Mohamed Benrejeb

On secure image transmission combining chaotic encryption and watermarking using dead beat synchronization of 4D Henon maps

In this paper, the main idea of the proposed method is to build a secure image transmission combining watermarking and encryption techniques. From one hand, it consists of an image embedded in another one using a Discrete Wavelet Transform (DWT) to guarantee the process of watermarking. Then, the resultant watermarked image is encrypted using the master 4D discrete-time hyperchaotic Henon maps. From another hand, the synchronization between the encryption and decryption process is performed using a dead beat observer design based on Borne and Gentina practical criterion for stability study and on Benrejeb arrow form matrix for system description. Finally, a watermarking extraction process is done to recover the original image. Numerical simulations are carried out to show the effectiveness of the proposed approach.

Robust Adaptive Control for a Class of Nonlinear Systems Using the Backstepping Method

This paper develops a robust adaptive control for a class of nonlinear systems using the backstepping method. The proposed robust adaptive control is a recursive method based on the Lyapunov synthesis approach. It ensures that, for any initial conditions, all the signals of the closed-loop system are regularly bounded and the tracking errors converge to zero. The results are illustrated with simulation examples.

Sliding Mode Control and Fuzzy Sliding Mode Control for DC-DC Converters

Switched mode DC-DC converters are electronic circuits which convert a voltage from one level to a higher or lower one. They are considered to be the most advantageous supply tools for feeding some electronic systems in comparison with linear power supplies which are simple and have a low cost. However, they are inefficient as they convert the dropped voltage into heat dissipation. The switched-mode DC-DC converters are more and more used in some electronic devices such as DC-drive systems, electric traction, electric vehicles, machine tools, distributed power supply systems and embedded systems to extend battery life by minimizing power consumption (Rashid, 2001). There are several topologies of DC-DC converters which can be classified into non-isolated and isolated topologies. The principle non-isolated structures of the DC-DC converters are the Buck, the Buck Boost, the Boost and the Cuk converters. The isolated topologies are used in applications where isolation is necessary between the input and the load. The isolation is insured by the use of an isolating transformer. The DC-DC converters are designed to work in open-loop mode. However, these kinds of converters are nonlinear. This nonlinearity is due to the switch and the converter component characteristics. For some applications, the DC-DC converters must provide a regulated output voltage with low ripple rate. In addition, the converter must be robust against load or input voltage variations and converter parametric uncertainties. Thus, for such case the regulation of the output voltage must be performed in a closed loop control mode. Proportional Integral and hysteretic control are the most used closed loop control solutions of DC-DC converters. This can be explained by the fact that these control techniques are not complicated and can be easily implemented on electronic circuit devises. Nowadays, the control systems such as microcontrollers and programmable logic devises are sophisticated and allow the implementation of complex and time consuming control techniques. The control theory provides several control solutions which can be classified into conventional and non-conventional controls. Many conventional controls, such as the PID control, were applied to DC-DC converters. The design of the linear controller is based on the linearized converter model around an equilibrium point near which the controller gives

PID-type fuzzy scaling factors tuning using genetic algorithm and Simulink Design Optimization for Electronic Throttle Valve

In this paper, is proposed a comparison between the Simulink Design Optimization (SDO) and Genetic Algorithm (GA), based on minimizing the Integral of the Squared Error (ISE), for tuning PID-type Fuzzy Logic Controller (FLC) scaling factors. The correspondent controller is applied to an Electronic Throttle Valve (ETV) for defined desired trajectory generated by using one of the flatness property. GA tuning shows a better and robust performance compared to SDO algorithm in terms of tracking a desired trajectory with disturbances rejection.

Nonlinear progressive accommodation of actuator fault with optimal control

In this paper, a method of actuator fault tolerant control for a class of nonlinear systems is proposed. It concerns the problem of nonlinear progressive accommodation to actuator failure. This strategy is based on the optimal nonlinear controller which obtained by solving the Generalized Hamilton-JacobiBellman Equation, and its objective to maintain the system closed loop stability when an actuator fault appear. An example is given to illustrate this approach.

On mixing chaotic systems via TS fuzzy modeling

This paper introduces a method for generating chaotic systems via TS fuzzy modeling of Lorenz and Rössler attractors, by combining the memberships functions of the obtained models. Simulation results are presented to show the effectiveness of the proposed method. The obtained global system exhibits a hyper-chaotic behavior and different strange attractors are designed in the phase plane.

Observer based discrete-time chaotic systems synchronization for secure image transmission

In this paper, a secure image transmission method based on discrete-time chaotic maps synchronization is proposed. This method is based on designed observer in order to achieve synchronization and secure image transmission between the transmitter and the receiver. Borne & Gentina criterion was used to establish sufficient conditions for global asymptotic stability of the dynamic error between the two coupled chaotic systems, associated to the Benrejeb arrow form matrix for the system description. Simulation results are given to show the efficiency of the proposed method.

Time-varying controller based on flatness for nonlinear anti-lock brake system

It is shown that by the use of flatness the problem of pole placement, which consists in imposing closed-loop system dynamics, can be related to track desired trajectories in the finite-dimensional linear time-invariant case. Polynomial two-degree-of-freedom controller can then be designed with the use of an exact observer and without resolving the Bézouts equation. In this paper, an extension of these developments is proposed in the linear time-varying (LTV) framework. The proposed approach is illustrated with the control of nonlinear model of an anti-lock brake system. The time-varying controller obtained from the LTV model ensures the trajectory tracking of the nonlinear model.

Generating a new strange attractor by mixing discret and continus TS fuzzy models

This paper introduces a method for generating new strange attractor by mixing continus and discret well known chaotic systems. This method is composed of three main stages: The first stage is a Takagi-Sugeno (TS) fuzzy modeling of the discret and continus chaotic systems, the second stage is the discretization of continuous-time TS fuzzy model and the third stage is the combination of the memberships functions of the obtained models. Simulation results are presented to show the effectiveness of the proposed method. The obtained global system exhibits an hyper-chaotic behavior and the strange attractor is designed in the phase plane.

New Approach for Stability Analysis of Interconnected Nonlinear Discrete-Time Systems Based on Vector Norms

The stability analysis of interconnected large-scale systems is generally characterized by some degree of difficulty, specifically when the interconnections gather a large number of nonlinear subsystems and the couplings evolve according to nonlinear functions in time. In this paper, a novel systematic analysis procedure of fully interconnected discrete-time nonlinear systems with nonlinear interconnections is presented. First, a new arrow form representation of the interconnected system state space model is generated. The obtained generalized thin arrow state matrix is developed by combining the instantaneous subsystems characteristic polynomials, as well as a set of arbitrary and freely parameters. Then, the stability analysis is achieved using the comparison principle and vector norms by translating the stability properties of the lower-dimensional comparison system into those of the considered interconnected system. Aside the proposed systematic formulation and simplicity over existing techniques based mainly on LMIs, it is shown that through an appropriate choice of the model parameters, the developed stability conditions are opportune to locate interesting estimation of the stability domains. Lastly, two numerical examples are included to show the effectiveness of the proposed approach.