Sara Dadras

Adaptive sliding mode control of chaotic dynamical systems with application to synchronization

We address the problem of control and synchronization of a class of uncertain chaotic systems. Our approach follows techniques of sliding mode control and adaptive estimation law. The adaptive algorithm is constructed based on the sliding mode control to ensure perfect tracking and synchronization in presence of system uncertainty and external disturbance. Stability of the closed-loop system is proved using Lyapunov stability theory. Our theoretical findings are supported by simulation results.

A New Fractional Order Observer Design for Fractional Order Nonlinear Systems

In this paper, a class of fractional order systems is considered and simple fractional order observers have been proposed to estimate the system’s state variables. By introducing a fractional calculus into the observer design, the developed fractional order observers guarantee the estimated states reach the original system states. Using the fractional order Lyapunov approach, the stability (zero convergence) of the error system is investigated. Finally, the simulation results demonstrate validity and effectiveness of the proposed scheme.Copyright

Adaptive control for ship roll motion with fully unknown parameters

This paper is concerned with the problem of adaptive control for roll motion of ship as a nonlinear system with five equilibrium points which faces external disturbance. The system parameters are fully unknown. The purpose is to design a robust controller for this model with these properties, under the influence of external sinusoidal disturbances. The capabilities of the proposed controller are verified via simulations.

Fuzzy surface-based control for uncertain unified chaotic systems

This paper proposes a fuzzy sliding mode control strategy for an uncertain unified chaotic system with input nonlinearity. Using the sliding mode control technique, a sliding surface is determined and the control law is established. A fuzzy system is used instead of sign function in the sliding mode control to reduce the chattering phenomenon on the sliding surface. Based on Lyapunov stability theory, stability of the fuzzy sliding control law is determined. Chattering in the system with nonlinearity input is also damped due to this control law. The illustrative simulation results are given to demonstrate the effectiveness of the proposed fuzzy sliding mode control design.

Generating one-,two-,three-and four-scroll attractors from a novel four-dimensional smooth autonomous chaotic system

A new four-dimensional quadratic smooth autonomous chaotic system is presented in this paper, which can exhibit periodic orbit and chaos under the conditions on the system parameters. Importantly, the system can generate one-, two-, three- and four-scroll chaotic attractors with appropriate choices of parameters. Interestingly, all the attractors are generated only by changing a single parameter. The dynamic analysis approach in the paper involves time series, phase portraits, Poincare maps, a bifurcation diagram, and Lyapunov exponents, to investigate some basic dynamical behaviours of the proposed four-dimensional system.

Control of chaotic uncertain brushless dc motors

In this paper, the problem of controlling chaotic uncertain brushless dc motor, exposed to external disturbances, is considered. Two different methods, feedback linearization and sliding mode control, are used to suppress chaos and regulate the system around one of its unstable equilibrium points. Although being able to do the job of regulating and also tracking very well, feedback linearization method is weak when there exist model uncertainties; nevertheless we can reach to a system which is robust to model uncertainties and external disturbances, by applying integral sliding mode approach. Simulation results confirm the effectiveness of these two methods.

Controlling chaos in Arneodo system

In this paper, the problem of controlling chaos in Arneodo chaotic system is considered for the first time. Three different methods, feedback linearization, backstepping design and sliding mode control, are used to suppress chaos and regulate the system around one of its unstable equilibrium points. Simulation results show that all these three methods are efficient. We may also make the system robust to model uncertainties and external disturbances by applying the sliding mode approach.

A nonlinear controller for marine vehicle Control roll motion of ship

The control problem of roll motion of ships which has multiple equilibrium points is investigated in this paper. A nonlinear control law is derived to make the states of this system asymptotically track and regulate the desired state. The control scheme is highly robust and achieves a stable closed loop system despite the presence of uncertainty and external disturbance. An illustrative simulation result is given to demonstrate the effectiveness of the proposed control design.

Control of uncertain butterfly-shaped chaotic system: Sliding-mode approach

A sliding mode control scheme for an uncertain butterfly-shaped chaotic dynamical system is proposes in this paper. A sliding surface is determined according to the sliding mode control technique and the control law is established. Stability of the sliding control law is determined using Lyapunov stability theory. The chattering phenomenon, which deteriorates the system performance and may cause unforeseen instabilities, is attenuated due to this control law. The effectiveness of the presented sliding mode control design is confirmed through numerical simulations.

An adaptive controller for a class of nonlinear systems An application to ship roll motion

In this paper, the problem of adaptive control for nonlinear systems is considered. Employing the adaptive method based on the Lyapunov stability theorem, the corresponding controller is constructed. Simulation results indicate that the proposed adaptive controller has a high performance in stabilizing the nonlinear systems in presence of noise and model uncertainties.