CNRS Laboratory of Computer Science and Automatic Control Systems

Poitiers, France

CNRS Laboratory of Computer Science and Automatic Control Systems

Poitiers, France
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Alkhoury Z.,CNRS Laboratory of Computer Science and Automatic Control Systems | Alkhoury Z.,Lille University of Science and Technology | Petreczky M.,CNRS Lille Research Center in Informatics, Signal and Automatic control | Mercere G.,CNRS Laboratory of Computer Science and Automatic Control Systems
Automatica | Year: 2017

In this paper, the identifiability of discrete-time Affine Linear Parameter-Varying (ALPV) models is studied. Examples are presented to show that, in general, the identifiability of ALPV model parameterizations does not guarantee the identifiability of the LTI parameterizations composed of frozen LTI models. A new sufficient and necessary condition is then introduced in order to guarantee the structural identifiability for ALPV parameterizations. The identifiability of this class of parameterizations is related to the lack of state–space isomorphisms between any two models corresponding to different parameter values. In addition, we present a sufficient and necessary condition for local structural identifiability, and a sufficient condition for (global) structural identifiability which are both based on the rank of a user-defined matrix. These latter conditions allow systematic verification of identifiability. Numerical examples are finally presented to illustrate our results. © 2017 Elsevier Ltd


Bernuau E.,French National Institute for Agricultural Research | Moulay E.,University of Poitiers | Coirault P.,CNRS Laboratory of Computer Science and Automatic Control Systems
Automatica | Year: 2017

The main goal of this article is to use properties of homogeneous systems for addressing the problem of stability for a class of nonlinear systems with sampled-data inputs. This nonlinear strategy leads to several kinds of stability, i.e. local asymptotic stability, global asymptotic stability or global asymptotic set stability, depending on the sign of the degree of homogeneity. The results are illustrated with the case of the double integrator. © 2017 Elsevier Ltd


Vayssettes J.,Higher Institute of Aeronautics and Space | Mercere G.,CNRS Laboratory of Computer Science and Automatic Control Systems | Prot O.,University of Limoges
Automatica | Year: 2016

This article aims at giving a new answer for the challenging problem of the parametrisation of multi-input multi-output matrix fraction descriptions. In order to reach this goal, new parametrisations of matrix fraction descriptions, called fully-parametrised left matrix fraction descriptions (F-LMFD), are first introduced. Their structural properties as well as their suitability for multi-input multi-output model description are more precisely analysed. As any over-parametrised model description, the F-LMFD cannot describe a transfer function uniquely. The structure of the space of equivalent F-LMFD is then investigated through the determination of its basis. The study carried out in this article is the prelude to a computational improvement of the identification of matrix fraction descriptions with gradient-based optimisation methods. © 2016 Elsevier Ltd. All rights reserved.


Mercere G.,CNRS Laboratory of Computer Science and Automatic Control Systems | Prot O.,University of Limoges | Ramos J.A.,Nova Southeastern University
IEEE Transactions on Automatic Control | Year: 2014

While determining the order as well as the matrices of a black-box linear state-space model is now an easy problem to solve, it is well-known that the estimated (fully parameterized) state-space matrices are unique modulo a non-singular similarity transformation matrix. This could have serious consequences if the system being identified is a real physical system. Indeed, if the true model contains physical parameters, then the identified system could no longer have the physical parameters in a form that can be extracted easily. By assuming that the system has been identified consistently in a fully parameterized form, the question addressed in this paper then is how to recover the physical parameters from this initially estimated black-box form. Two solutions to solve such a parameterization problem are more precisely introduced. First, a solution based on a null-space-based reformulation of a set of equations arising from the aforementioned similarity transformation problem is considered. Second, an algorithm dedicated to nonsmooth optimization is presented to transform the initial fully parameterized model into the structured state-space parameterization of the system to be identified. A specific constraint on the similarity transformation between both system representations is added to avoid singularity. By assuming that the physical state-space form is identifiable and the initial fully parameterized model is consistent, it is proved that the global solutions of these two optimization problems are unique. The proposed algorithms are presented, along with an example of a physical system. © 2014 IEEE.


Benammar N.,University of Poitiers | Ridouard F.,Universit& and x00E9 | Bauer H.,CNRS Laboratory of Computer Science and Automatic Control Systems | Richard P.,University of Poitiers
IEEE Transactions on Industrial Informatics | Year: 2017

Packet switched networks and message multiplexing have been a major upgrade for industrial systems communications. In the avionics domain, this evolution was brought by the introduction of Avionics Full Duplex Switched Ethernet (AFDX). Guaranteed upper bounds of end-to-end delays for messages transmitted over an AFDX network are mandatory for certification reasons. IEEE


Samie H.,CNRS Laboratory of Computer Science and Automatic Control Systems | Moulay E.,French National Center for Scientific Research | Coirault P.,CNRS Laboratory of Computer Science and Automatic Control Systems | Vauzelle R.,French National Center for Scientific Research
Automatica | Year: 2017

Uplink transmission power control is an essential task in Wireless Cellular Networks (WCNs) due to the resource limitation of the Mobile Stations (MSs). One remaining problem is the effect of the delay caused by measuring the signal strength and decision making in the Inner-Loop Power Control (ILPC). In this article, we develop the Potential Feedback Controller (PFC) for a linear scalar discrete-time system with disturbance in order to take into account an unknown bounded time-varying input delay for uplink ILPC. The main interest of the PFC is to treat easily a stabilization problem with a constraint on the state space by using a nonlinear feedback control with a short computation time. Simulations illustrate that by applying the PFC, the communication connectivity is ensured by maintaining the signal strength above a required limit. © 2017 Elsevier Ltd


Petreczky M.,University of Lille Nord de France | Petreczky M.,Ecole Des Mines de Douai | Mercere G.,CNRS Laboratory of Computer Science and Automatic Control Systems
Proceedings of the IEEE Conference on Decision and Control | Year: 2012

We formulate a Kalman-style realization theory for discrete-time affine LPV systems. We characterize those input-output behaviors which exactly correspond to affine LPV systems. In addition, we present necessary and sufficient conditions for minimality of affine LPV systems and show that equivalent minimal realizations are unique up to isomorphism. The results are derived by reducing the problem to the realization problem for linear switched systems. In addition, we show that an input-output map has a realization by an affine LPV system if and only if it satisfies certain types of input-output equations. © 2012 IEEE.


Bellatreche L.,CNRS Laboratory of Computer Science and Automatic Control Systems | Khouri S.,CNRS Laboratory of Computer Science and Automatic Control Systems | Khouri S.,National School in Computer Science | Berkani N.,National School in Computer Science
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2013

In last decades, semantic databases (SDB) emerge and become operational databases, since the major vendors provide semantic supports in their products. This is mainly due to the spectacular development of ontologies in several domains like E-commerce, Engineering, Medicine, etc. Contrary to a traditional database, where its tuples are stored in a relational (table) layout, a SDB stores independently ontology and its instances in one of the three main storage layouts (horizontal, vertical, binary). Based on this situation, SDB become serious candidates for business intelligence projects built around the Data Warehouse (DW) technology. The important steps of the DW development life-cycle (user requirement analysis, conceptual design, logical design, ETL, physical design) are usually dealt in isolation way. This is mainly due to the complexity of each phase. Actually, the DW technology is quite mature for the traditional data sources. As a consequence, leveraging its steps to deal with semantic DW becomes a necessity. In this paper, we propose a methodology covering the most important steps of life-cycle of semantic DW. Firstly, a mathematical formalization of ontologies, SDB and semantic DW is given. User requirements are expressed on the ontological level by the means of the goal oriented paradigm. Secondly, the ETL process is expressed on the ontological level, independently of any implementation constraint. Thirdly, different deployment solutions according to the storage layouts are proposed and implemented using the data access object design patterns. Finally, a prototype validating our proposal using the Lehigh University Benchmark ontology is given. © Springer-Verlag 2013.


Vizer D.,Budapest University of Technology and Economics | Mercere G.,CNRS Laboratory of Computer Science and Automatic Control Systems
Periodica Polytechnica, Electrical Engineering | Year: 2014

When the identification of linear parameter-varying (LPV) models from local experiments is considered, the question of the necessary number of local operating points as well as the problem of the efficient interpolation of the locally-estimated linear time-invariant models arise. These challenging problems are tackled herein by using the H∞-norm. First, thanks to the nu-gap metric, an heuristic technique is introduced to optimize the number as well as the position of the local operating points (along a given trajectory of the scheduling variables) with respect to the information brought by the local models. Having access to a reliable set of local models, the second step of the procedure, i.e., the parameter estimation step, consists of the optimization a second H∞-norm-based cost function measuring the fit between the local information (represented by the locally-estimated LTI models) and the local behavior of a parameterized global LPV model. A special attention is given to parameterized LPV models satisfying a fully-parametrized or a physically-structured linear fractional representation. © 2014, Technical University of Budapest. All rights reserved.


Cauet S.,CNRS Laboratory of Computer Science and Automatic Control Systems | Coirault P.,CNRS Laboratory of Computer Science and Automatic Control Systems | Njeh M.,CNRS Laboratory of Computer Science and Automatic Control Systems
Control Engineering Practice | Year: 2013

This paper presents a case of persistent harmonic active control for an HEV (Hybrid Electric Vehicle) powertrain. The active control is adapted for a hybrid powertrain consisting of a one-cylinder diesel engine, coupled with a PMSM (Permanent Magnet Synchronous Machine). The PMSM assures the propulsion of the vehicle, as in conventional mild-hybrid electrical vehicles. In addition, it provides speed ripple reductions of the diesel engine. Due to the HEV speed variation, the active control must match this variation. The speed is introduced as a parameter in order to devise an LPV (linear parameter varying) control strategy. The suitability of LPV control for engine torque ripple reduction is demonstrated through a torque control implementation of the PMSM. The control strategy uses the internal model principle of multi-sinusoidal persistent disturbances. The controller is designed to involve several steps, including LMI-based (Linear Matrix Inequalities) optimization. The results show that, for the first and second orders of the ripple, speed oscillations can be reduced when the speed varies. An industrial test bed is used to validate the effectiveness of the approach and the power consumption of the strategy is analyzed. © 2013 Elsevier Ltd.

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