Online ISSN
1751-8652
Print ISSN
1751-8644
IET Control Theory & Applications
Volume 1, Issue 3, May 2007
Volumes & issues:
Volume 1, Issue 3
May 2007
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- Author(s): T. Insperger and G. Stépán
- Source: IET Control Theory & Applications, Volume 1, Issue 3, p. 553 –557
- DOI: 10.1049/iet-cta:20060051
- Type: Article
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p.
553
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(5)
Linear n-dimensional discrete-time systems are considered with feedback delay r at the m-dimensional input. These systems have n+mr poles. The act-and-wait control concept is introduced: the feedback is periodically switched on and off during the control with period k. It is switched on for one step (act) and switched off for (k−1) number of steps (wait). It is shown that if the act-and-wait period is larger than the time delay (i.e. k>r), then mr poles of the system are equal to zero, and the remaining poles can be placed arbitrarily if the system matrices satisfy certain controllability conditions. - Author(s): A.-G. Wu ; G.-R. Duan ; S.-M. Zhao
- Source: IET Control Theory & Applications, Volume 1, Issue 3, p. 558 –563
- DOI: 10.1049/iet-cta:20060219
- Type: Article
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The concept of impulsive-mode controllablisability has been proposed. The criteria of impulsive-mode controllablisability are established in terms of the original system matrices. It is pointed out that the impulsive-mode controllablisability is the necessary and sufficient condition for the existence of impulsive-mode eliminating proportional–derivative (PD) state feedback control. Therefore the conditions for impulsive-mode elimination via PD state feedback are really given. - Author(s): C.-Y. Li and W.-X. Jing
- Source: IET Control Theory & Applications, Volume 1, Issue 3, p. 564 –571
- DOI: 10.1049/iet-cta:20060370
- Type: Article
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p.
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A fuzzy set-point weighting proportional–integral–derivative (PID) controller is applied in the development of the flight control system for a two-dimensional differential geometric (DG) guidance and control system, whose function is to guarantee the achieved angle of attack (AOA) and track the commanded AOA efficiently. In particular, a Lyapunov stability criterion is introduced to study the relation between the stability and the output of the fuzzy inference system, and a genetic algorithm is utilised to tune the PID gains in the simulations so as to show the full potentiality of the proposed control scheme. The results demonstrate that the designed controller yields a fast-responding and stable system that is robust to parameter variations. Moreover, the DG guidance law is viable and effective in a realistic missile defence engagement. - Author(s): J.-T. Huang
- Source: IET Control Theory & Applications, Volume 1, Issue 3, p. 572 –577
- DOI: 10.1049/iet-cta:20060130
- Type: Article
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Verifiable sufficient conditions for parameter convergence of a class of adaptive input-output linearisable systems with unknown parameters, including those affine with the control input, are provided. Certainty-equivalent adaptive control has solved the tracking problem for a wider class of systems; however, parameter convergence has not so far been verified a priori. By taking advantage of the obtained asymptotic tracking stability and the vanishing time derivatives of the estimated parameters, it is found that it can indeed be checked beforehand provided some mild assumptions are satisfied. The results are then applied directly to a Chua's circuit to demonstrate their utility. - Author(s): Z. Gao and S.X. Ding
- Source: IET Control Theory & Applications, Volume 1, Issue 3, p. 578 –585
- DOI: 10.1049/iet-cta:20050509
- Type: Article
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A descriptor system approach is introduced to investigate sensor fault reconstruction and sensor compensation for a class of nonlinear state-space systems with Lipschitz constraints. Letting the sensor fault term be an auxiliary state vector, an augmented descriptor system is constructed. Using the linear matrix inequality technique, a state-space nonlinear estimator is designed for the augmented descriptor plant. Accurate asymptotic estimates of the original system state vector and the sensor fault term are thus obtained readily. By subtracting the estimated sensor fault term from the measurement output, sensor compensation is performed, allowing the existing controller for the original plant (without sensor faults) to continue to function normally even when a sensor fault occurs. Robust sensor fault reconstruction and sensor compensation are also discussed in detail for systems with simultaneous sensor faults, input disturbances and output noises. Finally, numerical examples and simulations are given to illustrate the design procedures and demonstrate the efficiency of the approaches. The sensor fault considered may be in any form, and may even be unbounded. As a result, the present work possesses a wide scope of applicability. - Author(s): H.-J. Shieh and P.-K. Huang
- Source: IET Control Theory & Applications, Volume 1, Issue 3, p. 586 –594
- DOI: 10.1049/iet-cta:20060151
- Type: Article
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A filtering-type sliding-surface control (FTSSC) design with chattering alleviation compared to the traditional sliding-mode control (SMC) is proposed for precise trajectory tracking of a piezoelectric positioning stage (abbreviated by ‘piezo-stage’). First, considering the dynamics of motion of a mass-spring mechanical system, the differential equations of motion system – which contains the parameters of a linear viscous friction, spring-coefficient, and a nonlinear hysteresis function – are proposed to describe the dynamics of motion of the piezo-stage. Then, the frequency-dependent hysteresis responses from both the proposed equations and the practical piezo-stage are illustrated to validate the equations. Based on the equations proposed, a state-space model is developed in which the applied voltage to the stage is defined as an output of a new control variable. According to the state-space model, the FTSSC design is proposed to provide not only the advantages of the traditional SMC, but also chattering improvement. Using the proposed control approach to the trajectory tracking of the piezo-stage, we can obtain that (a) high-performance tracking response, (b) robustness to system uncertainties and (c) chattering alleviation compared with the traditional SMC. Experimental results are illustrated to validate the proposed control approach for practical applications in trajectory tracking. - Author(s): S.S. Yang and Y.S. Zhong
- Source: IET Control Theory & Applications, Volume 1, Issue 3, p. 595 –603
- DOI: 10.1049/iet-cta:20060165
- Type: Article
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A new robust controller consisting of a nominal controller and a robust compensator is proposed. The controller is applied to a permanent magnet synchronous motors servo system to eliminate speed-tracking error due to time-varying load torque uncertainty and parameter perturbations. It is proved that the speed-tracking error can be made as small as desired if the initial conditions are zeros. For cases where the initial conditions are non-zero but bounded, after a finite transient period, the same speed-tracking error reduction can be achieved. Simulation results are presented to confirm the efficiency of the proposed method. - Author(s): G. Ambrosino ; M. Ariola ; A. Pironti
- Source: IET Control Theory & Applications, Volume 1, Issue 3, p. 604 –610
- DOI: 10.1049/iet-cta:20060237
- Type: Article
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The output regulation problem for an LTI plant whose outputs to be regulated are more than the control inputs is considered. For the case of constant references, a two-degree-of-freedom control scheme that minimises a quadratic cost function is presented. This cost function weights the tracking error at steady state. The methodology is based on the singular value decomposition of the plant transfer matrix at s=0. It is then shown how, by introducing some stronger assumptions, it is possible to modify the controller so as to reduce the steady-state control effort at the cost of a higher tracking error. A detailed numerical design example is finally presented. - Author(s): T. Li ; L. Guo ; C. Lin
- Source: IET Control Theory & Applications, Volume 1, Issue 3, p. 611 –616
- DOI: 10.1049/iet-cta:20060235
- Type: Article
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A new stability criterion of uncertain time-delay systems is proposed. The uncertainty is of linear fractional form, which includes norm-bounded uncertainty as a special case. By introducing a free weighting parameter, free distribution parameter and free weighting matrices simultaneously, a new delay-dependent sufficient stability condition is obtained in terms of a linear matrix inequality. It is shown that this new criterion can provide less conservative results than some existing ones. Numerical examples are given to demonstrate the applicability of the proposed approach. - Author(s): C. Yang ; Q. Zhang ; L. Zhou
- Source: IET Control Theory & Applications, Volume 1, Issue 3, p. 617 –623
- DOI: 10.1049/iet-cta:20060349
- Type: Article
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Lur'e-type descriptor systems (LDS) described by a linear time-invariant descriptor system with feedback-connected nonlinearities are considered. Firstly, the notion of generalized absolute stability (GAS) is defined for LDS and a necessary and sufficient condition (NASC) is derived. It is shown that GAS for LDS implies that the nominal system is admissible and the overall system is globally exponentially stable. Then, a sufficient condition for a generalised absolutely stable LDS to be of index one and solvable is presented. Furthermore, a method to estimate the decay rate of the solutions to the system is obtained. Finally, the synthesis problem is addressed and an approach to designing a state-feedback controller that renders the closed-loop system is generalised absolutely stable with a given decay rate is given. A numerical example illustrates the approach. - Author(s): D.W. Clarke and S.P. Maslen
- Source: IET Control Theory & Applications, Volume 1, Issue 3, p. 624 –635
- DOI: 10.1049/iet-cta:20060208
- Type: Article
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A simple approach to digital control design is the local discretisation of an effective continuous-time control law, such as well-tuned PID (proportional-integral-derivative). There are rules of thumb (e.g. the sample rate should be at least 25× the closed-loop bandwidth) that ensure only marginal degradation in performance, but these often require fast and accurate implementations. Low-power microcontrollers, on the other hand, might be slow and have restricted word-length. An approach to discretisation is thus to employ a mixed realisation using an ‘analogue wrap-around’ in which a proportional signal bypasses the computer and is added to the computer's digitally-evaluated component. Analysis and simulated examples indicate that this can lead to a significant reduction of the sample rate required for good closed-loop control when compared with the classical methods of Tustin, step- and ramp-invariant transformations. - Author(s): Y. Zhang ; L. Guo ; H. Wang
- Source: IET Control Theory & Applications, Volume 1, Issue 3, p. 636 –645
- DOI: 10.1049/iet-cta:20050508
- Type: Article
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Motivated from some practical industrial processes, an optimal fault tolerant control (FTC) scheme is studied for stochastic continuous dynamic systems with time delays using output probability density functions (PDFs). Different from the classical FTC problems, the measured information is the PDFs of system output rather than its value, where the B-spline expansion technique is applied so that the output PDFs can be formulated in terms of the dynamic weightings. For the established weighting system with nonlinearities, uncertainties and time delays, the concerned FTC problem is investigated by using robust optimisation techniques. A linear matrix inequality (LMI) based feasible FTC method is presented to ensure that the fault can be well estimated and compensated, where the generalised H∞ performance is optimised for the time-delayed systems with the non-zero initial condition and the truncated norms. Simulations for a model in the paper-making process are given to demonstrate the efficiency of the proposed approach. - Author(s): H. Wu and F. Sun
- Source: IET Control Theory & Applications, Volume 1, Issue 3, p. 646 –656
- DOI: 10.1049/iet-cta:20060076
- Type: Article
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646
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A novel adaptive Kriging controller for a class of discrete-time nonlinear systems with known control gains is proposed. The dynamic models of the systems may involve uncertainties that can be described as realizations of Gaussian random functions. The Kriging system is used to approximate the uncertainties, and an adaptive control law is established so that the tracking error remains bounded. To eliminate the infinite increase of the data size in the Kriging system, which usually occurs in non-parametric estimator-based adaptive controllers, a recursive Kriging estimation algorithm is proposed. In addition, the application of the proposed control scheme is extended to the case of uncertain control gain. Finally, some numerical examples are given to show the viability and effectiveness of the proposed control approach. - Author(s): C.-C. Yang and C.-J. Wu
- Source: IET Control Theory & Applications, Volume 1, Issue 3, p. 657 –664
- DOI: 10.1049/iet-cta:20060132
- Type: Article
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The optimal large-angle reoriented manoeuvring control (OLRMC) of rigid spacecraft by three orthogonal momentum wheels with free final slewing time is investigated. The performance index to be minimised is defined as a combination of the time of manoeuvre and the integral squared sum of control torques. By utilising an iterative procedure, this control problem is formulated and solved as a constrained nonlinear programming (NLP) one. In this novel method, the count of control steps is fixed initially and the sampling period is treated as a variable in the optimisation process. An approach to find the initial feasible solutions of the NLP problem is also proposed. Since initial feasible solutions can be found easily, the optimisation process of the NLP problem can be started from different points to find the large-angle rest-to-rest manoeuvre of the rigid spacecraft between two attitudes. To show the feasibility of the proposed method, simulation results are included. - Author(s): K. Sreenath ; V. Giordano ; F. Lewis
- Source: IET Control Theory & Applications, Volume 1, Issue 3, p. 665 –674
- DOI: 10.1049/iet-cta:20060144
- Type: Article
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p.
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As sensor networks become increasingly autonomous and grow to include mobility and actuation, the need for predictability in the execution of complex missions becomes crucial. In this perspective, we propose a discrete event controller (DEC) as an effective framework for modelling task constraints, priority orders and task schedules of mobile sensor networks (MSNs) in charge of executing multiple missions. The focus is to show that, for such systems, risks of deadlock arise and that the proposed DEC is able easily to implement effective deadlock avoidance algorithms. Several experiments of coordination policies on an actual MSN test bed with shared heterogeneous resources are presented. - Author(s): W.-A. Zhang and L. Yu
- Source: IET Control Theory & Applications, Volume 1, Issue 3, p. 675 –681
- DOI: 10.1049/iet-cta:20050407
- Type: Article
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The delay-dependent guaranteed cost control problem for uncertain neutral systems with nonlinear time-varying parameter perturbations is studied. By using a newly established integral inequality, the delay-dependent conditions for the existence of memoryless and memory state feedback guaranteed cost controllers are derived in terms of nonlinear matrix inequalities without involving model transformation and bounding technique for cross terms. An iterative algorithm involving convex optimisation is presented to solve these nonlinear matrix inequalities. A numerical example is given to demonstrate the effectiveness and superiority of the proposed results. - Author(s): E. Assunçao ; C.Q. Andrea ; M.C.M. Teixeira
- Source: IET Control Theory & Applications, Volume 1, Issue 3, p. 682 –688
- DOI: 10.1049/iet-cta:20050506
- Type: Article
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The problem of signal tracking, in the presence of a disturbance signal in the plant, is solved using a zero-variation methodology. A state feedback controller is designed in order to minimise the ℋ2-norm of the closed-loop system, such that the effect of the disturbance is attenuated. Then, a state estimator is designed and the modification of the zeros is used to minimise the ℋ∞-norm from the reference input signal to the error signal. The error is taken to be the difference between the reference and the output signals, thereby making it a tracking problem. The design is formulated in a linear matrix inequality framework, such that the optimal solution of the stated control problem is obtained. Practical examples illustrate the effectiveness of the proposed method. - Author(s): B. Ayalew and K.W. Jablokow
- Source: IET Control Theory & Applications, Volume 1, Issue 3, p. 689 –698
- DOI: 10.1049/iet-cta:20060186
- Type: Article
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p.
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The implementation, testing and performance evaluation of a partial feedback linearising force tracking controller on an electrohydraulic actuator is described. The underlying assumptions necessary for the development of the controller are highlighted, and the control law is derived in detail. Performance comparisons are conducted against a linear state feedback with integral controller and a standard PID controller, the latter being the most common industrial solution. Results show that the nonlinear partial feedback linearising controller has improved tracking properties, as might be expected from its use of more modelling and feedback information. Multiple experiments are also conducted to investigate the robustness of the system to certain model parameters; it is shown that the controller tolerates a measurable shift in these parameters. - Author(s): Z. Ding
- Source: IET Control Theory & Applications, Volume 1, Issue 3, p. 699 –703
- DOI: 10.1049/iet-cta:20060148
- Type: Article
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Asymptotic rejection of periodic disturbances whose basic wave patterns can be described by odd functions is considered. This class of disturbances covers asymmetric waveforms in a half-period such as sawtooth waveforms, as well as disturbances with symmetric half-period waveforms such as sinusoidal and triangular disturbances. The systems considered can be transformed to a nonlinear output-feedback form. The amplitude and phase of the disturbances are unknown. The newly proposed half-period integration technique is used to estimate the unknown disturbances in the systems, together with observer design techniques to deal with nonlinearity. The proposed control design with disturbance estimation asymptotically rejects the unknown disturbance, and ensures the overall stability of the system. - Author(s): Y. Zhang ; S. Li ; Q. Zhu
- Source: IET Control Theory & Applications, Volume 1, Issue 3, p. 704 –712
- DOI: 10.1049/iet-cta:20050502
- Type: Article
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A novel decentralised PID controller design procedure based on backstepping principles is presented to operate multiple-input multiple-output (MIMO) dynamic processes. First, a control Lyapunov function (CLF) and virtual control variable based on the backstepping method are derived recursively for each loop and a multivariable controller is obtained. Appropriate selection of auxiliary control variables can then eliminate coupling effects between subprocesses, and a decentralised controller can be derived. By analysing the regulation dynamics, external disturbances are rejected via appropriate tuning of the backstepping design parameters. Sufficient stability conditions are then derived using the small-gain theorem for two-input two-output and MIMO closed-loop systems, respectively. Simulation results for the control of the Shell benchmark problem and experimental results with a real-time water-level control system are provided to demonstrate the effectiveness and practicality of the proposed design procedure. - Author(s): D. Ye and G.-H. Yang
- Source: IET Control Theory & Applications, Volume 1, Issue 3, p. 713 –721
- DOI: 10.1049/iet-cta:20060090
- Type: Article
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The reliable controller design problem for continuous-time linear systems with time delay and actuator faults is considered, based on a linear matrix inequality (LMI) technique and an adaptive method. A new delay-dependent memory state-feedback reliable controller is established in a parameter-dependent form, in which fault parameters are adjusted online based on an adaptive method to compensate automatically the fault effect on system. In the framework of the LMI technique, the stability and H∞ performance of closed-loop systems are guaranteed in normal and faulty cases. A numerical example and its simulations are given to illustrate the effectiveness of the proposed method. - Author(s): L. Zhang ; P. Shi ; E.-K. Boukas ; C. Wang
- Source: IET Control Theory & Applications, Volume 1, Issue 3, p. 722 –730
- DOI: 10.1049/iet-cta:20060127
- Type: Article
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p.
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The problem of robust l2–l∞ filtering for switched linear discrete-time systems with polytopic uncertainties and time-varying delays is investigated. The time delay is assumed to be time-varying and bounded, which covers constant delay and mode-dependent constant delays as special cases. A robust switched linear filter is designed based on the mode-switching idea and a parameter-dependent stability approach such that the corresponding filtering error system is robustly asymptotically stable and achieves a prescribed l2–l∞ performance index for all admissible uncertainties. The existence conditions for such a filter, dependent on the upper and lower bounds of time-varying delays, are formulated in terms of a set of linear matrix inequalities. By solving that corresponding convex optimisation problem, the desired filter is obtained and an optimal l2–l∞ noise-attenuation level bound of the resulting filtering error system is guaranteed as well. A numerical example is given to show the feasibility and potential of the theoretical results. - Author(s): W.-H. Ho ; J.-T. Tsai ; J.-H. Chou
- Source: IET Control Theory & Applications, Volume 1, Issue 3, p. 731 –742
- DOI: 10.1049/iet-cta:20060159
- Type: Article
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By integrating the robust stabilisability condition, the shifted-Chebyshev-series approach (SCSA), and the hybrid Taguchi-genetic algorithm (HTGA), an integrative method is presented in this work to design the robust-stable and quadratic-optimal fuzzy parallel distributed compensation (PDC) controller such that: (i) the Takagi-Sugeno (TS) fuzzy-model-based control system with elemental parametric uncertainties can be robustly stabilised, and (ii) a quadratic finite-horizon integral performance index for the nominal TS-fuzzy-model-based control system can be minimised. In this work, the robust stabilisability condition is proposed in terms of linear matrix inequalities (LMIs). Based on the SCSA, an algebraic algorithm only involving the algebraic computation is derived in this work for solving the nominal TS-fuzzy-model-based feedback dynamic equations. By using the SCSA and the LMI-based robust stabilisability condition, the robust-stable and quadratic-finite-horizon-optimal fuzzy PDC control problem for the uncertain TS-fuzzy-model-based dynamic systems is transformed into a static constrained-optimisation problem represented by the algebraic equations with constraint of LMI-based robust stabilisability condition; thus greatly simplifying the robust optimal PDC control design problem. Then, for the static constrained-optimisation problem, the HTGA is employed to find the robust-stable and quadratic-optimal PDC controllers of the uncertain TS-fuzzy-model-based control systems. A design example of the robust-stable and quadratic-optimal PDC controller for the nonlinear mass-spring-damper mechanical system with elemental parametric uncertainties is given to demonstrate the applicability of the proposed new integrative approach. - Author(s): C. Li ; X. Liao ; T. Huang
- Source: IET Control Theory & Applications, Volume 1, Issue 3, p. 743 –748
- DOI: 10.1049/iet-cta:20060045
- Type: Article
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Global asymptotic stability for a general class of neural networks with delays is reduced to that for interval linear delayed differential equations under the assumption of Lipschitz continuity. By employing Lyapunov–Krasovskii theory, the problem is further reduced to that of Hurwitz stability of interval matrices. Based on the later theory, several new sets of stability criteria for neural networks with constant delays are derived. This demonstration and comparison with recent results show that the present results are new stability criteria for the investigated neural network model. - Author(s): X.-M. Zhang and Q.-L. Han
- Source: IET Control Theory & Applications, Volume 1, Issue 3, p. 749 –755
- DOI: 10.1049/iet-cta:20060121
- Type: Article
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Stability analysis and H∞ filter design for linear neutral systems is discussed. First, a new Lyapunov–Krasovskii functional is constructed to derive a new less conservative delay-dependent stability condition. It is then shown that the introduction of more free matrices sometimes cannot help reduce the conservatism of the obtained conditions. This new criterion is applied to designing a suitable H∞ filter of the Luenberger observer type, and a new design scheme is formulated in terms of the feasibility of a linear matrix inequality. Finally, some examples are given to illustrate the effectiveness of the proposed approach. - Author(s): C.-S. Shieh
- Source: IET Control Theory & Applications, Volume 1, Issue 3, p. 756 –763
- DOI: 10.1049/iet-cta:20050349
- Type: Article
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The three-dimensional missile guidance law with saturating actuator is proposed for the pursuit of an unpredictably manoeuvring target. The proposed guidance law achieves a satisfactorily robust performance without having to solve a complicated nonlinear Hamilton–Jacobi partial differential inequality and without relying on Takagi–Sugeno linear fuzzy models. In the proposed guidance scheme, the nonlinear part of the relative motion equations between the missile and target is first cancelled. Then, a tunable state feedback guidance law is designed to eliminate the effect of external disturbance. The conditions of tunable parameters are also proved to achieve the desired goal. The proposed guidance law can achieve reduced interception time than others, yet it is considerably simpler. An example is proposed to confirm it. - Author(s): C.H. Lien ; K.W. Yu ; W.D. Chen ; Z.L. Wan ; Y.J. Chung
- Source: IET Control Theory & Applications, Volume 1, Issue 3, p. 764 –769
- DOI: 10.1049/iet-cta:20060299
- Type: Article
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The asymptotic stability for Takagi–Sugeno (T–S) fuzzy systems with interval time-varying delay and parameter uncertainties are investigated. Delay-dependent and delay-independent criteria are proposed to guarantee the asymptotic stability for the uncertain fuzzy systems with interval time-varying delay. Numerical examples are provided to show that the obtained results significantly improve the allowed bounds of time-varying delay over some existing ones in the literature. - Author(s): M. Dog̃an and Y. Istefanopulos
- Source: IET Control Theory & Applications, Volume 1, Issue 3, p. 770 –778
- DOI: 10.1049/iet-cta:20050272
- Type: Article
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Developing nonlinear adaptive and robust controllers for a two-link flexible robot arm is the main objective of this research. The dynamic state feedback controller is used to achieve robust regulation of the rigid modes as well as suppression of elastic vibrations. However, the control of highly nonlinear multi-link flexible arms is subject to uncertainties caused by backlash, payload changes and external disturbances. Therefore adaptive and robust control of multi-link flexible arms is a challenging problem. The internal model approach is adaptively tuned up for unknown disturbances, parallel with a robust stabiliser. The stabiliser part of the controller is optimised with a new evolutionary algorithm. - Author(s): G. Pujol ; J. Rodellar ; J.M. Rossell ; F. Pozo
- Source: IET Control Theory & Applications, Volume 1, Issue 3, p. 779 –785
- DOI: 10.1049/iet-cta:20050364
- Type: Article
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The problem of designing a decentralised control scheme for a class of linear large scale interconnected systems with norm-bounded time-varying parameter uncertainties under a class of control failures is addressed. These failures are described by a model that considers possible outages or partial failures in every single actuator of each decentralised controller. The control design is performed through two steps. First, a decentralised reliable guaranteed cost control set is derived and, second, a feasible linear matrix inequalities procedure is presented for the effective construction of the control set. A numerical example illustrates the efficiency of the proposed control scheme. - Author(s): O. Barambones ; A.J. Garrido ; F.J. Maseda
- Source: IET Control Theory & Applications, Volume 1, Issue 3, p. 786 –794
- DOI: 10.1049/iet-cta:20060239
- Type: Article
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A novel sensorless integral sliding-mode control for induction motors is discussed. Besides, the control scheme provides global asymptotic speed tracking in the presence of unknown parameters and load torque. For this purpose, the control scheme makes use of an improved method of speed estimation operating on the principle of a speed adaptive flux and current observer. As it is known, an observer is basically an estimator that uses a plant model and a feedback loop. In particular, an observer is constructed, which provides a speed estimation on the basis of the measured stator voltages and currents. Then a sliding-mode controller with an integral switching surface is considered. The closed-loop stability of the proposed controller is proved under parameter uncertainties and load disturbances, using the Lyapunov stability theory. Simulated results show that the proposed controller, jointly with the proposed observer, provide high-performance dynamic characteristics and that this scheme is robust with respect to plant parameter variations and external load disturbances. Finally, the feasibility of the proposed control scheme is proved by means of experimental results over a real induction motor. - Author(s): P. Li and J. Cao
- Source: IET Control Theory & Applications, Volume 1, Issue 3, p. 795 –801
- DOI: 10.1049/iet-cta:20050528
- Type: Article
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A new hybrid control, impulsive and feedback, strategy is proposed to stabilise and synchronise a class of chaotic systems. Some simple sufficient conditions, which are less conservative than the existing results, are derived to ensure the stabilisation and synchronisation of the chaotic systems. In addition, the proposed method has many advantages that includes taking less time and energy and having a more flexible design, over that of the simplex control method to achieve the stabilisation and synchronisation. Finally, as a typical example, Chua's chaotic system is given to illustrate and visualise the effectiveness of our results. - Author(s): M.N. Alpaslan Parlakçı
- Source: IET Control Theory & Applications, Volume 1, Issue 3, p. 802 –809
- DOI: 10.1049/iet-cta:20050517
- Type: Article
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p.
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A new class of augmented Lyapunov–Krasovskii functional is introduced for the robust stability of linear uncertain neutral systems. The uncertainties under consideration are norm bounded. Delay-dependent robust stability criteria in the form of linear-matrix inequalities are derived and model transformation and bounding of the cross terms are avoided. Numerical examples are presented to illustrate the significant improvement on the conservativeness of the delay bound over some reported results in the literature. - Author(s): G. Lu and G. Feng
- Source: IET Control Theory & Applications, Volume 1, Issue 3, p. 810 –816
- DOI: 10.1049/iet-cta:20060153
- Type: Article
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Issues of observer design for a class of Lipschitz nonlinear discrete-time systems with time-delay and disturbance input are addressed, where the Lipschitz condition is expressed in a componentwise rather than aggregated manner. It has been shown that both full-order and reduced-order robust H∞ observers can be obtained by means of the same convex optimisation procedure with minimisation of the disturbance attenuation upper bound γ>0. It is also shown that for a prescribed H∞-norm upper bound γ>0, the tolerable Lipschitz bounds can be obtained by another convex optimisation procedure. A numerical example is presented to show the effectiveness of the developed approach. - Author(s): Y.S. Chou ; J.L. Leu ; Y.C. Chu
- Source: IET Control Theory & Applications, Volume 1, Issue 3, p. 817 –829
- DOI: 10.1049/iet-cta:20060063
- Type: Article
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A unified approach to the strong stabilisation problem and the H∞ strong stabilisation problem is presented. New sufficient conditions for the existence of strongly stabilising controllers and stable H∞ controllers are derived, in a unified manner, in terms of the solvability of a positive real controller synthesis problem and a multi-objective control problem, respectively. A linear matrix inequality (LMI) technique developed by Scherer et al. is adopted to make the most use of its power to deal with the general case of the problems. Several advantages brought by the adopted LMI technique are explored. New parameterisations of stable controllers for both the problems are discussed. In particular, the parameterisations are independent of a particular method for solving strong stabilisation problems. Explicit state-space synthesis algorithms are given and numerical examples are provided to demonstrate the potential of the proposed methods. - Author(s): F. Xiao and L. Wang
- Source: IET Control Theory & Applications, Volume 1, Issue 3, p. 830 –837
- DOI: 10.1049/iet-cta:20060014
- Type: Article
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As a new area of research, consensus problems for multi-agent systems have been studied extensively in the literature. It is usually assumed that all agents share a common one-dimensional state space. The authors of this study concentrate on the consensus problems of multi-agent systems in the framework of high-dimensional state space. As a basis for the analysis, a general model is first introduced by presenting two typical examples along with some necessary and sufficient conditions for the system to solve a consensus problem. Then the structures of consensus functions are investigated and some algebraic characterisations are given. Finally, a class of switched multi-agent systems are discussed and some sufficient conditions for the possession of the consensus property are provided. Several examples to illustrate the effectiveness of theoretical results are given. - Author(s): E. Zerrik and M. Ouzahra
- Source: IET Control Theory & Applications, Volume 1, Issue 3, p. 838 –843
- DOI: 10.1049/iet-cta:20050174
- Type: Article
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An output stabilisation problem for infinite semilinear systems defined on a geometrical domain Ω is discussed. Also, the asymptotic behaviour of such a system only on a subregion ω of Ω̄ (ω may be interior to Ω or on its boundary ∂Ω) is studied. Then sufficient conditions to obtain a stabilising control are given. The problem is reconsidered minimising a given cost of performance. Illustrating examples are presented. - Author(s): Z. Doulgeri and G. Iliadis
- Source: IET Control Theory & Applications, Volume 1, Issue 3, p. 844 –853
- DOI: 10.1049/iet-cta:20060191
- Type: Article
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The task of stabilising an n-degree-of-freedom (dof) robot arm moving from free space to contact with a compliant surface is considered. A proportional derivative position controller with gravity compensation is used for the free motion and a parallel force/position controller for the contact task. The goal is to stabilise the robot in contact with the environment, exert a desired force and place the end-effector at a desired position. The robot is modelled as a switched system, and its stability is examined using hybrid stability theory by considering typical candidate Lyapunov functions for each of the two discrete system states. The stability analysis reveals that extra conditions involving control gains and control targets should be satisfied in order to guarantee asymptotic stability of the switched task in a Lyapunov sense. The system performance and robustness is illustrated by the simulation of a 3-dof planar robot. - Author(s): Q.-L. Han and D. Yue
- Source: IET Control Theory & Applications, Volume 1, Issue 3, p. 854 –859
- DOI: 10.1049/iet-cta:20060213
- Type: Article
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The problem of the absolute the stability of Lur'e systems with time-varying delay is addressed. Full consideration is given to two cases of time-varying delays – one being continuous-uniformly bounded and the other being differentiable-uniformly bounded with the derivative of the delay bounded by a constant. Some delay-dependent absolute-stability criteria are derived and formulated in the form of linear matrix inequalities. The relationship between the absolute stability criteria for the two cases of time-varying delays is built. A numerical example shows the effectiveness of the obtained results. - Author(s): C. Li ; G. Ma ; B. Song
- Source: IET Control Theory & Applications, Volume 1, Issue 3, page: 860 –860
- DOI: 10.1049/iet-cta:20050198
- Type: Article
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Act-and-wait control concept for discrete-time systems with feedback delay
Impulsive-mode controllablisability in descriptor linear systems
Fuzzy PID controller for 2D differential geometric guidance and control problem
Parameter convergence of adaptive input-output linearisable systems with application to Chua's circuits
Sensor fault reconstruction and sensor compensation for a class of nonlinear state-space systems via a descriptor system approach
Precise tracking of a piezoelectric positioning stage via a filtering-type sliding-surface control with chattering alleviation
Robust speed tracking of permanent magnet synchronous motor servo systems by equivalent disturbance attenuation
Optimal steady-state control for linear non-right-invertible systems
A new criterion of delay-dependent stability for uncertain time-delay systems
Generalised absolute stability analysis and synthesis for Lur'e-type descriptor systems
Discretising controllers with slow sampling
Robust filtering for fault tolerant control using output PDFs of non-Gaussian systems
Adaptive Kriging control of discrete-time nonlinear systems
Optimal large-angle attitude control of rigid spacecraft by momentum transfer
Avoiding shared resource conflicts in mobile sensor networks with multiple missions
Delay-dependent guaranteed cost control for uncertain neutral systems with nonlinear parameter perturbations
ℋ2 and ℋ∞-optimal control for the tracking problem with zero variation
Partial feedback linearising force-tracking control: implementation and testing in electrohydraulic actuation
Asymptotic rejection of a class of periodic disturbances in nonlinear output-feedback systems
Backstepping-enhanced decentralised PID control for MIMO processes with an experimental study
Adaptive reliable H∞ control for linear time-delay systems via memory state feedback
Robust l2–l∞ filtering for switched linear discrete time-delay systems with polytopic uncertainties
Robust-stable and quadratic-optimal control for TS-fuzzy-model-based control systems with elemental parametric uncertainties
Global stability analysis for delayed neural networks via an interval matrix approach
Stability analysis and H∞ filtering for delay differential systems of neutral type
Design of three-dimensional missile guidance law via tunable nonlinear H∞ control with saturation constraint
Stability criteria for uncertain Takagi–Sugeno fuzzy systems with interval time-varying delay
Optimal nonlinear controller design for flexible robot manipulators with adaptive internal model
Decentralised reliable guaranteed cost control of uncertain systems: an LMI design
Integral sliding-mode controller for induction motor based on field-oriented control theory
Stabilisation and synchronisation of chaotic systems via hybrid control
Robust stability of uncertain neutral systems: a novel augmented Lyapunov functional approach
Robust H∞ observers for Lipschitz nonlinear discrete-time systems with time delay
Stable controller design for MIMO systems: an LMI approach
Consensus problems for high-dimensional multi-agent systems
Output stabilisation for distributed semilinear systems
Stability of a contact task for a robotic arm modelled as a switched system
Absolute stability of Lur'e systems with time-varying delay
Comment: Stability considerations in quaternion attitude control using discontinuous Lyapunov functions
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