Lilia Sidhom

Adaptive Higher Order Sliding Modes for Two-dimensional Derivative Estimation

In this paper, some recent technical of the derivatives noisy transient signals estimation is extended to the two-dimensional case. This technique, which called higher order sliding modes is mostly used in the synthesis of robust controllers and is also shown a good results in the synthesis of the rth order robust dierentiators. In this work, such dierentiators are used as an edge detection method into image application. The proposed algorithm use an adaptive mechanism for tuning up its parameters in real time, in order to increase the efficiency of basic scheme. Some comparative study with a conventional methods of edge detection is performed.

Dynamic Gains Differentiator for Hydraulic System Control

This paper deals with online numerical differentiation of a noisy time signal where new higher order sliding mode differentiators are proposed. The key point of these algorithms is to include a dynamic on the differentiator parameters. These dynamics tune-up automatically the algorithm gains in real-time. Convergence properties of the new schemes are derived using a Lyapunov approach. Their effectiveness is illustrated via simulations and experimental tests, where comparative studies are performed between classical schemes and the new ones. Such algorithms are also used in the feedback control of an electrohydraulic system.

Adaptive sliding mode observer-differentiator for position and speed estimation of Permanet Magnet Synchronous Motor

In this paper, A supertwisting adaptive sliding mode observer - differentiator is proposed to estimate the speed and position of synchronous motor. Experimental tests have been carried out on a test bench and show the pertinence of the proposed scheme.

Robust Estimator Design for Control of Electropneumatic System

ABSTRACT This paper proposes a new estimation scheme for both speed and acceleration signals in order to include them in a control loop for dynamic system. The proposed scheme consists to improve higher order sliding modes estimator where it can cope with measurement noise better than the classic one. Then, the estimator parameters are online updated with respect to the measured signal variations to reach a good compromise between precision and noise robustness. The tuning formulas of gains estimator are developed by Lyapunov analysis. Simulation and experimental results are presented to confirm the expected performance of the proposed estimator. Thus, its validity is demonstrated by an experimental test in the control context for an electropneumatic system.

On Nonlinear Robust Adaptative Control: Application on Electro-Hydraulic Valve System

In this work, a robust adaptive control (RAC) of electro-hydraulic servo-system is investigated. The dynamics of hydraulic systems are highly nonlinear and the system may be subjected to some discontinuous nonlinearity due principally to servo-valve characteristics. Aside from the nonlinear nature of hydraulic dynamics, our test bench presents an intermediate interface between the actuator and the servo-valve, which leads to have some pressure drop between the servo-valve and the cylinder chambers. This pressure drop depends on some operating conditions. Therefore, the system may possess both parametric uncertainties and unknown nonlinear functions that may represent modelling errors. To address these challenging issues, the robust adaptive control (RAC) is applied. Based on adaptive update techniques, the parametric uncertainties are compensated. Moreover, a robust method is used to solve the problem derived from the modelling errors. The proposed controller ensure that the position tracking errors of the system remains bounded and can be made arbitrarily small. Simulation studies on the control of hydraulic servo-actuator show the effectiveness of the proposed scheme.

On speed estimation of permanent magnet synchronous motor using adaptive robust position observer and differentiator

This article concerns a novel method for sensorless speed control of Permanent Magnet Synchrounous Motor based on adaptive supertwisting sliding mode algorithm. This algorithm is used for motor position observation and for the derivation of the position to deduce the speed. The stability is deduced based on the Lyapunov theory. The Experimental tests, carried out on a test bench, show the pertinence of the proposed scheme.