Ali Yüce

Estimating the time response of control systems with fractional order PI from frequency response

This paper deals with the time response computation of closed loop control systems with fractional order PI controllers using the frequency response data of the closed loop system. The time response of fractional order transfer functions from frequency response data was first obtained by the authors using Fourier Series Method(FSM) and Inverse Fourier Transform Method(IFTM). In this paper, these methods are further extended for estimating unit step and unit impulse responses of control systems with fractional order PI controllers from the frequency response information of the closed loop system.

Computation of limit cycles in nonlinear feedback loops with fractional order plants

The paper deals with an aspect of the analysis of nonlinear feedback control systems with a fractional order transfer function. A review of the classical describing function (DF) method is given and its application to a control system with a fractional order plant is demonstrated. Unlike the DF method the frequency domain approach of Tsypkin is known to give exact results for limit cycles in relay systems and it is shown that this approach extends to systems with fractional order transfer functions. The formulation is done in terms of A loci which are related to and more general than the Tsypkin loci. Programs have been developed in MATLAB to compute the limit cycle frequency and also to show the results graphically. Examples are provided to illustrate the approach for a relay with no dead zone.

IIR filter design based on LabVIEW

In this paper, IIR filter has been designed using LabVIEW graphical based computer program belonging to National Instruments company. The LabVIEW program that consists of front panel and function diagram is used to develop virtual instrument. The program can be used to design filters by two different methods such as classical and order estimated methods. Also the designed filter has been tested for a noisy ECG signal. The aim of this study is to assist the applications in signal processing courses given in educational institutions and thus purposed to give lectures more efficiently.

Time Response Computation of Control Systems with Fractional Order Lag or Lead Controller

In recent years, there have been many studies in the field of fractional order control systems. Many results have been published related with the frequency and time domains analysis of closed loop fractional order control systems. However, obtaining exact time response of a fractional order system is a difficult problem since it is not possible to derive analytical inverse Laplace transform of a fractional order transfer function. In this paper, an exact method is presented for computation of the time response of a closed loop control system with a fractional order lag or lead controller using frequency response data of the closed loop system. The presented method is based on the results, which use Fourier series of a square wave and inverse Fourier transform of frequency response information, previously derived by the authors. Numerical examples are provided to show the success of the presented method.

Obtaining the time response of control systems with fractional order PID from frequency responses

The paper deals with obtaining the time response of closed loop control system with fractional order PID controller using frequency response data. For this aim, a feedback control system with an integer order plant and a fractional order PID controller are studied. The real and imaginary parts of the closed loop transfer function are obtained which depend on the parameters Kp, Ki, Kd, λ and μ of fractional order PID controller and real and imaginary parts of the plant. Then the time domain responses of the closed loop control system with fractional order PID controller are plotted by using Inverse Fourier Transform Method (IFTM) or Fourier Series Method (FSM). The presented idea is supported by some numerical examples.