Wyniki wyszukiwania - BazTech

1

Control Theory Applications in Logistics – MPC and other Approaches

Orzechowska J., Bartoszewicz A., Burnham K. J., Petrovic D.

Logistyka

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2012

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nr 3

EN

The paper concerns an application of engineering regulation theory concepts to modelling and effective control of logistic systems. Nowadays an achievement of inventory keeping cost vs. benefit trade-off becomes extremely important. This is, however, a complex task with respect to uncertain demand and lead times. These uncertainties result in such problems as high storage costs, varying inventory levels (bullwhip effect) and deterioration of goods. The paper shows a brief review of contributions made in this area of study with special focus on Model Predictive Control.

PL

Artykuł przedstawia krótki przegląd zastosowań metod teorii regulacji do modelowania i sterowania systemów logistycznych. Ponieważ osiągnięcie takiego poziomu zapasów, aby zredukować koszty ich magazynowania i jednocześnie zachować ciągłość podaży nie jest zadaniem łatwym, uzasadnione jest stosowanie do tego celu obecnie dobrze rozwiniętych metod teorii sterowania. Artykuł przedstawia zwięzły przegląd literatury dotyczący tej tematyki ze szczególnym uwzględnieniem bardzo skutecznych metod sterowania predykcyjnego.

2

Parity equations-based unknown input estimator for multiple-input multiple-output linear systems

Sumisławska M., Larkowski T., Burnham K. J.

Systems Science

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2010

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Vol. 36, no 3

49-59

EN

This paper presents a novel approach to the problem of unknown input estimation of multiple-input multiple-output systems. In the setup considered the measured output signals are affected by white zero-mean Gaussian measurement noise. The observer developed here is based on the parity equations concept and the Lagrange multiplier method is used to obtain an analytical solution for the filter parameters, hence minimising the unwanted effect of the noise. The paper extends the concept of the parity equation based unknown input observer approach, which has been previously developed by the authors for the case of single-input single-output systems. A simulation study is carried out, which illustrates a potential application of the proposed approach to a steel rolling mill for the purpose of improving the control performance.

3

Heating ventilation and air conditioning system; enhancement of energy consumption via control optimisation

Zajic I., Burnham K. J., Larkowski T., Hill D.

Systems Science

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2010

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Vol. 36, no 3

39-47

EN

Nowadays, because of higher energy costs and the awareness of the environmental issues a general trend can be observed to increase the energy efficiency of heating ventilation and air conditioning (HVAC) systems. The paper demonstrates that this aim can be achieved by highly stable control allowing for operation close to the specification limits, where the highest profitability can be obtained. In this regard, black-box models of both the controlled zone air temperature and humidity are constructed for a subsequent analysis of the present control system via a computer simulation. The results obtained are utilised for tuning of controllers on a real plant leading, subsequently, to substantial energy savings. The paper also investigates a potential scope for further energy savings.

4

A modified generalized predictive control approach

Kret P., Burnham K. J., King P. J.

Systems Science

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2010

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Vol. 36, no 3

13-18

EN

The paper presents a comparative simulation study which considers various formulations of generalised predictive control (GPC). The original GPC was formulated in an incremental manner. The first variant is to compare this to a non-incremental form (NIGPC). Following on from this a modified form of NIGPC whereby a feedforward term, which is an approximation to the mean value of the control, is utilized. It is shown that the modified form yields consistent improvement albeit of a marginal nature.

5

On abstraction and interpretability: a behavioural perspective

Pfaff R., Burnham K. J.

Systems Science

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2009

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Vol. 35, no 2

19-26

EN

The process of abstracting physical systems to obtain models and interpret these for the desired purpose is considered from a perspective originating from the behavioural framework. It is pointed out that for the purpose of modelling regenerative processes or passive controllers, the behavioural framework and bond graphs are well suited. The reader is introduced to modelling of dynamical systems in the behavioural framework; in this context system representations predominant in the behavioural framework are presented. In addition, the concepts of interconnection and control by interconnection are shown together with a numerical simulation and an illustrative example. Bond graphs for graphical modelling of systems without a priori assumptions of causality are presented, with the key concepts illustrated by repeating the illustrative example from the behavioural modelling section by help of bond graphs. A comparison shows that manifest behaviours of interconnected systems can be stated directly from the corresponding bond graph. This shows the common applicability of both techniques to handle real world modelling and control problems.

6

Structured total least norm for MISO ARX system identification

Larkowski T., Vinsonneau B., Burnham K. J.

Systems Science

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2007

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Vol. 33, no 4

73-83

EN

The errors-in-variables (EIV) identification framework concerns the identification of dynamic models of systems where all the variables are corrupted by noise. The total least squares (TLS) is one of the most prominent techniques that has proven to be both robust and reliable. The structured total least norm (STLN) can be seen as a natural extension to TLS that preserves any affine structure of the joint data matrix, which is mostly the case in identification schemes. In contrast to the least squares (LS), TLS or mixed LS-TLS problems, the STLN solution cannot be expressed in a closed form, therefore, an optimization procedure is required. Note that STLN allows different norms to be considered other than the usual square norm (or 2 norm). This paper describes a direct application of the STLN approach for systems that can be represented by auto-regressive with exogenous input (ARX) multi-input single-output (MISO) models. The performance of the proposed STLN algorithm (in the case of the square norm) is compared to the LS, the bias-eliminating LS (BELS), the extended matrix LS (EMLS), the instrumental variables (IV), TLS and the compensated TLS (CTLS) methods when applied to a simulated MISO ARX system. Results, obtained from Monte Carlo simulation, show that, under the conditions considered here, STLN surpasses all other investigated techniques, attaining the best estimates of the true system parameters.

7

A goal oriented approach to model identification of an industrial furnace system combining a priori knowledge and optimal estimation

Vinsonneau B., Martineau S., Goodall D. P., Burnham K. J.

Systems Science

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2007

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Vol. 33, no 4

103-110

EN

Prompted by the need to determine a unique tuning parameter, the paper proposes a conceptual model for a high temperature industrial furnace in which the notion of an unmeasurable "global temperature" plays a key role. The developed approach is designed to accommodate a priori knowledge of system nonlinearities, as well as the effects of an externally triggered burner firing cycle which gives rise to an oscillatory response present on the locally measured zone temperature. It is assumed that the variation in the global temperature is lower than that observed at the locally measured temperature at a point. The developed model is able to accommodate, and effectively separate, the effects of the combustion burner firing cycle and the underlying bilinear characteristic behaviour relating fuel combustion and temperature of each zone. It is assumed that these physical phenomena can be represented by a linear model, modelling the effects of the combustion burner firing cycle, cascaded with a bilinear model, where an intermediate variable is the global temperature. The result of employing a regularisation technique together with the cascade multiple model produces an optimal value for the tuning parameter of a four-term bilinear PID control system.

8

Goal oriented estimation of an industrial furnace to be controlled using bilinear PID

Vinsonneau B., Martineau S., Burnham K. J.

Systems Science

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2005

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Vol. 31, no 1

53-61

EN

PID control systems are tunable devices which provide acceptable performances and are widespread in many industries. However, it is assumed that local linearity holds for the plant to be controlled, with the tuning being valid around a particular operating point only. Extending the performance over a wider range usually involves an in-depth local understanding of plant nonlinearities. In some cases, this can be approximately expressed as a bilinearity. To illustrate the approach, appropriate system modelling and design of a bilinear control strategy for a high-temperature industrial furnace system is presented.

9

A comparison of methods of identifying operating condition for ship roll stabilization control

Engeln A-Z. E., Koshkouei A. J., Burnham K. J., Roberts G. N.

Systems Science

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2005

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Vol. 31, no 1

63-72

EN

Ship roll stabilisation may be improved by utilizing a bank of parallel controllers in which individual controllers are activated in pairs for roll control via actuation of rudder and tins. To achieve this, it is necessary to identify the ship's operating condition, thus facilitating the activation of the appropriate controller pair. Operating conditions depend mainly on ship speed and wave encounter angle and, whereas only the ship speed is known to the system, the other conditions need to be identified. An approach has been designed to detect the actual seagoing condition via roll frequency detection. Two different methods are illustrated and discussed in this work.

10

A comparison of control systems for ship roll stabilisation

Law Y., Koshkouei A. J., Burnham K. J.

Systems Science

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2005

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Vol. 31, no 2

77-87

EN

This paper presents the results of a fin-rudder controller synthesis for roll reduction where different types of controllers are tested and compared. Three different main types of controllers including PID, advance phase, dual loop transfer recovery (LTR) and sliding mode (SMC) controllers are considered to stabilise the ship motion. The system comprises three different controllers, fin and rudder controllers, and autopilot. Therefore, for each situation of the ship journey, the triple controllers should be designed. It is not necessary to have the same controller structure for all three submodels. This paper compares these various controllers individually for each submodel, and demonstrates the results of the implementation of controllers with different structures when applied to the entire system.

11

A comparison method for identifying operating conditions for ship roll stabilization

Koshkouei A. J., Burnham K. J., Roberts G. N.

Systems Science

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2005

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Vol. 31, no 4

75-85

EN

Ship roll stabilisation may be improved by utilizing a set of parallel controllers in which individual controllers are activated in pairs for roll control via actuation of rudder and fins. To this end, it is necessary to identify the ship's operating conditions for facilitating the activation of the appropriate controller pair. Operating conditions depend mainly upon ship speed, wave height and wave encounter angle and, whereas only the ship speed is known to the system, the other conditions need to he identified. An approach has been designed to detect the actual seagoing condition via roll frequency detection. Two different methods are illustrated and discussed in this paper.

12

Adaptive sliding mode backstepping output tracking controllers for feedforward uncertain systems

Koshkouei A.J., Burnham K.J.

Systems Science

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2003

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Vol. 29, nr 1

79-96

EN

Methods for control design for nonlinear feedforward uncertain systems are considered in this paper. These systems are not usually transformable to the parametric semi-strict feedback form, and it may include unmatched uncertainties consisting of disturbances and unmodelled dynamics. The design methods are based upon (i) the backstepping approach, and (ii) a combination of sliding mode and backstepping. A comparison method of the dynamic and static backstepping methods is presented by applying two methods on a gravity-flow/pipeline system.

13

Hybrid estimation algorithm for bilinear self-tuning control.

Dunoyer A., Balmer L., Burnham K. J., James D. J. G.

Systems Science

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1998

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Vol. 24, nr 4

29-35

EN

By exploiting the input dependent nature of the parameters of a discrete-time bilinear model structure, the paper combines knowledge of both discrete and continuous model parameters to form a hybrid approach to self-tuning controller design. With consideration given to an identified bilinear model of a high temperature heating plant application the appropriateness of the hybrid approach is demonstrated. In particular it is shown that the hybrid approach may be used to advantage within a Kalman filtering prediction/correction parameter estimation scheme. Practical issues relating to implementation of the approach are also discussed.