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CEINT: A general purpose modeling program
137
Abstracts 195 Control of a pH Plant Using Connectionist Representations D. Sbarbaro, pp 905.908
199 Opthnigation Based Design and Control D.Q. Mayne, E. Polak, pp 921-930
In this paper the control of a pH plant using connectionist representations is addressed. Four nonlinear control schemes based on connection/st representations of the controlled plant are developed and compared. The results show that it is possible to achieve better control than a linear control scheme, and that there are limitations imposed by the nonlinearity of the plant and the degree of approximation of the model over the different approaches studied.
The use of optimization for the design of control systems with many, competing design objectives is explored. A canonical form for the design problem is presented, and it is shown how a variety of design objectives may be transcribed into this form. Methods for solving the resulting mathematical programming problem are presented. The effective handling of control and state constraints requires a nonlinear controller. Receding-horizon, or medelpredictive (optimization-based) control is an effective method of achieving nonlinear control of constrained systems, when the plant is sufficiently slow to permit, on-line, approximate solution of open-loop optimal control problems. Recent research is described.
196 CEINT: A General Purpose Mudding Program C.S. Berger, pp 909-912
200 Perspectives on the Process of Identification L. Ljung, pp 931-939
A general-purpose identification algorithm has been developed which adapts its memory requirements to cope with the complexity of the problem. The modeling capability of the new method is compared with that of the CMAC on data obtained from computer controlled experiments on the application of mnsele-relaxant drugs.
To identify mathematical models of dynamic systems on the basis of observed inputs and outputs is an important task in many different applications. This paper reviews some perspectives on this process. The engineer's perspective is considered to be the most important one. 201 Process Control: Theories and Profits M.L. Brisk, pp 941-950
197 Hierarchical Intemgent Control with Flexible AC Transmission Systems Application R.R. Zakrzewskt, R.R. Molder, W J . Kolodzlej, pp 913-916 A novel hierarchical intelligent controller configuration is proposed using an artificial neural network as a control-mode classifier in the supervisory level, and a set of pre-designed controllers in the lower level. Controller outputs are modified nonlinearly by the classifying signals in a struoture resembling one artificial neuron with adaptively changed weights. The lowerlevel local controllers are implemented using neural networks. An illustrative example of this approach is based on the transient stabilization of a single-machine infinite-bns system studied in Flexible AC Transmission Systems (FACTS) research.
198 Fuzzy Anti-Reset Windup for P1D Controllers A. Hansson, P. Gruber, J. Tiidtli, pp 917-920 In this paper anti-windup schemes for PID controllers are proposed, that consider not only actuator constraints, but also process state constraints. The schemes are fuzzy generalizations and combinations of the traditional conditional integration antiwindup schemes.
There is an increasing body of evidence that the effective use of control technology achieves real benefits for the process industries, contributing dramatically to increased profitability. Yet these industries have been slow to take advantage of process control. This wary approach is more than partly conditioned by perceptions of the chequered history of applications of process-control theory. The reasons for these perceptions are reviewed, and some key issues identified for research in process-control theory to meet the current and future needs of industry.
202 Recent Developments In Digital Control Theory M. Arskl, p p 951-960 Recent research on the application of non-conventional digital controllers is surveyed. Here, "non-conventional digital controllers" mean digital controllers equipped with general hold circuits, general samplers or periodically time-varying discretetime compensators, and include multirate digital controllers as a special ease. First, their basic features are studied. Then, their advantages, pitfalls, and limitations are explained. After that, the problem of when and how to use nonconventional digital controllers is considered. The scope is limited to the control problems of time-invariant continuous-time plants. Emphasis is placed on explaining the basic aspects of the research, and clarifying their interrelations.
Customers wishing to purchase copies of the publications abstracted in this section should send orders to their regular supplier or their nearest Elsevier Science office (as below), quoting the ISBN and title: Elsevier Science Ltd The Boulevard Langford Lane Kidlington, Oxford OX5 1GB, UK
Elsevier Science Inc. 660 White Plains Road Tarrytown NY 10591-5153, USA
Abstracts 195 Control of a pH Plant Using Connectionist Representations D. Sbarbaro, pp 905.908
199 Opthnigation Based Design and Control D.Q. Mayne, E. Polak, pp 921-930
In this paper the control of a pH plant using connectionist representations is addressed. Four nonlinear control schemes based on connection/st representations of the controlled plant are developed and compared. The results show that it is possible to achieve better control than a linear control scheme, and that there are limitations imposed by the nonlinearity of the plant and the degree of approximation of the model over the different approaches studied.
The use of optimization for the design of control systems with many, competing design objectives is explored. A canonical form for the design problem is presented, and it is shown how a variety of design objectives may be transcribed into this form. Methods for solving the resulting mathematical programming problem are presented. The effective handling of control and state constraints requires a nonlinear controller. Receding-horizon, or medelpredictive (optimization-based) control is an effective method of achieving nonlinear control of constrained systems, when the plant is sufficiently slow to permit, on-line, approximate solution of open-loop optimal control problems. Recent research is described.
196 CEINT: A General Purpose Mudding Program C.S. Berger, pp 909-912
200 Perspectives on the Process of Identification L. Ljung, pp 931-939
A general-purpose identification algorithm has been developed which adapts its memory requirements to cope with the complexity of the problem. The modeling capability of the new method is compared with that of the CMAC on data obtained from computer controlled experiments on the application of mnsele-relaxant drugs.
To identify mathematical models of dynamic systems on the basis of observed inputs and outputs is an important task in many different applications. This paper reviews some perspectives on this process. The engineer's perspective is considered to be the most important one. 201 Process Control: Theories and Profits M.L. Brisk, pp 941-950
197 Hierarchical Intemgent Control with Flexible AC Transmission Systems Application R.R. Zakrzewskt, R.R. Molder, W J . Kolodzlej, pp 913-916 A novel hierarchical intelligent controller configuration is proposed using an artificial neural network as a control-mode classifier in the supervisory level, and a set of pre-designed controllers in the lower level. Controller outputs are modified nonlinearly by the classifying signals in a struoture resembling one artificial neuron with adaptively changed weights. The lowerlevel local controllers are implemented using neural networks. An illustrative example of this approach is based on the transient stabilization of a single-machine infinite-bns system studied in Flexible AC Transmission Systems (FACTS) research.
198 Fuzzy Anti-Reset Windup for P1D Controllers A. Hansson, P. Gruber, J. Tiidtli, pp 917-920 In this paper anti-windup schemes for PID controllers are proposed, that consider not only actuator constraints, but also process state constraints. The schemes are fuzzy generalizations and combinations of the traditional conditional integration antiwindup schemes.
There is an increasing body of evidence that the effective use of control technology achieves real benefits for the process industries, contributing dramatically to increased profitability. Yet these industries have been slow to take advantage of process control. This wary approach is more than partly conditioned by perceptions of the chequered history of applications of process-control theory. The reasons for these perceptions are reviewed, and some key issues identified for research in process-control theory to meet the current and future needs of industry.
202 Recent Developments In Digital Control Theory M. Arskl, p p 951-960 Recent research on the application of non-conventional digital controllers is surveyed. Here, "non-conventional digital controllers" mean digital controllers equipped with general hold circuits, general samplers or periodically time-varying discretetime compensators, and include multirate digital controllers as a special ease. First, their basic features are studied. Then, their advantages, pitfalls, and limitations are explained. After that, the problem of when and how to use nonconventional digital controllers is considered. The scope is limited to the control problems of time-invariant continuous-time plants. Emphasis is placed on explaining the basic aspects of the research, and clarifying their interrelations.
Customers wishing to purchase copies of the publications abstracted in this section should send orders to their regular supplier or their nearest Elsevier Science office (as below), quoting the ISBN and title: Elsevier Science Ltd The Boulevard Langford Lane Kidlington, Oxford OX5 1GB, UK
Elsevier Science Inc. 660 White Plains Road Tarrytown NY 10591-5153, USA