Online ISSN
1751-8652
Print ISSN
1751-8644
IET Control Theory & Applications
Volume 6, Issue 7, 3 May 2012
Volumes & issues:
Volume 6, Issue 7
3 May 2012
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- Author(s): C. Wang and Y. Shen
- Source: IET Control Theory & Applications, Volume 6, Issue 7, p. 875 –883
- DOI: 10.1049/iet-cta.2011.0484
- Type: Article
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p.
875
–883
(9)
This study investigates the problem of delay-dependent robust stability for uncertain stochastic systems with interval time-varying delay. No restrictions on the derivative of the time-varying delay are imposed, although lower and upper bounds of the delay interval are assumed to be known. By decomposing the delay interval into multiple equidistant subintervals, new Lyapunov–Krasovskii functionals are introduced on these intervals, which result in being much less conservative than most existing results in the literature. In addition, the reduction in the conservatism of the proposed stability criteria is also attributed to the free-weighting matrix technique and a newly proposed bounding condition, which is used to estimate the upper bound of stochastic differential of the Lyapunov–Krasovskii functional without neglecting any useful terms. All the stability criteria are formulated in the form of linear matrix inequalities (LMIs), which are dependent on the size of the time delay. Some numerical examples are given to show the less conservatism and applicability of the obtained results. Moreover, when the number of the divided subintervals increases, the corresponding criteria can provide an improvement on the results. - Author(s): N. Panchal ; M.T. Bayliss ; J.F. Whidborne
- Source: IET Control Theory & Applications, Volume 6, Issue 7, p. 884 –892
- DOI: 10.1049/iet-cta.2011.0438
- Type: Article
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p.
884
–892
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A general approach for the attitude control of directional drilling tools for the oil and gas industry is proposed. The attitude is represented by a unit vector, thus the non-linearities introduced by Euler angle representations are avoided. Three control laws are proposed, and their stability is proven. Their behaviour is tested by numerical simulation. The merits of the laws from an engineering perspective are highlighted, and some details for the implementation of the laws on directional drilling tools are provided. - Author(s): S. Wang and D. Xie
- Source: IET Control Theory & Applications, Volume 6, Issue 7, p. 893 –899
- DOI: 10.1049/iet-cta.2011.0282
- Type: Article
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p.
893
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This article studies the average-consensus problem of second-order multi-agent sampled control system with time-varying sampling interval. The sampled control protocol is induced from continuous-time linear consensus protocol by using sampling technology and zero-order hold circuit. First, by the iterative method, the continuous-time multi-agent system can be equivalently transformed into a linear discrete-time system. Then, by algebraic graph theory and matrix theory, the authors analyse the convergence of the system and not only prove the existence of the scaling parameter and time-varying sampling interval but also give the approach of how to choose them. In their study, the eigenvalues of the corresponding Laplacian matrix play a key role in reaching consensus. Finally, an example is provided to illustrate the effectiveness of the theoretical results. - Author(s): Z. Chen
- Source: IET Control Theory & Applications, Volume 6, Issue 7, p. 900 –910
- DOI: 10.1049/iet-cta.2010.0620
- Type: Article
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p.
900
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A double-loop control mechanism is developed for an inverting buck-boost converter. The robust converter is capable of operating in a wide range of reference voltage and load resistance with unmodelled parameters. The cause of the non-minimum phase behaviour is analysed. The boundary layer width of the output voltage in sliding mode is found to be dependent on the circuit and control parameters. The speeds of the inner and outer loop are quantitatively determined and compared. The transient responses of the circuit are forecastable. The controller is validated on a simulation circuit. - Author(s): X. Yang ; M. Garratt ; H. Pota
- Source: IET Control Theory & Applications, Volume 6, Issue 7, p. 911 –920
- DOI: 10.1049/iet-cta.2011.0046
- Type: Article
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p.
911
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This study presents a disturbance attenuation controller for horizontal position stabilisation for hover and automatic landings of a rotary-wing unmanned aerial vehicle (RUAV) operating close to the landing deck in rough seas. Based on a helicopter model representing aerodynamics during the landing phase, a non-linear state feedback ℋ∞ controller is designed to achieve rapid horizontal position tracking in a gusty environment. Practical constraints including flapping dynamics, servo dynamics and time lag effect are considered. A high-fidelity closed-loop simulation using parameters of the Vario XLC gas-turbine helicopter verifies performance of the proposed horizontal position controller. The proposed controller not only increases the disturbance attenuation capability of the RUAV, but also enables rapid position response when gusts occur. Comparative studies show that the ℋ∞ controller exhibits performance improvement and can be applied to ship/RUAV landing systems. - Author(s): X. Wang ; X. Sun ; S. Li ; H. Ye
- Source: IET Control Theory & Applications, Volume 6, Issue 7, p. 921 –934
- DOI: 10.1049/iet-cta.2011.0461
- Type: Article
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p.
921
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Force control of a single-rod electrohydraulic actuator is investigated. The model considers the friction effect of the actuator. First, a non-linear force controller using a feedback domination approach, which can globally finite-time stabilise the force tracking error system without the friction parameter uncertainties, is proposed. Then, another feedback domination controller is proposed to cope with the friction parameter uncertainties. To estimate the unmeasurable states, an observer with finite-time convergence is developed. Rigorous stability analysis is given. Compared with the conventional output feedback backstepping control method, the proposed output feedback domination control scheme provides a faster convergence rate and a higher tracking accuracy for force tracking. Numerical simulation results demonstrate the effectiveness of the proposed control design. - Author(s): M. Dogan
- Source: IET Control Theory & Applications, Volume 6, Issue 7, p. 935 –942
- DOI: 10.1049/iet-cta.2011.0173
- Type: Article
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935
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The vibration-based energy scavenger consists of beams with piezoelectric layers and proof mass, is usually designed by single-link or cantilever beam configurations. In order to overcome inherent problems, for example, insufficient bandwidth and model inaccuracies, we consider the motion of a two-link flexible arm with non-uniform cross-section. The governing equations consist of coupled non-linear partial differential equations (PDE) with appropriate boundary conditions. Most of the energy scavengers are based on linear electromechanical devices excited at resonance. Besides, realistic vibration environments can be described as stochastic, multi-frequency and time varying. Thus, narrow band linear systems could be highly inefficient under these conditions. On the contrary, non-linear systems are capable of responding over a broad frequency range and can have efficient performance in realistic vibration environments. The author shows that with the proposed non-linear-coupled set-up, the efficiency objectives are satisfied. In this research, tapered beam structure is exploited to achieve large bandwidth, tolerable excitation amplitude and maximum output power. The author also presents some simulation and experimental results to demonstrate the efficiency of proposed energy harvesting system. Consequently, the theoretical approach is verified by simulated and experimental results in compliance. - Author(s): C.-F. Caruntu and C. Lazar
- Source: IET Control Theory & Applications, Volume 6, Issue 7, p. 943 –952
- DOI: 10.1049/iet-cta.2011.0103
- Type: Article
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p.
943
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In networked control systems there are many network-induced imperfections and constraints: quantisation errors, packet dropouts, variable sampling periods, time-varying delays and communication constraints. The goal of this study is to provide a control design methodology that can assure the closed-loop performances of a network-controlled application, while compensating the time-varying delays introduced by the communication network. To this end, firstly, the error caused by the time-varying delays is modelled as a disturbance and a novel method of bounding the disturbances is proposed. Secondly, an one-step ahead predictive controller based on flexible control Lyapunov functions is designed, which explicitly takes into account the bounds of the disturbances caused by time-varying delays and guarantees also the input-to-state stability of the system. The methodology is then applied for a network-controlled direct current (DC) motor and the TrueTime simulations illustrate the effectiveness and robustness of the proposed delay modelling and control strategy. - Author(s): S. Yang and Q. Zhao
- Source: IET Control Theory & Applications, Volume 6, Issue 7, p. 953 –962
- DOI: 10.1049/iet-cta.2011.0430
- Type: Article
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953
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This study mainly concentrates on analytical characterisation of the detection delays and false alarms in an online sequential probability test-based fault detection (FD) scheme. The probability distributions of the fault detection delay (FDD) and the time between false alarms (TBFA) are investigated. Analytical expressions of the probability density functions of FDD and TBFA are obtained. The results in this work are important for evaluation of FD performances in fault tolerant control systems, and they can also find useful applications in industrial alarm management systems. - Author(s): M. Jimenez-Lizarraga ; M. Basin ; P. Rodriguez-Ramirez
- Source: IET Control Theory & Applications, Volume 6, Issue 7, p. 963 –970
- DOI: 10.1049/iet-cta.2011.0090
- Type: Article
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963
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In this study the authors present a solution to the problem of the quadratic mini–max regulator for polynomial uncertain systems. The main characteristic of this type of problems is that the parameters describing the dynamics of the non-linear plant depend on a vector of unknown parameters, which belongs to a finite parametric set, and the solution is given in terms of the worst-case scenario. That is to say, the result of the application of a certain control input (in terms of the cost function value) is associated with the worst or least favourable value of the unknown parameter. Based on the general necessary conditions for mini–max optimality, a closed form for the control is provided, which makes use of a p-linear form tensor representation of the polynomial system. In its turn, this allows one to present the solution in a way similar to the so-called Riccati technique. The final control is shown to be a convex combination (with some weights) of the optimal controls for each fixed parameter of the polynomial system. Several simulation examples are presented to show the effectiveness of our approach including the robust regulation of the well-known Duffing equation, which represents a typical (and challenging to control) non-linear polynomial system. - Author(s): C. Huang ; X. Ye ; Z. Sun
- Source: IET Control Theory & Applications, Volume 6, Issue 7, p. 971 –978
- DOI: 10.1049/iet-cta.2011.0214
- Type: Article
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p.
971
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In this study, the output regulation problem of multi-agent systems in fixed topologies is analysed. The agents studied are identical general linear systems that aim at tracking a desired trajectory in presence of certain determinate disturbances. Under a mild assumption that the augmented communication topology has a spanning tree, a distributed control law based on relative output measurements between the agents and state measurements within the agent itself is proposed. It is shown that this output regulation problem can be solved if a Riccati equation with parameters has a positive definite symmetric solution. Moreover, by parameter determination of this Riccati equation, we find that the lower bound of the second smallest eigenvalue associated with the augmented graph Laplacian of the communication topology is of great importance on both the stability property and the convergence rate. A lower bound for this eigenvalue is given for N-node graphs.
Delay partitioning approach to robust stability analysis for uncertain stochastic systems with interval time-varying delay
Attitude control system for directional drilling bottom hole assemblies
Consensus of second-order multi-agent systems via sampled control: undirected fixed topology case
Double loop control of buck-boost converters for wide range of load resistance and reference voltage
Non-linear position control for hover and automatic landing of unmanned aerial vehicles
Output feedback domination approach for finite-time force control of an electrohydraulic actuator
Efficient energy scavengers by flexible robot arm with non-uniform cross-section
Robustly stabilising model predictive control design for networked control systems with an application to direct current motors
Probability distribution characterisation of fault detection delays and false alarms
Robust mini–max regulator for uncertain non-linear polynomial systems
Output regulation problem of multi-agents in networked systems
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- Author(s): R. Zhang ; Y. Zhang ; C. Hu ; M.Q.-H. Meng ; Q. He
- Source: IET Control Theory & Applications, Volume 6, Issue 7, p. 979 –984
- DOI: 10.1049/iet-cta.2011.0451
- Type: Article
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p.
979
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This study concerns the problem of asynchronous ℋ∞ filtering in relation to a class of two-dimensional (2D) Markov jump systems. The asynchronous phenomenon is considered to occur in a random way, and the mismatch behaviour is determined by a stochastic variable with Bernoulli random binary distribution. A stochastic parameter-dependent approach is proposed for the design of ℋ∞ filter such that, for any admissible random mismatch, the filtering error system is mean-square asymptotically stable and has a prescribed ℋ∞ performance level. Moreover, a key relationship of the ℋ∞ performance between the results presented and the classical mode-dependent, mode-independent filtering is demonstrated. A numerical example is provided to illustrate the effectiveness and advantage of the developed theoretical results. - Author(s): J. Zhang ; H. Xu ; H. Zheng
- Source: IET Control Theory & Applications, Volume 6, Issue 7, p. 985 –991
- DOI: 10.1049/iet-cta.2011.0154
- Type: Article
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p.
985
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In this study, the authors address the problem of output tracking for single-input and single-output (SISO) parametric strict-feedback (PSF) non-linear systems in the presence of uncertain parameters under adaptive sampled-data control. The main contributions of this work are twofold: (i) the authors develop a systematic design procedure for adaptive sampled-data controller by combining the backstepping technique with two kinds of discretisation approaches; and (ii) they also provide a theoretical analysis for the performance of sampled-data controller, which shows that the proposed adaptive sampled-data controller can regulate the tracking error to any given neighbourhood of the origin and the state of the sampled-data closed-loop system is bounded. Finally, an illustrative example is given to demonstrate the effectiveness of the presented method. - Author(s): S.-J. Park
- Source: IET Control Theory & Applications, Volume 6, Issue 7, p. 992 –999
- DOI: 10.1049/iet-cta.2011.0507
- Type: Article
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p.
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A monopoly firm maximises profit by producing the quantity at which marginal revenue equals marginal cost. In order for a monopoly firm in a disequilibrium (non-profit-maximising) state to reach an equilibrium (profit-maximising) state, it usually adopts the following conventional strategy: when marginal revenue exceeds marginal cost, the firm increases output (the quantity of production), and when marginal cost exceeds marginal revenue, the firm decreases output. In this study, using supervisory control theory of discrete event systems, the authors study the dynamic monopoly problem: Does the monopoly firm’s conventional strategy always assure that the firm in disequilibrium eventually reaches an equilibrium state? The author show that the non-blocking property and controllability (which are the major concepts in supervisory control theory) are the necessary and sufficient conditions for the existence of a solution to the dynamic monopoly problem.
Asynchronous ℋ∞ filtering for a class of two-dimensional Markov jump systems
Adaptive sampled-data output tracking of parametric strict-feedback non-linear systems
Supervisory control for dynamic monopoly
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