Distribution by Scientific Domains
Distribution within Engineering

Kinds of Controllers

  • adaptive controllers
  • desired controllers
  • feedback controllers
  • fuzzy controllers
  • output feedback controllers
  • pi controllers
  • pid controllers
  • proposed controllers
  • robust controllers
  • stabilizing controllers
  • state feedback controllers

  • Selected Abstracts

    Operative Platform Applied to Building Automation

    João Figueiredo
    This structure is composed by three interrelated levels: the Operational level,where the field equipment is controlled, the Inter-Active level,where inhabitants communicate the building their preferences regarding control variables (lights, temperature, etc.), and the higher-level control, the Overall Building Well-Being Model, which manages the global building, taking into account the optimization of the inhabitants preferences, constrained by the available resources. At this third level, the inter-building communication is available. Each building has the capability to communicate with its neighbors, informing about fires, floods, security problems, power consumption expectations, and so on. This article implements one of the three above-referred interrelated control levels: the Operational-level control. This operative platform is structured over a cascade hierarchical control architecture where inner loops are performed by local PLCs (Programmable Logic Controllers), and the outer loop is managed by a centralized SCADA system (Supervisory Control and Data Acquisition) that interacts with the entire PLC network. The lower-level control loop assures high processing velocity tasks, the upper-level control loop updates the local references, knowing the complete system state. This operative model is tested on two prototypes, where all instrumentation in place is controlled by the industrial PLC network. Both prototypes worked perfectly showing the huge potential of communication systems between distributed processes. These communication systems allow intelligent centralized algorithms to manage decision-making problems in real-time environments. The system presented in this article combines several technologies (local PLCs, SCADA systems, and network communications) to reach the goal of efficient management of intelligent buildings. [source]

    Semi-global stabilization of discrete-time systems subject to non-right invertible constraints

    Xu Wang
    Abstract This paper investigates time-invariant linear systems subject to input and state constraints. We study discrete-time systems with full or partial constraints on both input and state. It has been shown earlier that the solvability conditions of stabilization problems are closely related to important concepts such as the right invertibility or non-right invertibility of the constraints, the location of constraint invariant zeros, and the order of constraint infinite zeros. In this paper, for general time-invariant linear systems with non-right invertible constraints, necessary and sufficient conditions are developed under which semi-global stabilization in the admissible set can be achieved by state feedback. Sufficient conditions are also developed for such a stabilization in the case where measurement feedback is used. Such sufficient conditions are almost necessary. Controllers for both state feedback and measurement feedback are constructed as well. Copyright © 2009 John Wiley & Sons, Ltd. [source]

    Robust control from data via uncertainty model sets identification

    S. Malan
    Abstract In this paper an integrated robust identification and control design procedure is proposed. The plant to be controlled is supposed to be linear, time invariant, stable, possibly infinite dimensional and a set of noise-corrupted input,output measurements is supposed to be available. The emphasis is placed on the design of controllers guaranteeing robust stability and robust performances, and on the trade-off between controller complexity and achievable robust performances. First, uncertainty models are identified, consisting of parametric models of different order and tight frequency bounds on the magnitude of the unmodelled dynamics. Second, Internal Model Controllers, guaranteeing robust closed-loop stability and best approximating the ,perfect control' ideal target, are designed using H,/,-synthesis techniques. Then, the robust performances of the designed controllers are computed, allowing one to determine the level of model/controller complexity needed to guarantee desired closed-loop performances. Copyright © 2004 John Wiley & Sons, Ltd. [source]

    Operability-based determination of feasible control constraints for several high-dimensional nonsquare industrial processes

    AICHE JOURNAL, Issue 5 2010
    Fernando V. Lima
    Abstract High-dimensional nonsquare systems, with more outputs than inputs, are common in industrial chemical processes. For such systems, it is impossible to control all the outputs at specific set-points. Interval control is needed for, at least, some of the output variables. An operability-based methodology, formulated in a Linear Programming framework, systematically determines the feasible set of the steady-state output constraints of high-dimensional nonsquare linear Model Predictive Controllers. These controllers are related to several industrial-scale chemical processes provided by Air Products and Chemicals and DuPont. It is shown that, for the operable cases, the constrained region of operation can be reduced, without causing infeasibilities, by a factor of 103,107 for systems that have an output dimensionality of 6,15. For the inoperable examples, the amount of constraint relaxation necessary to make the control problem feasible at the steady-state is also calculated. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source]

    Approximate Pole Placement with Dominance for Continuous Delay Systems by PID Controllers

    Qing-Guo Wang
    Abstract It is well known that a continuous-time feedback system with time delay has infinite spectrum and it is not possible to assign such infinite spectrum with a finite-dimensional controller. In such a case, only the partial pole placement may be feasible and hopefully some of the assigned poles are dominant. But there is no easy way to guarantee dominance of the desired poles. In this paper, an analytical PID design method is proposed for continuous-time delay systems to achieve approximate pole placement with dominance. Its idea is to bypass continuous infinite spectrum problem by converting a delay process to a rational discrete model and getting back continuous PID controller from its discrete form designed for the model with pole placement. Simulation results are included to illustrate the effectiveness of this method. Il est bien établi qu'un système de rétroalimentation continu dans le temps avec retard a un spectre infini et qu'il n'est pas possible d'assigner un tel spectre à un contrôleur à dimensions finies. Dans un tel cas, seul le placement de pôles partiels peut être réalisable, et heureusement, certains des pôles assignés sont dominants. Mais il n'y a pas de manière facile de garantir la dominance des pôles désirés. Dans cet article, on propose une méthode de conception PID analytique pour les systèmes avec retard continu dans le temps, afin d'effectuer le placement de pôles approximatif avec dominance. L'idée est de contourner le problème des spectres infinis continus en convertissant le procédé de retard en un modèle discret rationnel et de récupérer le contrôleur PID continu de sa forme discrète conçue pour le modèle avec placement de pôles. Les résultats des simulations sont inclus pour illustrer l'efficacité de cette méthode. [source]

    A Synthesis Method For Robust Pid Controllers For A Class Of Uncertain Systems

    Stefan Solyom
    ABSTRACT PID controller design is considered where optimal controller parameters are found with constraint on maximum sensitivity and robustness with regard to a cone bounded static nonlinearity acting in feedback with part of the plant. The design procedure has been successfully applied in the synthesis of a controller for an Anti-lock Braking System (ABS). [source]

    A Design Of Multiloop Predictive Self-Tuning Pid Controllers

    Masaru Katayama
    ABSTRACT In this paper, a new design scheme of multiloop predictive self-tuning PID controllers is proposed for multivariable systems. The proposed scheme firstly uses a static pre-compensator as an approximately decoupling device, in order to roughly reduced the interaction terms of the controlled object. The static matrix pre-compensator is adjusted by an on-line estimator. Furthermore, by regarding the approximately decoupled system as a series of single-input single-output subsystems, a single-input single-output PID controller is designed for each subsystem. The PID parameters are calculated on-line based on the relationship between the PID control and the generalized predictive control laws. The proposed scheme is numerically evaluated on a simulation example. [source]

    ChemInform Abstract: Sulfoxides as Stereochemical Controllers in Intermolecular Heck Reactions.

    CHEMINFORM, Issue 15 2002
    Nuria Diaz Bueno
    Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

    Vinyl Sulfoxides as Stereochemical Controllers in Intermolecular Pauson,Khand Reactions: Applications to the Enantioselective Synthesis of Natural Cyclopentanoids

    Marta Rodríguez Rivero
    Abstract The use of sulfoxides as chiral auxiliaries in asymmetric intermolecular Pauson,Khand reactions is described. After screening a wide variety of substituents on the sulfur atom in ,,,-unsaturated sulfoxides, the readily available o -(N,N -dimethylamino)phenyl vinyl sulfoxide (1,i) has proved to be highly reactive with substituted terminal alkynes under N -oxide-promoted conditions (CH3CN, 0,°C). In addition, these Pauson,Khand reactions occurred with complete regioselectivity and very high diastereoselectivity (de=86,>96,%, (S,RS) diastereomer). Experimental studies suggest that the high reactivity exhibited by the vinyl sulfoxide 1,i relies on the ability of the amine group to act as a soft ligand on the alkyne dicobalt complex prior to the generation of the cobaltacycle intermediate. On the other hand, both theoretical and experimental studies show that the high stereoselectivity of the process is due to the easy thermodynamic epimerization at the C5 center in the resulting 5-sulfinyl-2-cyclopentenone adducts. When it is taken into account that the known asymmetric intermolecular Pauson,Khand reactions are limited to the use of highly reactive bicyclic alkenes, mainly norbornene and norbornadiene, this novel procedure constitutes the first asymmetric version with unstrained acyclic alkenes. As a demonstration of the synthetic interest of this sulfoxide-based methodology in the enantioselective preparation of stereochemically complex cyclopentanoids, we have developed very short and efficient syntheses of the antibiotic (,)-pentenomycin I and the (,)-aminocyclopentitol moiety of a hopane triterpenoid. Se ha estudiado la utilización de sulfóxidos como auxiliares quirales en reacciones de Pauson,Khand intermoleculares. Tras considerar una amplia variedad de vinil sulfóxidos diferentemente sustituidos en el átomo de azufre, se ha encontrado que el o -(N,N -dimetilamino)fenil sulfóxido (1,i) presenta una elevada reactividad frente a alquinos terminales en reacciones de Pauson,Khand. Además, estas reacciones transcurren con regioselectividades completas y diastereoselectividades muy elevadas (ed=86,>96,%). Estudios teóricos y experimentales sugieren que la gran reactividad mostrada por el vinil sulfóxido 1,i se debe a la capacidad del grupo amino para coordinarse al complejo de dicobalto del alquino, favoreciendo así la posterior formación del cobaltaciclo intermedio. Por otro lado, estudios tanto teóricos como experimentales han demostrado que la elevada diastereoselectividad del proceso es consecuencia de la fácil epimerización termodinámica en la posición C-5 de las 5-sulfinil-2-ciclopentenonas finales. Teniendo en cuenta que hasta el momento la reacción de Pauson,Khand intermolecular estaba limitada al empleo de alquenos bicíclicos muy reactivos, principalmente norborneno y norbornadieno, este nuevo procedimiento constituye la primera versión asimétrica con alquenos acíclicos no tensionados. Como demostración de la utilidad sintética de esta nueva metodología en la preparación enantioselectiva de sistemas ciclopentánicos complejos, se han desarrollado síntesis muy eficaces del antibiótico (,)-pentenomicina I y de la unidad de aminociclopentitol de un triperpenoide. [source]

    Extended spatial keyframing for complex character animation

    Byungkuk Choi
    Abstract As 3D computer animation becomes more accessible to novice users, it makes it possible for these users to create high-quality animations. This paper introduces a more powerful system to create highly articulated character animations with an intuitive setup then the previous research, Spatial Keyframing (SK). As the main purpose of SK was the rapid generation of primitive animation over quality animation, we propose Extended Spatial Keyframing (ESK) that exploits a global control structure coupled with multiple sets of spatial keyframes, and hierarchical relationship between controllers. The generated structure can be flexibly embedded into the given rigged character, and the system enables the given character to be animated delicately by user performance. During the performance, the movement of the highest ranking controllers across the control hierarchy is recorded in layered style to increase the level of detail for final motions. Copyright © 2008 John Wiley & Sons, Ltd. [source]

    An educational tool for controlling of SRM

    Tuncay Yigit
    Abstract This article introduces an educational tool for a switched reluctance motor (SRM) drive system. It is prepared for undergraduate and graduate level students. Classical PI and Genetic PI controllers are used in SRM drive system. The Genetic PI controller was applied to the speed loop, replacing the classical PI controller. The tool software was implemented using C++ Builder on a PC. It has flexible structure and graphical interface. The students can be easily establishing a thorough understanding of both classical PI and genetic PI controller for a SRM drive system. The education tool allowed the student to interact with the SRM drive system and it is using controllers. Then it is responses on a dynamic and instantaneous basis under different operating conditions. © 2008 Wiley Periodicals, Inc. Comput Appl Eng Educ 16: 268,279, 2008; Published online in Wiley InterScience (; DOI 10.1002/cae20148 [source]

    Flexible manufacturing cell SCADA system for educational purposes

    Sarah Reynard
    Abstract This article deals with the development of a Supervisory Control and Data Acquisition SCADA system to be used in a flexible manufacturing cell for educational purposes in different automation engineering fields (SCADA development, PLC programming and industrial communications). When dealing with industrial communications or PLC programming the SCADA is employed as a supervision tool. In the other hand, when teaching SCADA systems the application will be developed by the students and the SCADA presented in this article is employed as a model. The application communicates through Internet with four controllers, by means of an OPC server, visualizes comprehensive information about the elements of the cell, includes the video streaming of an IP camera, and features traceability and report generation capabilities. © 2008 Wiley Periodicals, Inc. Comput Appl Eng Educ 16: 21,30, 2008; Published online in Wiley InterScience (; DOI 10.1002/cae.20115 [source]

    Pose Controlled Physically Based Motion

    Raanan Fattal
    Abstract In this paper we describe a new method for generating and controlling physically-based motion of complex articulated characters. Our goal is to create motion from scratch, where the animator provides a small amount of input and gets in return a highly detailed and physically plausible motion. Our method relieves the animator from the burden of enforcing physical plausibility, but at the same time provides full control over the internal DOFs of the articulated character via a familiar interface. Control over the global DOFs is also provided by supporting kinematic constraints. Unconstrained portions of the motion are generated in real time, since the character is driven by joint torques generated by simple feedback controllers. Although kinematic constraints are satisfied using an iterative search (shooting), this process is typically inexpensive, since it only adjusts a few DOFs at a few time instances. The low expense of the optimization, combined with the ability to generate unconstrained motions in real time yields an efficient and practical tool, which is particularly attractive for high inertia motions with a relatively small number of kinematic constraints. [source]

    Applying fuzzy logic and genetic algorithms to enhance the efficacy of the PID controller in buffer overflow elimination for better channel response timeliness over the Internet

    Wilfred W. K. Lin
    Abstract In this paper two novel intelligent buffer overflow controllers: the fuzzy logic controller (FLC) and the genetic algorithm controller (GAC) are proposed. In the FLC the extant algorithmic PID controller (PIDC) model, which combines the proportional (P), derivative (D) and integral (I) control elements, is augmented with fuzzy logic for higher control precision. The fuzzy logic divides the PIDC control domain into finer control regions. Every region is then defined either by a fuzzy rule or a ,don't care' state. The GAC combines the PIDC model with the genetic algorithm, which manipulates the parametric values of the PIDC as genes in a chromosome. The FLC and GAC operations are based on the objective function . The principle is that the controller should adaptively maintain the safety margin around the chosen reference point (represent by the ,0' of ) at runtime. The preliminary experimental results for the FLC and GAC prototypes indicate that they are both more effective and precise than the PIDC. After repeated timing analyses with the Intel's VTune Performer Analyzer, it was confirmed that the FLC can better support real-time computing than the GAC because of its shorter execution time and faster convergence without any buffer overflow. Copyright © 2005 John Wiley & Sons, Ltd. [source]

    A comparison of concurrent programming and cooperative multithreading under load balancing applications

    Justin T. Maris
    Abstract Two models of thread execution are the general concurrent programming execution model (CP) and the cooperative multithreading execution model (CM). CP provides nondeterministic thread execution where context switches occur arbitrarily. CM provides threads that execute one at a time until they explicitly choose to yield the processor. This paper focuses on a classic application to reveal the advantages and disadvantages of load balancing during thread execution under CP and CM styles; results from a second classic application were similar. These applications are programmed in two different languages (SR and Dynamic C) on different hardware (standard PCs and embedded system controllers). An SR-like run-time system, DesCaRTeS, was developed to provide interprocess communication for the Dynamic C implementations. This paper compares load balancing and non-load balancing implementations; it also compares CP and CM style implementations. The results show that in cases of very high or very low workloads, load balancing slightly hindered performance; and in cases of moderate workload, both SR and Dynamic C implementations of load balancing generally performed well. Further, for these applications, CM style programs outperform CP style programs in some cases, but the opposite occurs in some other cases. This paper also discusses qualitative tradeoffs between CM style programming and CP style programming for these applications. Copyright © 2004 John Wiley & Sons, Ltd. [source]

    Libertarian Free Will and CNC Manipulation

    DIALECTICA, Issue 3 2001
    Ishtiyaque Haji
    An agent who is the victim of covert and nonconstraining control (CNC) is unaware of being controlled and controllers get their way by manipulating the victims so that they willingly do what the controllers desire. Our primary objective is to argue that if cases of CNC manipulation undermine compatibilist accounts of the sort of control required for moral responsibility, they also undermine various agent-causal and non-agent-causal libertarian accounts as well. [source]

    Closed-form solution for seismic response of adjacent buildings with linear quadratic Gaussian controllers

    Y. L. Xu
    Abstract Closed-form solution for seismic response of adjacent buildings connected by hydraulic actuators with linear quadratic Gaussian (LQG) controllers is presented in this paper. The equations of motion of actively controlled adjacent buildings against earthquake are first established. The complex modal superposition method is then used to determine dynamic characteristics, including modal damping ratio, of actively controlled adjacent buildings. The closed-form solution for seismic response of the system is finally derived in terms of the complex dynamic characteristics, the pseudo-excitation method and the residue theorem. By using the closed-form solution, extensive parametric studies can be carried out for the system of many degrees of freedom. The beneficial parameters of LQG controllers for achieving the maximum response reduction of both buildings using reasonable control forces can be identified. The effectiveness of LQG controllers for this particular application is evaluated in this study. The results show that for the adjacent buildings of different dynamic properties, if the parameters of LQG controllers are selected appropriately, the modal damping ratios of the system can be significantly increased and the seismic responses of both buildings can be considerably reduced. Copyright © 2001 John Wiley & Sons, Ltd. [source]

    Gain-scheduling control of a rotary inverted pendulum by weight optimization and H, loop shaping procedure

    Kazuhiro Yubai
    Abstract Gain-scheduling control is an effective method for use with plants whose dynamics change significantly according to the operating point. The frozen parameter method, a practical gain-scheduling controller synthesis method, interpolates the controllers designed at prespecified (frozen) operating points according to the current operation point. Hyde and Glover proposed a gain-scheduling control method in which the H, loop shaping procedure is adopted as a controller synthesis method at each operating point. The H, loop shaping procedure is based on loop shaping of an open loop characteristic by frequency weights and is known to be effective for plants with bad condition numbers. However, weight selection satisfying the control specifications is a difficult job for a designer. This paper describes the design of suboptimal weights and a controller by means of an algorithm that maximizes the robust stability margin and shapes the open-loop characteristic into the desired shape at each operating point. In addition, we formulate the weight optimization problem as a generalized eigenvalue minimization problem, which reduces the burden on the designer in weight selection. Finally, we realize a robust, high-performance control system by scheduling both weights and controllers. The effectiveness of the proposed control system is verified in terms of the achieved robust stability margin and the experimental time responses of a rotary inverted pendulum, which involves strong nonlinear dynamics. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 163(2): 30,40, 2008; Published online in Wiley InterScience ( DOI 10.1002/eej.20647 [source]

    Dynamic COI-tracking concept for the control of generators in multi-machine power systems

    Zhou Lan
    Abstract In the conventional excitation control concept, the power angle and frequency of a generator are driven to a pre-designed operation point after the fault occurs. It is named as Constant Point Stabilization (CPS) concept in this paper. A novel concept, called dynamic Center of Inertia (COI)-tracking concept is proposed in this paper. In the concept, the power angle and frequency of each generator track the dynamic COI of the power system. Compared to CPS concept, a salient feature the suggested dynamic COI-tracking concept has is that the generators are not restricted to constant angle point or frequency any longer but track the dynamic COI trajectory of the system to keep synchronous in rotor angle and frequency. Wide area measurement system (WAMS) will be used to transform COI signals to each generator. The time delay within a certain limit of WAMS signals is permitted. To make comparison between the two concepts, the control system models based on the two concepts are first established. Then, using the back-stepping method, two robust controllers are designed to achieve the control objectives of the two concepts. At last, dynamic simulations are carried out based on a 2-area-4-machine test power system, and the control effects of the two controllers, together with that of the conventional AVR,+,PSS excitation system, are compared. Copyright © 2007 John Wiley & Sons, Ltd. [source]

    The application of NN technique to automatic generation control for the power system with three areas including smes units

    A. Demirören
    The study includes an application of layered neural network controller to study automatic generation control (AGC) problem of the power system, which contains superconducting magnetic energy storage (SMES) units. The effectiveness of SMES unit over frequency oscillations improvement against load perturbations in power system is well known. In addition, the proposed control scheme provides the steady state error of frequency and inadvertent interchange of tie-lines to be maintained in steady state values. The power system considered has three areas two of which including steam turbines while the other containing a hydro turbine, and all of them contain SMES units, in addition. In the power system each area with a steam turbine contains the non-linearity due to reheat effect of the steam turbine and all of the areas contain upper and lower constraints for generation rate. Only one neural network (NN) controller, which controls all the inputs of each area in the power system, is considered. In the NN controller, back propagation-through-time algorithm is used as neural network learning rule. The performance of the power system is simulated by using conventional integral controller and NN controller for the cases with or without SMES units in all areas, separately. By comparing the results for both cases, it can be seen that the performance of NN controller is better than conventional controllers. [source]

    Interactions and co-ordination of multiple-function FACTS controllers

    H. F. Wang
    This paper presents two study cases of interaction analysis of multiple-function FACTS (flexible AC transmission systems) controllers: - the contradiction between the voltage and the damping control of a SVC (static VAr compensator); - the interaction between the voltage control of the DC link capacitor and the damping control of a UPFC (unified power-flow controller). In the paper, an algorithm is proposed for the co-ordinated design of these two multiple-function FACTS controllers. Examples are presented to confirm the analytical conclusions obtained and to demonstrate the effectiveness of the algorithm of the co-ordination proposed. [source]

    New converter-fed power source to increase the dynamic performance of the three-phase electric arc furnace

    A. Wolf
    The conventional three-phase electric arc furnaces frequently cause undesired distortions in the power system, which has a low short-circuit capacity in the form of voltage fluctuations (flicker) at the point of common coupling. This is due to the fluctuating reactive power consumption of the furnace. This paper describes a electronic-controlled furnace transformer which enables the reactive power consumed by the furnace to be kept constant. This is made possible if the conventional power system of the three-phase electric arc furnace is supplemented with three-phase power controllers and a booster transformer. By regulating the (reactive) power input, these disturbances can be reduced to a minimum. This new power source was experimentally tested on a single-phase model and the results, which are presented, are very satisfactory. [source]

    Improvement of interactions among facts controls

    X. Lei
    Interaction among the FACTS (flexible AC transmission systems) devices in a multi-machine system can adversely influence the damping properties of individual FACTS devices. In some critical cases, it may even amplify power swings or increase voltage deviations. This paper presents a global tuning method for the FACTS controllers in a multi-machine system. Based on a non-linear optimization algorithm implemented in a simulation program, the parameter settings of the FACTS controllers involved can be simultaneously optimized at transient conditions in coping with the non-linear nature of the power system. By minimizing a non-explicit target function in which swing characteristics between areas are included, interactions among the FACTS controls at transient conditions in the multi-machine system are minimized. Two multi-machine power systems equipped individually with a TCSC (thyristor-controlled series compensator) and a SVC (static Var compensator) are applied to demonstrate the efficiency of the proposed tuning procedure. The results obtained from simulations validate the improvement in damping of overall power oscillations. The simulations also show that the optimized FACTS controllers are robust in providing adequate damping for a range of conditions on the system. [source]

    Steady-state power flow and voltage control by unified power-flow controllers, part 2: Applications

    Y. H. Song
    The unifiedpower-flowcontroller(UPFC) isa powerfuldeviceforthe reliejroj'transmission constraints. Part 1 of the paper proposes novel steady-state modelling and control algorithms for the study of UPFC, which use power-injection models to derive control parameters for UPFC to achieve the required line active power control and bus-voltage support. The proposed method does not change the symmetrical structures of Jacobian matrix, avoids the initialisations of control parameters and can cover a wide control range of UPFC due to the characteristics of optimal multiplier power-flow algorithms employed. This paper describes in detail the applications of the proposed theory in a 28-node system. The convergence of controlled power flow is analysed. Control performance has been evaluated. The numerical results presented clearly illustrate the effectiveness of the proposed approach. [source]

    Developments of fuzzy PID controllers

    EXPERT SYSTEMS, Issue 5 2005
    H. B. Kazemian
    Abstract: This paper describes the development and tuning methods for a novel self-organizing fuzzy proportional integral derivative (PID) controller. Before applying fuzzy logic, the PID gains are tuned using a conventional tuning method. At supervisory level, fuzzy logic readjusts the PID gains online. In the first tuning method, fuzzy logic at the supervisory level readjusts the three PID gains during the system operation. In the second tuning method, fuzzy logic only readjusts the proportional PID gain, and the corresponding integral and derivative gains are readjusted using the Ziegler,Nichols tuning method while the system is in operation. For the compositional rule of inferences in the fuzzy PID and the self-organizing fuzzy PID schemes two new approaches are introduced: the min implication function with the mean of maxima defuzzification method, and the max-product implication function with the centre of gravity defuzzification method. The fuzzy PID controller, the self-organizing fuzzy PID controller and the PID controller are all applied to a non-linear revolute-joint robot arm for step input and path tracking experiments using computer simulation. For the step input and path tracking experiments, the novel self-organizing fuzzy PID controller produces a better output response than the fuzzy PID controller; and in turn both controllers exhibit better process output than the PID controller. [source]

    How appropriate is asthma therapy in general practice?

    Laurent Laforest
    Abstract High association between burden of asthma and inadequate disease control make asthma management a major public health issue. We studied asthma management practices of general practitioners (GPs) in France to describe drug therapy and more specifically, to identify correlates of antibiotic prescriptions, a marker of inappropriate asthma management. Patients with persistent asthma aged 17,50 years were evaluated in a 12-month retrospective study using a computerized GPs database (Thales) and a patient survey, in which patients reported hospital contacts, use of oral corticosteroids and recent asthma symptoms. Therapy was described and the correlates of antibiotic prescriptions in the previous year were identified using multivariate logistic regression. During the study period, 16.4% of 1038 patients received one or more prescriptions of theophylline, 31.3% long-acting beta-agonists and 61.6% inhaled corticosteroids. Rates of prescription of antibiotics, expectorants, antihistamines, antitussives and nasal corticosteroids were 57.6, 42.0, 33.0, 19.9, and 14.4%, respectively. In parallel, 15% of patients reported at least one hospital contact for asthma and 43.1% used oral corticosteroids. Antibiotic prescriptions were more likely co-prescribed in patients using expectorants [odds ratio (OR) = 13.0, 95% confidence interval (CI) = 8.5,19.8] and antitussives (OR = 6.5, 95% CI =3.7,11.6). Moreover, patients using courses of oral corticosteroids, and often visiting their GP (more than four times) during the study period were more likely to receive antibiotics. The results were unchanged when analyses were restricted to non-smokers and younger patients (,40 years). Asthma management was sub-optimal among asthma patients treated by general practitioners in France. Antibiotics, expectorants, antihistamines, antitussives and nasal corticosteroids were commonly prescribed while asthma controllers were under-used. [source]

    Application of decentralized control for remote power system stabilization by installing renewable energy power plant

    Tomonobu Senjyu Senior Member
    Abstract The generating power of wind turbines varies in proportion to the cube of wind speed, hence, they cannot supply constant power and this causes fluctuations in frequency and voltage. This article presents a methodology for controlling grid frequency, hydrogen volume, and terminal bus voltage. This system consists of diesel generators, wind turbines, and load. Aqua electrolyzer and fuel cells are introduced in order to control grid frequency, voltage, and hydrogen volume. By applying H, control, frequency, voltage fluctuation, and hydrogen volume, controls are achieved. H, decentralized controllers are designed and installed for diesel generators, aqua electrolyzers, and fuel cells in series. In order to verify the effectiveness of the suggested system, MATLAB/SIMULINK is used for simulation. © 2008 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [source]

    Reduced-order controllers for control of flow past an airfoil

    S. S. Ravindran
    Abstract Reduced-order controller design by means of reduced-order model for control of a wake flow is presented. Reduced-order model is derived by combining the Galerkin projection with proper orthogonal decomposition (POD) or with other related reduced-order approaches such as singular value decomposition or reduced-basis method. In the present investigation, we discuss the applicability of the reduced-order approaches for fast computation of the optimal control for control of vortex shedding behind a thin airfoil through unsteady blowing on the airfoil surface. Accuracy of the reduced-order model is quantified by comparing flow fields obtained from the reduced-order models with those from the full-order simulations under the same free-stream conditions. A control of vortex shedding is demonstrated for Reynolds number 100. It is found that downstream directed blowing on the upper surface of the airfoil near the leading edge is more efficient in mitigating flow separation and suppressing the vortex shedding. Copyright © 2005 John Wiley & Sons, Ltd. [source]

    Design of adaptive variable structure controllers for T,S fuzzy time-delay systems

    Tai-Zu Wu
    Abstract In this paper, the adaptive variable structure control problem is presented for Takagi,Sugeno (T,S) fuzzy time-delay systems with uncertainties and external disturbances. The fuzzy sliding surfaces for the T,S fuzzy time-delay system are proposed by using a Lyapunov function, and we design the adaptive variable structure controllers such that the global T,S fuzzy time-delay system confined on the fuzzy sliding surfaces is asymptotically stable. One example is given to illustrate the effectiveness of our proposed methods. Copyright © 2009 John Wiley & Sons, Ltd. [source]

    Adaptive regulation of MIMO linear systems against unknown sinusoidal exogenous inputs

    Maurizio Ficocelli
    Abstract This paper deals with the adaptive regulation problem in linear multi-input multi-output systems subject to unknown sinusoidal exogenous inputs, where the frequencies, amplitudes, and phases of the sinusoids are unknown and where the number of sinusoids is assumed to be known. The design of an adaptive regulator for the system under consideration is performed within a set of Q -parameterized stabilizing controllers. To facilitate the design of the adaptive regulator, triangular decoupling is introduced in part of the closed-loop system dynamics. This is achieved through the proper selection of the controller state feedback gain and the structure of the Q parameter. Regulation conditions are then presented for the case where the sinusoidal exogenous input properties are known. For the case where the sinusoidal exogenous input properties are unknown, an adaptation algorithm is proposed to tune the Q parameter in the expression of the parameterized controller. The online tuning of the Q parameter allows the controller to converge to the desired regulator. Convergence results of the adaptation algorithm are presented. A simulation example involving a retinal imaging adaptive optics system is used to illustrate the performance of the proposed adaptive system. Copyright © 2008 John Wiley & Sons, Ltd. [source]