Serdar Ethem Hamamci

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

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.

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

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.

A robust model-based control for uncertain systems

A new robust control strategy coefficient diagram method (CDM), which is an algebraic approach applied to a polynomial loop in the parameter space, is studied in this paper. Here, a model-based CDM is developed and proposed for uncertain systems. A special diagram called a coefficient diagram, which is used as a vehicle to carry the necessary information and as the criteria of good performance, is designed and modified accordingly. The performance of this novel controller is illustrated through several examples, and numerical results are provided.

A Program for the Design of Linear Time Invariant Control Systems: CDMCAD

Coefficient Diagram Method (CDM) is a new method proposed for the analysis and design of linear time‐invariant control systems. The control system design by this method results with satisfactory stability, time response and robustness properties compatible with, and in most cases better than, the ones obtained by the other present design methods. In this study, the design procedure described in the literature for CDM is improved so that a systematic and easy tool with understandable sufficient detail is presented. A visual toolbox, which can be used efficiently both for education and research, is obtained based on the procedure presented by using MATLAB.

Stability region analysis in Smith predictor configurations using a PI controller

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.

A Practical PI Tuning Approach For Time Delay Systems

Abstract In this paper, a simple PI tuning method for time delay systems is proposed. The main characterization of the method is first to obtain the stability region in the ( k p , k i )-plane using the stability boundary locus method and then to find the weighted geometrical center point of this region through its stability boundaries. Finally, this center point of the stability region in the ( k p , k i )-plane gives the tuning parameters for the PI controller. The proposed method gives a simple and reliable result which is illustrated by several examples, and hence is practically useful for the designers in the analysis and control of time delay systems.

Transient Response Control by Fractional-Order PI Controllers

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 (PIλ ) controllers is presented. The main characterization of the method is first to construct the global stability region in the (kp , ki )-plane for any fixed value of λ and then to obtain ts and Mp curves corresponding to special settling time and maximum overshoot values in this region. Finally, by intersection of these curves, the Dλ -stability region in the (kp , ki )-plane is found. Changing the value of λ in the range of (0, 2), a set of Dλ -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 kp , ki and λ. 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.Copyright

Fractional order PI λ control strategy for a Liquid Level System

This paper deals with the design of fractional order proportional integral (PIλ) controller for Liquid Level System (LLS). To achieve this, a fractional order model of LLS (FO-LLS) is obtained using J-index optimization method. Based on this model, a fractional order PIλ controller satisfying required gain margin (GM) and phase margin (PM) using Stability Boundary Locus method is designed. Simulation of LLS control system is carried out for the set point tracking. Performance of the PIλ controller designed by FO-LLS model is compared to that of Chidambarams integer order PI controller for integer order model. Finally, the robustness of both control systems is considered.

Implementation of applied prediction with YSA for data groups with association rule

Nowadays, increasing data sizes have grown at incredible levels. Many firms want to interpret their produced data and reach the useful information. In this study, by making customer basket analysis of a company operating in the retail sector, to organize suitable campaigns for the customers has been aimed and sales amounts of campaign items have been predicted before the campaign. The association rules for the items purchased by the customers has been obtained by using the Apriori algorithm. Sales amounts of associated items have been predicted with Artificial Neural Networks (ANN). For prediction process with ANN, MATLAB-NNTOOL toolbox has been used. With these prediction process, sales amounts of the campaign items offered to the customers have been determined and an idea about the success of campaign success has been obtained. In the study, 34 months sales data has been considered.

Advances in Control Theory and Applications: Selected papers from TOK 2013

The Turkish National Committee of Automatic Control (TOK) is the National Member Organization (NMO) of IFAC in Turkey. The TOK meeting is a major national meeting on automatic control, which has been organized annually since 1994 with the aim of reporting on recent advances in control theory and applications in Turkey. The 15th TOK national meeting (TOK 2013) was held at Inonu University in Malatya, Turkey, on 26–28 September 2013. It was organized by Inonu University and Istanbul Technical University, and supported by TOK. All papers submitted to TOK 2013 were reviewed by three separate reviewers; 185 papers were accepted for oral presentation and 63 papers for poster presentation. The TOK 2013 technical programme consisted of 31 oral sessions (three being special sessions) and four poster sessions. The programme also included three plenary lectures, given by leading experts in the field – Professors Derek P. Atherton from the University of Sussex, UK, YangQuan Chen from the University of California, Merced, USA, and _ Ismail Yuksek from Yildiz Technical University, Turkey. A preconference workshop programme was organized on 25 September, with lectures presented by Professor Derek P. Atherton and Professor YangQuan Chen. All accepted papers for TOK 2013, which were written in Turkish, were screened for this special issue of the Transactions of the Institute of Measurement and Control. Eleven papers were selected and extended versions, written in English, were further reviewed by three different reviewers, whom we thank for their efforts. These papers constitute this special issue. ‘Design of a multiple-model switching controller for ABS braking dynamics’, by M. Dousti, S.C. Baslamisli, E. T. Onder and S. Solmaz: the purpose of this study is to design high-performance active braking control and observer algorithms for passenger vehicles equipped with electromechanical brake systems. These algorithms are designed to be adaptive with changing driving and road conditions in a switched multiple-model manner to ensure high performance and robustness. The effectiveness of a set of multiple-model switching lead-lag controllers is evaluated during transitions between different road friction coefficients. Meanwhile, a multiple-model switching observer algorithm is developed to estimate the shape of the tyre braking force curve with respect to the longitudinal slip. Each switched observer predicts signals according to its preset tyre model. The observers are designed based on different Burckhardt tyre models that are parameterized for different road conditions. In the simulations, the value of the friction coefficient is assumed to be unknown and our switching algorithms are observed to estimate successfully the varying friction coefficients by comparing a quadratic cost function of measured signals from the vehicle with signals generated by observers. It is demonstrated that the proposed algorithms provide high reliability and fast response, thus ensuring a stopping distance close to the theoretical minimum. ‘Receding horizon HN control of time-delay systems’, by F.Y. Tas xc xikaraoglu, L. Ucun and I.B. Kuc xukdemiral: this paper deals with the disturbance rejection problem for discrete-time linear systems having time-varying state delays and control constraints. The study proposes a novel receding horizon HN control method utilizing a linear matrix inequality based optimization algorithm, which is solved in each step of run-time. The proposed controller attenuates disturbances having bounded energies on controlled output, and ensures the closed-loop stability and dissipation while meeting the physical control input constraints. The originality of the work lies on the extension of the idea of the well-known HN receding horizon control technique developed for linear discretetime systems to interval time-delay systems having timevarying delays. The efficiency of the proposed method is illustrated through simulation studies that are carried out on a couple of benchmark problems. ‘Stability region analysis in Smith predictor configurations using a PI controller’, by F.N. Deniz, N. Tan, S.E. Hamamci and I. Kaya. This paper deals with the stabilization problem