given fractional-order system with time delay using fractional-order PllambdaDmu controllers. It is based on determining a set of global stability regions in the (kp, Ki, Kd)-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.

Stabilization using fractional-order PI and PID controllers

Abstract: This paper presents a solution to the problem of stabilizing a given fractional dynamic system using fractional-order PIλ and PIλDμ controllers. It is based on plotting the global stability region in the (kp, ki)-plane for the PIλ controller and in the (kp, ki, kd)-space for the PIλDμ controller. Analytical expressions are derived for the purpose of describing the stability domain boundaries which are described by real root boundary, infinite root boundary and complex root boundary. Thus, the complete set of stabilizing parameters of the fractional-order controller is obtained. The algorithm has a simple and reliable result which is illustrated by several examples, and hence is practically useful in the analysis and design of fractional-order control systems.

Calculation of all stabilizing fractional-order PD controllers for integrating time delay systems

Abstract: In this paper, a simple and effective stabilization method for integrating time delay systems using fractional order PD controllers C(s)=k"p+k"ds^@m 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^@m 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^@m controllers can provide larger stability regions than the integer order PD controllers.

Design of PI controllers for achieving time and frequency domain specifications simultaneously.

Abstract: This paper deals with the design of PI controllers which achieve the desired frequency and time domain specifications simultaneously. A systematic method, which is effective and simple to apply, is proposed. The required values of the frequency domain performance measures namely the gain and phase margins and the time domain performance measures such as settling time and overshoot are defined prior to the design. Then, to meet these desired performance values, a method which presents a graphical relation between the required performance values and the parameters of the PI controller is given. Thus, a set of PI controllers which attain desired performances can be found using the graphical relations. Illustrative examples are given to demonstrate the benefits of the method presented.

Simulation and implementation of memristive chaotic system and its application for communication systems

Abstract: One of the most popular applications for chaotic systems is secure communication. The main purpose is to hide the information signal to be transmitted in a secure way, into a chaotic signal which is difficult to detect, and then to recover the information signal again. In response to this, memristor discovered by Leon O. Chua, known as the fourth basic element or the missing relationship can be implemented in chaotic circuit for a secure communication. The memristor based chaotic circuits which consist of three basic elements, have been used to obtain chaotic secure communication scheme in this paper. Using numerical simulation methods, including phase portraits, the largest Lyapunov exponents and bifurcation diagrams, the nonlinear dynamics are examined. In this respect, the advantage of chaotic feature of memristor and a memristor-based system was benefited for masking chaotic signals which are complicated to be analysed in communication systems. Therefore, the system was modelled with the help of LabVIEW and circuit with chaotic specialty was implemented in a secure communication. Simulation results confirm that the constituted design is likely to be utilizable in a secure communications application.

An Algorithm for Stabilization of Fractional-Order Time Delay Systems Using Fractional-Order PID Controllers

Abstract: This technical note presents a solution to the problem of stabilizing a given fractional-order system with time delay using fractional-order PllambdaDmu controllers. It is based on determining a set of global stability regions in the (kp, Ki, Kd)-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.

On the selection of tuning methodology of FOPID controllers for the control of higher order processes.

Abstract: In this paper, a comparative study is done on the time and frequency domain tuning strategies for fractional order (FO) PID controllers to handle higher order processes. A new fractional order template for reduced parameter modelling of stable minimum/non-minimum phase higher order processes is introduced and its advantage in frequency domain tuning of FOPID controllers is also presented. The time domain optimal tuning of FOPID controllers have also been carried out to handle these higher order processes by performing optimization with various integral performance indices. The paper highlights on the practical control system implementation issues like flexibility of online autotuning, reduced control signal and actuator size, capability of measurement noise filtration, load disturbance suppression, robustness against parameter uncertainties etc. in light of the above tuning methodologies.