18 research outputs found

    SYNCHRONIZATION OF CHAOTIC SYSTEMS USING VARIABLE STRUCTURE CONTROLLERS

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    ABSTRACT In this paper a variable structure system based upon sliding mode control with time varying sliding surface and variable boundary layer is introduced to synchronize two different chaotic systems with uncertain parameters. The method is applied to Lur'e-Genesio chaotic systems, as drive-response systems to investigate the effectiveness and robustness of the controlling method. In addition the simulation is repeated with a conventional sliding mode to compare the performance of the proposed sliding mode technique with a simple sliding mode control. The results show the high quality and improved performance of the method presented in the paper for synchronization of different drive-response chaotic systems

    Electronic Simulation and Hardware Implementation of Two Coupled Periodically Forced Duffing and Van der Pol oscillators and its Application to Secure Communication

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    Confirmation of the existence of complex behavior and synchronization of non-identical chaotic systems as reported in literature attracts much interest in secure communication, but practical implementation is still challenging. In this work, the dynamics of coupled non-identical circuits comprising periodically forced Duffing and Van der Pol oscillators is investigated via electronic simulation using Multism software and hardware implementation on electronic circuits board. After complete synchronization is achieved between the Duffing (Transmitter) and Van der Pol (receiver) circuits through the variation of the coupling resistor of the controller, its application to secure communication is therefore demonstrated experimentally and via multism. The results from the electronic simulation and hardware implementation on bread board using analog components are in good agreement with the numerical results in literature

    An improved stability criterion for discrete-time time-delayed Lur’e systemwith sector-bounded nonlinearities

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    The absolute stability problem of discrete-time time-delayed Lur\u27e systems with sector bounded nonlinearities is investigated in this paper. Firstly, a modified Lyapunov-Krasovskii functional (LKF) is designed with augmenting additional double summation terms, which complements more coupling information between the delay intervals and other system state variables than some previous LKFs. Secondly, some improved delay-dependent absolute stability criteria based on linear matrix inequality form (LMI) are proposed via the modified LKF and the relaxed free-matrix-based summation inequality technique application. The stability criteria are less conservative than some results previously proposed. The reduction of the conservatism mainly relies on the full use of the relaxed summation inequality technique based on the modified LKF. Finally, two common numerical examples are presented to show the effectiveness of the proposed approach

    Output feedback robust synchronization of networked Lur'e Systems with incrementally passive nonlinearities

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    In this paper we deal with robust synchronization problems for uncertain dynamical networks of identical Lur’e systems diffusively interconnected by means of measurement outputs. In contrast to stabilization of one single Lur’e system with a passive static nonlinearity in the negative feedback loop, in the present paper the feedback nonlinearities are assumed to be incrementally passive. We assume that the interconnection topologies among these Lur’e agents are undirected and con- nected throughout this paper. A distributed dynamical protocol is proposed. We establish sufficient conditions for the existence of such protocol that robustly synchronizes the Lur’e dynamical network. The protocol parameter matrices are computed in terms of the system matrices defining the individual agent, but also the second smallest and largest eigenvalues of the Laplacian matrix associated with the interconnection topology

    Output feedback robust synchronization of networked Lur'e Systems with incrementally passive nonlinearities

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    In this paper we deal with robust synchronization problems for uncertain dynamical networks of identical Lur’e systems diffusively interconnected by means of measurement outputs. In contrast to stabilization of one single Lur’e system with a passive static nonlinearity in the negative feedback loop, in the present paper the feedback nonlinearities are assumed to be incrementally passive. We assume that the interconnection topologies among these Lur’e agents are undirected and con- nected throughout this paper. A distributed dynamical protocol is proposed. We establish sufficient conditions for the existence of such protocol that robustly synchronizes the Lur’e dynamical network. The protocol parameter matrices are computed in terms of the system matrices defining the individual agent, but also the second smallest and largest eigenvalues of the Laplacian matrix associated with the interconnection topology

    Controller Synthesis of Multi-Axial Robotic System Used for Wearable Devices

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    Wearable devices are commonly used in different fields to help improving performance of movements for different groups of users. The long-term goal of this study is to develop a low-cost assistive robotic device that allows patients to perform rehabilitation activities independently and reproduces natural movement to help stroke patients and elderly adults in their daily activities while moving their arms. In the past few decades, various types of wearable robotic devices have been developed to assist different physical movements. Among different types of actuators, the twisted-string actuation system is one of those that has advantages of light-weight, low cost, and great portability. In this study, a dual twisted-string actuator is used to drive the joints of the prototype assistive robotic device. To compensate the asynchronous movement caused by nonlinear factors, a hybrid controller that combines fuzzy logic rules and linear PID control algorithm was adopted to compensate for both tracking and synchronization of the two actuators.;In order to validate the performance of proposed controllers, the robotic device was driven by an xPC Target machine with additional embedded controllers for different data acquisition tasks. The controllers were fine tuned to eliminate the inaccuracy of tracking and synchronization caused by disturbance and asynchronous movements of both actuators. As a result, the synthesized controller can provide a high precision when tracking simple actual human movements

    5th EUROMECH nonlinear dynamics conference, August 7-12, 2005 Eindhoven : book of abstracts

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