Discrete-time synchronization of chaotic systems for secure communication

This paper deals with the problem of designing an exact nonlinear reconstructor for discrete-time chaotic encrypted messages. More precisely, we investigate the problem of designing a discrete-time dead-beat observer for nonlinear systems with unknown inputs. The application of the proposed observer in the context of secure communication and data transmission is also investigated

Grazing Analysis for Synchronization of chaotic hybrid systems

International audienceIn this paper, a Grazing bifurcation analysis is proposed and a way to chaos is presented. Moreover, based on this analysis an observer design for the synchronization of chaotic hybrid system is given

Nonlinear dynamic of the multicellular chopper

International audienceIn this paper, the dynamics of multicellular chopper are considered. The model is described by a continuous time three-dimensional autonomous system. Some basic dynamical properties such as Poincaré mapping, power spectrum and chaotic behaviors are studied. Analysis results show that this system has complex dynamics with some interesting characteristics

A canonical form for the design of unknown input sliding mode observers

International audienceIn this work, a new approach to solve the problem of designing an unknown input observer for linear systems is developed. An algorithm is given in order to find a suitable change of coordinates for the design of a step-by-step second order sliding mode observer. This observer provides, by usingthe equivalent output injections, a finite time estimation of both state and unknown inputs. Since the observer is based on second order sliding mode algorithms, the equivalent output injections are obtained in a continuous way without any use of low pass filters

Tire/Road Contact Condition Identification Using Algebraic Numerical Differentiation

International audienceIn this paper, a realistic simulation model for Wheeled Mobile Robot (WMR) is given by a dynamical system that switches between three models corresponding to three different tire/road contact conditions: ideal condition, skidding condition and slipping condition. Then, an algebraic based numerical identification for the discrete state (tire/road contact condition) of this switching system is proposed. Finally, specific estimators for the uncertain parameters encountered in the identification scheme are given

On sliding mode and adaptive observers design for multicell converter

International audienceIn this paper, a sliding mode and adaptive observers are proposed for multicell converter. The aim is to solve the problem of capacitor's voltages estimation by tacking account the hybrid behavior appearing in the multicell converters. Furthermore, an analysis of convergence for both observers is introduced. Finally some illustrative results of a 3-cell-converter are given in order to show the efficiency of the designed observers. The applicability of the designed observers are emphasized by the robustness test with respect to resistance load variation

State Observer and Observability Conditions for a Class of Hybrid Continuous-Discrete Dynamic System

International audienceThis paper deals with observability conditions and state observer design for a class of hybrid systems combining continuous and discrete dynamics. The main contribution of the work lies in the performed observability conditions for this class of systems and a design of hybrid observer to reconstruct both continuous and discrete states starting only from the knowledge of a continuous output. An illustrative example is presented showing the efficiency of the proposed observer

Geometrical Conditions for Output Depending Observability Normal Form

International audienceWe give geometrical conditions, which guarantee the existence of a diffeomorphism in order to transform a nonlinear system without inputs into a canonical normal form depending on its output. Moreover we extend our results to a class of systems with inputs. We end this paper by some examples and its simulations to highlight the proposed algorithm

Analogue private communication based on hybrid chaotic systems with delays

International audienceSince most of private communication schemes based on chaotic synchronization are not robust again plain-texts attacks, the introduction of delays in the schemes can be regarded as an efficient method to improve the security degree with respect to such attack. As an extension of our recent work, this paper proposes a new analogue private communication scheme based on hybrid chaotic systems with delays. The proposed scheme is based on the notation of weakly left invertibility of switched systems, and an illustrative example is given for the purpose of highlighting the feasibility of the proposed method

Single output dependent quadratic observability normal form

International audienceIn this paper, two quadratic observability normal forms dependent on output respectively correspondent to drift dominant term and forced dominant term are firstly discussed. Moreover characteristic numbers are studied in order to simplify the calculation of these two normal forms