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Control Theory and Applications, IEE Proceedings -

Issue 5 • Date 23 Sept. 2004

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Displaying Results 1 - 19 of 19
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  • Decentralised sliding-mode control for multimachine power systems using only output information

    Page(s): 627 - 635
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (312 KB)  

    A robust stabilisation problem for multimachine power systems is considered using only output information. The power system is formed from an interconnected set of lower-order systems through a transmission network which is nonlinear and has an associated nonlinear bound. Uncertainty in the input distribution matrices of the subsystems and mismatched uncertainty associated with the interconnections are both considered. Under some mild conditions, a decentralised sliding mode control scheme is developed. The conservatism of the results obtained is reduced by fully using the system output information and the structure of the uncertainties. Simulation results for a three-machine power system are presented to show the effectiveness of the proposed method. View full abstract»

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  • Numerical method for global optimisation: dynamic encoding algorithm for searches

    Page(s): 661 - 668
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (477 KB)  

    A fast and reliable non-gradient optimisation method is proposed. The basic structure of the proposed numerical method is a binary matrix in which each row represents an encoded string for the corresponding parameter. The operations of adding a binary digit and performing an increment or a decrement to a selected row make successive approximations of the local minima, and the restart is undertaken from an unexplored initial matrix as an escape scheme. To verify the feasibility of the proposed method for global optimisation, several test functions are optimised as a benchmark, and the parameter identification of an induction motor is carried out on experimental data. Both the results of the benchmarking and the parameter identification show that the proposed non-gradient optimisation method is capable of fast and reliable global search for various problems. View full abstract»

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  • PID controller design for disturbed multivariable systems

    Page(s): 567 - 576
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (323 KB)  

    A linear-quadratic-regulator-based (LQ-regulator-based) design methodology is proposed to design proportional-integral-derivative (PID) controllers for multivariable systems with load disturbances. Except for a few parameters that are preliminarily selected, most of the PID parameters are systematically tuned using the developed plant state-feedback and controller state-feedforward LQR approach, such that satisfactory performance with guaranteed closed-loop stability is achieved. In order to access the plant state variables and carry out disturbance rejection, an observer-based disturbance rejection technique is proposed, which through an 'equivalent disturbance' concept, retains the observation error to be used for disturbance compensation. This makes disturbance measurement unnecessary and the disturbance rejection tuning independent of the set-point response adjustment. A robust stability analysis is also included for the modelling error. An illustrative example is given for comparison with alternative techniques. View full abstract»

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  • Design and experimental evaluation of a multivariable self-tuning PID controller

    Page(s): 645 - 652
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (320 KB)  

    A multivariable self-tuning PID (proportional-integral-derivative) controller design scheme is proposed which has a static matrix precompensator to reduce the interaction terms of the process transfer function matrix adjusted by an online estimator. The p×p precompensated multivariate system is then controlled via 'p' univariate self-tuning PID controllers whose parameters are adjusted by a second identifier placed around the precompensated plant. The PID parameters are calculated online based on the relationship between the PID and generalised minimum variance control laws. The scheme is experimentally evaluated on a 2×2 level plus temperature control system. Experimental results illustrate the effectiveness of this scheme. View full abstract»

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  • Receding-horizon control for input constrained linear parameter-varying systems

    Page(s): 547 - 553
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (285 KB)  

    The parameter set of a linear parameter-varying system is divided into a number of subsets so that robust feedback gains may be designed for each subset of parameters. The concept of a quasi-invariant set is introduced, which allows finite steps of delay in re-entrance to the set. A positively invariant set with respect to a gain-scheduled state feedback control can be easily obtained from the quasi-invariant set. A constrained receding-horizon control algorithm that deploys degrees of freedom to steer the current state into a positively invariant set was developed. The proposed receding-horizon control method is formulated as linear programming and its computational load can be reduced significantly using a superposition technique. View full abstract»

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  • Delay-dependent output feedback stabilisation of Markovian jump system with time-delay

    Page(s): 561 - 566
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (262 KB)  

    This work deals with the stabilisation problem of a Markovian jump system with time-delay. Based on the application of the descriptor model transformation and a recent result on bounding of cross products of vectors, a new delay-dependent stabilisation condition using a dynamic output feedback controller is formulated in terms of matrix inequalities. A numerical algorithm is developed to construct a full-order output feedback controller guaranteeing a suboptimal maximal delay such that the system can be stochastically stabilised. In addition, the errors of the paper by Boukas et al. (IEE Proc.-Control Theory Appl., 2002, 149, (5), 379-386) are highlighted. View full abstract»

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  • Robust H control for a class of uncertain nonlinear time-varying systems and its application

    Page(s): 601 - 609
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (334 KB)  

    The problem of designing robust H controls for a large class of uncertain nonlinear time-varying systems involving parametric uncertainties, unmodelled perturbations, and external disturbances is addressed. A nonlinear H control technique is combined with the adaptive control technique and the variable structure control technique to construct a hybrid robust adaptive stabilisation controller that allows a H control to be achieved. Furthermore, the developed robust H stabilisation control scheme can be easily applied to the solution of robust tracking control design problems for a general class of uncertain nonlinear systems. A simulation problem involving the control of a nonlinear chaotic Chua's circuit is solved to confirm the effectiveness and performance of the developed tracking control scheme. View full abstract»

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  • Cost effective combined axial fan and throttling valve control of ventilation rate

    Page(s): 577 - 584
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (324 KB)  

    The proportional-integral-plus (PIP) control of ventilation rate in mechanically ventilated agricultural buildings is investigated. In particular, a fan and throttling valve control system for a 22 m3 test chamber that represents a section of a livestock building or glasshouse that is housed at the Katholieke Universiteit Leuven is presented. The throttling valve is used to restrict the airflow at the outlet, thereby generating a higher static pressure difference over the control fan. In contrast with previous approaches, however, the throttling valve is directly used as a second control actuator, utilising airflow from either the axial fan or natural ventilation. The proposed combined fan/valve configuration is compared with a commercially available PID-based (proportional-integral-derivative-based) controller and a previously developed scheduled PIP design, yielding a reduction in power consumption in both cases of up to 45%. View full abstract»

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  • H control for Markovian jump linear singularly perturbed systems

    Page(s): 637 - 644
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (296 KB)  

    The stochastic stability and H disturbance attenuation is studied for Markovian jump linear singularly perturbed systems (MJLSPS) via a matrix inequality approach. Both analysis and synthesis problems are investigated. In analysis, the stochastic stability and H performance conditions are derived and recast in the formulation of a set of coupled linear matrix inequalities. In synthesis, the sufficient conditions under which the closed-loop H disturbance attenuation performance turn out to be in the form of a set of coupled bilinear matrix inequalities and are solved with a proposed heuristic algorithm, and an ε-independent H controller can then be obtained. The reduced controller which is independent of the fast states is also developed. The results proposed apply not only to standard, but also to nonstandard MJLSPS. An example is presented to illustrate the proposed algorithm. View full abstract»

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  • Piecewise generalised H2 controller synthesis of discrete-time fuzzy systems

    Page(s): 554 - 560
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (443 KB)  

    A generalised H2 controller synthesis method for discrete-time fuzzy systems based on a piecewise Lyapunov function is presented. The basic idea of the proposed approach is to construct a controller for the discrete-time fuzzy systems in such a way that a piecewise Lyapunov function can be used to establish global stability with generalised H2 performance for the resulting closed-loop fuzzy control systems. It is shown that the control laws can be obtained by solving a set of linear matrix inequalities that are numerically tractable with commercially available software. An example is presented to demonstrate the advantage of the proposed approach. View full abstract»

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  • Adaptive tracking control solely using displacement feedback for a piezo-positioning mechanism

    Page(s): 653 - 660
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (458 KB)  

    An adaptive displacement tracking control using only displacement feedback is proposed for a piezo-positioning mechanism. In order to develop a dynamic model to represent the overall system dynamics of the controlled piezo-positioning mechanism, a specific function is proposed. This function that describes the hysteresis of the controlled mechanism contains information on the mechanical motion dynamics, hysteresis friction, disturbance load and parameter variations. Based on the developed model, an adaptive backstepping displacement tracking control is proposed, in which the backstepping adaptation of the specific function and the estimation of the reconstructed state with an unknown specific function are presented. The proposed control design leads to an improved tracking performance, and robustness to the external load-disturbance, and variations in system parameters. The validity of the proposed control design is demonstrated by experimental results. View full abstract»

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  • Stabilising intervalwise receding horizon H tracking controls for continuous time-varying systems

    Page(s): 526 - 530
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (258 KB)  

    A stabilising intervalwise receding horizon H tracking control (IHTC) for continuous time-varying systems that has a flexible computation time and guarantees a H norm bound is proposed. We also propose a stabilising IHTC with an integral control action for time-invariant systems that makes the tracking error approach zero asymptotically for a constant tracking command as well as satisfying a H norm bound. We illustrate the proposed results via simulation studies. View full abstract»

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  • Robust stability of linear neutral systems with nonlinear parameter perturbations

    Page(s): 539 - 546
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (289 KB)  

    The robust stability of uncertain linear neutral systems with time-varying discrete and neutral delays is investigated. The uncertainties under consideration are nonlinear time-varying parameter perturbations and norm-bounded uncertainties, respectively. Both delay-dependent and delay-derivative-dependent stability criteria are proposed and are formulated in the form of linear matrix inequalities. The presented results contain some existing results as their special cases. Numerical examples are also given to indicate significant improvements over existing results. View full abstract»

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  • Design of a dynamic output feedback controller for a class of neutral systems with discrete and distributed delays

    Page(s): 610 - 614
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (250 KB)  

    The design problem for a dynamic output feedback controller for asymptotic stabilisation of a class of neutral delay differential systems with discrete and distributed time delays is investigated. A criterion for the existence of such controllers is derived based on the matrix inequality approach combined with the Lyapunov method. A parameterised characterisation of the controllers is given in terms of the feasible solutions to the certain matrix inequalities, which can be solved by various convex optimisation algorithms. A numerical example is given to illustrate the availability of the proposed results. View full abstract»

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  • Stability bounds of singularly perturbed delay systems

    Page(s): 585 - 588
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (240 KB)  

    The stability problem of a linear time-invariant singularly perturbed delay system is considered. A sufficient condition is proposed to guarantee that the delay system is asymptotically stable. Both the time-varying delay and time-invariant delay are discussed. An explicit stability bound is obtained by using a state transformation and the Lyapunov direct method. A numerical example is presented to show the application of the proposed techniques. View full abstract»

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  • Pseudospectral technique for continuation methods with application to nonlinear control problems

    Page(s): 531 - 538
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (426 KB)  

    Continuation methods have been successfully applied to complicated nonlinear control systems design. Using a continuation algorithm, a nonlinear control problem can be transferred into a sequence of linear time-varying controls that can be solved using linear control theory. However, since the sequence of linear controls requires that the values of the previous state variables and control signal at each time interval be memorised and integrated as the initial values for the next linear control, the computation is quite intensive. Pseudospectral methods are proposed to solve the problem so that the heavy computational burden can be eased. Since a nonlinearly constrained programming problem becomes a sequence of linearly constrained programming problems due to the application of the continuation method, the presented algorithm prevents a main difficulty encountered in normally using pseudospectral algorithms for nonlinear optimal systems: a local minimum. This advantage makes the proposed scheme attractive to solve problems involving large and highly nonlinear control systems. View full abstract»

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  • Output feedback control of a class of nonlinear systems using direct adaptive fuzzy controller

    Page(s): 615 - 625
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (349 KB)  

    A stable adaptive fuzzy-logic controller based on output measurements is proposed for feedback linearisable nonlinear systems with unknown dynamics. A direct adaptive controller is derived. The fuzzy system approximates the optimal controller. A state feedback version of the controller is presented first which incorporates a supervisory control term to ensure system stability. The supervisory control technique is shown to be inadequate to provide system stability in output feedback. An output feedback version of the controller is presented which incorporates a high-gain observer with the advantage of casting the problem in a standard singular perturbation form, which helps in stability study. The system is shown to be semiglobally stable without the need for the supervisory control term. A detailed stability analysis is given which shows the boundedness of all system signals. Also, an upper bound on the tracking error norm is derived. Simulation results for a benchmark problem confirm the analysis and illustrate the performance of the proposed controller. View full abstract»

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  • Intelligent hybrid control for uncertain nonlinear systems using a recurrent cerebellar model articulation controller

    Page(s): 589 - 600
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (528 KB)  

    An intelligent hybrid control scheme, using an adaptive recurrent cerebellar model articulation controller (CMAC), is developed for a class of nonlinear dynamical systems. In this control system, an adaptive recurrent CMAC is used as the main tracking controller which mimics a perfect control law, and a compensated controller is designed to compensate for the difference between the perfect control law and the adaptive recurrent CMAC. The online adaptive laws of the control system are derived based on the Lyapunov stability theorem, so that the stability of the system can be guaranteed. In addition, in order to relax the requirement for a bound on the minimum approximation error, an adaptive estimation law is derived to estimate the approximation error bound in the compensated controller. Finally, the proposed control system is applied to control a Duffing forced oscillation system and a rocking motion for an aircraft wing. Simulation results demonstrate the effectiveness of the proposed control scheme for nonlinear systems with unknown dynamic functions. View full abstract»

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