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International audience; Many advanced techniques are applied to obtain robust and accurate control for pneumatic actuators. These strategies need that all states are measured, which is not always the case. For this reason, in this paper, the observability problem of pneumatic actuator is treated. Since the cylinder pressure are not simultaneously observable on according to the cylinder dynamic nature. Firstly, a high gain observer is proposed to estimate the velocity of the rod and the pressure on one side of cylinder from the measurement of the pressure on the other side of the cylinder and the position of the rod. Then, an adaptive sliding mode control is presented in order to compensate the estimation error of the proposed observer and reduce the chattering phenomenon of classic sliding mode control. Real implementation on pneumatic benchmark is carried out due to simplicity of the proposed observer. Experimental results show the applicability of the high gain observer and its effectiveness.

This paper addresses the control of induction motor (IM) drives. In this work, we propose a new consideration of backstepping control. However, this control provides a systematic method to carry out the controller design while guaranteeing the stability of the controller-process couple. Furthermore, the incorporation of an integral action in the synthesis of the control system with state feedback presents a robust rejection of echelon-level disturbances. A detailed analytic study and simulation results are given showing the operation of the IM drives control. The results prove the accuracy and robustness of the proposed control scheme. Also, comparison results with another study dealing with control prove that the proposed method shows excellent transient and steady-state speed and a great estimation of flux and load torque.

This paper investigates the applicability of two state feedback controllers for a class of uniformly controllable and observable nonlinear systems. The first one is based on an appropriate high gain control principle that has been developed by duality from the high gain observer principle. The state feedback control gain is particularly provided by a synthesis function satisfying a well-defined condition, leading thereby to a unification of the high gain control designs. The second one is a backstepping controller that has been developed from a suitable combination of the backstepping control approach bearing in mind the high gain control principle pursued for the first controller design. A common engineering design feature that is worth to be mentioned consists in properly formulating their underlying control problems as a regulation problem involving a suitable reference model with respect to the structure of the system as well as the control design principle under consideration. Of fundamental interest, the involved reference model is systematically derived thanks to the flatness and backstepping principles using an appropriate Lyapunov approach. An experimental evaluation is carried out to illustrate the efficiency of the proposed nonlinear controllers.

International audience; In this work, an Adaptive Sliding Mode Control (ASMC) is proposed for a class of nonlinear MIMO system with external disturbances. Although the Sliding Mode Control (SMC) is known for its precision and robustness against disturbance and uncertainties, it suffers from a chattering phenomenon and the choice of sliding surface parameters. To solve such problems, the SMC discontinuous term was replaced by a proportional derivative term and a moving sliding surface was used. The adaptive parameters were obtained by Lyapunov stability analysis to guarantee the stability of the closed loop system. In order to illustrate the efficiency of the proposed controller, experimental results on electropneumatic system were presented and compared to a classic sliding mode controller.

This paper presents a photovoltaic (PV) system with an adaptive sliding mode control based maximum power point tracking (MPPT) algorithm. The main aim of this work is to maximize power extraction from the photovoltaic generator. A novel method, which is able to achieve this aim, is presented by using an adaptive sliding mode controller (ASMC) that drives a boost converter connected between the PV generator and the load. Both robustness and stability of the ASMC controller are investigated against weather changing conditions. Simulation results with real data, under MATLAB-SIMULINK, are given to demonstrate the effectiveness of the proposed approach.

In this work, we develop a robust controller based on adaptive sliding mode strategy to control the position of electro-pneumatic system. The Sliding Mode Control (SMC) is renowned for its precision, robustness against uncertainties and disturbance. However, it suffers from chattering phenomenon. To overcome it, we substitute the discontinuous term of SMC by a proportional derivative term and to improve tracking performance and robustness with respect to parameters variations, we use moving sliding surface. The adaptive parameters are obtained basing on Lyapunov stability analysis to guarantee stability of closed loop system. Experimental results on a electro-pneumatic actuator are presented to show the robustness of the proposed controller.

This paper aims to propose and develop an adaptive moving sliding mode controller (AMSMC) that can be applied for nonlinear single-input single-output (SISO) systems with external disturbances. The main contribution of this framework consists to overcome the chattering phenomenon problem. The discontinuous term of the classic sliding mode control is replaced by an adaptive term. Moreover, a moving sliding surface is proposed to have better tracking and to guarantee robustness to the external disturbances. The parameters of the sliding surface and the adaptive law are deduced based on Lyapunov stability analysis. An experimental application of electropneumatic system is treated to validate the theoretical results.

This paper deals with the estimation of the actuator temperature in an electropneumatic system. First, an appropriate nonlinear system that accounts for the actuator temperature dynamics is introduced. Then in order to overcome the difficulty of installing temperatures sensors in each chamber of the actuator, two nonlinear high-gain observers are proposed to provide online estimate of these temperatures. The gain of both observers can be tuned by the choice of a scalar design parameter. However, the design parameter is constant for the first observer and its choice has to satisfy a compromise between an accurate estimation of the state estimation and a satisfactory sensitivity of the observer with respect to the unavoidable output noise measurements. This difficulty is overcome in the second observer since the scalar design parameter is time varying and is governed by a Riccatti differential equation. The involved adaptation process of the design parameter is mainly driven by the power of the output observation error norm computed on a moving horizon window. Simulation results are given to show the effectiveness of the proposed observers and in particular to compare the performance of both observers, namely, the accuracy of the respective estimates and their sensitivity with respect to noise measurements.

The current work, we present a free chattering sliding mode control with an adaptive algorithm to track pneumatic actuator position. The Sliding Mode Control (SMC) is robust against uncertainties and external disturbance. However, it may induce undesirable oscillation in the control signal. To overcome this drawback, we replace the discontinuous term of SMC law with an adaptive Proportional Derivative PD term. Using Lyapunov theory, we have proved the stability of the closed loop system. In the objective of checking the efficiency of the mentioned solution, experimental results on a benchmark are presented.

Nonlinear control laws become the most important strategies to control electropneumatic actuator. To get high accuracy and performance, we need the knowledge of all state variables. This paper focus on the design of high gain observer which estimates the unmeasured states (velocity and pressure in chamber N) from the measurements of the position and pressure in chamber P. Simulations results are presented to test the effectiveness of our high gain observer which is applied to sliding mode controller in order to control tracking position and pressure.

This paper deals with the H∞ control of nonlinear fuzzy descriptor system described by Takagi-Sugeno fuzzy models. In the first step, we present a stability analysis of nonlinear fuzzy descriptor system. The stability conditions are given in LMI form. In the second step, we have developed H∞ PDC control law in order to reject the effects of external disturbances submitted to the system. Finally, a simulation example is presented to illustrate the mains results.