Doctorant sous la direction de

**F. LAMNABHI-LAGARRIGUE****Titre de la thèse:**Sample data observers with time-varying gain for a large class of nonlinear systems

**Résumé de la thèse:**The control and observation of systems called Networked control systems (NCSs) are currently attracting a lot of attention in the control community. In many applications, the interest for NCSs is motivated by many advantages they offer such as the ease of maintenance and installation, the greater flexibility and the low cost. For these reasons, many industrial control applications use a serial communication channel to connect sensors and controllers. In NCSs, the serial communication channel has many nodes (sensors and actuators) but the signals of these nodes cannot be transmitted at the same time. The rule that selects which node will use the network to transmit its data, is called scheduling network protocol. It is well known that the stability of these systems is largely determined by the transmission protocol used and by the so-called maximum allowable transfer interval (MATI), i.e., the maximum allowable time between any two successive transmissions in the network. Enlarging the sampling intervals in the networked control/estimation is a hot topic [1, 2]. In a recent paper [3] it was shown that a time-varying gain improves the exponential convergence of the observer in the presence of the measurement delay. In our group, we recently shown, by combining results from [3] and [4] that using a time varying gain for some classes of nonlinear sampled-data systems, in the presence of the measurement delay, allows to enlarge significantly the sampling intervals that preserve the stability. We derived sufficient conditions described by some Linear Matrixes Inequalities which involve both the parameter and the bound of the maximum allowable sampling interval. The subject of this thesis will be to use this recent work for larger classes of systems (those of [5] for instance) and to show that the introduction of the above time varying gain can significantly enlarge the bound on the sampling intervals compared to constant gain cases.

2019

Journal articles

- titre
- Observer design for a class of parabolic systems with large delays and sampled measurements
- auteur
- Tarek Ahmed-Ali, Emilia Fridman, Fouad Giri, Mohamed Kahelras, Françoise Lamnabhi-Lagarrigue, Laurent Burlion
- article
*IEEE Transactions on Automatic Control*, Institute of Electrical and Electronics Engineers, 2019, pp.1-1. ⟨10.1109/TAC.2019.2941434⟩- Accès au bibtex

Theses

- titre
- Observer Design for Different Classes of Nonlinear Delayed Systems.
- auteur
- Mohamed Kahelras
- article
- Automatic Control Engineering. Université Paris-Saclay, 2019. English. ⟨NNT : 2019SACLS005⟩
- Accès au texte intégral et bibtex

2018

Conference papers

- titre
- Observer design for a class of parabolic systems with arbitrarily delayed measurements
- auteur
- Tarek Ahmed-Ali, Emilia Fridman, Fouad Giri, Mohamed Kahelras, Françoise Lamnabhi-Lagarrigue, Laurent Burlion
- article
*2018 IEEE Conference on Decision and Control (CDC)*, Dec 2018, MIAMI BEACH, United States. pp.2199-2204, ⟨10.1109/CDC.2018.8618938⟩- Accès au bibtex

2016

Conference papers

- titre
- Observer Design for Triangular Nonlinear Systems Using Delayed Sampled-Output Measurements
- auteur
- Mohamed Kahelras, Tarek Ahmed-Ali, Theo Folin, Fouad Giri, Françoise Lamnabhi-Lagarrigue
- article
*55th IEEE Conference on Decision and Control (CDC)*, Dec 2016, Las Vegas, NV, United States- Accès au bibtex