Online ISSN
1751-8652
Print ISSN
1751-8644
IET Control Theory & Applications
Volume 4, Issue 2, February 2010
Volumes & issues:
Volume 4, Issue 2
February 2010
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- Author(s): A. Hussain ; H. Wang ; A. Nobakhti
- Source: IET Control Theory & Applications, Volume 4, Issue 2, p. 173 –175
- DOI: 10.1049/iet-cta.2010.9006
- Type: Article
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173
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(3)
- Author(s): N. Chen ; G. Zhai ; W. Gui ; C. Yang ; W. Liu
- Source: IET Control Theory & Applications, Volume 4, Issue 2, p. 177 –185
- DOI: 10.1049/iet-cta.2008.0580
- Type: Article
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p.
177
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In this study, the authors consider quantisers and controllers design for uncertain interconnected H∞ decentralised feedback networked systems with two quantised signals in outputs and control inputs. The authors first assume that a decentralised output feedback controller has been designed for an interconnected continuous-time networked system so that the closed-loop system is stable and a desired H∞ disturbance attenuation level is achieved. However, since the measurement outputs and control inputs are quantised by general quantisers before they are passed to the controller and the system, the system's performance is not guaranteed. For this purpose, the authors propose an output-dependent strategy for updating the quantisers' parameters, so that the closed-loop system is asymptotically stable and achieves the same H∞ disturbance attenuation level. Both the pre-designed controllers and the quantisers' parameters are constructed in a decentralised manner, depending on local information. Finally, a numerical example is given to show the effectiveness of the proposed approach. - Author(s): G.W. Irwin ; J. Chen ; A. McKernan ; W.G. Scanlon
- Source: IET Control Theory & Applications, Volume 4, Issue 2, p. 186 –196
- DOI: 10.1049/iet-cta.2008.0542
- Type: Article
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p.
186
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(11)
This study presents a co-design approach to wireless network control systems (WNCS). Experimental studies are carried out to identify and analyse the delays inherent in WNCS, with a new inverse Gaussian model for their statistical distribution proposed. Two different packet-based predictive control schemes are presented. One uses dynamic matrix control (DMC), the other is a linear quadratic (LQ) controller incorporating multiple observers. Lyapunov stability is derived using linear matrix inequalities (LMIs) for the multi-observer LQ control whereas Monte-Carlo simulation results on a cart-mounted inverted pendulum are presented to confirm the performance advantages of packet-based DMC. Finally, results from a real-time implementation of the multi-observer LQ controller are also presented. - Author(s): Y. Li ; S.H. Yang ; Z. Zhang ; Q.-G. Wang
- Source: IET Control Theory & Applications, Volume 4, Issue 2, p. 197 –205
- DOI: 10.1049/iet-cta.2008.0572
- Type: Article
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197
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This study presents a design method for Internet-based control systems in a dual-rate configuration to achieve load minimisation and dynamic performance specifications. It avoids the complexity of large-scale system design by focusing on individual control systems. In the dual-rate configuration, the plant under control is first stabilised by a local controller with a high sampling rate. The remote proportional integral derivative (PID) controller, which regulates the output according to the desirable reference, adopts a low sampling rate to reduce load on the network. The upper bound of the remote PID controller's sampling time which meets the requirement on control performance is derived and a simple tuning method for the remote PID controller is presented. Simulation and real-time examples are provided for illustration. - Author(s): L. Lu ; Z. Lin ; A. Bateman
- Source: IET Control Theory & Applications, Volume 4, Issue 2, p. 206 –227
- DOI: 10.1049/iet-cta.2008.0605
- Type: Article
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This study considers the design of decentralised controllers for large-scale linear systems under actuator saturation. Saturation in the magnitude of the control input is first considered. For the closed-loop system under a saturating decentralised state feedback law, conditions are identified under which an ellipsoid is contractively invariant and thus within the domain of attraction, or the restricted ℒ2 gain from the disturbance to the output is less than or equal to a pre-specified value γ. Based on these conditions, the designs of decentralised state feedback laws that achieve large domains of attraction or low ℒ2 gains can be formulated as optimisation problems with bilinear matrix inequality (BMI) constraints. Numerical algorithms are developed to solve these BMI problems. These developments are also extended to the situation where the inputs are subject to nested saturation, such as simultaneous actuator magnitude and rate saturation. Throughout the study, numerical examples are used to demonstrate the effectiveness of the proposed design method. - Author(s): N. Sadati and M.H. Ramezani
- Source: IET Control Theory & Applications, Volume 4, Issue 2, p. 228 –243
- DOI: 10.1049/iet-cta.2008.0528
- Type: Article
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228
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In this paper, a new interaction prediction approach for hierarchical control of non-linear large-scale systems is presented. The proposed approach uses a new gradient-type coordination scheme which is robust with respect to the parameters' variation, and also has a good convergence rate. In classical coordination strategies, which can be divided into the gradient-type and substitution-type approaches, it is not possible to improve the robustness and the convergence rate at the same time, since by increasing one the other decreases. The proposed approach has the main advantages of the gradient-type algorithms in being independent of the parameter's variation and also the initial guess of the coordination vector. In addition, because of the proposed coordination strategy, in which the update of the coordination vector directly causes the reduction of the coordination error, the number of iterations is considerably reduced. The robustness and convergence rate of the proposed approach against the other interaction prediction approaches are shown through simulations of a benchmark problem. The simulation results also show the effectiveness of the proposed approach in solving constrained optimisation problems having non-quadratic cost functions. Comparisons are also made with the solutions obtained using centralised approach. - Author(s): W.-J. Mao and J. Chu
- Source: IET Control Theory & Applications, Volume 4, Issue 2, p. 244 –252
- DOI: 10.1049/iet-cta.2008.0600
- Type: Article
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244
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The problem of robust decentralised state-feedback stabilisation for discrete-time singular large-scale systems with interval uncertainties is addressed in this study. By using the matrix norm operation and the rank-1 matrix technique for interval matrices, two sufficient conditions to check the robust decentralised stabilisability of uncertain discrete-time singular large-scale systems are, respectively, obtained. At the expense of problem size (numerical complexity), the second condition gives a less conservative result than the first one. It is therefore reasonable to check the robust stabilisability by the first condition, and then if it fails, resort to the second one. Finally, illustrative examples show that the proposed conditions are effective for the design of robust decentralised stabilising state-feedback controller for not only the uncertain discrete-time singular large-scale systems but also the uncertain discrete-time regular large-scale systems. - Author(s): G. Li ; D.P. Stoten ; J.-Y. Tu
- Source: IET Control Theory & Applications, Volume 4, Issue 2, p. 253 –264
- DOI: 10.1049/iet-cta.2009.0011
- Type: Article
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p.
253
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Dynamically substructured systems (DSS) are increasingly used by the dynamics testing community. DSS involves the physical testing of full-size critical components in parallel with numerical testing of the remaining components. This has certain advantages over other testing methods. However, the synchronisation of the signals at the interface between the physical and numerical substructures of DSS requires a high fidelity controller. In practice, the performance of the DSS testing can be degraded by input saturation of the actuators. In this study, the authors use model predictive control (MPC) to cope with the saturation problem in DSS. To facilitate the MPC and observer design for DSS, a modified DSS framework based on an existing one is proposed. As a case study, a quasi-motorcycle (QM) system is converted into the modified DSS framework and a traditional on-line MPC control strategy is implemented in real time. - Author(s): H. Fujioka and T. Nakai
- Source: IET Control Theory & Applications, Volume 4, Issue 2, p. 265 –272
- DOI: 10.1049/iet-cta.2009.0012
- Type: Article
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p.
265
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Motivated by the widespread use of networked and/or embedded control systems, an algorithm for stabilising sampled-data feedback control systems with uncertainly time-varying sampling intervals is proposed. The algorithm is an extension of that for stability analysis in the authors' previous study, and is based on the robustness against the variation of sampling intervals derived by the small-gain condition. The validity of the algorithm is demonstrated by numerical examples. - Author(s): Q.-K. Li ; J. Zhao ; G.M. Dimirovski ; X.-J. Liu
- Source: IET Control Theory & Applications, Volume 4, Issue 2, p. 273 –281
- DOI: 10.1049/iet-cta.2008.0618
- Type: Article
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p.
273
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The issue of state convergence property for perturbed switched linear time-delay systems is explored. By introducing the variation-of-constants formula, the conditions for state convergence property of perturbed switched linear time-delay systems are established, and the difficulties caused by the interactions between the switchings and the time delay are alleviated. Based on the general result of perturbed switched linear time-delay systems, under two different switching schemes, new delay-dependent and -independent stability criteria for switched linear systems with time delay are derived. Two numerical examples along with the respective simulation results are given to demonstrate feasibility and validity of the theoretical results. - Author(s): M. Kragelund ; J. Leth ; R. Wisniewski
- Source: IET Control Theory & Applications, Volume 4, Issue 2, p. 282 –293
- DOI: 10.1049/iet-cta.2008.0613
- Type: Article
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p.
282
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This study addresses the problem of an optimal actuator selection when economic value is considered. The objective is to minimise the economical cost of operating a given plant. The problem has been formulated using mathematic notions from economics. Functionals describing the business objectives of operating a power plant has been established. The selection of actuator configuration has been limited to the fuel system which in the considered plant consists of three different fuels – coal, gas and oil. The changes over 24 h of operation is established and a strategy for using a plant utilising the three fuels is developed which will yield a greater profit than a coal fired plant. - Author(s): J.A. Villegas ; S.R. Duncan ; H.G. Wang ; W.Q. Yang ; R.S. Raghavan
- Source: IET Control Theory & Applications, Volume 4, Issue 2, p. 294 –302
- DOI: 10.1049/iet-cta.2009.0039
- Type: Article
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294
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In this study, operating conditions for a batch fluidised bed dryer are found that achieve the specifications on the final moisture level, while minimising the energy consumption. The operating conditions are obtained by solving an optimisation problem, where the specification for the final moisture content of the bed is included as a constraint. The optimisation is based on a lumped mechanistic model that describes the heat and mass transfer between solid, gas and bubble phases in the bed. Experimental validation of this model shows that it can be used to predict the particle moisture content and temperature profiles during the drying process and it is shown that the wall temperature has a major effect on the predictions. Compared to the standard approach of maintaining the inlet air temperature and flow rate at constant values, the optimal operating conditions for a lab-scale bed dryer reduce the energy consumption by 26% and shorten the duration of a batch by 20 min. - Author(s): Y.J. Zhou ; T.X. Mei ; S. Freear
- Source: IET Control Theory & Applications, Volume 4, Issue 2, p. 303 –313
- DOI: 10.1049/iet-cta.2008.0601
- Type: Article
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p.
303
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This study presents the development of a field programmable gate array (FPGA)-based accelerator that is highly suited to the implementation of complex and computationally demanding control or real-time simulation tasks. The application studied in this article is for the real-time simulation of wheel–rail contact laws, which may be used for hardware-in-the-loop experimental studies of the latest active control technology for wheelset stabilisation and steering. The complex wheel–rail contact laws are implemented using a single FPGA chip that outperforms substantially modern general-purpose CPU or DSP in the aspects of processing time, configuration flexibility and cost. The algorithms are restructured to utilise the FPGA's parallel processing capability. Reusable IP core are used for the floating point operations. The scheduling of the operations is optimised to ensure effective and efficient use of the FPGA's resources.
Editorial: Advances in complex control systems theory and applications
Decentralised H∞ quantisers design for uncertain interconnected networked systems
Co-design of predictive controllers for wireless network control
Network load minimisation design for dual-rate Internet-based control systems
Decentralised state feedback design for large-scale linear systems subject to input saturation
Novel interaction prediction approach to hierarchical control of large-scale systems
Robust decentralised stabilisation of interval discrete-time singular large-scale systems
Model predictive control of dynamically substructured systems with application to a servohydraulically actuated mechanical plant
Stabilising systems with aperiodic sample-and-hold devices: state feedback case
State convergence property of perturbed switched linear time-delay systems
Optimal usage of coal, gas and oil in a power plant
Optimal operating conditions for a batch fluidised bed dryer
Field programmable gate array implementation of wheel–rail contact laws
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