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Control Theory and Applications, IEE Proceedings -

Issue 5 • Date 9 Sept. 2005

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Displaying Results 1 - 14 of 14
  • Optimal dual-rate digital redesig ith closed-loop order reduction

    Page(s): 489 - 498
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (331 KB)  

    A optimal dual-rate digital redesig method is proposed that ca be applied to continuous-time and fast-rate discrete-time control systems. The paper presents a technique, hich relies o the solutio of a dual-rate H2 discrete-time control problem, to convert such systems to either a slo -rate or a dual-rate sampled-data control system hile guaranteeing closed-loop stability and performance i the discrete-time H2 sense. The proposed technique results i sampled-data control systems providing satisfactory closed-loop performances over an extended range of sampling rates, as compared ith other idely used methods of digital redesign. Furthermore, the proposed digital redesig technique is useful i practice since it allo s the designer to constrai the complexity of the digital controllers, thus resulting in lo -order digital controllers easily implementable i soft are code and free of causality and real-time problems. Numerical examples provide a compariso of the proposed digital redesig technique ith ell-kno approaches. View full abstract»

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  • A fast estimatio algorithm for stochastic descriptor systems ith delayed measurements

    Page(s): 499 - 506
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (224 KB)  

    The problem of state estimatio for discrete-time stochastic descriptor systems ith delayed measurements is addressed. Using the method of measurements reorganisation, the recursive state estimatio and corresponding filtering error covariance are derived. The calculatio of the estimator includes t o steps. One is for the steady estimator and the other is the 'non-steady-state' estimator. The former is obtained by the autoregressive moving average (ARMA) innovatio model and projectio formula. The latter is derived by utilising the singular value decompositio and standard Kalma filtering. The authors' concept is the measurements reorganisatio hich converts the time-delay system into a delay-free but ith-different-measurement system, and leads to the computatio saving of the estimator. A numerical example is presented to illustrate the give algorithm. View full abstract»

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  • Finite-time composite control for a class of singularly perturbed nonlinear systems via successive Galerkin approximation

    Page(s): 507 - 512
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (221 KB)  

    This paper presents a ne algorithm of the finite-time closed-loop composite control for a class of singularly perturbed nonlinear systems ith respect to performance criteria, using the successive Galerki approximatio (SGA). The singularly perturbed nonlinear system is decomposed into t o subsystems of a slo -time scale and a fast-time scale via singular perturbatio theory, and the t o optimal control la s are obtained to each subsystem using the SGA method. Composite control theory guarantees near-optimal closed-loop performance but the resulting problem is difficult to solve for nonlinear systems. To overcome the difficulties inherent i the optimal control problem, the suitable optimal feedback control la ca be constructed i term of the approximated solutio to a Hamilton-Jacobi-Bellma equatio using SGA. The finite-time composite control la for singularly perturbed nonlinear systems is designed by a linear combinatio of the slo and fast variables. View full abstract»

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  • H controller synthesis of uncertain piece ise continuous-time linear systems

    Page(s): 513 - 519
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (166 KB)  

    A H controller synthesis method is presented for uncertai piece ise linear systems based o a piece ise smooth Lyapunov function. The basic idea of the proposed approach is to search for a piece ise controller and a piece ise continuous Lyapunov function simultaneously and constructively so that the global stability ith H performance of the resulting closed-loop control systems ca be established. It is sho n that the control la and Lyapunov functio ca be obtained by solving a set of bilinear matrix inequalities (BMI). T o examples are give to illustrate the application of the proposed method. View full abstract»

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  • Polynomial operator based sparse controller structures ith stability consideration

    Page(s): 521 - 530
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (229 KB)  

    T o ne efficient controller structures are derived based o a polynomial operator approach. The first one ca be considered as a improved versio of the recently proposed direct-form II transposed (DFIIt) structure i the ρ-operator, i hich the first-order ρ-operators are replaced ith a set of second-order operators, hile the second one is the equivalent state-space realisation. A pole modulus sensitivity based stability measure is obtained and the corresponding expressio of the stability robustness for each structure is derived. The optimal structure problem is solved by maximising the stability robustness under the parameter dynamical range constraints for fixed-point implementations. A design example is given, hich sho s that the ne ly developed structures ca achieve much better stability performance tha those structures i first-order ρ-operators and furthermore, outperform the fully parametrised optimal realisatio i terms of both stability robustness and implementatio efficiency. View full abstract»

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  • Parameter-dependent filter desig ith guaranteedH performance

    Page(s): 531 - 537
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (168 KB)  

    I the paper, the problem of H filtering for a class of linear uncertai systems is studied. The parameter uncertainties are assumed to reside in a polytope. The paper is focused o the desig of a parameter-dependent filter hich guarantees the filtering error system to be asymptotically stable and has a prescribed H performance. By employing a parameter-dependent Lyapunov functio approach, sufficient conditions are established for the existence of the desired filters i terms of linear matrix inequalities, hich ca be handled easily by using the available toolbox. Both continuous- and discrete-time cases are investigated. It is sho n, via a numerical example, that the proposed filter desig methods are more effective and less conservative tha some existing results. View full abstract»

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  • Time-domai implementatio of fractional order controllers

    Page(s): 539 - 552
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (311 KB)  

    Fractional order derivatives may be implemented i the time domai for control purposes i many ays. A exhaustive study of the performance of 28 different alternatives is presented and compared ith discretised Crone controllers. Placement of zeros and poles, impulse and step responses and frequency responses are addressed. No formula is clearly better tha all others i all situations, but it is expected that this survey ill allo the choosing of the best possibility for each particular case. View full abstract»

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  • Robust H state feedback control methods for bilinear systems

    Page(s): 553 - 559
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (219 KB)  

    Robust H state feedback control methods for continuous-time bilinear systems ith a additive disturbance input are presented. The robust H control for bilinear systems requires a solutio of the state dependent algebraic Riccati equatio (SDARE). Ho ever, the proposed robust H control techniques based o the successive approximatio method solve the SDARE by converting the bilinear system into the time varying linear system and solving a sequence of algebraic Riccati and Lyapunov equations, respectively. Numerical examples are considered to verify the efficiency of the proposed algorithms. View full abstract»

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  • Nonlinear PI control of a class of nonlinear singularly perturbed systems

    Page(s): 560 - 566
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (183 KB)  

    The robust asymptotic stabilisatio of a class of nonlinear uncertai singularly perturbed systems by using nonlinear PI control techniques is presented. The original system is decomposed into t o reduced-order systems, to hich the nonlinear uncertai term belongs. I order to alleviate the deterioratio of these nonlinear uncertainties, the nonlinear PI controllers are applied to each subsystem and the results are combined to construct the composite controller of the full-order system. A example is give to illustrate the desig procedures and good performance of the proposed control scheme. View full abstract»

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  • Absolute stability of feedback systems independent of internal point delays

    Page(s): 567 - 574
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (183 KB)  

    The absolute stability, independent of the delays, of time-delay systems ith non-commensurate internal point delays for any non-linearity satisfying a standard time positivity inequality is discussed. That property holds if an associate delay-free system is absolutely stable and the size of the delayed dynamics is sufficiently small. The results are obtained for non-linearities belonging to sectors [0, k] and [h, k+h], k≥0 and are based o a parabola test type. View full abstract»

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  • Adaptive motio tracking control of uncertai nonholonomic mechanical systems including actuator dynamics

    Page(s): 575 - 580
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (157 KB)  

    The desig of positio tracking control of mechanical systems ith classical nonholonomic constraints incorporating actuator dynamics is discussed. A adaptive controller is designed at the actuator level and the controller guarantees that the configuratio state of the system tracks the desired trajectory. A detailed numerical example is presented to illustrate the developed method. View full abstract»

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  • Normalised-generalised-velocity-component-based controller for a rigid serial manipulator

    Page(s): 581 - 586
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (193 KB)  

    A controller based o first-order decoupled equations of motio for applicatio to rigid serial manipulators is presented. The equations result from a modificatio of equations expressed i generalised velocity components form. It is sho that using the proposed quasi-velocities i.e. normalised generalised velocity components (NGVCs) leads to differential equations that contai the identity mass matrix (instead of a diagonal matrix). Using the proposed controller and equations ritte i terms of NGVCs it is possible to obtai informatio o the system dynamics. The considered controller is stable i the Lyapunov sense. Experimental results obtained o a 2DOF (t o-degree-of-freedom) manipulator illustrate the effectiveness of the proposed technique. View full abstract»

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  • Genetic algorithms for local controller net ork construction

    Page(s): 587 - 597
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1636 KB)  

    Local Controller Net orks (LCNs) provide nonlinear control by interpolating bet ee a set of locally valid, subcontrollers covering the operating range of the plant. Constructing such net orks typically requires kno ledge of valid local models. This paper describes a ne genetic learning approach to the constructio of LCNs directly from the dynamic equations of the plant, or from modelling data. The advantage is that a priori kno ledge about valid local models is not needed. I additio to allo ing simultaneous optimisatio of both the controller and validatio functio parameters, the approach aids transparency by ensuring that each local controller acts independently of the rest at its operating point. It thus is valuable for simultaneous desig of the LCNs and identificatio of the operating regimes of a unkno plant. Applicatio results from a highly nonlinear pH neutralisation process and its associated neural net ork representation are utilised to illustrate these issues. View full abstract»

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  • Hierarchical fuzzy control for autonomous navigatio of heeled robots

    Page(s): 598 - 606
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (789 KB)  

    The autonomous navigatio heeled robots ( R) requires integrated kinematic and dynamic control to perform trajectory tracking, path follo ing and stabilisation. Considering a R is a nonholonomic dynamic system ith intrinsic nonlinearity, unmodelled disturbance and unstructured unmodelled dynamics, fuzzy logic system based control is appropriate and practical. Ho ever, the multivariable control structure of the R results i the curse of dimensionality of the fuzzy desig and prevents a domai expert from building the linguistic rules for autonomous navigation. Hierarchical fuzzy desig decomposes the controller into three lo -dimensionality fuzzy systems: fuzzy steering, fuzzy linear velocity control and fuzzy angular velocity control, so that manual constructio of each rule base becomes feasible and easy. The proposed design enables a R to perform positio control i trajectory tracking and velocity profile tracking i continuous drive. The coupling effect bet ee linear and angular motion dynamics is considered i the fuzzy steering by building appropriate linguistic rules. To facilitate the autonomous navigatio desig and verification, a prototype and the model of a kind of R have bee developed, and equipped ith the hierarchical fuzzy control system. The simulatio and experimental results are sho and compared. View full abstract»

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