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Performing experiments for system identification is often a time-consuming task which may also interfere with the process operation. With memory prices going down and the possibility of cloud storage, years of data is more and more commonly stored (without compression) in a history database. In such stored data, there may already be intervals informative… (More)

- Krister Forsman
- 1993

LINKÖPING This report and other reports from the automatic control group in Linkk oping are available by anonymous Abstract. We analyze Glad/Fliess algebraic observability for polynomial control systems from a commutative algebraic/algebro-geometric point of view. Furthermore we show some relations between algebraic observabil-ity and realization theory for… (More)

- Krister Forsman
- 1992

I reproduce an elementary proof for the jacobian criterion for algebraic dependence and give an introduction to the basics of Kahler di erentials. All results presented are known, but some of them are not easily accessible, either because the references are hard to get hold of or because they are di cult to read for non-algebraists.

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)

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)

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)

A method for detecting static friction (stiction) in control valves is proposed. The method is model-based and is inspired by ideas from the fields of change detection and multi-model mode estimation. Opposed to existing methods only limited process knowledge is needed and it is not required that the loop has oscillating behavior. The advantage of the… (More)

- Krister Forsman
- 1993

Some connections between constructive real algebraic geometry and constrained optimization are exploited. We show how the problem of determining the projection of a real-algebraic variety on a certain axis is equivalent to a problem in nonlinear programming. As an application, Grr obner bases are used to deal with an optimization problem arising in the… (More)

- Anna Lindholm, Charlotta Johnsson, +6 authors Krister Forsman
- MIM
- 2013

The integration of scheduling and control in the process industry is a topic that has been frequently discussed during the recent years, but many challenges remain in order to achieve integrated solutions that can be implemented for large-scale industrial sites. In this paper we consider production control under disturbances in the supply of utilities at… (More)