# Observers and robust output regulation for nonlinear systems

Abstract : Observers and output regulation are two central topics in nonlinear control system theory. Although many researchers have devoted their attention to these issues for more than 30 years, there are still many open questions. In the observer theory a key role is played by the so called high-gain observers. The purpose of the first part of the thesis is to study novel techniques which allow to overcome or at least to mitigate some of the main drawbacks characterizing this class of observers. We propose a novel class of high-gain observers, denoted as low-power'', which allows to overcome numerical problems, to avoid the peaking phenomenon and to improve the sensitivity properties to high-frequency measurement noise. The second part of the thesis addresses the output regulation problem, solved for linear systems during the 70's by Francis and Wonham who coined the celebrated internal model principle''. Constructive solutions have also been proposed in the nonlinear framework but under restrictive assumptions that reduce the class of systems to which this methodology can be applied. In this thesis we focus on the output regulation problem in presence of periodic disturbances and we propose a novel approach which allows to consider a broader class of nonlinear systems. The resulting design is robust in the sense defined by Francis and Wonham.
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Cited literature [103 references]

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2016PSLEM091_archivage.pdf
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• HAL Id : tel-01774046, version 1

### Citation

Daniele Astolfi. Observers and robust output regulation for nonlinear systems. Automatic. PSL Research University; Università degli studi (Bologne, Italie), 2016. English. ⟨NNT : 2016PSLEM091⟩. ⟨tel-01774046⟩

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