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Multirate sampled data system robustness: Frequency analysis

Abstract:

Frequency analysis is an appropriated tool to study the robustness of a controlled system to either disturbances or uncertainties. In this paper, a multirate based approach allows to consider the intersampling behaviour of the system by selecting a faster sampling rate at the output signal. Using the frequency analysis of multirate systems, the controlled process robustness to model uncertainties and disturbances can be derived. Although some authors claim that a dual rate inferential control could be more robust than a fast single rate one assuming some kind of parametric uncertainty in the process, a counterexample will show the opposite conclusion. Our approach is used to computationally show that this is not always true, and some assumptions about the model uncertainties should be taken. For the sake of comparison, the control performances using a non conventional dual-rate controller are also computed. © 2008 Civil-Comp Press.