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Home>Products>Journal and Reviews>I.RE.A.CO.>Latest issue
International Review of Automatic Control (Theory and Applications) - September 2008 - Papers
International Review of Automatic Control - Papers
by H. Bourray, A. Kamal, A. Boutoulout Vol. 1. n. 3, pp. 263-271
Abstract - In this paper, we are concerned with regional controllability and observability problems for distributed semilinear parabolic systems. In this work, we gives definitions of this notions and we show that under some hypothesis, the regional controllability/observability of linear parabolic systems allows the regional controllability/observbility for semilinear ones. Then we develop some approaches both for regional controllability and observability which allows to reach such objective in a subregion target of the system evolution domain. The obtained results are performed through various examples and simulations. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: controllability, fixed-point theorems, parabolic systems, regional, observability, Semilinear systems.
by P. Dostál, V. Bobál, F. Gazdoš Vol. 1. n. 3, pp. 272-279
Abstract - The paper deals with continous-time adaptive control of a MIMO nonlinear process. A nonlinear model of the process is approximated by a continuous-time external linear model. Its parameters are estimated via an external delta model with the same structure as the CT model. The control system configuration with two feedback controllers is considered. For controllers design, the polynomial approach is used. Resulting controllers ensure asymptotic tracking of step references and step load disturbances attenuation. A control quality is achieved using the exact pole placement method as well as by selectable weight matrices dividing weights among numerators of transfer functions of subcontrollers. The control is tested on a two input – two output nonlinear process. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Adaptive control, MIMO system, continuous-time model, delta model, parameter estimation, polynomial method.
Vol. 1. n. 3, pp. 280-286
Abstract - We propose in this paper an algorithm for robust predictive control for Multi-Inputs Single-Output (MISO) systems decomposed on Generalized Orthonormal Basis Functions (GOBF). A min-max optimisation problem is solved by introducing techniques of Linear Matrix Inequalities (LMIs) where the constraints interest the measurement signals and the parameter uncertainties of the model coefficients. The uncertainty parameter domain is an ellipsoid that can be updated by applying Unknown But Bounded Error (UBBE) approaches. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Robust Predictive control, Generalized Orthonormal Basis Functions, min-max optimisation, Linear Matrix Inequalities, Linear programming, MISO, Ellipsoid, UBBE.
Vol. 1. n. 3, pp. 287-293
Abstract - The paper presents a new approach to tuning a control loop. It uses a gradual iterative way to adapt settling-time and overshoot of a controlled process output. The algorithm exploits the virtual reference feedback tuning methodology – a direct method for controller design. Results are demonstrated using simulation experiments on a system from a test batch of models suitable for control purposes. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Controller Tuning, Iterative Methods, Virtual Reference Feedback Tuning.
Vol. 1. n. 3, pp. 294-302
Abstract - This paper describes an intelligent PWM control accompanied by a better regulation for three-phase shunt active power filter to eliminate harmonics and to compensate the reactive power of three-phase rectifier. Where a novel adaptive hysteresis band current control technique is introduced, its principle is based on a simple and fast prediction of the hysteresis band added to a phase-locked-loop control in order to ensure constant switching frequency and synchronization of modulation pulses contrary to the conventional fixed hysteresis band current control technique. This allows high accuracy in tracking highly distorted current waveforms and minimises the ripple in three-phase systems. This technique determines the switching signals of the three-phase shunt active power filter and the algorithm based on the dc side capacitors voltage regulation using fuzzy logic controller is developed to determine the suitable current reference signals. The advantage of fuzzy control is that it is based on a linguistic description and does not require a mathematical model of the system; its dynamic behaviour is found to be better than the conventional proportional-integral controller. The performances of the proposed novel adaptive hysteresis band current control technique and the regulation by fuzzy logic controller are fully verified by simulation using MATLAB/SIMULINK. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Shunt active power filter, Hysteresis current control, Predictive control, Switching frequency, Interference phenomena, Fuzzy controller.
Vol. 1. n. 3, pp. 303-310
Abstract - This paper deals with the design of a robust fuzzy sliding mode controller for Buck converters. The proposed controller specifies changes in the control signal based on knowledge of the surface and the surface change to satisfy the sliding mode stability and attraction conditions. The performances of the proposed fuzzy sliding mode controller are compared to those obtained by a classical sliding mode controller and it is implemented using a dSPACE control board. The satisfactory experimental and simulation results show the efficiency of the proposed control law which is robust against variation of the input voltage and the load resistance of the studied Buck converter. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Buck converter, Sliding Mode Control, Fuzzy Sliding Mode Control, Robustness, dSPACE control board.
Vol. 1. n. 3, pp. 311-320
Abstract - This paper proposes a robust controller for superconducting magnetic energy storage (SMES) unit to stabilize a grid connected fixed speed wind generator system. The SMES system with a voltage-source IGBT (insulated gate-turn-off bipolar transistor) converter and two-quadrant DC-DC chopper is analyzed as a controllable energy source. The objective of the proposed SMES control strategy is to smooth the wind farm output fluctuating due to random wind speed variations by absorbing or providing real power. Moreover, its reactive power output can also be controlled to keep the wind farm terminal voltage constant. The SMES controller is also designed to enhance the system damping performance and robustness against transient disturbance. The control methodology of SMES system is suitable for the objectives stated above. The performance of the proposed system is evaluated by dynamic simulations using a test power system. Real wind speed data is used in the simulation analyses, which validates the effectiveness of the proposed control strategy. Simulation results clearly show that the proposed SMES system is a very effective means for stabilizing wind generator as well as the entire power system. The effectiveness of the proposed system is verified by simulation analyses using PSCAD/EMTDC. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Minimization of fluctuations, transient stability enhancement, superconducting magnetic energy storage (SMES), wind generator stabilization, DC-DC chopper, voltage source converter (VSC).
Vol. 1. n. 3, pp. 321-326
Abstract - This paper presents a new method for the voltage build-up process of an isolated-loaded induction generator, which delivers an active power to the load via a converter connected to a single capacitor on the dc side. So, during the voltage build-up process, the necessary stator currents references to be injected by the converter can be calculated from the desired active power to be sent to the load which is determined by the dc-bus voltage regulation, from the reactive power required for the machine magnetization and finally from the three instantaneous voltages induced. Since the converter/capacitor model is non linear, a fast and simple control strategy based on the input-output feedback linearization technique is applied to assure the dc-bus voltage regulation. The computer simulations are provided to verify the validity of the proposed control algorithm. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Induction Generator, Self-Excitation, Input-Output Feedback Linearization, Voltage Control.
Vol. 1. n. 3, pp. 327-340
Abstract - Power transformer is one of the key components of power systems. Transient free operation of the same enhances the overall system efficiency. Magnetizing current inrush is one of the major problems during switching operation. In this paper, an equivalent circuit model is presented to analyze this transient phenomenon. This model predicts the remnant levels, extent of inrush for both arbitrary and controlled re-energization. In this paper, a controller circuit is also presented which estimates the last remnant and utilizing this data, it controls the next re-energization instant to achieve inrush-free switching. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Inrush, remnant, prospective flux, sequential energization, controlled switching.
Vol. 1. n. 3, pp. 341-346
Abstract - This paper presents the Continuous Genetic Algorithm (CGA) to solve the Economic Environnemental Dispatch (EED) problem. The equality constraints of power balance and the inequality generator capacity constraints are considered. The EED problem is a biobjective non linear optimization problem since it is obtained by considering both the economy and emission objectives. This biobjectives problem is converted into a single objective function using a price penalty factor approach. In this paper CGA are tested on six generators system and the results are compared. The solutions are quite encouraging and useful in the EED. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Genetic Algorithm, continuous codage, optimization problem, transmission line loss, emission and economic dispatch.
Vol. 1. n. 3, pp. 347-354
Abstract - This research project concentrates on the design and control of a two-degrees-of-freedom orientation system for the photovoltaic solar panels in sunny regions which are considered very rich in solar energy. A brief background on the sun path and behavior at Latitude 31° as an example is discussed to help in the calculations of the needed angle ranges. The orientation system calculations are based on astronomical data and the system is assumed to be valid for any region with small modifications. The system is designed to control the Altitude angle in the vertical plane as well as the Azimuth angle in the horizontal plane of the photovoltaic panel workspace. The mechanical design is a simplified one using rotary joints and DC motors. This orientation system is expected to save more than 40% of the total energy of the panels by keeping the panel’s face perpendicular to the sun. This percentage is assumed to be lost energy in the fixed panels. The dynamics of the panel behave like a low-pass filter which facilitates the job of the controller that behaves as a good vibration isolator passing the orientation torques at low frequency and attenuating the high frequency disturbance signals coming from the surrounding environment. Point to point open-loop control is proposed in this mechanism to ensure intermittent motion when tracking the sun. To solve the problem of cloudy days, closed-loop control can be added to the system by using solar tracking sensors and feedback control loops. A special care should be taken to the design of the grid arrangement of panels in the collecting plant. The distance between two panels has to be twice the dimension of the panel to avoid the problem of shadow when the sun is inclined not only in the morning but also in the afternoon hours. A specific architecture and arrangement of panels in the collecting grid is proposed at the end of the document. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Solar Photovoltaic Panels, Orientation, Solar Tracking, Open-loop Control.
Vol. 1. n. 3, pp. 355-363
Abstract - In this article, we apply novel nonlinear control approach to a synchronous power generator driven by steam turbine and connected to an infinite bus based on backstepping technique. The aim is to obtain high dynamic performances for the terminal voltage and the rotor speed simultaneously under a large sudden fault and a wide range of operating conditions. The stabilizing feedback law for the power system is shown to be globally asymptotically stable in the context of Lyapunov theory. The detailed derivations of the control have been given for controller design. The effectiveness of the proposed novel control action is demonstrated through some computer simulations on a single-Machine-Infinite-Bus (SMIB) power system and compared with classical linear control. Simulation results confirm that the proposed controller can effectively improve the voltage stability, damp oscillation and enhance the transient stability of power system. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Backstepping design, Lyapunov method, non linear control, synchronous generator, transient stability.
Vol. 1. n. 3, pp. 364-370
Abstract - A variable structure model reference adaptive control (VS-MRAC) strategy for active steering assistance of a two wheel steering car is proposed. An ideal steering system with fixed properties and moving on an ideal road is used as the reference model, and the active steering assistance system is forced to attain the same behavior as the reference model. The proposed system can treat the nonlinear relationships between the side slip angles and lateral forces on tire, and the uncertainties on friction of the road surface, whose compensation are very important under critical situations. Simulation results show improvements on yaw rate and side slip. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Variable Structure, Adaptive Control, Model reference, Active steering assistance.
Vol. 1. n. 3, pp. 371-377
Abstract - The indistinctness of the manufacturing processes makes that a parts cannot be realized in an absolutely exact way towards the specifications on the dimensions. It is thus necessary to assume that the effectively realized product has to belong in a very strict way to compatible intervals with a correct functioning of the parts. This paper presents an approach based on a new modelling tool: the Interval Constrained Petri Nets. This tool is introduced in order to extend some properties of p-time PN to non-temporal constraint. A robust command of a mechanical assembly process is presented as an application. This command will then have to maintain the specifications interval of parts in front of the variations. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Intervals of tolerances – Interval Constrained Petri Nets, Robust command, production rate.
by J. Rezaeepazhand, L. Pahlevan Vol. 1. n. 3, pp. 378-382
Abstract - Electrorheological (ER) fluids are a class of smart materials that exhibit significant reversible changes in their mechanical properties under the influence of an applied electric field. In the present work, the applicability of these materials as a torque control (viscous coupling) device for an artificial joint is presented. The output torque capacity of the clutch is controlled by applying the appropriate electric field. A PID controller is used to achieve the desire output torque. The application of an electric field between the input and output parts alters the viscosity of the fluid and consequently the output torque for the joint. Both homogeneous and non-homogeneous ER fluids are considered as the working liquid in the clutch. Based on the results presented herein, the desirable output torque can be achieved. However, the applied particle type required higher input voltage. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: ER Fluid, Artificial Joint, ER Clutch, Torque Control.
by F. Bounaama, K. Lammari, B. Draoui Vol. 1. n. 3, pp. 383-389
Abstract - This work describes the application of fuzzy logic control (FLC) and neuro-fuzzy hybrid system for temperature regulation in agricultural process. The treated greenhouse is considered a non- linear SISO process and subject to strong external disturbances. The inside outsides climate model of the environmental greenhouse, and the automatically collected data sets of Avignon, France are used to simulate and test the proposed method. The control objective is to maintain inside air temperature of an almost closed greenhouse at a specified set-point by manipulating the heating air flux. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Climate model, Greenhouse, Temperature, FLC, Neuro-fuzzy hybrid system.
by M. Boutalbi, B. Boulebtateche, S. Toumi Vol. 1. n. 3, pp. 390-395
Abstract - This paper describes work done during three years of research with the goal of designing a compact low-cost colorimetric sensor incorporated in a complete system for a direct monitoring and controlling of dye exhaustion profile during textile dyeing. The temperature is often the principal variable taken into account to control the exhaustion of the dye bath. However, the goal is not to control temperature per se, but to control the final colour and strike (rate of dye uptake). Therefore, if one could control or predict the exhaustion profile during dyeing, one could control the amount and rate of dye uptake onto the fabric. The difficulty is in the measurement of the dye concentration deposited onto the fabric. For this reason, the design of a low cost compact colorimetric sensor, enabled us to approach the field of the textile dye bath control with minimum investment (i.e. without expensive spectrophotometer). A system of real-time data acquisition is developed. Results and test on single dye and mixture of dyes are encouraging. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Real-Time Processing, Colorimetric Sensors, Dyeing Textile Processes, Dye Exhaustion Control.
by E. Grigorieva, E. Khailov Vol. 1. n. 3, pp. 396-406
Abstract - A two-dimensional microeconomic model with three bounded controls is created and investigated. The model describes a manufacturer producing a consumer good and a retailer that buys this product in order to resell it for a profit. The interactions between the manufacturer and retailer will be modeled as a differential hierarchical game with the retailer to be the leader. We will consider the difficult case in which the maximum of the objective functions can be reached only on the boundary of the admissible set. Optimal strategies for manufacturer and retailer in the game will be found. The object of our interest is the investigation of the vertical integration of retail and industrial groups. We will determine the conditions of interaction that produce a stable and maximally effective structure over given planning periods. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Optimal Control, Game Theory, Economic Models.
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