Dp 451 en

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Control of ill-conditioned systems[edit]

Author: Pich Jiří

Diplomové práce 2011

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The aim of this thesis is to propose modifications of Model Predictive Controller (MPC) that will improve control of ill-conditioned systems. Based on a background research, an overview of currently used directionality measure and MPC applications for ill-conditioned systems is presented in the thesis. The suitable directionality measures are used for system conditioning analysis. Based on current knowledge and available methods, two extensions of MPC for illconditioned systems control are proposed in this thesis. The first of the presented methods extends the MPC cost function by a term penalizing absolute value of system input. This approach limits the size of the system input absolute value and prevents its unconstrained rise, which may occur if a system output should track a reference which requires a step corresponding to the system small singular values. The second proposed method extends the cost function by a term penalizing the system input movement in directions corresponding to the small system singular values. This modification prevents undesirably high system inputs in directions where the input has a small impact on the reference tracking abilities. The proposed MPC modifications are applied to a model of a distillation column to show the reference tracking properties and to check the robust stability of the extended MPC. Robust stability of the system is checked for different uncertainty representations in order to show how the additional criteria influence the frequency characteristics for these different uncertainty representations.

Práce vytvořena ve spolupráci se společností Honeywell.

Dp 2011 pich jiri.pdf