Dynamic Optimization in Business-wide Process Control

The chemical marketplace is a global one with strong competition between man- ufacturers. To continuously meet the customer demands regarding product quality and delivery conditions without the need to maintain very large stor- age levels chemical manufactures need to strive for production on demand. In this thesis we research how market-oriented production can be realized for the particular class of multi-grade continuous processes. For this class of processes production on demand is particularly challenging due to the the complex trade- off between performing costly and time-consuming changeovers and maintaining high storage levels. The first requirement for market-oriented production is that production management cooperates with purchasing and sales management. We propose the use of a scheduler as a decision support system in a cooperative organization constituted by these players. In such a scheduler, decision making is represented using decision variables and their effect on the company-wide objective, which is chosen to be the added value of the company, is modeled. The scheduler then selects a decision strategy that is optimal with respect to the objective and presents this strategy to the decision makers who use it to base their actual decision taking on. The company-market interaction is modeled using a transaction-based mod- eling framework. Therein not the actual market behavior is modeled but the expected effect of the interaction of the company with the market. Two types of transactions can be modeled in this framework: orders, which result from contracts with suppliers and customers, and opportunities, which express the expected sales and purchases. Two different approaches to the modeling of production decisions are taken, the choice of which depends largely on the im- plementation of the process control hierarchy that is assumed. In the first approach, production management and control is performed by a single level controller and the control decisions are the minute to minute manipulation of the valves. This approach is academically interesting, though practically in- tractable due to the combination of long horizons and fast sampling times. In the second approach the process control hierarchy consists of a scheduling layer at which it is determined what products will be produced when, and a process control layer which determines how this production is realized. This approach is taken in the rest of the thesis.Design, Engineering and Productio

Jerk derivative feedforward control for motion systems

This work discusses reference trajectory relevant model based feedforward design. For motion systems which contain at least one rigid body mode and which are subject to reference trajectories with mostly low frequency energy, the proposed feedforward controller improves tracking performance significantly. The feedforward controller may be of much lower order than the plant. The proposed feedforward controller is introduced using a model of an industrial XY-table as an application exampl

Jerk derivative feedforward control for motion systems

This work discusses reference trajectory relevant model based feedforward design. For motion systems which contain at least one rigid body mode and which are subject to reference trajectories with mostly low frequency energy, the proposed feedforward controller improves tracking performance significantly. The feedforward controller may be of much lower order than the plant. The proposed feedforward controller is introduced using a model of an industrial XY-table as an application exampl

Fixed structure feedforward controller design exploiting iterative trials: application to a wafer stage and a desktop printer

In this paper, the feedforward controller design problem for high-precision electromechanical servo systems that execute finite time tasks is addressed. The presented procedure combines the selection of the fixed structure of the feedforward controller and the optimization of the controller parameters by iterative trials. A linear parametrization of the feedforward controller in a two-degree-of-freedom control architecture is chosen, which results in a feedforward controller that is applicable to a class of motion profiles as well as in a convex optimization problem, with the objective function being a quadratic function of the tracking error. Optimization by iterative trials avoids the need for detailed knowledge of the plant, achieves the controller parameter values that are optimal with respect to the actual plant, and allows for the adaptation to possible variations that occur in the plant dynamics. Experimental results on a high-precision wafer stage and a desktop printer illustrate the procedure

Suppressing non-periodically repeating disturbances in mechanical servo systems

Non-periodically repeating (NPR) disturbances are fixed-shape disturbances that occur randomly in time. We can provide a control system with the capability to suppress this type of disturbance by adding in parallel to the input of the nominal feedback controller a learning look-up-table based feedforward controller that is activated using an NPR-disturbance detector

Advances in data-driven optimization of parametric and non-parametric feedforward control designs with industrial applications

The performance of many industrial control systems is determined to a large extent by the quality of both setpoint and disturbance feedforward signals. The quality that is required for a high tracking performance is generally not achieved when the controller parameters are determined on the basis of a detailed model of the plant dynamics or manual tuning. This chapter shows that the optimization of the controller parameters by iterative trials, i.e., data-driven, in both parametric and non-parametric feedforward control structures avoids the need for a detailed model of the plant dynamics, achieves optimal controller parameter values, and allows for the adaptation to possible variations in the plant dynamics. Two industrial applications highlight the large benefits of the data-driven optimization approach. The optimization of the feedforward controller parameters in a wafer scanner application leads to extremely short settling times and higher productivity. The optimization of the current amplifier setpoints in a digital light projection (DLP) application leads to nearly constant color rendering performances of the projection system in spite of large changes in the lamp dynamics over its life span

A two-level strategy of integrated dynamic optimization and control of industrial processes - a case study

Published in: J. Grievink; J. van Schijndel (eds.): 'European Symposium on Computer Aided Process Engineering 12', Elsevier, (2002), p. 511-516SIGLEAvailable from TIB Hannover: RR 8872(2001,29) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekEuropean Union (Euro), Brussels (Belgium)DEGerman