Said Oucheriah

PWM-Based Adaptive Sliding-Mode Control for Boost DC–DC Converters

In this paper, a robust adaptive sliding-mode controller is designed for a boost converter with an unknown resistive load and external input voltage. Adaptation laws are designed using state observers. The closed-loop system for the boost converter is shown to be asymptotically stable. Finally, the robustness of the adaptive controller to input voltage and load uncertainties and variations is tested experimentally.

Robust tracking and model following of uncertain dynamic delay systems by memoryless linear controllers

A linear memoryless controller is developed for a class of uncertain linear time-delay systems to track dynamic inputs of a non-delay reference model. For matched uncertainties, the controller designed guarantees uniform ultimate boundedness of the tracking error, and the error bound can be made arbitrarily small. For mismatched uncertainties a condition is derived under which the controller designed ensures ultimate boundedness of the tracking error. However, in this case there is no control over the tracking error bound. Finally, examples are included to illustrate the results developed in this paper.

Decentralized stabilization of large scale systems with multiple delays in the interconnections

In this paper, the problem of robust stabilization of a class of time-varying large scale systems subject to external disturbances, uncertain parameters and multiple time-varying delays in the interconnections and non-linear inputs is considered. Linear memory less controllers are developed to guarantee that all solutions of the class of systems considered are uniformly ultimately bounded. Also, non-linear memoryless controllers are synthesized to guarantee that the solutions are uniformly ultimately bounded with respect to a bound with any prespecified convergence rate towards it. Finally, an example is included to illustrate the results developed in this paper.

Global stabilization of a class of linear continuous time-delay systems with saturating controls

The author considers global stabilization of a class of linear continuous time-delay systems subject to saturating actuator. Under certain conditions, a globally stabilizing linear state feedback controller is synthesized by means of an asymptotic observer (with a prescribed stability degree) for time delay systems. Finally, an example is included to illustrate the results developed in this work.

Exponential stabilization of linear delayed systems using sliding-mode controllers

This brief deals with the problem of robust exponential stabilization of a class of time-delay systems using sliding-mode controllers. Continuous controllers are synthesized to guarantee that the motions of the sliding surface are uniformly exponentially convergent to a ball whose radius and the rate of exponential convergence toward it can be chosen arbitrarily. Furthermore, the reduced-order sliding-mode dynamics as well as the deviation from ideal sliding motion are uniformly exponentially convergent to a ball whose radius is minimized and the exponential convergence toward it is maximized. The problem is formulated as an optimization problem with linear matrix inequality constraints. Finally, an example is included to illustrate the results developed in this brief.

Robust exponential convergence of a class of linear delayed systems with bounded controllers and disturbances

This brief paper deals with the problem of robust exponential stabilization of a class of dynamic systems subject to time-varying delays, external disturbances and control saturation. A linear memoryless state feedback controller is synthesized to guarantee that there is a domain of admissible initial conditions from which all solutions of the class of systems considered converge exponentially to a ball with a prespecified convergence rate. The problem is formulated as a two-step optimization problem with matrix inequality constraints to enlarge the size of the ball of admissible initial conditions.

Dynamic compensation of uncertain time-delay systems using variable structure approach

In this brief the robust stabilization of uncertain time-delay systems with nonlinear parametric perturbations using a dynamic compensator in the sliding mode is considered. Dynamic switching surfaces are chosen such that the system is robustly stable with a prescribed stability degree. A simple procedure for the selection of such switching surfaces and an example to illustrate the method are given. >

Synthesis of controllers for time-delay systems subject to actuator saturation and disturbance

The problem of robust stabilization of a class of dynamic systems subject to time delays, external disturbance, and control saturation is addressed in this paper Delay-dependent sufficient conditions via LMI formulation are derived to guarantee that the solutions of the system considered are uniformly bounded. The problem of designing memoryless linear state feedback controllers such that the domain of safe admissible initial states is enlarged is formulated and solved as an optimization problem with LMI constraints. Finally, an example is included to illustrate the results developed in this paper.

Robust Sliding Mode Control of Uncertain Dynamic Delay Systems in the Presence of Matched and Unmatched Uncertainties

A nonlinear continuous controller is developed for a class of uncertain dynamic delay-systems in the presence of matched and unmatched uncertainties. The controller designed guarantees uniform ultimate boundedness of all motions of the class of uncertain time-delay systems considered. Furthermore, the parameters of the controller can be adjusted so that the deviation from ideal sliding mode can be made arbitrarily small. Finally, an example is included to illustrate the proposed design procedure.

Measures of robustness for uncertain time-delay linear systems

Several delay-dependent criteria to test the stability of time-delay systems that were proposed require solving the Lyapunov matrix equation. This can be a troublesome task and often non-trivial. In this note, a delay-dependent sufficient condition that guarantees the robust stability of linear uncertain time-delay systems is presented. The stability test criterion derived in this paper is based on induced norms and matrix measures. The salient feature of the result obtained is its simplicity and ease in testing the robust stability of uncertain time-delay linear systems.