WSEAS CONFERENCES. WSEAS, Unifying the Science

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 Volume 6, 2011
Print ISSN: 1991-8763
E-ISSN: 2224-2856








Issue 1, Volume 6, January 2011

Title of the Paper:  An Exploratory Method for Effective Deployment of Programmable Logic Controllers (PLCs)


Authors: Lucien Ngalamou, Leary Myers

Abstract: This paper presents a preliminary study of an approach that models programmable logic controllers (PLCs) for their effective deployment in industrial control processes. A working model is developed for automatic allocation of PLCs and also a formal verification of Ladder Diagram representations of control processes using the Symbolic Model Verifier (SMV) tool. Automatic resource allocation is achieved through the proposition of a digraph model for any Ladder Diagram representation of a control process, which is then translated into an XML (Extensible Mark Up Language) model. The required PLC resources needed to implement a control process are extracted from the XML model. These resources are then used by a selection engine to determine, from a PLC database, the most appropriate PLCs or Embedded Controllers (EBCs) that can satisfy the resource requirements. Additionally, information extracted from the XML model is used to generate a formally verifiable SMV code of the system. This paper focuses on the practical implementation, testing, and verification of three conceptual modules applied to a control process. These are, the XML model of the control process, the PLC Database Automatic Resource Allocation, and the XML-to-SMV translator. This work was significantly motivated by the ever increasing number of industries who seek to increase their productivity by automating their processes.

Keywords: Automatic Resource Allocation, XML Model, Programmable Logic Controllers (PLCs), PLC Database, XML to SMV Translation, and Formal Verification

Title of the Paper:  Robust Design for Etching Process Parameters of Hard Disk Drive Slider Fabrication Using Data Mining and Multi Response Optimization


Authors: Pongsak Holimchayachotikul, Komgrit Leksakul, Guido Guizzi

Abstract: This paper is to provide a proper insight into solving a multi-response optimization problem using hybrid response surface methodology (RSM) based on robust parameter design (RPD) concepts and data mining (DM) for the multi-response optimization of a RIE process. Over the recent years in many high precision manufacturing organizations, domain experience and engineering judgment have been used to handle multiple response optimization problems. These manners have led to the increase in uncertainty during the decision-making process. This situation has also happened in the hard disk drive fabrication based on reactive ion etching (RIE). This process is highly complicated in setting the parameters using the slider to the right customer specifications. Therefore, this paper presents a hybrid model to optimize the concerning responses of this process in terms of mean and variance. The silicon plates with a patterned wet film photo resistance as a base substrate are used to demonstrate this research. To begin the proposed approach, design of experiment (DOE), named central composite design (CCD), was employed to accumulate the process records and to specify the significant parameters of the process. Then, support vector regression (SVR) was brought into play to institute the nonlinear multivariate relationships between process parameters and responses. Data obtained from DOE were used in the training process. Last but not least, the regression decision tree and domain engineering knowledge were opted for the initial point of optimization algorithms as well. In conclusion, the reduced gradient search algorithm, a hill-climbing procedure and desirability function were adapted to the DOE model while grid search and desirability function were adapted to the SVR model to find the optimum parameter setting. SVR was found to be the technique with the highest prominent accuracy performance, so it was selected to construct a RIE process model. Consequently, the optimum condition from the final model has been efficiently enabled to be applied in real production based on its experiment confirmation.

Keywords: Reactive Ion Etching (RIE), Response Surface Methodology (RSM), Support Vector Regression (SVR) Multi-response Optimization, Robust Parameter Design (RPD), Data Mining (DM)

Title of the Paper:  Adaptive Wavelet Neural Controller Design for a DC-DC Power Converter using an FPGA Chip


Authors: Yu-Hsiung Lin, Chun-Fei Hsu

Abstract: The DC-DC power converters are widely used; however, the controller design for the DC-DC power converters cannot easily design if the load dynamics vary widely. This paper proposes an adaptive wavelet neural control (AWNC) system for a forward DC-DC power converter. The proposed AWNC system is composed of a neural controller and a robust controller. The neural controller uses a wavelet neural network to online mimic an ideal controller and the robust controller is designed to cope with the approximation error between the neural controller and the ideal controller. A proportional-integral (PI) type parameter tuning mechanism is derived based on the Lyapunov stability theory; thus not only the system stability can be guaranteed but also the convergence of the tracking error can be speeded up. Finally, a comparison among the PI controller, the fuzzy controller, the adaptive neural fuzzy control, the adaptive neuro-wavelet control and the proposed AWNC is made. The experimental results show that the proposed AWNC system is robust with regard to different input voltages and load resistance variations.

Keywords: Adaptive control; robust control; sliding-mode control, wavelet neural network; DC-DC power converter

Issue 2, Volume 6, February 2011

Title of the Paper:  Subtractive Fuzzy C-means Clustering Approach with Applications to Fuzzy Predictive Control


Authors: Ji-Hang Zhu, Hong-Guang Li

Abstract: To identify T-S models, this paper presents a so-called “subtractive fuzzy C-means clustering” approach, in which the results of subtractive clustering are applied to initialize clustering centers and the number of rules in order to perform adaptive clustering. This method not only regulates the division of fuzzy inference system input and output space and determines the relative member function parameters, but also overcomes the impacts of initial values on clustering performance. Additionally, the orthogonal least square algorithm is employed to identify the parameters of consequents and linearize the systems over every sample time, ultimately resulting in the entire T-S fuzzy models. With this approach available, a fuzzy model predictive control system is established, along with corresponding control algorithms derived, as well as control system simulations carried out which explicitly demonstrate the effectiveness of the proposed method.

Keywords: T-S mode identification; subtractive clustering; fuzzy C-means clustering; Generalized Predictive Control

Title of the Paper:  Sliding Mode Control Law for a Variable SpeedWind Turbine


Authors: Oscar Barambones, Jose Maria Gonzalez De Durana, Patxi Alkorta, Jose Antonio Ramos, Manuel De La Sen

Abstract: Modern wind turbines are designed in order to work in variable speed operations. To perform this task, wind turbines are provided with adjustable speed generators, like the double feed induction generator. One of the main advantage of adjustable speed generators is improving the system efficiency compared to fixed speed generators, because turbine speed can be adjusted as a function of wind speed in order to maximize the output power. However this system requires a suitable speed controller in order to track the optimal reference speed of the wind turbine. In this work, a sliding mode control for variable speed wind turbines is proposed. An integral sliding surface is used, because the integral term avoids the use of the acceleration signal, which reduces the high frequency components in the sliding variable. The proposed design also uses the vector oriented control theory in order to simplify the generator dynamical equations. The stability analysis of the proposed controller has been carried out under wind variations and parameter uncertainties by using the Lyapunov stability theory. Finally simulated results show, on the one hand that the proposed controller provides a high-performance dynamic behavior, and on the other hand that this scheme is robust with respect to parameter uncertainties and wind speed variations, that usually appear in real systems.

Keywords: Wind Turbine Control, Variable Structure Control, Modeling and Simulation

Title of the Paper:  Hidden Oscillations in Dynamical Systems


Authors: G. A. Leonov, N. V. Kuznetsov, O. A. Kuznetsova, S. M. Seledzhi, V. I. Vagaitsev

Abstract: The classical attractors of Lorenz, R¨ossler, Chua, Chen, and other widely-known attractors are those excited from unstable equilibria. From computational point of view this allows one to use standard numerical method, in which after transient process a trajectory, started from a point of unstable manifold in the neighborhood of equilibrium, reaches an attractor and identifies it. However there are attractors of another type: hidden attractors, a basin of attraction of which does not contain neighborhoods of equilibria. Study of hidden oscillations and attractors requires the development of new analytical and numerical methods which will be considered in this paper.

Keywords: Hidden oscillation, attractor localization, hidden attractor, harmonic balance, describing function method, Aizerman conjecture, Kalman conjecture, Hilbert 16th problem

Issue 3, Volume 6, March 2011

Title of the Paper:  Unstable Systems - Tracking and Disturbance Attenuation


Authors: Roman Prokop, Natalia Volkova, Zdenka Prokopova

Abstract: The paper is aimed to the design of linear continuous controllers for unstable single input – output systems. The controller design is studied in the ring of (Hurwitz) stable and proper rational functions RPS. All stabilizing feedback controllers are given by a general solution of a Diophantine equation in RPS. Then asymptotic tracking and disturbance attenuation is obtained through the divisibility conditions in this ring. The attention of the paper is focused on a class of unstable systems. Both, one and two degree of freedom (1DOF, 2DOF) control structures are considered. Control loops with a feedforward part significantly reduce overshoots in control responses. The methodology brings a scalar parameter for tuning and influencing of controller parameters. As a result, a class of PI, PID controllers are developed but the approach generates also complex controllers. Simulations and verification are performed in the Matlab+Simulink environment.

Keywords: Unstable systems, Diophantine equation, asymptotic tracking, Disturbance attenuation

Title of the Paper:  Root Locus Analysis of a Retarded Quasipolynomial


Authors: Libor Pekar

Abstract: Time delay systems (TDS), called hereditary or anisochronic as well, can be frequently found in many engineering problems and they constitute a widespread family of industrial plants. Modelling, identification, stability analysis, stabilization, control, etc. of TDS are challenging and fascinating tasks in modern systems and control theory as well as in academic and industrial applications. One of their possible linear representations in the form of the Laplace transform yields the transfer function expressed as a fraction of quasipolynomials, instead of polynomials, with delay (exponential) terms in denominators. In this contribution, detailed root location analysis of a characteristic retarded quasipolynomial of degree one is presented, which gives rise to the spectrum of a retarded TDS. The presented analysis represents also a powerful tool for controller tuning in pole-placement control algorithms for delayed systems. A simulation example clarifies the results obtained vie proven propositions, lemmas and theorems.

Keywords: Time delay systems, root locus, stability analysis, retarded quasipolynomials

Title of the Paper:  Matlab & Simulink Simulation with FPGA-Based Implementation Sliding Mode Control of a Permanent Magnet Synchronous Machine Drive


Authors: Badre Bossoufi, Mohammed Karim, Silviu Ionila, Ahmed Lagrioui, Gabriel V. Iana

Abstract: This paper starts with an overview of FPGA technology development, followed by a presentation of design methodologies, development tools and relevant CAD environments, including the use of portable hardware description languages and system level programming/design tools. In this paper, a new contribution for the FPGA-Based implementation of controls electrical. This approach is based on concept modularity and reusability. In this paper is presents a detailed description of the structure by Indirect Sliding Mode of Permanent Magnet Synchronous Machine PMSM. Experimental results carried from a prototyping platform are given to illustrate the efficiency and the benefits of the proposed approach and the various stages of implementation of this structure in FPGA.

Keywords: Permanent Magnet Synchronous Machine (PMSM), FPGA, Indirect Sliding Mode Control, Power System Control, Systems Generator, Reusability, PWM

Issue 4, Volume 6, April 2011

Title of the Paper:  Land Mine Detecting Robot Capable of Path Planning


Authors: Muhammad Zubair, Muhammad Ahmad Choudhry

Abstract: The purpose of Landmine detecting robot is to cover maximum possible area, presentation of landmines and the left over area on a visual map with accuracy in millimeters. This paper presents a prototype model of land mine detecting robot that is powerful yet low cost, easy controllable, having the required accuracy and is equipped with visual interface for landmines plotting, PID tuning and cameras alignment. Emphasis is placed on the control of the differential drive robot in auto mode, semi auto mode and the manual mode. The image processing is used to find the accurate position of robot which provides the live reckoning feedback to the dead reckoning servo control of the robot. Balance Beat metal detector is the sensor used to detect landmines. The use of graphical user interface for the remote terminal computer to control the robot provides the user a simple but powerful control. The overall aspiration of system is to provide the user a powerful, cost effective and the same time intelligible to an average user.

Keywords: Land Mine detection, robot path mapping, image processing, Graphical user interface, PIC microcontroller

Title of the Paper:  Interdisciplinarity in Computer-Aided Analysis of Thermal Therapies


Authors: Daniela Carstea, Ion Carstea, Iulia Maria Carstea

Abstract: The interdisciplinarity in computer-aided analysis of the human body is an attitude of high education and top research and our work is an illustrative example in this area. The thermal therapies, thermal injury and thermal comfort can be understood if the temperature distribution in space and time in the living tissue can be estimated or predicted. But this objective can be fulfilled by a team of different specialists as engineers, doctors, mathematicians and programmers. The work tries to present some computational aspects in numerical simulation of the thermal model in skin tissue and the limits of the mathematical models used in this approach. The bioheat equation is discussed in the context of some clinical applications as irradiated skin tissue by laser or a fire pulse. A thermal model based on the finite element method was used.

Keywords: Thermal therapy; Numerical solution; Bioheat transfer equation; Interdisciplinarity

Title of the Paper:  Solar Cell Emulator and Solar Cell Characteristics Measurements in Dark and Illuminated Conditions


Authors: Yousry Atia, Mohamed Zahran, Abdullah Al-Hossain

Abstract: This paper describes a novel data acquisition system designed and implemented with facilities for measuring and monitoring the characteristics of a PV solar cell, module and/or system. The functioning of the equipment is based on the so-called virtual instrumentation. This is a non-conventional concept, however it does not have the many limitations in other systems. Additionally, the whole equipment can be implemented at significantly lower cost than the commercial one. The dark characteristics test facility, based on LabVIEW software to design an easy handling Graphical User Interface (GUI) and use a single chip microcontroller with a serial interface. The system is used to acquire the measured data from the cell under test and transfer it to a supervisory computer for monitoring and other signal processing. The preliminary test we have made indicates that the equipment we propose here is highly reliable, which allows measuring and monitoring variety of solar cell characteristics with a good accuracy.

Keywords: LabVIEW, AVR Microcontroller, Solar Cells & Solar Array, I-V Curve Measurements, Solar Cell Emulator

Title of the Paper:  A Study on RTD-A Controller for Multiple Input Multiple Output System and an Application Example


Authors: Du Bin, Chu Jizheng, Cao Xi

Abstract: RTD-A (Robustness Tracking Disturbance rejection-global Aggressiveness) controller, proposed by Babatunde A. Ogunnaike, is suitable for single input single output system (SISO). On the basis of it, a new RTD-A controller for Multiple Input Multiple Output system (MIMO) is illustrated and the global optimal control solution is also discussed in this paper. Simulation results prove that compared with IMC-PID (Internal Model Control), this new algorithm has good performances in set-point tracking, disturbance rejection and robustness.

Keywords: IMC-PID, RTD-A Controller, Multiple Input Multiple Output System (MIMO), Robustness

Issue 5, Volume 6, May 2011

Title of the Paper:  Hierarchical Control of a Complex Conveyors Belt System


Authors: Corina Maria Dinis, Gabriel Nicolae Popa, Angela Iagar

Abstract: Using the software-oriented technologies which contain maximum of integrated software resources in product, in this work has been developed the software for the hierarchical control of a complex conveyors system. This ensures hardware simpleness, implementing of some evolved control algorithms, on-screen measuring devices, a friendly graphic interface, which makes that the entire system to show high reliability and flexibility. It shows the advantages of microcontroller installations comparatively with classical control installations.

Keywords: Software-oriented hierarchical control, belt conveyors system, microcontroller

Title of the Paper:  Contact-Bounce Control and Remote Monitoring Interface Implementation of a PM Contactor


Authors: Chih-Yu Hung

Abstract: This paper aims at researching the relationship between the dynamic stability of an electromagnetic contactor (abbreviated as EM contactor below) and the magnetic energy stored in the contactor. Explored contactors are in terms of an equivalent nonlinear and time-varying inductor and the basic characteristics of the contactor. Some special feature during closing phase and voltage sag events occurred through the definitions of passivity conditions theorem are found. By means of magnetic circuit analyzing method, a mathematic modeland its numerical computer program of a contactor are first established in our laboratory. Some important experiments such as the dynamic stability of contactor during closing process and voltage-sag events are carried out by using this model. These simulation results are compared with the experimental results forvalidating the correctness of this contactor model. The final comparing results are in agreement with well. For purpose of further to know the voltage sensitivity of the experimental contactor, the CBEMA curves are used and obtained as well. Finally, the dynamic stability of the contactor during closing process and voltage sags is examined in terms of the energy stored by means of the simulation model to simulate and there are some very valuable results are obtained.

Keywords: Electromagnetic contactor, permanent magnet contactor, CBEMA curve, passivity energy, dynamic stability 1 Introduction

Title of the Paper:  Geometrical Model of Plant Presented on a State Surface of a Complex Error


Authors: Oleg N. Agamalov

Abstract: In paper considered a geometric approach for presentation the mathematical model of a control plant, based on calculation a complex error, allowing define an optimal control law of a plant as an equation of the geodesic curve on a state surface of a complex error.

Keywords: Control system, Hilbert transform, complex error of control, state surface of a complex error, geodesic curve

Title of the Paper:  Modeling and Simulation of a New Active Vibration Control System for Flexible Structures


Authors: Alireza Tavakolpour, Musa Mailah, Intan Z. M. Darus

Abstract: This paper investigates the feasibility of using active force control (AFC) method for the problem of active vibration control (AVC) of a flexible thin plate structure through simulation. The plate system was first modeled and simulated using Finite Difference (FD) method. Then, the validity of the obtained computational model was investigated through comparative studies between the plate natural frequencies redicted by the model and the exact values of resonance modes found in literature. The AFC algorithm was then embedded within the FD simulation platform to study the performance of the control scheme. An appropriate value of the mass gain in the AFC algorithm was estimated to be 14 kg through crude approximation technique which was later shown to be close to the real mass of the plate system. Different types of disturbances were applied to excite the plate system at different excitation points so that the robustnessof the proposed control algorithm can be evaluated in terms of its performance in reducing the vibration at observation point. Results of the study clearly demonstrated the effectiveness of the proposed control strategy to attenuate the unwanted vibrations of the flexible thin plate system.

Keywords: Active force control, finite difference, flexible plate, vibrations

Issue 6, Volume 6, June 2011

Title of the Paper:  Evolutionary Programming Versus Artificial Immune System in Evolving Neural Network for Grid-connected Photovoltaic System Output Prediction


Authors: Shahril Irwan Sulaiman, Titik Khawa Abdul Rahman, Ismail Musirin, Sulaiman Shaari

Abstract: This paper presents the evolutionary neural networks for the prediction of energy output from a grid-connected photovoltaic (GCPV) system. Two evolutionary neural network (ENN) models have been proposed using evolutionary programming and artificial immune system (AIS) respectively. The artificial neural network (ANN) employed for these models utilized solar radiation and ambient temperature as its input whereas the kilowatt-hour energy of the GCPV system is the only targeted output. The evolution of ANN involves the search of the optimal number of nodes, the learning rate, the momentum rate, the transfer function and the learning algorithm of a single-hidden layer multi-layer feedforward ANN. The results showed that evolutionary programming-ANN (EPANN) outperformed artificial immune system-ANN (AISANN) in terms of correlation coefficient, R as well as computation time. In addition, EPANN had also produced better convergence of the evolving parameters compared to the AISANN.

Keywords: Artificial neural network (ANN), multi-layer feedforward neural network (MLFNN), photovoltaic (PV), grid-connected photovoltaic system (GCPV), correlation coefficient (R), evolutionary programming (EP), artificial immune system (AIS) and prediction

Title of the Paper:  A Novel Block Matching Algorithm Based on Particle Swarm Optimization with Mutation Operator and Simplex Method


Authors: Zhang Ping, Wei Ping, Yu Hongyang

Abstract: To improve the performance of motion estimation in video coding, we propose a novel block matching algorithm, which utilize the global search ability of particle swarm optimization (PSO) with mutation operator and the local search ability of simplex method (SM).According to the center-biased and temporal-spatial correlation feature of motion vector and the global randomness of PSO, the fixed and random points are selected as the initial individual. Then, block matching process is executed by the updating of the position and velocity of individual. In order to accelerate the convergence of PSO and improve the accuracy of local search, mutation operator and simplex method are used. Meanwhile, based on the feature of static macro blocks, the proposed algorithm intelligently uses early termination strategies. Experimental results demonstrate that the proposed algorithm has better PSNR values than conventional fast block matching algorithms especially for video sequences with violent motion while the computational complexity of the proposed algorithm has negligible increase.

Keywords: Motion estimation, block matching algorithm, particle swarm optimization, mutation, simplex method, early termination

Title of the Paper:  Necessary Conditions for Optimal Control Problems with and without State Constraints: A Comparative Study


Authors: Md. Haider Ali Biswas

Abstract: It is commonly accepted that optimal control theory was born with the publication of a seminal paper by Pontryagin and collaborates last century, at the end of 50’s. Since then optimal control theory has played a relevant role not only in the dynamic optimization but also in the control and system engineering. Another crucial moment in this theory is closely related with the development of nonsmooth analysis during the 70’s and 80’s. Nonsmooth analysis has triggered a renew interest in optimal control problems and brought new solutions to old problems. Nowadays optimal control theory is essential to different areas like system engineering, economics and biology since many problems are modelled as optimal control problems. A challenging area of study in this theory remains that of state constraints. In this paper we review the very basic notions of optimal control problems with and without state constraints focussing on necessary conditions of optimality for state constrained problems.

Keywords: Optimal control, State constraints, Maximum principle, Nonsmooth analysis

Title of the Paper:  Identification of Coherent Generators for Large-Scale Power Systems Using Fuzzy Algorithm


Authors: Mahdi M. M. El-Arini, Ahmed Fathy

Abstract: This paper presents a new proposed method for identifying the coherent groups of generators for any large power system, this is based on two different techniques; the first one is based on applying two proposed coherency criterions introduced by using time response of the linearized power system model; the second one is based on the application of Fuzzy C-Means clustering algorithm (FCM). Also a new technique of constructing the dynamic equivalent of power system is presented in this work. The proposed method is applied on two different power systems. The obtained results proved that the proposed technique is highly effective in determining the coherent groups of generators and in constructing the dynamic equivalent of power system with high accuracy.

Keywords: Coherent groups of generator, Fuzzy C-Means Clustering Algorithm, Dynamic equivalents, Network reduction, Dynamic aggregation, Large-scale power system.

Issue 7, Volume 6, July 2011

Title of the Paper:  Effective Optimization of the Control System for the Cement Raw Meal Mixing Process: I. PID Tuning Based on Loop Shaping


Authors: Dimitris Tsamatsoulis

Abstract: The objective of the present study is to use a reliable model of the raw meal mixing process dynamics in raw meal production installations, in order to tune effectively PID controllers, thus regulating the product’s quality. The system is described by a TITO process. The M - Constrained Integral Gain Optimization (MIGO) loop shaping method is utilized to adjust the controller parameters. Long term actual industrial data are used for this purpose while the controller robustness is also investigated. Taking into account the maximum sensitivity constraint and the model uncertainty the controller is parameterized and implemented to industrial raw meal production units by replacing previous controllers or manual regulation. The results indicate remarkable enhancement of the raw meal homogeneity fed to the kiln. Therefore the tuning methodology applied provides effective PID controllers, able to attenuate the disturbances affecting the raw meal quality.

Keywords: Dynamics, Raw meal, Quality, Mill, Model, Uncertainty, PID, Robustness, Sensitivity

Title of the Paper:  On Plant Modeling for the PIM Digital Redesign of a Power System Stabilizer


Authors: G. Shabib

Abstract: This paper is concerned with the plant modeling for the digital redesign of a continuous-time power system stabilizer PSS for the single machine power system using the so-called Plant –Input-Mapping PIM method. The traditional approach has been to use the bilinear transform (Tustin’s method), but this gives numerical difficulties with large sampling intervals which are now becoming usual with modern control hardware. The proposed technique guarantees the stability for any sampling rate and takes the closed-loop characteristics into account. The proposed technique is successfully applied to the discretization of a continuous time PSS for single-machine power system. For comparison studies the proposed technique is compared with continuous-time PSS and Tustin’s PSS. The simulation results show that the proposed digital redesign technique reflects the frequency and dynamic responses of the system more accurately as the continuous-time PSS. Also, they show that Tustin’s method falls when sampling interval becomes larger while the proposed PIM method guarantees stability even with relatively slow sampling rates.

Keywords: Digital redesign, Discretization, Dynamic stability, Power systems, Sampled-data system

Title of the Paper:  Model Predictive Control Approach Based Load Frequency Controller


Authors: Ali Mohamed Yousef

Abstract: The present paper investigates the design of Load-Frequency Control ( LFC) system for improving power system dynamic performance over a wide range of operating conditions based on model predtictive control MPC technique. The objectives of load frequency control (LFC) are to minimize the transient deviations in area frequency and tie-line power interchange variables . Also steady state error of the above variaables forced to be zeros. The two control schems namely Fuzzy logic control and proposed model predictive control are designed. Both the two controllers empoly the local frequency deviation signal as input signal. The dynamic model of two-area power system under study is estabilished . To validate the effectiveness of the proposed MPC controller, two-area power system is simulated over a wide range of operating conditions. Further, comparative studies between the fuzzy logic controller (FLC), and the proposed MPC load frequency control are evaluated.

Keywords: Model predictive control - Fuzzy logic controller, Load Frequency Control, Two area power system

Title of the Paper:  Effective Optimization of the Control System for the Cement Raw Meal Mixing Process: II. Optimizing Robust PID Controllers Using Real Process Simulators


Authors: Dimitris Tsamatsoulis

Abstract: The present study is aiming to develop a simulator of the mixing process in production installations of raw meal comprising all the main characteristics of the process and raw materials. The system is described by a TITO process regarding the adjustment of the two main quality indicators of the raw meal and regulated via PID controllers. The M - Constrained Integral Gain Optimization (MIGO) method is used to tune the controller parameters. Based on actual industrial data the simulator is implemented to determine the optimum PID parameters according to the subsequent criteria: (a) specified robustness constraint and (b) minimum variance of the raw mix chemical modules in raw mill outlet and kiln feed. The simulator offers the possibility to analyze the effect of the process parameters on the raw meal homogeneity. Other digital PID implementations except the one utilized or other control laws can be investigated as well.

Keywords: Dynamics, Raw meal, Quality, Mill, Simulation, Uncertainty, PID, Robustness

Issue 8, Volume 6, August 2011

Title of the Paper:  Stability Enhancement for a Superconducting Generator in Multimachine Power System Using STATCOM


Authors: R. A. Amer, G. A. Morsy, H. A. Yassin

Abstract: This paper investigates the multi-machine power systems stability enhancement by means of STATCOM-based stabilizers. To demonstrate the influence of the introduction of the STATCOM to the power systems, a comparative study is implemented by attaching a single SVC or a single STATCOM to the studied power system. The under-study power system includes a superconducting generator (SCG) and nine conventional units of different types and ratings. In view of control, various types of control systems are used such as Proportional Integral Derivative (PID) controller and power system stabilizers (PSSs). The system’s nonlinear model is established by achieving a satisfactory degree of accuracy and tested for various types of contingency. The simulation results reveal that, the introduction of STATCOM is achieving further enhancement of the system performance in terms of damping increase and fast return of system variables to their nominal values under different disturbances such as 3-phase short circuit, step increase in load, and line outage compared to the SVC-based stabilizers.

Keywords: Multi-machine power systems, Control systems, Superconducting generator, Static var compensator, STATCOM, PID controller

Title of the Paper:  Morphing Motion in Modular Robots


Authors: Fei Yanqiong, Wang Yong

Abstract: Two kinds of basic modules are presented to set up the modular robots. One is the cuboid module, the other is the cubic module. Four connecting types of cuboid modules and two connecting types of cubic modules are analyzed based on their geometric feature. For deriving the transformation matrix of each connecting type, the concepts of basic group are proposed. Then, the geometric relationships of each connecting type are derived with the group theory. The basic motion of modules is presented. With the rotary motion around the neighboring module, the morphing motion from a quadruped to two-leg modular robot is shown and the kinematics of modular robots is generated with product of matrix exponentials. Examples of kinematics on a quadruped and a two-leg modular robot are given to demonstrate the applicability of the proposed methods.

Keywords: Modules, Robot, Kinematics, Morphing, Motion

Title of the Paper:  DC Characteristic Analysis of Three-Phase LC Filter- Uncontrollable Rectifier Using Circuit DQ Transformation


Authors: Xin Geng, Xi-Jun Yang, Zhe-Min Zhang, Hou-Jun Tang, Liang-Yu Bai

Abstract: The three-phase uncontrollable rectifiers are still widely applied, at present, in kinds of household appliances, because of its low cost, simple structure and excellent applicability. There are no LC filters in some simplified schematics. Sometimes, filter inductors are connected between rectifiers and power grids. For some higher requirements the three-phase passive power factor correction techniques with input LC filter are used in getting a higher power factor, just as the high power inverter air conditioners. Since the three-phase LC filter uncontrollable rectifier circuit is a strong coupling nonlinear system, it is difficult to analyse, model and select the parameters of LC filters. In this paper, circuit DQ transformation method is adopted to analyse the circuit’s working principle better. It can convert the nonlinear circuit into linear system, then propose the novel concepts of the equivalent switching function, the control angle and the overlapping angle of uncontrollable rectifier. From this way, it makes the system controllable and discovers the controllability in three-phase LC filter uncontrollable rectifier systems. Through the analysis of the system DC characteristics, the expressions of output voltage, active power, passive power and power factor are calculated, which are identical to those of other controlled rectifiers. The relationship between the control angle and the load resistance are obtained through the simulation analysis. Experimental results on the rated output power 7.5kW three-phase rectifying system has proven the above theoretical analysis and circuit DQ transformation method. It has also proven the proposed concepts, which is practical to analyze the performances of the uncontrollable rectifier systems.

Keywords: Three-phase passive PFC, Uncontrollable rectifier, DQ transformation, Power factor correction, Input LC filter, Equivalent switching function

Issue 9, Volume 6, September 2011

Title of the Paper:  SCG Stability Enhancement Using STATCOM Based-ANN Controller


Authors: R. A. Amer, G. A. Morsy, H. A. Yassin

Abstract: Artificial neural network (ANN) control of static compensator (STATCOM) to improve the damping of power systems is presented. The proposed control strategy is applied on a STATCOM attached to a single machine-infinite bus (SMIB) and a multi-machine power systems that include a superconducting generator (SCG). The proposed control method, ANN-STATCOM is designed based on proportional integral derivative (PID) by means of minimization of the system’s deviations. The damping provided by the ANNSTATCOM controller is compared with a fixed-parameter PID-STATCOM controller. In view of power systems control, various conventional types of control systems are employed such as PID controller for SCG and power system stabilizers (PSSs) for conventional units. The simulation results demonstrate the effectiveness of the proposed ANN-STATCOM controller in stabilizing the power systems performance for various disturbances at multiple operating points.

Keywords: Power system control, Superconducting generator, Static compensator, ANN control

Title of the Paper:  Reliability and Quality Improvement of Robotic Manipulation Systems


Authors: Yaser Maddahi, Ali Maddahi

Abstract: This paper reports the procedure of experimental evaluation and objective/quantitative comparison, among different performance parameters, of the Cartesian (3P) robots. Here, first by implementing the equations of motion, the mechanical model of this type of robot is simulated using Working Model software. Next, the initial model of robot is designed based on the results concluded from the simulated model and the robot structure including control unit, mechanical elements and operating procedure is described. Also, some tests are applied on the prototype robot in order to verify the analytical side of design procedure. The experiments consist of calibrating the robot motion along all three axes (prismatic joints) and validation of three performance indices, which are easy to measure via simple experimentations namely accuracy, repeatability and maximum allowable load carrying capacity. The acceptable values of the indices are predefined as input of design process. The data derived from the experimental tests showed that the robot satisfies the acceptable values. The main contribution of this paper is to improve the robot design by exerting the changes obtained from assessment of some defined statistical and mechanical indices.

Keywords: Design, Cartesian robot, Performance index, Experimental test, Design improvement

Title of the Paper:  Techniques for Predictor Design in Multivariable Predictive Control


Authors: Marek Kubalcik, Vladimir Bobal

Abstract: Model Based Predictive Control (MBPC) or only Predictive Control is one of the control methods which have developed considerably over a few past years. It is mostly based on discrete models of controlled systems. Model of a controlled system is used for computation of predictions of the systems output on the basis of past inputs, outputs and states and designed sequence of future control increments. This paper is focused in comparison of various approaches to computation of multi–step–ahead predictions using a multivariable input – output model. Computational aspects of derivation of predictions can be limiting especially in adaptive predictive control. Many processes are affected by external disturbances that can be measured. Inclusion of measurable disturbances into prediction equations for different approaches was also elaborated.

Keywords: Predictive control, multivariable systems, multi-step-ahead prediction, Diophantine equations, CARIMA model

Issue 10, Volume 6, October 2011

Title of the Paper:  The Torque Control with Multi-Objective Performance for E-Bike Systems with Human Power Assistance


Authors: Pang-Chia Chen, Chih-Ching Hsiao, Sun-Li Wu, Shyue-Bin Chang

Abstract: This paper proposes a velocity control approach for the light electric bike with human power assistance. The velocity control signal is composed of two signals. One is a velocity-dependent equilibratory torque to compensate the wind resistance. Another is a deviation torque to achieve desired multi-objective performance represented in terms of linear matrix inequality (LMI) conditions. The formulated multi-objective performances includes the invariant set of state variable under the magnitude bounded disturbance, the magnitude bound on the regulated output, and the ?H performance optimization for attenuation of various disturbance effects on the regulated output. The disturbances include the deviations of tire resistance, human assistant torque, and driver’s weight from nominal values. Based on the parameters and specifications of the EL-168 electric bike produced by KENTFA Advanced Technology, Taiwan, the design results are verified through time-response simulations under both the flat and linear varying gradient road conditions.

Keywords: Electric Bike, Torque Control, LMI, Multi-Objective Control, Human Power Assistance

Title of the Paper:  Hysteresis Model Parameters Identification for the SAS Rotational MR Damper


Authors: Yousef Iskandarani, Hamid Reza Karimi

Abstract: Comfort, reliability, functionality performance which provide a longer life cycle requires thourogh understanding and analysis of the vibrations, this is a general rule for most of the static and dynamic when studying the functionality performance of any application. Vibrations is an extremely important issue to consider when designing various systems.The hysteresis in the dampers is very important issue when characterizing the damper used to suppress the vibrations, it is a very complex phenomena but very important to understand and consider during the design phase. The hysteresis equations of Bouc-Wen, Lugre, and Dahl have been modeled and simulated in Matlab/Simulink. Afterward, the different parameters in the models was manipulated and their effects on the outcome was analyzed. The hysteresis models of Bouc-Wen, Dahl and LuGre have been analyzed and compared analytically to really show the difference in the models. At last the Bouc-Wen model was implemented together with the SAS(Semi Active Suspension) system. The model parameters were tuned manually to try to fit the response of the system. In this paper a predefined methodology has been applied for determining the hysteresis loop parameters using the data collected for vibration analysis under predefined test specifications. The following data has been used later to regenerate the vibration signal, so on get as closer to the real signal.In the coming work, advanced method will be used to determine the exact parameters for the hysteresis loop as well as using the inverse hysteresis to improve the of the vibration suspension in the Semi Active Suspension system.The behavior of MR dampers can be presented with different mathematical models. The Bouc-Wen model was found to be model to both illustrate the MR damper and recreate the behavior of the SAS system.

Keywords: Bouc-Wen model, Dahl model, Hysteresis, Lugre model, Magnetorheological damper,Parameters identification, Semi-Active Suspension System

Title of the Paper:  Robust Stability of Linear Fractional Systems with Non Linear Uncertainties


Authors: Ouadia El Figuigui, Nourreddine El Alami

Abstract: Using the differentiation and integration of fractional order or non-integer order in systems control is gaining more and more interest from the systems control community. In the present document, we study the stability of multivariable fractional systems using robust fractional controller. Some important mathematical inequalities and particularly the Gronwall inequality are employed to investigate the robust stability conditions which are based to non linear bounded uncertainties.

Keywords: Fractional system, robust stability, controller, Gronwall Bellman, inequality, multivariable system

Issue 11, Volume 6, November 2011

Title of the Paper:  Fuzzy Tracking Control Based on H? Performance for Nonlinear Systems


Authors: Trihastuti Agustinah, Achmad Jazidie, Mohammad Nuh

Abstract: This paper presents a fuzzy tracking control design based on H? performance for nonlinear systems. The Takagi-Sugeno fuzzy model is employed to approximate a nonlinear system. Based on the H? tracking performance, the nonlinear system output is controlled to track a reference signal, and at the same time the tracking performance is attenuated to a prescribed level. Linear matrix inequalities (LMI) techniques are used to solve the fuzzy tracking control problem. The proposed method has been applied to control of a laboratory pendulum-cart system. Hence, the performance has been evaluated in simulations as well as in real-time control.

Keywords: Fuzzy tracking control, H? performance, LMI, Pendulum-cart system

Title of the Paper:  On-Line Adaptive Fuzzy Switching Controller for SCARA Robot


Authors: Marwan A., Farrukh Nagi, Ksm Sahari, Hanim S., Fadi. I.

Abstract: This paper presents the design, development and implementation of a new on-line adaptive MIMO switching controller (FSC) for real-time tracking control of an industrial SCARA robot. Two link SCARA robot is a nonlinear plant. The fuzzy control is based on the Takagi-Sugeno’s type fuzzy architecture model with on-line self-tuning so that both the desired transient and steady state responses can be achieved at different operation conditions. The online real-time self-tuning is based on the gradient steepest descent method, which tunes the inputs and outputs scaling factors of the proposed fuzzy controller. This controller simplifies the Real-time control implementation and improves the control performance. Real-time controller is implemented in Matlab’s xPC Real-time workshop environment. SCARA robot system identification was accomplished by using Auto Regression with external input method (ARX) to determine the discrete time transfer function necessary for the controller design. Comparison between the self-tuned fuzzy switching controller and fixed fuzzy switching controller was made to evaluate the real time tuning’s performance. The comparison is based on the tracking ability subjected to large payload. Based on the real time results the performance of fuzzy switching controller with this tuning strategy was found to be superior and it matches favourably to the operating conditions.

Keywords: SCARA robot , two-link manipulators, fuzzy switching control, online self-tuning, xPC Target, educational robotics

Title of the Paper:  Stability Condition for Discrete Systems with Multiple State Delays


Authors: Sara Pakzad, Mohammad Ali Pakzad

Abstract: Many natural systems have intrinsic delays, caused by input, output or state variables. In an openloop system, input delay doesn’t affect the stability but if feedback of the state is utilized for controlling the systems, the delay is transferred to closed-loop state and would affect the stability of the system. It is important to evaluate/examine the stability of continuous and discrete delayed-systems. In continuous systems existence of delay increases system dimension to infinity (number of poles is infinite). In discrete systems, number of poles increases but it is finite. Due to the lack of proper and powerful tools in discrete systems, the evaluations of stability in these systems are very important. In this paper, an approach has been proposed based on Lyapunov equation and frequency domain stability analysis for systems which have delay in their states. In this approach, stability conditions have been obtained for discrete systems with delay in a specific interval. All previous works on discrete systems are often for single-delay in state. The purpose of this paper is to extend the existence approaches for systems that have multiple delays in their states. Performance of the proposed method has been studied in several examples.

Keywords: Discrete-time systems with delay, stability, Lyapunov equation, state delay

Issue 12, Volume 6, December 2011

Title of the Paper:  Wind Driven Induction Generator Regulation Using Ant system Approach to Takagi Sugeno Fuzzy PID Control


Authors: A. H. Besheer

Abstract: This study introduces new tuning technique for the PID control scheme and its application to regulate the voltage magnitude and the frequency of wind energy conversion system (WECS). The developed technique is stem from blending the ant system optimization method with Takagi Sugeno (T-S) fuzzy system approach. The optimum relationship between the PID controller gains and the parameters of T-S fuzzy modules is explored using Ant system algorithm. A steady-state analysis for self excited slip ring induction generator is performed. The calculated and the experimental results on 1.1 KW laboratory machine enables the control characteristics to be deduced. Different simulation examples are provided to illustrate the effectiveness of the proposed technique. Finally, the response of a closed loop control scheme for WECS using chopper controlled external rotor resistance and fixed capacitor with thyristor controlled reactor shows that the proposed control approach exhibits a superior performance to that of established traditional control methods.

Keywords: T-S fuzzy control, PID control, Ant system optimization, WECS

Title of the Paper:  Gain Scheduled Automatic Flight Control Systems Design for a Light Commercial Helicopter Model


Authors: Erkan Abdulhamitbilal, Elbrous M. Jafarov

Abstract: In this paper, nonlinear rigid body dynamics for rotorcraft mathematical model is studied. A linearization of helicopter flight dynamics is evaluated. Automatic Flight Control System (AFCS) with gain scheduled LQ optimal control is designed based on look-up tables. Stability analyses are performed and results are illustrated graphically for open and closed-loop systems. As seen from results, LQ optimal control system pushes eigenvalues to left side of imaginary axis without excessive control inputs to maintain stability of naturally unstable rotorcraft dynamics. Proposed AFCS is tested by nonlinear flight dynamics model in Matlab- Simulink environment. Simulation results illustrate effectiveness of evaluated method and techniques.

Keywords: helicopter, flight dynamics, nonlinear model, simulation

Title of the Paper:  Control Design for Uncertain Singularly Perturbed Systems with Discrete Time Delay


Authors: Bahador Makki, Baharak Makki

Abstract: The problem of state-feedback control design for a class of singularly perturbed systems with time delays and norm-bounded nonlinear uncertainties is studied in this paper. The system under consideration considers discrete delays in both slow and fast dynamics and norm-bounded nonlinear uncertainties. It is shown that the control gains are obtained to guarantee the stability of the closed-loop system for all perturbed parameters in terms of linear matrix inequalities (LMIs). We present an illustrative example to demonstrate the applicability of the proposed design approach.

Keywords: singularly perturbed systems, time delay, control design, LMI

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