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Control Theory & Applications, IET

Issue 4 • Date March 7 2013

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Displaying Results 1 - 15 of 15
  • Distributed Kalman filtering: a bibliographic review

    Publication Year: 2013 , Page(s): 483 - 501
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (801 KB)  

    In recent years, a compelling need has arisen to understand the effects of distributed information structures on estimation and filtering. In this study, a bibliographical review on distributed Kalman filtering (DKF) is provided. The study contains a classification of different approaches and methods involved to DKF. The applications of DKF are also discussed and explained separately. A comparison of different approaches is briefly carried out. Focuses on the contemporary research are also addressed with emphasis on the practical applications of the techniques. An exhaustive list of publications, linked directly or indirectly to DKF in the open literature, is compiled to provide an overall picture of different developing aspects of this area. View full abstract»

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  • Bounded real lemma for positive discrete systems

    Publication Year: 2013 , Page(s): 502 - 507
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (148 KB)  

    The bounded real lemma for positive discrete time-invariant systems is addressed in this study. The results about bounded real lemma for continuous time-invariant systems are extended into discrete time-invariant systems. Such systems are asymptotically stable and their H norm less than one is equivalent to that the corresponding linear matrix inequality admits a diagonal positive-definite solution. The last example in this study illustrates the result does not hold for general discrete time-invariant systems. View full abstract»

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  • Exponential synchronisation of hybrid impulsive and switching dynamical networks with time delays

    Publication Year: 2013 , Page(s): 508 - 514
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (324 KB)  

    This study formulates and studies a model of hybrid impulsive and switching dynamical networks with time delays. There are two separable switching functions acting on the network. One drives inherent network structures and the other induces finite-state feedback in the control law. These hybrid networks have both continuous-time and discrete-time dynamics. At each moment, the coupling structure changes from one graph to another. At the same time, the continuous state variables may jump from one value to another. Time delays considered in this paper exist in isolated dynamical nodes, interconnections and impulsive noise disturbances. Based on Lyapunov stability theory, some new sufficient criteria are derived for exponential convergence of disagreement dynamics, which implies that network synchronisation of such hybrid-delayed network is achieved. An illustrative example of a delayed chaotic network with switching topology and impulse effects is used to demonstrate the main results. View full abstract»

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  • Diagonal stabilisation of a class of single-input discrete-time switched systems

    Publication Year: 2013 , Page(s): 515 - 522
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (295 KB)  

    The stabilisation problem for a class of single-input discrete-time switched control systems is considered based on common diagonal quadratic Lyapunov functions and switched diagonal quadratic Lyapunov functions, respectively. Sufficient conditions for diagonal stabilisation of the concerned systems are derived in terms of linear inequalities. Numerical examples are finally used to illustrate the effectiveness of the obtained results. View full abstract»

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  • Robust H output feedback control with partly quantised information

    Publication Year: 2013 , Page(s): 523 - 536
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (495 KB)  

    This study is concerned with the stability and stabilisability problems of networked control systems (NCSs) with partly quantised information. More precisely, the remote state variables transported from other sub-systems experience different network-induced time delays and quantisation errors, whereas the local state variables do not. This consideration is much more natural in NCSs because of the distributive nature of sensors and controllers, even systems. Network-induced time delays are introduced as a Markov chain and quantisation errors are represented as convex polytopic uncertainties. Based on the Lyapunov-Krasovskii functional approach, sufficient conditions for the existence of a quantised robust H output feedback controller for NCSs are presented. Such conditions are obtained in terms of bilinear matrix inequalities (BMIs). Furthermore, a cone complementarity algorithm is utilised to convert these BMIs into a convex optimisation problem. Finally, a simulation example is provided to demonstrate the efficiency of proposed theorems. View full abstract»

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  • Signed directed graph-based hierarchical modelling and fault propagation analysis for large-scale systems

    Publication Year: 2013 , Page(s): 537 - 550
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (951 KB)  

    The signed directed graph (SDG) model can be considered as a qualitative model to describe the variables and their cause-effect relations in a continuous process. Such models can allow one to obtain the fault propagation paths using the method of graph search. In this way, the authors can use SDGs to model and analyse the propagation of faults in large-scale industrial systems. However, with increasing system scales, the time requirements of a graph search method would be too onerous. This can be alleviated by transforming a single-layer SDG model into a hierarchical model to improve search efficiency. The hierarchical model would be composed of three layers: the top layer would consist of independent sub-systems; the middle layer would have control systems configuration and the bottom layer would have all the variables. The possible root causes of faults can then be searched in this model, layer by layer according to the initial response of the system. The efficacy of the proposed approach is illustrated by application to a four-tank system and a generator system in a power plant. The methodology presented here can also be used in process hazard analysis. View full abstract»

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  • Non-linear generalised minimum variance control using unstable state-dependent multivariable models

    Publication Year: 2013 , Page(s): 551 - 564
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (823 KB)  

    A non-linear generalised minimum variance (NGMV) control law is derived for systems represented by an input-output state dependent non-linear (NL) subsystem that may be open-loop unstable. The solution is obtained using a model for the multivariable discrete-time process that includes a state-dependent (NL and possibly unstable) model that links the output and any `unstructured' NL input subsystem. The input subsystem can involve an operator of a very general NL form, but this has to be assumed to be stable. This is the first NGMV control solution that is suitable for systems containing an unstable NL sub-system which is contained in the state-dependent model. The process is also assumed to include explicit common delays in input or output channels. The generalised minimum variance cost index to be minimised involves both dynamically weighted error and control signal costing terms. It may also include weighted values of the system states for greater generality. The controller derived is simple to implement considering the complexity of the system represented. If the plant is stable the controller structure can be manipulated into an internal model control form. This form of the controller is like an NL version of the Smith Predictor which is valuable for providing confidence in the solution. View full abstract»

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  • Domain of attraction and guaranteed cost control for non-linear quadratic systems. Part 2: controller design

    Publication Year: 2013 , Page(s): 565 - 572
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (282 KB)  

    This study addresses the problem of designing a guaranteed cost controller for non-linear discrete quadratic systems. More specifically, the main contribution concerns a sufficient condition for the existence of a state-feedback controller achieving a certain guaranteed cost, whenever the state trajectories start from a prescribed set of initial conditions. The controller design requires the solution of a convex optimisation problem involving linear matrix inequalities, which can be efficiently solved via available optimisation algorithms. Finally, the proposed design methodology is illustrated via an example concerning the attitude control of an unmanned aerial vehicle. View full abstract»

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  • Brief Paper - Universal Kriging control of hypersonic aircraft model using predictor model without back-stepping

    Publication Year: 2013 , Page(s): 573 - 583
    Cited by:  Papers (3)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (548 KB)  

    This study describes the design of adaptive universal Kriging (UK) controller for the longitudinal dynamics of a generic hypersonic flight vehicle (HFV). The altitude subsystem is transformed into the explicit four-step ahead state predictor model, which provides the relationship between states and future outputs. Furthermore, the input--output predictor model is derived to obtain the input information for the UK estimator. The UK takes advantages of the parametric regression model and simple Kriging model to describe the systematic aspects and local fluctuations of unknown functions simultaneously. With the state prediction feedback and input--output UK estimation, the controller is synthesised. The control scheme is considerably simpler than the ones based on back-stepping since only one Kriging system is employed to approximate the lumped system uncertainty. Owing to the prediction function and the UK structure, the novel stochastic Lyapunov function-based stability analysis is conducted. The closed-loop system achieves almost surely boundedness. The effectiveness of the proposed control approach is verified by step tracking. View full abstract»

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  • Brief Paper - Multi-stage control strategy for quantised feedback control systems

    Publication Year: 2013 , Page(s): 584 - 593
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (944 KB)  

    This study establishes a multi-stage control strategy that can systematically reduce the effect of quantisation errors without resort to any prescribed control gains applicable to the stabilisation of quantisation-free systems. First of all, a two-stage control strategy is built under a fixed quantisation sensitivity, and then a multi-stage control strategy is established on the possibility of adjusting on-line the quantisation sensitivity. In the derivation, the overall control law is constructed with linear and non-linear feedback controls, where non-linear feedback control plays an important role of eliminating the effect of control input quantisation errors. View full abstract»

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  • Brief paper - H state-feedback control of bilateral teleoperation systems with asymmetric time-varying delays

    Publication Year: 2013 , Page(s): 594 - 605
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (656 KB)  

    In this study, a novel controller synthesis method is proposed for the bilateral teleoperation systems with asymmetric time-varying delays. The main idea of the proposed method is to deal with the control problem for a bilateral teleoperation system under asymmetric time-varying delays as a control problem for a system with multiple input time delays, and then to find the state-feedback control law to stabilise the system with guaranteed H performance on the defined control output. With intentionally introducing the pretend time delays to the (local) state variables of the master or the slave, the teleoperation controller design problem is converted to a controller synthesis problem for a system with multiple input time delays. Then the state-feedback controllers are designed for both the master and the slave by defining an appropriate Lyapunov-Krasovskii functional candidate and solving linear matrix inequalities. The designed controllers guarantee the closed-loop system stability and system transparency performance in terms of the optimised H norm on the position and force tracking errors between the master and the slave. At last numerical simulations are used to validate the effectiveness of the proposed method. The results show that the designed controllers can effectively stabilise the present teleoperation system with good transparency performance under time-varying delays. View full abstract»

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  • Brief Paper - Controlled invariance-based fault detection for multisensory control systems

    Publication Year: 2013 , Page(s): 606 - 611
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (257 KB)  

    In this study, set theoretic methods are used to design a fault-tolerant scheme for a multisensor control application. The basic principle is the separation of the invariant sets for the estimations of the state and tracking error under healthy and faulty functioning. The fault scenario assumes abrupt changes of the observation equations. The main contribution of this paper is the introduction of controlled invariant sets in the fault detection mechanism. The control action is chosen in order to guarantee the closed-loop positive invariance of a candidate region when the exogenous signals (additive disturbances, noise and reference/set-points) are bounded. View full abstract»

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  • Brief Paper - Distributed thermal aware load balancing for cooling of modular data centres

    Publication Year: 2013 , Page(s): 612 - 622
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (678 KB)  

    Thermal management in data centres requires a complicated trade-off between cooling costs and thermally induced equipment failure rates. Using ideas from cooperative control and distributed rate limiting, in this study the authors describe a distributed architecture that can be used for thermal aware load balancing for a common type of modular data centre; namely an algorithm that, for a given demand D*, distributes load to individual machines such that the temperatures in the individual modules are equalised. The benefit of shifting load based on thermal considerations is that significant gains in cooling cost can be achieved. We evaluate the performance of the algorithm using computational fluid dynamics and Matlab simulations. The results show that significant cost savings can be made by applying such algorithms, and that these can be achieved without the need for detailed modelling and tuning of controllers. View full abstract»

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  • Brief Paper - Output tracking control for a class of switched non-linear systems with partial state constraints

    Publication Year: 2013 , Page(s): 623 - 631
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (422 KB)  

    In this study, we deal with the output tracking control problem for a class of switched non-linear systems in lower triangular form subject to constraints on the states. To prevent states from transgressing the constraints, we employ a barrier Lyapunov function (BLF), which grows to infinity when its arguments approach domain boundaries. Based on the simultaneous domination assumption, we design a continuous feedback controller for the switched system. Furthermore, we show that asymptotic tracking is achieved without violation of the constraints and all closed-loop signals remain bounded, when a mild requirement on the initial values is imposed. Finally, the effectiveness of the proposed results is demonstrated using two simulation examples. View full abstract»

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  • Correction to 'New controllability condition for siphons in a class of generalised Petri nets'

    Publication Year: 2013 , Page(s): 632 - 633
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (78 KB)  

    Siphons control plays an important role in deadlock prevention for flexible manufacturing systems modelled with Petri nets [1, 2]. In a generalised Petri net, siphon controllability is investigated in [3-8]. In the above paper [9], a weaker controllability condition of siphons is proposed. However, there are some misprints. View full abstract»

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IET Control Theory & Applications is devoted to control systems in the broadest sense, covering new theoretical results and the applications of new and established control methods.

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