Online ISSN
17518652
Print ISSN
17518644
IET Control Theory & Applications
Volume 4, Issue 7, July 2010
Volumes & issues:
Volume 4, Issue 7
July 2010

 Author(s): T.C. Yang ; C. Peng ; D. Yue ; M.R. Fei
 Source: IET Control Theory & Applications, Volume 4, Issue 7, p. 1109 –1121
 DOI: 10.1049/ietcta.2008.0571
 Type: Article
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Recently there is a great research interest in networked control systems (NCSs). The intended contributions of this study, in the order of they are presented, are (a) to point out a major limitation of current studies on NCSs: many theoretical results – although important and have some significant technical merit – cannot be applied to distributed control systems and therefore have little application value; (b) in contrast to that simple numerical examples – often linear systems – are widely used to demonstrate some theoretical results. The authors study the NCS controller design for a nonlinear unstable system, which has been historically used for the study of largescale system control; (c) application of a new design approach: it is suggested that the NCS controller design problem, where data packet time delay, loss or outoforder need to be addressed, is equivalent to a design problem where the system is pointtopoint connected but has delayed and unreliable measurement subsystems; (d) a theorem for the asymptotic stability of a class of nonlinear timedelay systems and (e) the stability theorem and the proposed new design approach are applied to the controller design for a model of a networkconnected nonlinear unstable system stated in (b). Extensive simulation results presented here have demonstrated the effectiveness of the proposed new design approach and the stability theorem.  Author(s): M. Sun and Y. Jia
 Source: IET Control Theory & Applications, Volume 4, Issue 7, p. 1122 –1130
 DOI: 10.1049/ietcta.2008.0415
 Type: Article
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In this study, a delaydependent H_{∞} performance criterion that possess decoupling structure is derived for a class of timedelay systems. It is then extended to H_{∞} statefeedback synthesis for timedelay systems with polytopic uncertainty and multichannel H_{∞} dynamic outputfeedback synthesis for timedelay systems. All the conditions are given in terms of the linear matrix inequalities. In some previous descriptor methods, the products of controller matrices and Lyapunov matrices are completely separated in performance analysis, whereas it is not the case in controller synthesis. However, with the method in the paper, the weakness is eliminated. Numerical examples illustrate the effectiveness of our solutions as compared to results obtained by other methods.  Author(s): H.K. Lam
 Source: IET Control Theory & Applications, Volume 4, Issue 7, p. 1131 –1144
 DOI: 10.1049/ietcta.2008.0599
 Type: Article
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This study investigates the system stability of sampleddata fuzzymodelbased control systems. To conduct the stability analysis, Takagi–Sugeno (TS) fuzzy model is employed to represent the continuoustime nonlinear plant. Based on the fuzzy model, a sampleddata fuzzy controller is proposed to perform the control task. By using a digital computer or microcomputer, the sampleddata fuzzy controller can be realised at low implementation cost. However, the following difficulties are needed to be addressed to put the sampleddata fuzzy controller into practice. First, as the zeroorderhold unit keeps the system states and control signal constant during the sampling period, the immediate system states cannot be accessed to compute the required control signal as what the continuoustime fuzzy control does. Second, the analoguetodigital and digitaltoanalogue converters introduce quantisation error to the control process, which is a source of instability. Third, the sampling activity introduces discontinuity to complicate the system dynamics, which makes the stability analysis difficult. Furthermore, it is due to the sampling activity and zeroorderhold unit, the nice property of continuoustime fuzzymodelbased control system for stability analysis vanishes which leads to conservative stability analysis results. In this study, these difficulties are addressed and the system stability is investigated based on the Lyapunov stability theorem. Membership function conditions are developed to facilitate the stability analysis. An application example is presented to illustrate the effectiveness of the proposed approach.  Author(s): Y. Zou ; T. Chen ; S. Li
 Source: IET Control Theory & Applications, Volume 4, Issue 7, p. 1145 –1156
 DOI: 10.1049/ietcta.2008.0577
 Type: Article
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This study investigates the problem of model predictive control (MPC) for networked multirate control systems (NMCSs) with the output sampling period several times larger than the input updating period. Both sensortocontroller and controllertoactuator networkinduced delays are considered and are assumed to be upperbounded by one output sampling period. Firstly, using a modified multirate MPC scheme, where the future control sequence is used to compensate for the networkinduced time delays, the closedloop NMCSs are described as switched systems. Sufficient stability conditions are established via a switched Lyapunov function approach. Then, a controller design method for stabilising NMCSs is proposed based on a finite input and state horizon cost with a finite terminal weighting matrix. The feedback gain matrix dependent of every sampling output can be obtained by solving linear matrix inequalities (LMIs). Finally, examples are provided to show the effectiveness of the proposed method.  Author(s): M. Bonin ; V. Seghezza ; L. Piroddi
 Source: IET Control Theory & Applications, Volume 4, Issue 7, p. 1157 –1168
 DOI: 10.1049/ietcta.2009.0217
 Type: Article
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The simulation error minimisation (SEM) approach is very effective for polynomial nonlinear autoregressive with exogenous variables (NARX) model selection, but is typically limited to the exploration of candidate regressor sets of limited size because of the computational cost involved in model simulation and the complexity of the empirical structure selection process over large candidate regressor sets. This study investigates the combination of a SEM algorithm for model selection, known as simulation error minimisation with pruning (SEMP), with the least absolute shrinkage and selection operator, which operates a regularisation that balances model accuracy with size in parameter estimation. The combined approach can greatly reduce the computational effort of the SEMP, without significantly affecting its accuracy, and sometimes improve the model selection quality with respect to the plain SEMP.  Author(s): L. De Tommasi ; B. Gustavsen ; T. Dhaene
 Source: IET Control Theory & Applications, Volume 4, Issue 7, p. 1169 –1178
 DOI: 10.1049/ietcta.2009.0025
 Type: Article
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The study introduces an enhanced version of the magnitude vector fitting (magVF) algorithm, a robust procedure for the identification of a transfer function from magnitude frequency domain data. The approach is based on the rational approximation of the magnitude square function with enforcement of symmetric poles and zeros, followed by the elimination of poles and zeros located in the right halfplane. The obtained transfer function is stable and of minimumphase shift type. Robustness and accuracy of the basic magVF algorithm are enhanced by enforcing that the magnitude square rational function is nonnegative definite and by introducing a new method to remove purely imaginary conjugate poles from the approximation. Practical application of the proposed approach is demonstrated for measured transformer responses and transmission line propagation functions.  Author(s): R. Ambrosino ; M. Ariola ; F. Amato
 Source: IET Control Theory & Applications, Volume 4, Issue 7, p. 1179 –1187
 DOI: 10.1049/ietcta.2008.0603
 Type: Article
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In this article, the authors study the robustness analysis problem for linear continuoustime systems subject to parametric timevarying uncertainties making use of piecewise linear (polyhedral) Lyapunov functions. A given class of Lyapunov functions is said to be ‘universal’ for the uncertain system under consideration if the search of a Lyapunov function that proves the robust stability of the system can be restricted, without conservatism, to the elements of the class. In the literature, it has been shown that the class of polyhedral functions is universal, while, for instance, the class of quadratic Lyapunov functions is not. This fact justifies the effort of developing efficient algorithms for the construction of optimal polyhedral Lyapunov functions. In this context, the authors provide a novel procedure that enables to construct, in the general ndimensional case, a polyhedral Lyapunov function to prove the robust stability of a given system. Some numerical examples are included, where the authors show the effectiveness of the proposed approach comparing it with other approaches proposed in the literature.  Author(s): B.S. Rüffer ; C.M. Kellett ; P.M. Dower ; S.R. Weller
 Source: IET Control Theory & Applications, Volume 4, Issue 7, p. 1188 –1200
 DOI: 10.1049/ietcta.2009.0233
 Type: Article
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Systems and control theory have found wide application in the analysis and design of numerical algorithms. The authors present an equivalent discretetime dynamical system interpretation of an algorithm commonly used in information theory called belief propagation (BP). BP is one instance of the socalled sum–product algorithm and arises, for example, in the context of iterative decoding of lowdensity paritycheck codes. The authors review a few known results from information theory in the language of dynamical systems and show that the typically very highdimensional, nonlinear dynamical system corresponding to BP has interesting structural properties. For the linear case, they completely characterise the behaviour of this dynamical system in terms of its asymptotic input–output map. Finally, the authors state some of the open problems concerning BP in terms of the dynamical system presented.  Author(s): G.S. Deaecto ; J.C. Geromel ; F.S. Garcia ; J.A. Pomilio
 Source: IET Control Theory & Applications, Volume 4, Issue 7, p. 1201 –1210
 DOI: 10.1049/ietcta.2009.0246
 Type: Article
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1201
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This study presents a novel procedure for switched affine systems control design specially developed to deal with switched converters where the main goal is to attain a set of equilibrium points. The main contribution is on the determination of a switching function, which assures global stability and minimises a guaranteed quadratic cost. The implementation of the switching function taking into account only partial information is analysed and discussed with particular interest. The theoretical results are applied to buck, boost and buck–boost converters control design. Several simulations show the usefulness of the methodology and its favourable impact in a class of realworld control design problems.  Author(s): F. Hao and X. Zhao
 Source: IET Control Theory & Applications, Volume 4, Issue 7, p. 1211 –1221
 DOI: 10.1049/ietcta.2009.0164
 Type: Article
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This study is concerned with the static outputfeedback stabilisation problem of discretetime networked control systems. If the controlled plant is a discretetime system, the networked control system with timevarying networkinduced delays and data packet dropouts in the transmission is modelled as a discretetime system with timevarying delays in the state. The networkinduced delays are assumed to have both an upper bound and a lower bound. Next, an asymptotic stability condition for the networked control systems is established, which depends on the upper and lower bounds of delay times. Then, three approaches to the static outputfeedback controller are proposed, where the effect of both networkinduced delays and data packet dropouts has been considered. Furthermore, the robust stability condition and controller design method for such networked control systems with structured uncertainties are presented. All the results are formulated in the terms of linear matrix inequalities (LMIs), which are numerically very efficiently solved via LMI toolbox in the Matlab. Finally, three examples are worked out to illustrate the feasibility and effectiveness of the proposed method.  Author(s): K. Xiong ; L. Liu ; Y. Liu
 Source: IET Control Theory & Applications, Volume 4, Issue 7, p. 1222 –1234
 DOI: 10.1049/ietcta.2009.0076
 Type: Article
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In this study, a nonlinear robust filter (NRF) is proposed for a satellite attitude determination system. The system under consideration is subject to both the model parameter uncertainties and the linearisation errors. The proposed NRF is derived to guarantee an optimised upper bound on the estimation error covariance. The characteristics of the filter are analysed using some standard results from stochastic stability theory. It is specified that the stability of the proposed algorithm can be guaranteed independent of the model uncertainties as well as the linearisation errors. In addition, the efficiency of the NRF is demonstrated with the telemetry data from a satellite. The algorithm is developed in general such that it can be applied to stochastic uncertain nonlinear systems other than satellite attitude determination.  Author(s): H. Yuan and Z. Qu
 Source: IET Control Theory & Applications, Volume 4, Issue 7, p. 1235 –1244
 DOI: 10.1049/ietcta.2008.0413
 Type: Article
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The feedback stabilisation problem of nonholonomic chained systems and a novel feedback design scheme is proposed, which renders a smooth, timevarying, aperiodic, pure feedback control with exponential convergence rates. There are three main advantages with the proposed design. (i) In general, timevarying designs are mostly periodic and render asymptotic stability, whereas the proposed approach is aperiodic and have exponential convergent rates. (ii) A novel state scaling transformation is proposed. It shows that even though u_{1} vanishes in regulation problems, intrinsic controllability of chained systems can be regained by judiciously designing the input u_{1} and by applying the state scaling transformations. (iii) A class of memory functions is introduced into the control design, the controller dependency on the system's initial conditions in our previous work is removed and the control is a pure feedback. Moreover, the design is shown to be inversely optimal. Simulations and comparisons are conducted to verify the effectiveness of the proposed approach.  Author(s): Z.Y. Li ; B. Zhou ; Y. Wang ; G.R. Duan
 Source: IET Control Theory & Applications, Volume 4, Issue 7, p. 1245 –1253
 DOI: 10.1049/ietcta.2009.0015
 Type: Article
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The matrix equation Σ^{l}_{i=1}A_{i}XB_{i} = C, which contains the wellknown Sylvester matrix equation and Lyapunov matrix equation as special cases, has many important applications in control system theory. This study presents an iterative algorithm to solve such linear matrix equation. It is shown that the proposed algorithm converges to the unique solution to the linear matrix equation at finite steps for arbitrary initial condition. Moreover, if the matrix equation is not consistent, the least squares solution can be obtained by alternatively solving a linear matrix equation in the same form, which can also be solved by the proposed iterative algorithm. Numerical example shows the effectiveness of the proposed approach.  Author(s): F.K. Yeh
 Source: IET Control Theory & Applications, Volume 4, Issue 7, p. 1254 –1264
 DOI: 10.1049/ietcta.2009.0026
 Type: Article
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In this study, the authors propose two nonlinear attitude controllers, mainly consisting of the slidingmode attitude tracking controller and the slidingmode adaptive attitude tracking controller, for spacecrafts with thrusters to follow the predetermined trajectory in outer space by use of employing the spacecraft's attitude control. First, the attitude model and nonlinear controllers of the attitude control system of a spacecraft are established and derived, considering the external forces suffering from the gradient torque in a gravitational field because of universal gravitation, the optical torque because of solar shining and so on, to utilise the slidingmode and/or adaptive control theory for designing the nonlinear attitude controllers. Also, we consider the variation of moment inertia matrix of a spacecraft during the whole flying course to analyse their influences for the practical controller design as the conditions of limitation and correction. Simultaneously, the authors use both the adaptive control theory and the slidingmode control to estimate parameters and eliminate disturbances of the attitude control system. Accordingly, the nonlinear attitude controllers of a spacecraft are designed while the spacecraft is flying. Finally, the authors employ the Lyapunov stability theory to fulfil the stability analysis of two nonlinear controllers for the overall nonlinear attitude control system. Extensive simulation results are obtained to validate the effectiveness of the proposed attitude controllers.  Author(s): R. MuñozMansilla ; J. Aranda ; J.M. Díaz ; D. Chaos
 Source: IET Control Theory & Applications, Volume 4, Issue 7, p. 1265 –1276
 DOI: 10.1049/ietcta.2009.0152
 Type: Article
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In this work, the problem of stabilisation of a highspeed craft with coupled dynamics is addressed. The action of the actuators to control the longitudinal dynamics (heave and pitch modes) produces a coupling in the transversal dynamics (roll mode), and vice versa. A combination of quantitative feedback theory (QFT) robust methodology and eigenstructure assignment (EA) methods is used to control the coupled system on a highspeed craft. The multiinput multioutput (MIMO) problem is firstly handled with the EA technique in order to decouple the dynamics, which results in three singleinput singleoutput (SISO) systems to solve with QFT design. Dynamic responses of roll, pitch and heave modes of the entire fast ferry system are analysed at different sea states and angles of incidence. Timedomain simulations and frequencydomain performance analyses provide satisfactory results. It is shown that the combined EA/QFT technique is a feasible and very suitable robust method that can accomplish decoupling and damped responses and consequently a reduction in the motion sickness.
New study of controller design for networked control systems
Delaydependent robust H_{∞} control of timedelay systems
Sampleddata fuzzymodelbased control systems: stability analysis with consideration of analoguetodigital converter and digitaltoanalogue converter
Networkbased predictive control of multirate systems
NARX model selection based on simulation error minimisation and LASSO
Robust transfer function identification via an enhanced magnitude vector fitting algorithm
Stability and instability conditions using polyhedral Lyapunov functions
Belief propagation as a dynamical system: the linear case and open problems
Switched affine systems control design with application to DC–DC converters
Linear matrix inequality approach to static outputfeedback stabilisation of discretetime networked control systems
Nonlinear robust filter design for satellite attitude determination
Smooth timevarying pure feedback control for chained nonholonomic systems with exponential convergent rate
Numerical solution to linear matrix equation by finite steps iteration
Slidingmode adaptive attitude controller design for spacecrafts with thrusters
Robust control for highspeed crafts using QFT and eigenstructure assignment

 Author(s): B. Zhou ; J. Hu ; G.R. Duan
 Source: IET Control Theory & Applications, Volume 4, Issue 7, p. 1277 –1281
 DOI: 10.1049/ietcta.2008.0597
 Type: Article
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p.
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Positive realness is an important concept in control theory. For linear discretetime descriptor systems, the positive realness lemma involves nonstrict linear matrix inequality (LMI) and may cause numerical problems in practice. Here, strict LMI characterisation for positive realness for linear discretetime descriptor systems is established. The new characterisation can be efficiently solved by the standard LMI toolbox and may take important functions in related design problems.  Author(s): Q. Zong ; Z.S. Zhao ; J. Zhang
 Source: IET Control Theory & Applications, Volume 4, Issue 7, p. 1282 –1289
 DOI: 10.1049/ietcta.2008.0610
 Type: Article
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A higher order sliding mode control (SMC) with selftuning law algorithm for uncertain nonlinear systems is proposed. The method can be viewed as the finite time stabilisation based on geometric homogeneity and integral SMC. In order to reduce chattering and solve system uncertainties with unknown bound, a bipolar sigmoid function online adaptation and an adjustable control gain tuning approach without highfrequency switching are developed. Control system stability is ensured using the Lyapunov method. An example is given to show the effectiveness of the developed approach.  Author(s): Q. Quan ; D. Yang ; K.Y. Cai
 Source: IET Control Theory & Applications, Volume 4, Issue 7, p. 1290 –1297
 DOI: 10.1049/ietcta.2009.0135
 Type: Article
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This study mainly focuses on the stability of a class of linear neutral systems in a critical case, that is, the spectral radius of the principal neutral term (matrix H) is equal to 1. It is difficult to determine the stability of such systems by using existing methods. In this study, a sufficient stability criterion for the critical case is given in terms of the existence of solutions to a linear matrix inequality (LMI). Moreover, it is also shown that the proposed stability criterion conforms with a fact that the considered linear neutral systems are unstable when H has a Jordan block corresponding to the eigenvalue of modulus 1. An illustrative example is presented to determine the stability of a linear neutral system whose principal neutral term H has multiple eigenvalues of modulus 1 without Jordan chains. This is difficult in existing studies.  Author(s): D.Y. Chao
 Source: IET Control Theory & Applications, Volume 4, Issue 7, p. 1298 –1302
 DOI: 10.1049/ietcta.2009.0118
 Type: Article
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p.
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Siphonbased control suffers from the problem that the number of problematic siphons grows quickly with the size of the system. To reduce the number of monitors, Li and Zhou proposed to divide problematic siphons into elementary and dependent ones. Monitors are added only for elementary siphons; the number of which grows linearly. They adjust the control depth variable for a dependent siphon, if the siphon does not satisfy the controllability and can become unmarked. The control policy for weakly dependent siphons is rather conservative because of some negative terms in the controllability. This study proposes a better estimate of the negative terms and the policy needs no longer be that conservative.
Strict linear matrix inequality characterisation of positive realness for linear discretetime descriptor systems
Higher order sliding mode control with selftuning law based on integral sliding mode
Linear matrix inequality approach for stability analysis of linear neutral systems in a critical case
Conservative control policy for weakly dependent siphons in S^{3}PR based on elementary siphons
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