UKACC International Conference on Control (CONTROL '98)
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- Location: Swansea, UK
- Conference date: 1-4 Sept. 1998
- ISBN: 0 85296 708 X
- Conference number: CP455
- The following topics were dealt with: fuzzy control; signal processing; symbolic algebra; energy utilities; power systems control; robotics; machine control; neural networks; decentralised control; fault diagnosis; fault tolerant control; process control; robust control; nonlinear systems; human systems engineering; predictive control; adaptive control; discrete event systems; aerospace control; distributed parameter systems; large scale systems; identification; simulation and modelling; self tuning systems; gas turbines; multivariable control systems; intelligent control; two dimensional systems; optimisation; building management systems; and mechatronics
1 - 20 of 296 items found
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Industrial control: set-points for 2010
- Author(s): G.C. Goodwin
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Control is a core enabling technology for industry. It underpins many economically related factors including quality, efficiency and safety. In recent years, additional pressures have arisen from the globalization of markets and the world wide concern for environmental issues. These pressures will lead to increased emphasis on control in the future. Also, the technologies underpinning control science are presently undergoing rapid development. Thus the stage is set for a period of change. This paper gives a personal reflection on where the field might go over the next few years and suggests some possible research directions. Key factors underpinning control science include technological developments (sensors, actuators, communications and computing), the theory of design (identification, and constraint management), performance assessment (fundamental limitations and architectural issues) and condition monitoring (fault diagnosis and adaptation). The paper will briefly touch on a selection of these issues. At times, we also present some supporting analysis where the topic happens to coincide with a current personal research interest.
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Continuous learning automata and adaptive digital filter design
- Author(s): M.N. Howell and T.J. Gordon
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In the design of adaptive IIR filters, the multi-modal nature of the error surfaces can limit the use of gradient-based and other iterative search methods. Stochastic learning automata have previously been shown to have global optimisation properties making them suitable for the optimisation of filter coefficients. Continuous action reinforcement learning automata are presented as an extension to the standard automata which operate over discrete parameter sets. Global convergence is claimed, and demonstrations are carried out via a number of computer simulations.
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On the connections among the electric torque, residue, functional sensitivity, participation and Partial Multi-Modal Decomposition
- Author(s): H.F. Wang
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The electric torque, residue, functional sensitivity, participation and partial multi-modal decomposition (PMMD) are the most popular and effective techniques proposed so far for the analysis and design of power system damping controllers, such as power system stabilizers (PSS) and FACTS-based stabilizers. In this paper, the connections among these techniques are revealed through theoretical analysis so that a deep insight into the techniques and a theoretical basis for their comparisons are provided.
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Wavelet analysis of arcing fault phenomena with particular reference to development of new protection and control techniques
- Author(s): I.K. Yu and Y.H. Song
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In this paper, the faulty transients generated by primary and secondary arcs are analysed using wavelet transform with particular reference to the development of new protection and control techniques. Daubechies D4 wavelet transform is adopted and the numerical analyses reveal that certain wavelet components can be effectively used as the features to detect and identify faults in transmission systems. The outcome of the study clearly indicates a novel way to advance the development of power system protection.
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Disturbances Auto-Rejection Control of TCSC in power systems
- Author(s): C. Zhang ; X.X. Zhou ; Y.J. Cao ; Q.H. Wu
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Presents a disturbances auto-rejection control (DARC) strategy for control of thyristor controlled series compensation (TCSC) to improve the power system transient stability. This novel nonlinear controller possesses a simple structure and its design does not require system models. DARC performs as an adaptive control scheme with a robust feature in rejecting disturbances. A simulation study undertaken based on nine-machine and forty-one-bus power system shows that DARC can provide satisfactory control performance and improve system stability with a great potential for control of FACTS in power systems.
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Input/output selection for robust control
- Author(s): M. van de Wal and B. de Jager
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Two new input/output (IO) selection methods are proposed. The aim is to find the IO sets for which there exists a controller that achieves robust performance. IO selection could thus be based on μ-synthesis, but to avoid this often time-consuming process H∞ controller existence conditions are used instead. To reduce conservatism, the structure in the combined uncertainty/performance block Δ is “eliminated”. The first (sufficiency-based) method augments the plant by diagonal scalings, whereas the second (necessity-based) method absorbs an uncertainty representation into the plant. An active suspension control problem illustrates both methods.
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Robust piecewise-linear control for polytopic systems with input constraints
- Author(s): J. Schuurmans and J.A. Rossiter
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This paper considers the problem of controlling uncertain systems with constraints. The aim is to tackle this problem in a simple and computationally efficient way. We propose a novel control algorithm that selects each sample time a pre-designed linear robust stabilizing controller that optimizes predicted performance. The algorithm is shown to be asymptotically stable. An example illustrates the method.
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Robust synthesis by fictitious Bayesian identification approach
- Author(s): M. Gauvrit and C. Manceaux
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We examine a new robust control procedure in order to ensure the best trade-off performance/parametric robustness. This study extends the research performed into an analysis method called PRABI (parameter robust analysis Bayesian identification). Its basic idea was the close relationship between quality of fictitious parametric Bayesian identification in closed-loop and stability robustness against variations of inherent parameters. The algorithm detailed below generalizes the concept in parametrizing the synthesis step for the study of performance robustness. Robust control design of a flexible system is demonstrated to prove the relevance of the theoretical methodology, which is easy to implement.
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Magnitude and phase envelopes of systems with affine linear uncertainty
- Author(s): N. Tan and D.P. Atherton
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In this paper, the magnitude and phase extremums of a family of polynomials of the form P(s, q)=a0(q)+a1(q)s+...+an(q)sn whose coefficients depend linearly on q=[p1, p2, …, pq]T and Q={q: pi∈[pi, pi],i=1, 2, …, q} are first obtained by using the geometric structure of the value set. The magnitude and phase extremums of this polynomial family multiplied with a fixed polynomial are then investigated. Finally, a procedure is presented for computing the Bode envelopes of a control system with parametric uncertainty. The distinguishing feature of the results given in this paper is the efficient procedure introduced for constructing the 2q-convex parpolygon of P(s, q).
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Generalized (A, B)-invariant subspaces and robust disturbance-rejection for infinite-dimensional systems
- Author(s): N. Otsuka and H. Hinata
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In the framework of the so-called geometric approach, this paper studies generalized (A, B)-invariant subspaces for infinite-dimensional systems and then gives solvability conditions for the robust disturbance-rejection problem with state feedback.
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Anti-reset windup designs using LQG/H∞ and frequency domain methods
- Author(s): K. Hui and C.W. Chan
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Many compensators and ad hoc design methods exist in the literature for the anti-reset windup problem of actuator saturation. However, they are seldom applicable over wide ranges of operating conditions and global stability of the compensated systems is not guaranteed. This paper presents one systematic design method in frequency domain with incorporated operating conditions. For stabilizable systems, global asymptotic stability can be guaranteed. Comparison with an elaborate LQG controller with H∞ performance bounds demonstrates the practicality of the proposed method in aspects of simplicity, robustness, transient response, guaranteed domain of stability attraction and design efficiency.
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Design is a document [control systems CAD]
- Author(s): A.S.A.M.M. Halepota ; P.W. Grant ; C.P. Jobling
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In this paper the document as a container environment paradigm is explored. Utilizing this paradigm a platform neutral prototype control system design environment is being developed which uses a document as the user interface. This document acts as the integrator of various tools. A JavaBeans component based solution allows the environment to be extended and modified as needed.
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Bond graphs, symbolic algebra and the modelling of complex systems
- Author(s): P.J. Gawthrop
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The paper discusses the generation of symbolic models of complex systems using hierarchical bond graphs. The uses to which such models can be put include simulation code generation, linearisation, system inversion for actuator sizing and controller design. This methodology is illustrated with reference to three modelling projects: aircraft systems, plastic-onto-wire extrusion and a gravity wave detector.
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A frequency domain toolbox using interval arithmetic
- Author(s): W. Haas ; K. Schlacher ; J. Weinhofer
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In linear control theory the frequency domain approach and the state-space approach are equivalent. But for the implementation of numerical algorithms the use of state-space equations is preferred. To avoid the numerical problems caused by a polynomial arithmetic, the use of an interval arithmetic with variable length of the mantissa is suggested. Some basic algorithms for polynomial and transfer-function matrices implemented in interval arithmetic are stated. A control example shows the feasibility of this method.
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Using standard forms for controller design
- Author(s): D.P. Atherton and A.F. Boz
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The paper revisits the problem of the use of standard forms of closed loop transfer functions in control system design. New performance criteria for the standard forms are introduced and the results extended to include a system zero. It is shown how the results can be used in the design of PI and PI-PD controllers, where the latter is shown to have advantages over the traditional PID controller.
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A servomechanism controller design tool
- Author(s): T.M.R.E. Roberts
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A controller design technique for a range of positioning servomechanisms was required. Each servo was to deliver an identical performance using different brushless DC motor, leadscrew and carriage components. The components were selected dependent upon space and available power. Performance was defined in terms of sensitivity and complementary sensitivity functions. From these, weighting functions were derived and used in an H∞ optimization to find a suitable control algorithm. The same weighting functions could then be used for servomechanisms using different components, so achieving similar performance without further control engineer design input. Tests for stability within parameter tolerance ranges and overall performance confidence checks were developed. The process was used on two servomechanisms.
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Control system design using real-time design patterns
- Author(s): M.J. Pont
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In this paper, some of the problems faced by software engineers involved in the development of control systems are considered, and it is argued that the success of such projects may be enhanced through the use of appropriate design patterns. The meaning of `design patterns' is explained, and the application of a collection of real-time patterns in the design and implementation of a simple cruise-control system is discussed.
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Secondary measurement selection and scaling sensitivity
- Author(s): Y. Cao ; D. Owens ; D. Rossiter
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Often in process control, it is necessary to use extra measurements, or so-called secondary outputs for monitoring processes. Traditionally, the selection of these outputs is based on criteria which need to be calculated scheme-by-scheme resulting in a combinatorial problem. In this work, it is shown that these secondary outputs can be selected using an efficient measure, the output effectiveness (OE) when the outputs are scaled in a special way. This method does not need any scheme-by-scheme calculation so that the combinatorial problem is avoided. Since the OE measure is dependent on output scaling, its sensitivity to this scaling is also discussed. A scaling sensitivity matrix is derived for the designer to quickly determine the effect of different choices of scaling factors on the OE measure. This information can then be used for efficient output selection. This is demonstrated on a distillation example.
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Verification of control logic based on Process Control Event Diagram
- Author(s): S.H. Yang ; G. Rong ; P.W.H. Chung
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Computer based logic control has been widely used in chemical processes, which is responsible for safe and reliable start-up, shut-down and sequence control. Some incidents in the computer controlled processes occur not because of computer hardware failures but because of errors in the control logic. Achieving a safe control logic is the first step of designing a safe logic control system. In this paper an improved modelling representation, process control event diagram (PCED), is described and used to express the control logic and its effect on a process. The control logic is verified by qualitative simulation based on the PCED. The technique is illustrated by reference to a case study.
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Optimal design and control of double-effect distillation systems
- Author(s): V. Bansal ; R. Ross ; J.D. Perkins ; E.N. Pistikopoulos
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A general, rigorous dynamic model is described for studying the interactions of design and control in double-effect distillation systems. A sequential strategy for optimal design and control is implemented for a binary system; potential operability bottlenecks are identified and the economic advantage of double-effect systems over conventional single column systems is demonstrated. A simultaneous optimization strategy is also adopted and used to obtain a more economically beneficial double-effect design and control system than that obtained using the sequential approach.
