Controller Design (controller + design)

Distribution by Scientific Domains

Kinds of Controller Design

  • robust controller design

  • Terms modified by Controller Design

  • controller design problem

  • Selected Abstracts


    DSP-BASED CONTROLLER DESIGN OF AN XY-TABLE AND ITS APPLICATION TO VIRTUAL FISHING SYSTEM

    ASIAN JOURNAL OF CONTROL, Issue 3 2007
    Ming-Shyan Wang
    ABSTRACT The paper is focused on controller design of a hybrid XY-table equipped with both a PMSM and a PMLSM and application of the XY-table system to a virtual fishing system (VFS), which incorporates a boat simulator, an interactive fishing rod system, virtual reality fishing scenes, and a player in the loop. The fishing rod system consists of the XY-table system acting as interactive force feedback hardware. Adaptive fuzzy control is adopted in the controller to track the command trajectory. The fishing boat is simulated by a three-axis manipulator, which is composed of three pneumatic cylinders serving as extensive linkages. Through the shunt combination of the cylinders, the movement of the fishing boat can be arbitrarily adjusted. Summarily, VFS creates a spontaneous and interactive environment and offers the experience of fishing in a remote location on the sea at home or at the amusement park. [source]


    NETWORK-INDUCED DELAY-DEPENDENT H, CONTROLLER DESIGN FOR A CLASS OF NETWORKED CONTROL SYSTEMS

    ASIAN JOURNAL OF CONTROL, Issue 2 2006
    Xiefu Jiang
    ABSTRACT This paper is concerned with the problem of robust H, controller design for a class of uncertain networked control systems (NCSs). The network-induced delay is of an interval-like time-varying type integer, which means that both lower and upper bounds for such a kind of delay are available. The parameter uncertainties are assumed to be normbounded and possibly time-varying. Based on Lyapunov-Krasovskii functional approach, a robust H, controller for uncertain NCSs is designed by using a sum inequality which is first introduced and plays an important role in deriving the controller. A delay-dependent condition for the existence of a state feedback controller, which ensures internal asymptotic stability and a prescribed H, performance level of the closed-loop system for all admissible uncertainties, is proposed in terms of a nonlinear matrix inequality which can be solved by a linearization algorithm, and no parameters need to be adjusted. A numerical example about a balancing problem of an inverted pendulum on a cart is given to show the effectiveness of the proposed design method. [source]


    ROBUST OUTPUT FEEDBACK CONTROLLER DESIGN WITH COVARIANCE AND DISC CLOSED-LOOP POLE CONSTRAINTS

    ASIAN JOURNAL OF CONTROL, Issue 3 2005
    Li Yu
    ABSTRACT This paper is concerned with the problem of robust output feedback controller design for a class of linear discrete-time systems with normbounded uncertainty. The objective is to design a controller such that the closed-loop poles are assigned within a specified disc and the steady regulated output covariance is guaranteed to be less than a given upper bound. Using a linear matrix inequality (LMI) approach, the existence conditions of such controllers are derived, and a parametrized characterization of a set of desired controllers (if they exist) is presented in terms of the feasible solutions to a set of LMIs. A procedure is given to select a suitable output feedback controller that minimizes the desired control effort. [source]


    AN AFM PROBE CONTROLLER DESIGN BASED ON ,-SYNTHESIS

    ASIAN JOURNAL OF CONTROL, Issue 1 2005
    Kuo-Jung Lan
    ABSTRACT The atomic force microscope (AFM) is one of the most important tools for measuring atomic resolution. The AFM system maintains constant force between a tip and the sample in order to track the sample topography. The controller that maintains the constant interaction force plays a significant role in measurement accuracy. This paper presents a ,-synthesis controller design to deal with model uncertainty and establish a measurement error bound. The system's nonlinearity and the set-point drift are lumped into a multiplicative uncertainty. The performance bound allows specification of the error magnitude over the frequency range. Simulation results show that the proposed control can tolerate uncertainties. The error spectrum from the experiments shows consistency with the design specifications. Images were taken to compare ,-synthesis control with a well-tuned PID control at a 480,m/s scan rate. The results verify the outstanding performance of the ,-controller. [source]


    DYNAMIC ANALYSES AND ROBUST STEERING CONTROLLER DESIGN FOR AUTOMATED LANE GUIDANCE OF HEAVY-DUTY VEHICLES

    ASIAN JOURNAL OF CONTROL, Issue 3 2000
    Jeng-Yu Wang
    ABSTRACT In this paper, we present various linear analyses of the linearized lateral dynamics of heavy-duty vehicles (HDVs) (tractor-semitrailer type), which include time domain, frequency domain and pole/zero analyses. These analyses are conducted to examine the vehicle response to the steering input subjected to variations of speed, road adhesion coefficient, cargo load in the trailer, and look-ahead distance for the lateral deviation sensor. These parameters (uncertainties) have significant influence on vehicle dynamics. It has been shown that redefining the look-ahead lateral error as the controlled output has a favorable impact on the lateral control problem. Based on these analyses, a robust steering controller using H, loop-shaping procedure is designed for a tractor semitrailer combination to follow the road center line on both curved and straight highway sections. The proposed controller ensures the robust performance under model uncertainties which include varying vehicle longitudinal speed, road adhesion coefficient, and cargo load in the trailer. The performance of the designed controller is evaluated by simulations and validated by experiments. [source]


    Nonlinear Controller Design for PWM,Controlled Converters

    PROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2003
    A. Kugi Prof. Dr. techn.
    This contribution is concerned with the nonlinear controller design for a certain class of PWM (pulse width modulation) , controlled converter systems. It will be shown that under certain assumptions the SSA (state space averaging) , model of the PWM,controlled converter with the duty ratio as the plant input has a very special mathematical structure. Based on this mathematical model a modified version of the nonlinear H2,design where an integral term is systematically included in the nonlinear controller will be presented. [source]


    An Advanced Physiological Controller Design for a Left Ventricular Assist Device to Prevent Left Ventricular Collapse

    ARTIFICIAL ORGANS, Issue 10 2003
    Yi Wu
    Abstract: A continuous flow left ventricle assist device (LVAD), which is mainly composed of a continuous flow blood pump and a physiological controller, has only one control input, the rotational speed of the pump, but at least three performance criteria to meet. The challenge for the physiological controller of a long-term continuous flow LVAD is the adaptability to different cardiovascular loading situations and the ability to handle systemic and parametric uncertainties with only one control input. The physiological LVAD controller presented in this article exhibits good performance in terms of the three performance criteria in different physiological loading conditions, such as disturbance, resting, and moderate exercise, for a patient with congestive heart failure. The collapse of the left ventricle, which is an inherent problem for a continuous flow LVAD, has been prevented because of the control algorithm design. [source]


    Robust Neural Network Controller Design For A Biaxial Servo System

    ASIAN JOURNAL OF CONTROL, Issue 4 2007
    Chih-Hsien Yu
    ABSTRACT A robust control method for synchronizing a biaxial servo system motion is proposed in this paper. A new neural network based cross-coupled control and neural network techniques are used together to cancel out the skew error. In the proposed control scheme, the conventional fixed gain PID cross-coupled controller (PIDCCC) is replaced with the neural network cross-coupled controller (NNCCC) to maintain biaxial servo system synchronization motion. In addition, neural network PID position velocity and velocity controllers provide the necessary control actions to maintain synchronization while following a variable command trajectory. This scheme provides strong robustness with respect to uncertain dynamics and nonlinearities. The simulation results reveal that the proposed control structure adapts to a wide range of operating conditions and provides promising results under parameter variations and load changes. [source]


    Robust H, Non-Fragile Controller Design for Uncertain Descriptor Systems with Time-Varying Discrete and Distributed Delays

    ASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 3-4 2005
    Dong Yue
    This paper is concerned with the design problem of non-fragile H, controller for uncertain descriptor systems with time-varying discrete and distributed delays and controller gain variations. The designed controller is shown to be robust not only to parameter uncertainties, but also to errors in the controller coefficients. The obtained criterion to derive an efficient non-fragile H, control design is expressed as a set of nonconvex matrix inequalities, which can be solved by combining both linear matrix inequalities technique and come complementarity method. A numerical example is given to demonstrate effectiveness of the proposed methods. [source]


    Nonsingular path following control of a unicycle in the presence of parametric modelling uncertainties

    INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 10 2006
    L. Lapierre
    Abstract A new type of control law is derived to steer the dynamic model of a wheeled robot of unicycle type along a desired path. The methodology adopted for path following control deals explicitly with vehicle dynamics and plant parameter uncertainty. Furthermore, it overcomes stringent initial condition constraints that are present in a number of path following control strategies described in the literature. This is done by controlling explicitly the rate of progression of a ,virtual target' to be tracked along the path, thus bypassing the problems that arise when the position of the virtual target is simply defined by the projection of the actual vehicle on that path. In the paper, a nonlinear adaptive control law is derived that yields convergence of the (closed-loop system) path following error trajectories to zero. Controller design relies on Lyapunov theory and backstepping techniques. Simulation results illustrate the performance of the control system proposed. Copyright 2006 John Wiley & Sons, Ltd. [source]


    Non-diagonal controllers in MIMO quantitative feedback design

    INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 4 2002
    Edward Boje
    Abstract This paper discusses multivariable quantitative feedback design through the use of controllers with off-diagonal elements. Controller design for multivariable plants with significant uncertainty is simpler and potentially less conservative if some sort of dominance is achieved (by reducing the interaction effect of off-diagonal plant elements) before a diagonal (decentralized) controller design is attempted. Traditional approaches for achieving dominance are not applicable when plant uncertainty must be considered. This paper discusses parallel and series implementations and for the latter, a pseudo-Gauss elimination approach to the design has been developed. The interaction is measured using the Perron,Frobenius root of an interaction matrix. In some applications, it is possible to trade off individual plant cases against each other in order to reduce to the worst-case interaction over the entire plant set. Copyright 2002 John Wiley & Sons, Ltd. [source]


    Controller design for natural and robotic systems with transmission delays

    JOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 5 2002
    Abhay Kataria
    Robust stability and two-dimensional trajectory following problems are considered for n -link robotic systems with transmission delays. Such problems appear in telerobotics, where the controller is physically far from the robot, and in neural control of musculo-skeletal (biological) systems, where muscle actuation and neural sensing are subject to time delays. A typical second-order nonlinear dynamical model is taken with input and output time delays. In a prior work by the authors, a control strategy was developed for stable movement of the planar linkage system, using the standard Q -parameterization and solving an H, control problem to determine the free parameter. In this article, a new control scheme is proposed to eliminate the steady-state errors seen in the tracking performance of the controller derived in the earlier work. Simulation examples are shown to demonstrate the effectiveness of the proposed control methodology. 2002 Wiley Periodicals, Inc. [source]


    Controller design for optimal tracking response in discrete-time systems

    OPTIMAL CONTROL APPLICATIONS AND METHODS, Issue 5 2007
    O. A. Sebakhy
    Abstract The problem of designing a controller, which results in a closed-loop system response with optimal time-domain characteristics, is considered. In the approach presented in this paper, the controller order is fixed (higher than pole-placement order) and we seek a controller that results in closed-loop poles at certain desired and pre-specified locations; while at the same time the output tracks the reference input in an optimal way. The optimality is measured by requiring certain norms on the error sequence,between the reference and output signals,to be minimum. Several norms are used. First, l2 -norm is used and the optimal solution is computed in one step of calculations. Second, l, -norm (i.e. minimal overshot) is considered and the solution is obtained by solving a constrained affine minimax optimization problem. Third, the l1 -norm (which corresponds to the integral absolute error-(IAE)-criterion) is used and linear programming techniques are utilized to solve the problem. The important case of finite settling time (i.e. deadbeat response) is studied as a special case. Examples that illustrate the different design algorithms and demonstrate their feasibility are presented. Copyright 2007 John Wiley & Sons, Ltd. [source]


    Controller design based on similar skew-symmetric structure for nonlinear plants

    ASIAN JOURNAL OF CONTROL, Issue 1 2010
    Yicheng Liu
    Abstract This paper proposes a novel controller design approach for nonlinear plants. A class of stable nonlinear systems with a similar skew-symmetric structure is chosen as the objective closed loop system, and two design methods are proposed with backstepping and direct construction. Compared with the conventional backstepping method, the proposed backstepping method need not construct a Lyapunov function step by step, thus the design procedure is simplified. The direct construction method can be applied to some nonlinear plants for which the conventional backstepping is not feasible; and the design can be accomplished in only one step. Furthermore, for some nonlinear plants which have a lower triangular structure with two subsystems, simpler controllers can be derived by the proposed direct construction method than those derived by backstepping design. In addition, the proposed methods are both system structure oriented, therefore their designs are more intuitive than the conventional backstepping design. Two controllers are derived for satellite attitude control by employing the proposed methods; simulation results demonstrate their effectiveness. Copyright 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society [source]


    Nonlinear parametric predictive control.

    ASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 6 2009
    Application to a continuous stirred tank reactor
    Abstract This paper presents a nonlinear model-based controller based on the ideas of parametric predictive control applied to a continuous stirred tank reactor (CSTR) process unit. Controller design aims at avoiding the complexity of implementation and long computational times associated with conventional NMPC while maintaining the main advantage of taking into account process nonlinearities that are relevant for control. The design of the parametric predictive controller is based on a rather simplified process model having parameters that are instrumental in determining the required changes to the manipulated variables for error reduction. The nonlinear controller is easy to tune and can operate successfully over a wide range of operating conditions. The use of an estimator of unmeasured disturbances and process-model mismatch further enhances the behavior of the controller. Copyright 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source]


    MATLAB based GUIs for linear controller design via convex optimization

    COMPUTER APPLICATIONS IN ENGINEERING EDUCATION, Issue 1 2003
    Wathanyoo Khaisongkram
    Abstract Owing to the current evolution of computational tools, a complicated parameter optimization problem could be effectively solved by a computer. In this paper, a CAD tool for multi-objective controller design based on MATLAB program is developed. In addition, we construct simple GUIs (using GUIDE tools within MATLAB) to provide a visual approach in specifying the constraints. The linear controller design problem can be cast as the convex optimization subjected to time domain and frequency domain constraints. This optimization problem is efficiently solved within a finite dimensional subspace by a practical ellipsoid algorithm. In the design process, we include a model reduction of the resulting controller to speed up the computational efficiency. Finally, a numerical example shows the capability of the program to design multi-objective controller for a one-link flexible robot arm. 2003 Wiley Periodicals, Inc. Comput Appl Eng Educ 11: 13,24, 2003; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.10035 [source]


    A substructure shaking table test for reproduction of earthquake responses of high-rise buildings

    EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 12 2009
    Xiaodong Ji
    Abstract When subjected to long-period ground motions, high-rise buildings' upper floors undergo large responses. Furniture and nonstructural components are susceptible to significant damage in such events. This paper proposes a full-scale substructure shaking table test to reproduce large floor responses of high-rise buildings. The response at the top floor of a virtual 30-story building model subjected to a synthesized long-period ground motion is taken as a target wave for reproduction. Since a shaking table has difficulties in directly reproducing such large responses due to various capacity limitations, a rubber-and-mass system is proposed to amplify the table motion. To achieve an accurate reproduction of the floor responses, a control algorithm called the open-loop inverse dynamics compensation via simulation (IDCS) algorithm is used to generate a special input wave for the shaking table. To implement the IDCS algorithm, the model matching method and the H, method are adopted to construct the controller. A numerical example is presented to illustrate the open-loop IDCS algorithm and compare the performance of different methods of controller design. A series of full-scale substructure shaking table tests are conducted in E-Defense to verify the effectiveness of the proposed method and examine the seismic behavior of furniture. The test results demonstrate that the rubber-and-mass system is capable of amplifying the table motion by a factor of about 3.5 for the maximum velocity and displacement, and the substructure shaking table test can reproduce the large floor responses for a few minutes. Copyright 2009 John Wiley & Sons, Ltd. [source]


    Robust active vibration suppression control with constraint on the control signal: application to flexible structures

    EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 11 2003
    A. Forrai
    Abstract A unified mathematical framework, sustained by experimental results, is presented for robust controller design taking into account the constraint on the control signal. The design procedure is exemplified for an active vibration suppression control problem with applications to flexible structures. The considered experimental set-up is a three-storey flexible structure with an active mass driver placed on the last storey. First, the considered flexible structure is identified and the model's parametric uncertainties are deduced. Next, control constraints are presented for the robust control design problem, taking into account the restriction imposed on the control signal. Finally, the effectiveness of the control system is tested through experiments, when the input disturbance is assumed to be a sinusoidal one as well as a historical earthquake record (1940 El Centro record). Copyright 2003 John Wiley & Sons, Ltd. [source]


    Reduced-order controllers for control of flow past an airfoil

    INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 5 2006
    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]


    Adaptive controller design and disturbance attenuation for SISO linear systems with zero relative degree under noisy output measurements

    INTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 4 2010
    Sheng Zeng
    Abstract In this paper, we present robust adaptive controller design for SISO linear systems with zero relative degree under noisy output measurements. We formulate the robust adaptive control problem as a nonlinear H, -optimal control problem under imperfect state measurements, and then solve it using game theory. By using the a priori knowledge of the parameter vector, we apply a soft projection algorithm, which guarantees the robustness property of the closed-loop system without any persistency of excitation assumption of the reference signal. Owing to our formulation in state space, we allow the true system to be uncontrollable, as long as the uncontrollable part is stable in the sense of Lyapunov, and the uncontrollable modes on the j,-axis are uncontrollable from the exogenous disturbance input. This assumption allows the adaptive controller to asymptotically cancel out, at the output, the effect of exogenous sinusoidal disturbance inputs with unknown magnitude, phase, and frequency. These strong robustness properties are illustrated by a numerical example. Copyright 2009 John Wiley & Sons, Ltd. [source]


    Longitudinal auto-landing controller design via adaptive backstepping

    INTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 7 2009
    Hann-Shing Ju
    Abstract This paper presents an auto-landing controller for glide-slope tracking and the flare maneuver via adaptive backstepping design and describes a flight path command generator for indirect altitude control in order to provide precise altitude trajectories for auto-landing of unmanned aerial vehicles (UAVs). Using the adaptive backstepping procedure to synthesize a glide-slope tracking and flare maneuver control law is being used differently from designing the guidance and control loops separately in autopilot. An adaptive controller is proposed to control aircraft from glide-slope to flare by following the flight path angle command for indirect altitude control via elevator and maintaining the constant airspeed control via throttle. Simulation results demonstrate that the adaptive auto-landing controller is capable of effectively guiding the UAV along the flight path angle command under the presence of the wind turbulence. Copyright 2008 John Wiley & Sons, Ltd. [source]


    Reduced-order robust adaptive control design of uncertain SISO linear systems

    INTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 7 2008
    Qingrong Zhao
    Abstract In this paper, a stability and robustness preserving adaptive controller order-reduction method is developed for a class of uncertain linear systems affected by system and measurement noises. In this method, we immediately start the integrator backstepping procedure of the controller design without first stabilizing a filtered dynamics of the output. This relieves us from generating the reference trajectory for the filtered dynamics of the output and thus reducing the controller order by n, n being the dimension of the system state. The stability of the filtered dynamics is indirectly proved via an existing state signal. The trade-off for this order reduction is that the worst-case estimate for the expanded state vector has to be chosen as a suboptimal choice rather than the optimal choice. It is shown that the resulting reduced-order adaptive controller preserves the stability and robustness properties of the full-order adaptive controller in disturbance attenuation, boundedness of closed-loop signals, and output tracking. The proposed order-reduction scheme is also applied to a class of single-input single-output linear systems with partly measured disturbances. Two examples are presented to illustrate the performance of the reduced-order controller in this paper. Copyright 2007 John Wiley & Sons, Ltd. [source]


    Modelling and simulation of a double-star induction machine vector control using copper-losses minimization and parameters estimation

    INTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 9 2002
    M.F. Mimouni
    Abstract This paper shows that it is possible to extend the principle of field-oriented control (FOC) approach to a double-star induction motor (DSIM). In the first stage, a robust variable structure current controller based on space phasor voltages PWM scheme is established. In this current controller design, only the stator currents and rotor speed sensors are used. In the second stage, the FOC method developed for DSIM is motivated by the minimization of the copper losses. The developed approach uses a loss model controller (LMC) and an adaptive rotor flux observer to compute the adequate rotor flux value minimizing the copper losses. The control variables are the stator currents or the machine input power. Compared to the constant rotor flux approach, it is proved that higher performances are achieved. However, the sensitivity of the FOC to parameter error of the machine still remains a problem. To guarantee the performance of the vector control, the stator and rotor resistances are adapted on-line, based on the Lyapunov theory. An appropriate choice of the reference model allows building a Lyapunov function by means of which the updating law can be found. The simulation results show the satisfactory behaviour of the proposed identification algorithm. Copyright 2002 John Wiley & Sons, Ltd. [source]


    Experimental modelling and intelligent control of a wood-drying kiln

    INTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 8 2001
    Givon Chuen Kee Yan
    Abstract Proper control of the wood-drying kiln is crucial in ensuring satisfactory quality of dried wood and in minimizing drying time. This paper presents the development, implementation, and evaluation of a control system for a lumber drying kiln process incorporating sensory feedback from in-wood moisture content sensors and intelligent control such that the moisture content of lumber will reach and stabilize at the desired set point without operator interference. The drying process is difficult to model and control due to complex dynamic nonlinearities, coupling effects among key variables, and process disturbances caused by the variation of lumber sizes, species, and environmental factors. Through system identification scheme using experimental data and recursive least-squares algorithm for parameter estimation, appropriate models are developed for simulation purpose and controller design. Two different control methodologies are employed and compared: a conventional proportional-integral-derivative (PID) controller and a direct fuzzy logic controller (FLC), and system performance is evaluated through simulations. The developed control system is then implemented in a downscaled industrial kiln located at the Innovation Centre of National Research Council (NRC) of Canada. This experimental set-up is equipped with a variety of sensors, including thermocouples for temperature feedback, an air velocity transmitter for measuring airflow speed in the plenum, relative humidity sensors for measuring the relative humidity inside the kiln, and in-wood moisture content sensors for measuring the moisture content of the wood pieces. For comparison, extensive experimental studies are carried out on-line using the two controllers, and the results are evaluated to tune the controller parameters to achieve good performance in the wood-drying kiln. The combination of conventional control with the intelligent control promises improved performance. The control system developed in this study may be applied in industrial wood-drying kilns, with a clear potential for improved quality and increased speed of drying. Copyright 2001 John Wiley & Sons, Ltd. [source]


    Adaptive AQM controllers for IP routers with a heuristic monitor on TCP flows

    INTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 1 2006
    Yang Hong
    Abstract We propose adaptive proportional (P) and proportional-integral (PI) controllers for Active Queue Management (AQM) in the Internet. We apply the classical control theory in the controller design and choose a proper phase margin to achieve good performance of AQM. We have identified a simple heuristic parameter that can monitor the changes of network environment. Our adaptive controllers would self-tune only when the dramatic change in the network parameters drift the monitoring parameter outside its specified interval. When compared to P controller, a PI controller has the advantage of regulating the TCP source window size by adjusting the packet drop probability based on the knowledge of instantaneous queue size, thus steadying the queue size around a target buffer occupancy. We have verified our controllers by OPNET simulation, and shown that with an adaptive PI controller applied, the network is asymptotically stable with good robustness. Copyright 2005 John Wiley & Sons, Ltd. [source]


    Absolute stability of Lurie networked control systems

    INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 12 2010
    Fei Hao
    Abstract This paper is concerned with the absolute stability problem of networked control systems (NCSs) with the controlled plant being Lurie systems (Lurie NCSs), in which the network-induced delays are assumed to be time-varying and bounded. First, in consideration of both the time-varying network-induced delays and data packet dropouts, the Lurie NCSs can be modeled as a multiple-delays Lurie system. Then, a delay-dependent absolute stability condition is established by using the Lyapunov,Krasovskii method. Next, two approaches to controller design are proposed in the terms of simple algebra criteria, which are easily solved via the toolbox in Matlab. Furthermore, the main results can be extended to robust absolute stability of Lurie NCSs with the structured uncertainties, where robust absolute stability conditions and approaches to robust controller design are presented. Finally, two numerical examples are worked out to illustrate the feasibility and the effectiveness of the proposed method. Copyright 2009 John Wiley & Sons, Ltd. [source]


    Multi-loop control synthesis for unstable systems and its application: An approach based on interaction measure

    INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 15 2009
    Adarsha Swarnakar
    Abstract This paper presents a new practical framework for multi-loop controller design in which controllers are designed independently, i.e. a controller in one loop is designed without exploiting information of other controllers. The method is based on the (block) diagonal approximation of a system that is different from its (block) diagonal elements. The focus of this work is on unstable systems and the approximated systems are obtained by minimizing an upper bound of a scaled ,, norm for the error systems. This extends the applicability of conventional -interaction measure to a more general scenario. The proposed approach is applied to a numerical example and to a simulated industrial boiler system. Copyright 2008 John Wiley & Sons, Ltd. [source]


    Output feedback control design for station keeping of AUVs under shallow water wave disturbances

    INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 13 2009
    Shuyong Liu
    Abstract In this paper, we consider the problem of autonomous underwater vehicle (AUV) station keeping (SK) in shallow water area. During SK, an AUV is required to maintain position and orientation with respect to a fixed reference point at the sea floor. When AUV operates in shallow water, high-frequency disturbances due to waves will significantly affect the motion of the AUV. In order to derive wave disturbance information for control purposes, a nonlinear observer is first designed to estimate the shallow water wave velocities and AUV relative velocities by using position and attitude measurement. Using the observer estimates, a nonlinear output feedback controller is subsequently synthesized by applying observer backstepping technique. Global exponential stability (GES) of the proposed nonlinear observer,controller design is proved through Lyapunov stability theory. Simulation studies on a model based on an actual AUV were performed to verify the performance of the proposed nonlinear observer and output feedback controller. Copyright 2008 John Wiley & Sons, Ltd. [source]


    Passivity-based control of a magnetically levitated flexible beam

    INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 6 2009
    T. Shimizu
    Abstract This paper solves the asymptotic stabilization problem for a magnetically levitated flexible beam using a nested-loop passivity-based controller design. Passivity analyses reveal that the system can be decomposed into two passive subsystems: a mechanical subsystem that consists of a flexible beam with both ends free and that defines a passive map from external forces to the velocity of the points on the flexible beam at which the external forces act; and an electrical subsystem that consists of a pair of electromagnets and that defines a strictly output-passive map from voltages applied across the electromagnets to magnetic fluxes. The standard method for designing passivity-based controllers leads to a nonlinear feed-forward controller for the electrical subsystem, which enables the electrical subsystem to generate given desired magnetic forces, and an output feedback compensator for the mechanical subsystem, which computes the desired forces required to regulate the position and vibration of the beam. The asymptotic stability of each controller may be proven using Lyapunov's stability theory and LaSalle's invariant set theorem. Numerical simulations confirm the asymptotic stability of the equilibrium configuration of the closed-loop system formed by the magnetically levitated flexible beam together with the proposed controllers. Copyright 2008 John Wiley & Sons, Ltd. [source]


    A hybrid controller design for bi-axial inverted pendulum system

    INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 5 2009
    Long-Hong Chang
    Abstract This study presents the use of Tustin's friction model and a disturbance observer (DOB) to improve the steady-state error (SSE) of a bi-axial inverted pendulum,cart system (IPCS). Furthermore, a hybrid controller contains a feedback linearization control for pendulum angle in the region of 3,12 to enlarge the angle of operation and an H, control using loop shaping design procedure (LSDP) for cart position and pendulum angle in the region of 0,3 to stabilize the IPCS, respectively. Experimental results reveal that the pendulum maximum angle of operation is improved from 7 to 12; the SSE of the angle of the pendulum is reduced from 0.85 to 0.1, and the SSE of the position of the cart is reduced from 10 to 1.4,mm. Experimental results are illustrated and films are provided at the web site http://hinfinity.myweb.hinet.net to show the effectiveness and robustness of the hybrid controller with Tustin's friction model and DOB compensation. Copyright 2008 John Wiley & Sons, Ltd. [source]