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Öğe Analogue Implementation of a Fractional-PI? Controller for DC Motor Speed Control(Institute of Electrical and Electronics Engineers Inc., 2019) Herencsar N.; Kartci A.; Koton J.; Sotner R.; Alagoz B.B.; Yeroglu C.In this paper, an approach to design a fractional-order integral operator s where -1 < ?< 0, using an analogue technique, is presented. The integrator with a constant phase angle -80.1 degree (i.e. order ? = -0.89), bandwidth greater than 3 decades, and maximum relative phase error 1.38% is designed by cascade connection of first-order bilinear transfer segments and first-order low-pass filter. The performance of suggested realization is demonstrated in a fractional-order proportional-integral (FOPI) controller described with proportional constant 1.37 and integration constant 2.28. The design specification corresponds to a speed control system of an armature controlled DC motor, which is often used in mechatronic and other fields of control theory. The behavior of both proposed analogue circuits employing two-stage Op-Amps is confirmed by SPICE simulations using TSMC 0.18 ?m level-7 LO EPI SCN018 CMOS process parameters with ±0.9 V supply voltages. © 2019 IEEE.Öğe Detection of RR interval alterations in ECG signals by using first order fractional filter(Institute of Electrical and Electronics Engineers Inc., 2016) Alagoz B.B.; Yeroglu C.; Kavuran G.; Ates A.Sleep apnea syndrome deteriorates sleeping quality and daily performance of many individuals. This study presents utilization of fractional-order low pass filtering for the detection of RR interval alteration from electrocardiogram (ECG) signals. In the case of sleeping apnea, cardiac interbeat intervals prolong and it is viewed as an indication of obstructive sleep apnea state. The prolonged interbeat intervals manifest themselves as the decrease of R peak frequency (increase of RR intervals) in ECG signals. It results in shifting of spectral components composing R peaks towards lower frequencies in energy signal of ECG. In order to detect prolonging interbeat intervals, energy signal calculated from ECG is applied to low-pass fractional-order filter. Transition band of the low-pass filter is used as a ramp filter in order to detect frequency variations in the energy of R peaks. We compare results of the first order fractional-order and integer order low-pass filters and demonstrate that the fractional-order filter can improve the detection performance of low-pass filtering by modifying transition band slope of low-pass filters. © 2016 IEEE.Öğe Disturbance rejection fopid control of rotor by multi-objective bb-bc optimization algorithm(American Society of Mechanical Engineers (ASME), 2017) Ates A.; Alagoz B.B.; Yeroglu C.; Yuan J.; Chen Y.This paper presents a FOPID tuning method for disturbance reject control by using multi-objective BB-BC optimization algorithm. Proposed method allows multi-objective optimization of set-point performance and disturbance rejection performances of FOPID control system. The objective function to be minimized is composed of the weighted sum of MSE for set-point performance and RDR for disturbance rejection improvement. The proposed optimization performs maximization of RDR and minimization of MSE and it can deal with the tradeoff between RDR performance and step-point performance. Application of the method is shown for autotuning of FOPID controller that is employed for control of TRMS model. We observed that low-frequency RDR indices can be used to improve disturbance rejection performance in multi-objective controller tuning problems. Particularly, for flight control application, disturbance reject control is very substantial to robust performance of propulsion systems. © Copyright 2017 ASME.Öğe Limit cycle prediction for fractional order systems with static -onlinearities(IFAC Secretariat, 2010) Yeroglu C.; Tan N.This paper deals with limit cycle prediction for nonlinear systems which have fractional order transfer functions. Describing function method is used for the analysis of fractional order nonlinear systems. It is observed that the limit cycle frequencies obtained from the simulation of the fractional order nonlinear systems, agree with the theoretical values of the limit cycle frequencies obtained from Nyquist plots of the fractional order plant and complex plot of the negative inverse of describing function. The critical gain of the system is estimated from Nyquist plot. The fractional order nonlinear system becomes stable for the gain smaller than the critical gain value. System starts to oscillate for the gain bigger than the critical gain value. © 2010 IFAC.Öğe A new tuning method for PI?D? controller(2009) Yeroglu C.; Onat C.; Tan N.The paper presents development of a new tuning method for fractional order PID controller for the systems which have integer order transfer functions. AU the parameters of the controller, namely proportional gain kp, integral gain ki, derivative gain kd, fractional order of integrator k and fractional order of differentiator ? can be obtained by using this method. It is clearly shown that the fractional order controller, which the parameters obtained by the proposed method, gives better response than the integer order one for the same system.Öğe Note on describing function analysis of fractional order nonlinear control systems(Systems Research Institute, 2015) Yeroglu C.; Tan N.This paper presents extensions of some results, obtained for the analysis of classical nonlinear control systems, to the nonlinear fractional order systems. It is shown that the results related to limit cycle prediction using describing function method can be applied to the fractional order plants. The frequency and the amplitude of the limit cycle are used for auto-tuning of the PID controller for nonlinear control systems with fractional order transfer functions. Fractional order control system with parametric uncertainty is also considered for the nonlinear case. On the other hand, a new method is provided for stability margin computation for fractional order nonlinear control system with parametric uncertainty structure using the Nyquist envelopes of the fractional order uncertain plant and the describing function that represents the nonlinearity of the system. Maximum perturbation bounds of the parameters of the fractional order plant are computed. Numerical examples are included to illustrate the methods presented.Öğe Sigmoid based PID controller implementation for rotor control(Institute of Electrical and Electronics Engineers Inc., 2015) Ates A.; Alagoz B.B.; Yeroglu C.; Alisoy H.This paper presents a sigmoid based variable coefficient PID (SBVC-PID) controller design for Twin Rotor MIMO System (TRMS). The proposed SBVC-PID controller dynamically changes controller coefficients according to a modified sigmoid function of the error signal. The modified sigmoid function is used to limit variability of PID controller coefficients in a predefined range. In the proposed method, each parameters of PID, namely pk, kt and kd, alter between predefined upper and lower bounds. A modified sigmoid function adjusted by a transition coefficient is used to alter each of the PID parameters between these bound limits. The variable coefficients of SBVC-PID maintain a hypercube in kp, kt and kd parameter space satisfying robust stability of the system. Well-known Kharitonov polynomials are used to ensure that the SBVC-PID coefficient alteration takes place in the robust stability intervals. Due to dynamically change of PID coefficients depending on magnitude of error signal, the control performance can be improved compared to conventional PID control. Performance of SBVC-PID controller is demonstrated via theoretical examples and TRMS rotor control simulations. © 2015 EUCA.Öğe Space charge formation in non-cristalline polymers and GaSe by DBD in SF6 medium(2008) Alisoy H.Z.; Yeroglu C.; Koseoglu M.In this study, we investigate the formation mechanism of space charges in PI-Polyimide, PTFE-Polytetrafluoroethylene, PET - Polyethylene Terephtalate and GaSe(Sn) - GaSe dopped with (0.05at%) Sn which are exposed to dielectric barrier discharge (DBD) in SF6 medium. The expressions for the concentration of trapped electrons in materials, electrical field strength and total charge are derived by solving total current equation at stationary state. Space charges are determined experimentally by using thermally stimulated depolarization current (TSDC) method, and TSDC spectrums are illustrated for investigated materials. © 2008 IEEE.Öğe A theoretical investigation on consideration of initial conditions in fractional-order transfer function modeling(Institute of Electrical and Electronics Engineers Inc., 2017) Alagoz B.B.; Tepljakov A.; Petlenkov E.; Yeroglu C.This paper presents an investigation on contributions of initial condition consideration to fractional-order transfer functions in modeling linear time invariant systems. In this theoretical study, firstly, initial conditions are considered for fractional-order transfer function modeling in s-domain, and then impacts of initial conditions on model dynamics are discussed. An illustrative example is also presented to evaluate theoretical findings. © 2017 IEEE.
