Meetings

Meetings

July 11-13th, 2018 - Final ROCC - SYS WORKSHOP (Villeneuve d’Ascq, France)

See the program and the book of abstracts.

June 30th, 2017 - ROCC-SYS Public Seminar at Centrale Lille (Villeneuve d'Ascq)

Mert Bastug - Minimal and Reduced Order Models for Aperiodic Sampled Data Systems

Networked and embedded control systems are ubiquitous nowadays in practical applications. The detailed, accurate models for such systems can be very complex due to the interactions of different subsystems in the network, the inherent complexity of the models of the subsystems and due to the sampling phenomenon itself. In turn, the dimension of corresponding state-space models for such systems can be very big. Simulations for control synthesis or performance specifications regarding the output behavior can easily become intractable due to the complexity of the original model. Hence, computing low-order accurate models for such systems can be of great importance. In this presentation, this problem is precisely addressed by studying two main topics for aperiodically sampled-data systems which are used as modeling abstractions for networked control systems: Firstly, we formulate minimal order models capturing the whole behavior of the abstractions of networked control systems with taking into account all possible sampling patterns. Secondly, we investigate a model reduction method for such abstractions, to further simplify their models without losing much of the accuracy.

Zohra Kader - Robust relay feedback controller design for LTI systems stabilization

Relay feedback systems have been widely studied in control theory. Due to their simplicity and robustness, relays represent an interesting substitute to continuous control laws. Generally, the states measurements are subject to perturbations. In addition, in many practical cases, the state of the system is not fully available for measurements. This talk is devoted to the presentation of some results about the stabilization of LTI systems by relay feedback with perturbed measurements. A state-dependent switching law is designed in a robust manner,

while taking into account the perturbed states. A design approach for observer-based relay feedback controller will also be presented. The switching law dependent on the estimated states is designed while using a Luenberger observer.

Andrey Polyakov - Relay Control Design using Attractive Ellipsoids Method

Based on the attractive ellipsoids method the problem of rejection of both matched and mismatched exogenous

disturbances is studied for a linear plants controlled by the generalized relays. Some existing results about local stabiliz-

ability as well as matching condition are refined for the system under consideration. The procedure of robust control design

for optimal rejection of bounded exogenous disturbances is proposed. The theoretical results are supported with numerical

simulations.

March 30th, 2017 - 30 months status Meeting at Centrale Lille (Villeneuve d'Ascq)

November 9th, 2016 - 24 Months Status Meeting at Centrale Lille (Villeneuve d'Ascq)

October 26-28, 2016 - joint workshop with the ANR projects COMPACS and LIMICOS at Toulouse, France

Co4: Control subject to Computational and Communication Constraints

Organizers: Sophie Tarbouriech (LAAS), Antoine Girard (L2S), Laurentiu Hetel (CRIStAL). See the program and the book of abstracts.

March 25th, 2016 - 18 Months Status Meeting at Centrale Lille (Villeneuve d'Ascq)

November 19th, 2015 - ROCC-SYS Public Seminar at INRIA - Nord Europe (Villeneuve d'Ascq)

Zohra KADER (work with C. Fiter, L. Hetel, L. Belkoura) : Stabilization of switched affine systems with disturbed state dependent switching law

In this presentation, we will speak about the stabilization problem for a class of switched affine systems with a state-dependent switching law. Since the states measurements are in general subject to perturbations and noises, we propose a robust switching law design method. Qualitative conditions of the stability of the closed loop switched systems are given. Stability conditions are also formulated as Linear Matrix Inequalities (LMIs) in order to allow numerical implementations. Results are illustrated by a numerical example in order to show the efficiency of the method and its limits.

Andrey POLYAKOV (work with L. Hetel): Relay control design for robust finite-time stabilization of MIMO systems

The problem of robust finite-time stabilization of perturbed multi-input linear system by means of relay feedback is considered. A new control design procedure, which combines convex embedding technique with implicit Lyapunov function method, is developed. The issues of practical implementation of the obtained implicit relay feedback are discussed. Theoretical result is supported by numerical simulation.

Laurentiu HETEL (work with R. Delpoux and A. Kruszweski): Parameter Dependent Relay Control: Application to Permanent Magnet Synchronous Motors

We present a novel relay control design strategy for some classes of nonlinear systems. The main idea of this work is to use an Linear Parameter-Varying (LPV) modeling to design nonlinear switching surfaces. This modeling is motivated by the fact that numerical tools such as LMI may be used by exploiting the quasi-linear structure of the system. Here we propose an LMI formulation providing criteria for the design of switching surfaces. This design is seen as the synthesis of Parameter Dependent Relay (PDR). The second contribution of this article is the implementation of this relay strategy for Permanent Magnet Synchronous Motors (PMSM). Since the LPV framework can encompass the PMSM model, the obtained relay control depends on the motor speed variations. Experimental results on a PMSM are presented.

October 7th, 2015 - 12 Months Status Meeting at Ecole Centrale de Lille (Villeneuve d'Ascq)

June 16th - 17th, 2015 - Joint summer school with the ANR projects COMPACS and LIMICOS at JD/JN MACS 2015, Bourges

Organisateurs : Antoine Girard (LJK), Laurentiu Hetel (CRIStAL), Marc Jungers (CRAN), Sophie Tarbouriech (LAAS)

16 juin 2015 :

Tutoriel systèmes à commutation : Marc Jungers (CRAN)

Tutoriel systèmes dynamiques hybrides : Luca Zaccarian (LAAS)

Vérification des systèmes hybrides et validation de l'implémentation de contrôleurs : Goran Frehse (Verimag)

17 juin 2015:

Echantillonnage apériodique, commande événementielle - cas linéaire : Laurentiu Hetel (CRIStAL) / Alexandre Seuret (LAAS)

Commande événementielle - cas non-linéaire : Romain Postoyan (CRAN)

Prise en compte des contraintes de communication: Sophie Tarbouriech (LAAS) / Samson Lasaulce (LSS)

The slides are available on line https://sites.google.com/site/sdhmacs/actions.

March 26th, 2015 - 6 Months Status Meeting at INRIA - Nord Europe (Villeneuve d'Ascq)

March 19th, 2015 - ROCC-SYS Public Seminar at INRIA - Nord Europe (Villeneuve d'Ascq)

Overview of ROCC-SYS

Laurentiu HETEL: Tutorial on systems with aperiodic sampling

Embedded and networked control systems are often required to share a limited amount of computational and transmission resources between different applications. This may lead to fluctuations of the sampling interval, due to the interaction between real-time control algorithms and task / communication scheduling protocols. From the control theory point of view, these variations in the sampling interval need to be treated in a robust manner since they may have a destabilizing effect if they are not properly taken into account. Furthermore, aperiodic controller implementations may actually have interesting properties in distributed control applications, when explicitly evaluating energy, computation and communication costs. The new trend in control is to intentionally modify the sampling interval as an additional control parameter using event- and self-triggering control schemes. This presentation is focused on the stability of systems with time-varying sampling intervals. Basic concepts and recent research directions will be presented. An overview of time-delay, hybrid, discrete-time and input-output models for systems with aperiodic sampling will be given and specific analysis tools will be introduced. At last, an emerging topic concerning the design of stabilizing state-dependent sampling laws will be discussed.

Hector RIOS : Vector Lyapunov Function based Stability for a Class of Impulsive Systems

This presentation deals with the exponential stability analysis for impulsive dynamical systems based on a vector Lyapunov function and its divergence operator. The proposed method relies on a 2D time domain representation. The results are applied to analyze the exponential stability of linear impulsive systems based on LMIs. Some examples illustrate the feasibility of the proposed approach.

Christophe FITER: Stability of Piecewise Affine Systems with State-Dependent Delay, and Application to Congestion Control

In this work, we consider the exponential stability of piecewise affine systems with time- and state-dependent delay, and delayed-state-dependent switching. The stability analysis is based on the use of Lyapunov-Krasovskii functionals, and is divided into two parts. First, global stability conditions are proposed in the case of systems with (state-independent) time-varying delay. Then, local stability conditions are derived in the case of systems with time- and state-dependent delay. In the latter case, estimations of the domain of attraction are also proposed. The theoretical results are applied to the congestion control problem, which can be modeled by such systems.

October 9th, 2014 - ROCC-SYS Kick Off Meeting at Ecole Centrale de Lille (Villeneuve d'Ascq)