V. Van Breusegem

An industrial application of multivariable linear quadratic control to a cement mill circuit

There are a variety of control strategies that one may consider for cement mill circuit control and often several methods for implementing each strategy. Ideally, the control strategy selected and methodology used in its implementation should not only optimize circuit performance in terms of productivity but also be able to optimize quality. A linear quadratic multivariable controller has been applied to milling circuits and these goals successfully accomplished. The results are a stable circuit with mill and separator optimized, producing a consistent quality product of a predictable fineness. This enables one to use cement quality as the single circuit control set point.

Adaptive nonlinear regulation of fed-batch biological reactors: an industrial application

The authors present a general methodology for the design of adaptive regulators for fed-batch biological reactors with the aid of an illustrative case study which has given rise to a genuine industrial application. The application under consideration is the feedback optimization of yeast fermentations, which are of particular interest because yeasts are among the most frequently used microorganisms in genetic engineering for the production of high added value metabolites. The case study is representative of a wide class of control problems in biotechnology where the regulation of some substrate or metabolite concentration helps to solve yield/productivity conflicts.<<ETX>>

Bicarbonate Control Strategies for Anaerobic Digestion Processes

Proposes efficient bicarbonate control strategies for anaerobic digestion processes. The bicarbonate concentration which is easier and cheaper to measure than volatile acids concentration is regulated in order to stabilize the process. Adaptive linearizing and L/A control strategies using as control input either the dilution rate or the influent bicarbonate are proposed. The controllability properties of both inputs for the assumed nonlinear mathematical model are analyzed through linearization around steady-states. Simulations results are presented and discussed.

Optimal Adaptive Control of Fed-batch Fermentation Process with Growth/Production Decoupling

Abstract We consider the design of a substrate feeding rate controller for a class of biotechnological processes in continuous stirred tank reactors, characterized by a decoupling between biomass growth and product formation. The main contribution is to illustrate how the insight, obtained by preliminary optimal control studies, leads to the design of an easy to implement adaptive controller. The controller derived this way combines a near optimal performance with good robustness properties against modeling uncertainties and process disturbances. As an example, simulation results are given for the penicillin G fed-batch fermentation process.

On Forbidden State Problems for Colored Closed Controlled State Machines

Abstract Control of Discrete Event Dynamical Systems (DEDS) is an emerging theory where the problem of computational complexity is of great importance for practical applications. A typical control objective for DEDS is to guarantee, by disabling certain transitions, that some forbidden states cannot be reached. This paper presents a rigourous analysis of the forbidden state problem for the class of DEDS which can be modelled as Colored Closed Controlled State Machines (CCCtlSMs) which constitute a special class of controlled Petri nets (CtlPNs)

An industrial application of mutlivariable linear quadratic control to a cement mill

The paper presents the design development of a model-based control algorithm for the regulation of tailings and product flow rates in a cement mill. The control variables are the feed rate and the classifier speed. Experimental results of a full-scale industrial application are reported and discussed with a view to the control of the fineness of the cement.

TRAFFIC MODELLING AND CONTROL FOR METRO CIRCLE LINES

Most of the metro networks are operated as loop lines: a given number of trains are operated on a closed circuit, with the consequence that the delays are cumulated from circuit to circuit. The paper deals with modelling, stability and feedback control for the traffic on such loop lines. It extends the results obtained in the rather unrealistic case of open lines. The authors develop a mathematical model and state space formulations, putting in evidence the traffic instability on loop lines, and propose state feedback traffic control laws ensuring the stability of the closed loop system. Simulation results show the benefit to be expected from an efficient traffic control.

Combined Feedback Control of Metro Line and Train Operation

Abstract This paper provides a Discrete Event Dynamical System based methodology for the design of both logical and timed control in a metro or train network. The goals optimal recovery from disturbances subject to satisfaction of all the safety requirements. Controlled Petri nets and linear optimal control theory are used as tools in a hierarchical procedure.

An Industrial Application of Multivariable Linear Quadratic Control to a Cement Mill

Abstract The paper presents the design procedure of a model-based control algorithm for the regulation of tailings and product levels in a cement mill. The control variables are the feeding rate and the classifier speed. Experimental results of a real life industrial application arc reported and discussed with a view to the control of the fineness.

State Feedback Traffic Control of the Transient Behaviour of Underground Public Transportation Systems

This paper proposes two methods of traffic regulation of public underground transportation systems during transients, for example during the modification of the intervals between the trains. Both methods are based on optimal control theory for linear systems with quadratic criterion. In the first approach the system is controlled with respect to a nominal time schedule to be generated according to the new situation, while the second method realizes interval control without reference to a nominal schedule. The properties of both methods are analyzed and simulation results are discussed and compared.