UKACC International Conference on Control. Control '96
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- Location: Exeter, UK
- Conference date: 2-5 Sept. 1996
- ISBN: 0 85296 666 0
- Conference number: CP427
- The following topics were dealt with: fuzzy systems and fuzzy control; neurocontrol; manufacturing and process control; robotics; optimal control; neural networks; modelling and simulation; system identification; parameter estimation; robust control; fault diagnosis and condition monitoring; computerised control; optimisation; switching systems; genetic algorithms; control design methods; nonlinear systems; aerospace control; adaptive control; timed discrete event systems; hybrid control systems; and evolutionary algorithms in control
1 - 20 of 255 items found
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Multivariable self-tuning temperature control of a thermo-analyzer
- Author(s): V. Bobal ; J. Machacek ; M. Hruby ; R. Prokop
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The paper deals with the multivariable self-tuning temperature control of a thermo-analyzer. The controller parameters are derived on the basis of the deadbeat approach. For parameter estimation of the process model, the recursive least squares method with LD decomposition and directional forgetting is applied. This multivariable controller has been designed especially for technological processes, where the process output variables without overshoot or with prescribed overshoot are desired and reference signals are changed with steps and linear increasing.
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Application of an expert system for robust controller design
- Author(s): D.W. Gu ; S.J. Goh ; T. Fitzpatrick ; I. Postlethwaite ; N. Measor
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This paper describes an expert system and its application to robust control system design. The need for expert systems to aid practising control engineers to perform robust control systems design is discussed. A brief introduction of the H∞ loop shaping design procedure is included. The role of expert systems in robust control systems design is discussed. We outline the structure of the expert system for designing robust controllers based on the H∞ loop shaping design procedure. A design example is included to illustrate the capability of the expert system to design robust controllers in realistic cases.
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Robust disturbance rejection for left invertible systems with measurable and nonmeasurable disturbances
- Author(s): F.N. Koumboulis and M.G. Skarpetis
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The problem of robust disturbance rejection for left invertible linear systems, with nonlinear uncertain structure and with measurable and nonmeasurable disturbances, is studied and solved for the first time. The necessary and sufficient conditions for the problem to have a solution, via an independent of the uncertainties static feedback law, are established. The general explicit expression of the feedback matrix is derived. The feedback invariant poles are determined. Sufficient conditions for robust disturbance rejection with simultaneous robust stability, are established.
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A simplified non-linear model of NOx emissions in a power station boiler
- Author(s): N. Li and S. Thompson
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When considering NOx development in power stations, experiments show that its formation is slower than the combustion process. Therefore in this paper the modelling of NOx emissions is decoupled from the combustion process. A NOx model for Kilroot Power Station in Northern Ireland is then derived from the extended Zeldovich mechanism. The physical parameters in the model are determined from experiments. The comparison of the simulated values with the real measurements is also presented.
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Adaptive active noise and vibration control
- Author(s): M.O. Tokhi ; K. Mamour ; M.A. Hossain
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This paper presents an investigation into the development of an adaptive active control strategy for noise cancellation and vibration suppression using a multi-source configuration. A self-tuning control algorithm is developed on the basis of optimum cancellation of broadband noise/vibration at a set of observation points. The algorithm is implemented on a digital processor and its performance assessed in the cancellation of noise in a free-field medium and suppression of vibration in a flexible beam structure.
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Robust control of a high temperature multiburner heating plant
- Author(s): A.I. Bhatti ; S.K. Spurgeon ; C. Edwards
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The design of robust linear and nonlinear controllers for a multiburner heating plant commonly seen in industry is described. First a nonlinear controller design based on sliding mode theory is developed. A nonlinear observer is used for state estimation and the resulting nonlinear controller-observer pair is implemented on a nonlinear simulation facility. An H∞ approach is employed to design a linear robust controller. The nonlinear simulation results for this controller are also shown. Finally, a quantative comparison between the performance of both controllers is presented.
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Hierarchical control scheme for chain-grate stoker coal combustion
- Author(s): P.F. MacConnell ; D. Neuffer ; D.H. Owens ; M.A. Patrick
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The control of coal combustion on chain-grate stokers is a complex problem which is of importance to environmental concerns. Producing efficient combustion in spite of material and feed disturbances is a difficult task, allying this to the meeting of stringent emissions criteria even more so. A mathematical model has been used to develop a control scheme, some simulation results of which are shown.
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Water resources sharing planning and management problems
- Author(s): E. Avogadro and R. Minciardi
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The problem of water resources sharing is dealt with in this paper. In the solution of such a problem, water quality constraints have to be taken properly into account, as a considerable reduction of the flow in a river may seriously compromise the surviving of the river ecological system, especially in presence of polluting discharges of sewerage water. The water resources sharing problem may be considered within two different decisional frameworks. In the first one, a planning problem is stated and solved, which corresponds to fixing the set points for the second decisional framework, which is an online management problem. The latter problem has the objective of keeping the system's behaviour close to the nominal one which has been determined via the solution of the planning problem. In other words, online management policies react to deviations from the nominal system behaviour and are based on freshly acquired information about the system.
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Evaluation of ℋ∞ loop shaping controller design on a process control problem
- Author(s): A. Pantas and S. Walsh
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This paper examines the application of an ℋ∞-controller to a typical process control problem. A new weight selection procedure is proposed, which aims to aid the loop-shaping methodology by linking the weight selection directly with a method for estimating achievable bandwidth, based on nominal phase characteristics. The success of the procedure is demonstrated on a nonlinear simulation. This paper also highlights some problems with using the ℋ∞ loop-shaping methodology which deserve further attention to enhance the utility of this approach to controller design.
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Cumulant/bispectrum model structure identification applied to a pH neutralization process
- Author(s): H.E. Emara-Shabaik ; J. Bomberger ; D.E. Seborg
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A process model structure identification criteria based on the cumulants and bispectrum of output response data is applied to a laboratory-scale pH neutralization process. The resulting model structure is appropriate and is consistent with a priori physical information.
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Chemical dosing philosophies for a water treatment plant: results of some pilot plant experimentation
- Author(s): C.S. Cox ; P. Daniel ; A. Adgar ; A. Lowdon
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The tight control of pH prior to coagulation is the first phase of a longer term comprehensive research programme. Due to the complex interactions between so many variables it is a necessary precursor to other work. For example, coagulant dose control by means of a streaming current detector (SCD) or feedforward algorithm, which are other areas of on-going investigations, are heavily influenced by pH. Therefore eliminating the effect of this variable via good process regulation is an important and necessary development.
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Control of pH in-line using a neural predictive strategy
- Author(s): J.B. Gomm ; S.K. Doherty ; D. Williams
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Control of an experimental in-line pH process exhibiting varying nonlinearity and deadtime is described. A radial basis function (RBF) artificial neural network is used to model the nonlinear dynamics of the process. Accommodation of the varying process deadtime in the neural model is achieved by the generation of a feed-forward signal, for input to the neural network, from a downstream pH measurement. The feedforward signal is derived from a variable delay model based on process knowledge and a flow measurement. The neural model is then used to realise a predictive control scheme for the process. Development of the neural process model is described and results are presented to illustrate the performance of the neural predictive control scheme which is tested as a regulator at different setpoints.
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Enhanced self-tuning control with application to a combined heat and power system
- Author(s): C.A. Smith ; K.J. Burnham ; D.J.G. James
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This paper describes enhanced self-tuning control methods which have been tailored for application to the speed control of a gas engine driven combined heat and power system. The enhanced algorithms have been developed to accommodate for improved estimation and overall control of systems exhibiting fast dynamic and nonlinear behaviour. Refinements that are required to be made to enable the techniques to be applied in practice are described and real-time results illustrate the performance of the resulting scheme.
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A parallel predictive controller
- Author(s): F.M.F. Gaston ; D.W. Brown ; J. Kadlec
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A parallel architecture for general predictive control is presented which has a number of advantages for VLSI implementation over those previously published. It has a regular structure with identical processing cells which can be implemented in fixed point, or floating point, or a hybrid arithmetic. Data can be extracted and controlled easily. The controller includes an effective regularisation scheme which allows a priori information about the plant and the controller to be included and kept permanently present in the identification scheme. Users can select the level of the influence of this a priori information on the controller adaptation relative to the effect of the measured data. The resultant architecture is suitable for fixed-point VLSI, or DSP, application aiming for low-power and minimal complexity, or maximal speed.
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Adaptive implicit control using extremum control methods
- Author(s): L.B. Navarro and M.B. Zarrop
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Extremum control has uses beyond the conventional optimisation of performance indices related to productivity: it can also fulfill a dynamic control objective. This has been shown by presenting an algorithm that directly optimises a GMV-type of cost function, showing good local convergence properties as well.
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Some practical recommendations in anti-windup design
- Author(s): D. Vrancic and Y. Peng
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The paper gives several practical recommendations on how to implement anti-windup compensators in a PID controller. The paper considers different problems related to direct process input measuring and possible controller error caused by anti-windup algorithm. The same problem arises when the process actuator contains general nonlinearity. The method with a free parameter of the anti-windup compensator is proposed.
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Empirical studies of output feedback MRAC algorithm with minimal controller synthesis
- Author(s): K.I. Aziz and M. Thomson
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The minimal controller synthesis (MCS) algorithm is an adaptive control law based upon hyperstability theory and Popov's criterion which assumes that all states of the plant are accessible, but in many cases this assumption is not valid. This paper deals with the output feedback problem of the MCS algorithm where only the plant output is available and is used to derive the adaptive law. Results of simulation studies and actual plant trials are presented which demonstrate the excellence of control that can be achieved.
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A robust limited memory recursive filter
- Author(s): Y.P. Grishin
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New robust limited memory recursive filter have been developed for situations when input observations contain outliers. The model of the outliers is supposed to be described by the Gaussian-Markov sequences. On the basis of this model an optimal procedure of outliers rejection is obtained. The results of a numerical simulation are presented.
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Optimal quadratic filtering of quantization noise in non-Gaussian systems
- Author(s): M. Dalla Mora ; C. Manes ; P. Palumbo
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This work deals with the problem of state estimation for a class of discrete time linear systems forced by non-Gaussian noise where the quantization on measured output is modeled, as usual, as additive noise having uniform probability distribution. The best linear estimate, computed through the Kalman filter, in this case may not give good results. To improve the covariance of the estimation error the best estimator with quadratic structure is developed in this paper. The optimal quadratic filter, proposed by Santis et al. (1995), is preliminarily introduced using a geometric approach. Then its application is shown in a case in which the state noise is strongly non-Gaussian to best appreciate the improvement w.r.t. standard linear filtering.
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Noise control in three-dimensional propagation
- Author(s): M.O. Tokhi and K. Mamour
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This paper presents an investigation into the process of noise cancellation in a three-dimensional non-dispersive (linear) propagation medium using a multiple-source system configuration. The process of field cancellation is considered from a frequency-domain viewpoint. The degree of cancellation is analysed in relation to source-related and geometry-related parameters of the system leading to a three-dimensional description of the pattern of cancellation and reinforcement in the medium and merits of the system design. Moreover, the effect of implementation errors on the physical extent of cancellation and the extent of error tolerances, for consideration in the process of design of the system, are analysed and discussed.
