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Control Theory and Applications, IEE Proceedings -

Issue 6 • Date 4 Nov. 2005

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Displaying Results 1 - 14 of 14
  • Sampled-data stabilisation of networked control systems with nonlinearity

    Publication Year: 2005 , Page(s): 609 - 614
    Cited by:  Papers (35)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (163 KB)  

    A new approach to robust stabilisation of a class of sampled-data systems with nonlinear uncertainties is proposed. The case that the plant and the controller are connected via a network channel, which may be subjected to data packet dropout and communication delays is of particular interest. Such systems as continuous-time nonlinear systems with delayed input are modelled. Sufficient conditions on the existence of stabilising state feedback controllers are established in terms of linear matrix inequalities (LMIs). One advantage of the present method is that the maximum bound on the nonlinearity can be computed by solving a constrained convex optimisation problem; another is that the upper bound on the delayed input can be obtained by solving a quasi-convex optimisation problem. Finally, a simulation example is worked out to illustrate the efficiency and feasibility of our proposed approach. View full abstract»

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  • Reinforcement adaptive fuzzy control of wing rock phenomena

    Publication Year: 2005 , Page(s): 615 - 620
    Cited by:  Papers (5)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (227 KB)  

    Wing rock phenomena is a limit cycle roll oscillation experienced by aircraft with slender delta wings at a high angle of attack. A new reinforcement adaptive fuzzy control scheme is proposed for suppressing or tracking wing rock phenomena. A fuzzy logic system is used to approximate a unknown nonlinear dynamics in which a variable universe technique is applied to modify the premise parameters of FLS for improving its interpolation precision, and the derived adaptive law combining with a reinforcement-learning strategy is applied to tune its consequent parameters. The novelty of the proposed control scheme is mainly in its simplicity, robustness and stability so that it can be applied for online learning and real-time control. Three cases of time-varying wing rock control under disturbances are simulated to confirm the effectiveness and robustness of the proposed scheme. View full abstract»

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  • Eigenvalue assignment with optimal spectral conditioning by static output feedback

    Publication Year: 2005 , Page(s): 621 - 627
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (156 KB)  

    This paper presents a method for the robust assignment of the eigenvalues of a linear system by static output feedback, based on the minimisation of the spectral condition number of the closed-loop dynamic matrix. The procedure relies on an assignment method recently proposed by the authors, that enables the explicit parameterisation of the set of the feedback gain matrices which assign the prescribed closed-loop spectrum, and on the column-scaling properties of eigenvector matrices. The efficiency of the approach is demonstrated using several extensive numerical experiments. View full abstract»

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  • Delay-dependent robust H controller design for uncertain descriptor systems with time-varying discrete and distributed delays

    Publication Year: 2005 , Page(s): 628 - 638
    Cited by:  Papers (11)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (206 KB)  

    The design problem of a delay-dependent robust H controller for uncertain descriptor systems with time-varying discrete and distributed delays is investigated. The designed controller can guarantee the closed-loop system is regular, impulse-free and exponentially stable with an H norm bound constraint. The obtained criteria to derive an efficient robust H control design are expressed as a set of nonconvex matrix inequalities, which can be solved by combining both the linear matrix inequalities technique and the cone complementarity method. Two numerical examples are given to demonstrate effectiveness and less conservativeness of the proposed method. View full abstract»

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  • Successive-approximation approach of optimal control for bilinear discrete-time systems

    Publication Year: 2005 , Page(s): 639 - 644
    Cited by:  Papers (21)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (169 KB)  

    A successive-approximation approach designing optimal controllers is developed for bilinear discrete-time systems with a quadratic performance index. By using the successive-approximation approach, the original optimal control problem is transformed into a sequence of nonhomogeneous linear two-point boundary-value problems. The optimal control law consists of an accurate linear term and a nonlinear compensating term that is the limit of the adjoint vector sequence. Through a finite-step iteration process of a nonlinear compensating sequence a suboptimal control law is obtained. Simulation results show that the algorithm is easily implemented and has a fast convergence rate. View full abstract»

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  • Steering control of a hopping robot model during the flight phase

    Publication Year: 2005 , Page(s): 645 - 653
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (270 KB)  

    Two different types of steering control strategies for a hopping robot model during the flight phase are presented. The first strategy presents a time-varying feedback law based on the model reference approach, where the trajectory of the extended system is chosen as the model reference trajectory. The controllers are designed in such a way that after each time period the trajectory of the hopping robot model intersects the trajectory of the model reference, which can be made asymptotically stable. The second strategy presents discontinuous, state-dependent feedback control laws based on the construction of a cost function V which is the sum of two semi-positive definite functions V1 (consists of the first m state variables which can be steered along the given vector fields) and V2 (consists of the remaining n-m state variables which can be steered along the missing Lie brackets). The values of the functions V1 and V2 allow the determination of a desired direction of system motion and permit the construction of a sequence of controls such that the sum of these functions decreases in an average sense. View full abstract»

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  • Low-hump sensitivity function design for dual-stage HDD systems with different microactuators

    Publication Year: 2005 , Page(s): 655 - 661
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (392 KB)  

    The paper focusses on a control design that aims to achieve a low hump sensitivity function for dual stage servo systems in hard disk drives. Two microactuator models are studied, a MEMS (microelectromechanical system) actuator and a PZT (piezoelectric) actuator. A nearly flat sensitivity function is accomplished in the continuous-time domain for the dual-stage servo loop using the H-loop shaping method and an LMI (linear matrix inequality) approach. The implementation result for the parallel dual-stage system with a PZT-actuated suspension demonstrates the effectiveness of the proposed design and the hump of the sensitivity function is shown to be lower than 3 dB. View full abstract»

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  • H model reduction of linear systems with distributed delay

    Publication Year: 2005 , Page(s): 662 - 674
    Cited by:  Papers (6)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (306 KB)  

    This paper is concerned with the problem of H model reduction for linear distributed-delay systems. For a given stable system containing both discrete and distributed delays in the state, our attention is focused on the construction of reduced-order model of the same structure, which guarantees the corresponding error system to be asymptotically stable and has a prescribed H norm error performance. This problem is solved through a delay-dependent approach. By defining a new Lyapunov functional and making use of the Newton-Leibniz formula, a delay-dependent bounded real lemma is first established in terms of linear matrix inequalities (LMIs). Based on this performance criterion and by employing the projection lemma, sufficient conditions are formulated for the existence of admissible reduced-order models. Owing to the presence of matrix inverse constraints, these conditions are intrinsically nonconvex. An algorithm based on the sequential linear programming matrix method is proposed for verifying these conditions, which can be readily implemented by using standard numerical software. Desired reduced-order models can be constructed if these conditions are satisfied. The effectiveness of the proposed model reduction method is illustrated via a numerical example. View full abstract»

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  • Computation of performance robustness bounds for control systems with parameter uncertainties: an LMI approach

    Publication Year: 2005 , Page(s): 675 - 682
    Cited by:  Papers (3)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (178 KB)  

    The problem of computing an upper bound on the size of parameters to guarantee the β-boundedness of control systems with parametric uncertainties is focused. Based on an improved linear matrix inequality (LMI) representation of β-boundedness criteria for polytopic uncertain systems, this problem is transformed into a generalised eigenvalue problem, which can be easily tested with efficient LMI algorithms. Results are proved to be less conservative than those results based on the classical β-bounded criterion. Two numerical examples are given to illustrate the results. View full abstract»

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  • Synchronised trajectory-tracking control of multiple 3-DOF experimental helicopters

    Publication Year: 2005 , Page(s): 683 - 692
    Cited by:  Papers (18)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1811 KB)  

    A synchronised trajectory-tracking control strategy is proposed for multiple experimental three-degrees-of-freedom helicopters. The model-based controller includes a feedforward compensation term and a PD feedback control term. Asymptotic convergence is achieved for both trajectory tracking and motion synchronisation. A proposed generalised synchronisation error concept allows the design of different synchronisation strategies so that different synchronisation performance can be reached. Experimental results verify the effectiveness of the proposed controller. View full abstract»

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  • H2 gain scheduled state feedback for LPV system with new LMI formulation

    Publication Year: 2005 , Page(s): 693 - 697
    Cited by:  Papers (25)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (133 KB)  

    The H2 gain scheduled state feedback problem is considered by using the parameter-dependent Lyapunov function for linear parameter varying system, in which the dependent parameter is assumed to be measurable on-line in a polytope space. First, a new linear matrix inequality (LMI) representation provides a type of H2 cost computation for this system. With the introduction of the extra variable, this condition provides a decoupling between Lyapunov function matrix and system matrices and will be useful for a synthesis problem study. Secondly, using a polytopic characteristic of the dependent parameter, based on this representation gain scheduled state, the feedback synthesis problem can be transformed into finite-dimensional LMIs formulation. In addition, by using the parameter-dependent Lyapunov function, it can reduce the conservatism that occurred before in the H2 performance synthesis problem with a fixed Lyapunov function. Finally, a numerical example is included to illustrate the efficiency of the proposals. View full abstract»

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  • Neural observer by coordinate transformation

    Publication Year: 2005 , Page(s): 698 - 706
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (246 KB)  

    Nonlinear control affine systems with maximum relative degree and a class of nonlinear differential equations can be transformed into a state representation known as the normal form. Based on the normal form an observer is designed using neural networks as approximation of nonlinear terms in the normal form and the observer gain is determined with a previous result in a triangular form. View full abstract»

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  • Delay-dependent stability criteria for uncertain neutral systems with multiple time-varying delays via LMI approach

    Publication Year: 2005 , Page(s): 707 - 714
    Cited by:  Papers (12)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (171 KB)  

    The asymptotic stability conditions for a class of uncertain neutral system with multiple time-varying delays are considered. LMI-based delay-dependent criteria are proposed to guarantee the asymptotic stability of systems. Based on the results of this paper, the model transformation is not used in finding the delay-dependent results. Significant improvement for the delay-dependent results has been developed and proposed. Finally, some numerical examples are illustrated to show the improvement of this paper. View full abstract»

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  • Global positioning system receiver tracking-loop optimisation via an H approach

    Publication Year: 2005 , Page(s): 715 - 722
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (356 KB)  

    The application of H optimal control theory to global positioning system receiver tracking loops is investigated. The design of an H controller for the receiver tracking-loop is presented. The H controller is particularly attractive because it is a robust design in the sense that small disturbances lead to small tracking errors. Furthermore, it easily accommodates the inclusion of plant uncertainties as part of the plant model. By adding unstructured or structured perturbations to the plant model, it is possible to design controllers that ensure stability robustness and performance robustness of the closed-loop system. In order to apply the H optimal design, the GPS receiver tracking loop is rewritten into a two-input two-output generalised plant model. Various levels of disturbances are derived using a software-based GPS L5 signal generator which are then used as test inputs to evaluate the performance of the proposed tracking loop. View full abstract»

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