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- Peter Rosander, Alf J. Isaksson, Johan Löfberg, Krister Forsman
- 2011

Frequent inlet flow changes typically cause problems for averaging level controllers. For a frequently changing inlet flow the upsets do not occur when the system is in steady state and the tank level at its set-point. For this reason the tuning of the level controller gets quite complicated, since not only the size of the upsets but also the time in… (More)

- Krister Forsman
- 1993

This paper describes the features and implementation of the Maple package Polycon which is intended to assist the control theorist in the analysis of nonlinear dynamical systems, in continuous and discrete time. Polycon handles systems where all nonlinearities are polynomial or rational functions. It implements functions that are not available at a \usable"… (More)

- Krister Forsman
- 1993

This report collects some useful results from commutative algebra and describes how they can be used to decrease the complexity in Grr obner base computations. As a byproduct we see how Grr obner bases relate to characteristic sets. The algorithms presented are well known but have, as far as the author knows not been collected in one place earlier.

Methods from computer algebra, mostly so called Grr obner bases from commutative algebra, are used to solve the algebraic Riccati equation (ARE) symbolically. The methods suggested allow us to track the innuence of parameters in the system or penalty matrices on the solution. Some non-trivial aspects arise when addressing the problem from the point of view… (More)

- Krister Forsman
- 1992

LINKÖPING This report and other reports from the automatic control group in Linkk oping are available by anonymous Abstract. I reproduce an elementary proof for the jacobian criterion for algebraic dependence and give an introduction to the basics of KK ahler diierentials. All results presented are known, but some of them are not easily accessible, either… (More)

- Krister Forsman
- 1992

- Peter Rosander, Alf J. Isaksson, Johan Löfberg, Krister Forsman
- 2012

In the presence of frequent inlet flow upsets, tuning of averaging level controllers is typically quite complicated since not only the size of the individual steps but also the time in between the subsequent steps need to considered. One structured way to achieve optimal filtering for such a case is to use Robust Model Predictive Control. The robust MPC… (More)

Use of utilities, such as steam and cooling water, is very common at industrial sites. Utilities are often shared between several production areas, and a disturbance in the supply of a utility is therefore likely to affect a large part of the production site, and cause great loss of revenue. In order to minimize the loss of revenue due to disturbances in… (More)

- Krister Forsman
- 1993

We discuss how the external behavior of a polynomial automatic control system can be determined, i.e. how to nd the diierential equation relating the input and the output of the system given a state space description, focussing on algorithmic aspects. This problem is equivalent to what is known as implicitization in computational algebraic geometry and one… (More)