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Saifia D.,Jijel University | Chadli M.,CNRS Laboratory of Modelisation of Information and Systems | Labiod S.,Jijel University | Karimi H.R.,University of Agder
Mathematical Problems in Engineering | Year: 2012

This paper proposes a method for designing H ∞ fuzzy control of DC-DC converters under actuator saturation. Because linear control design methods do not take into account the nonlinearity of the system, a T-S fuzzy model and a controller design approach is used. The designed control not only handles the external disturbance but also the saturation of duty cycle. The input constraint is first transformed into a symmetric saturation which is represented by a polytopic model. Stabilization conditions for the H ∞ state feedback system of DC-DC converters under actuator saturation are established using the Lyapunov approach. The proposed method has been compared and verified with a simulation example. © 2012 D. Saifia et al. Source


Mohamed K.,Industrial Process Control Unit | Chadli M.,CNRS Laboratory of Modelisation of Information and Systems | Chaabane M.,Industrial Process Control Unit
International Journal of Automation and Computing | Year: 2012

This paper deals with the simultaneous estimation of states and unknown inputs for a class of Lipschitz nonlinear systems using only the measured outputs. The system is assumed to have bounded uncertainties that appear on both the state and output matrices. The observer design problem is formulated as a set of linear constraints which can be easily solved using linear matrix inequalities (LMI) technique. An application based on manipulator arm actuated by a direct current (DC) motor is presented to evaluate the performance of the proposed observer. The observer is applied to estimate both state and faults. © 2012 Institute of Automation, Chinese Academy of Sciences and Springer-Verlag Berlin Heidelberg. Source


Saifia D.,Jijel University | Chadli M.,CNRS Laboratory of Modelisation of Information and Systems | Karimi H.R.,University of Agder | Labiod S.,Jijel University
Journal of the Franklin Institute | Year: 2015

Friction and disturbances of the road are the main sources of nonlinearity in the Electric Power Steering (EPS) System. Consequently, conventional linear controllers design based on a simplified linear model of the EPS system will result in poor dynamic performance or system instability. On the other hand, a brush-type DC motor is more used in EPS control with an input current that is limited in practice. The control laws designed without taking into account the saturation effect may have undesirable consequences on the system stability. In this paper, a Takagi-Sugeno (T-S) fuzzy is used to represent the nonlinear behavior of an EPS system, and stabilization conditions for nonlinear EPS system with both constrained and saturated control input cases are proposed in terms of linear matrix inequalities (LMI). Simulation results show that both the saturated and constrained controls can stabilize the resulting closed-loop EPS system and provide a stable driving in the presence of nonlinear friction, disturbance of the road and actuator saturation. © 2014 The Franklin Institute. Source


Saifia D.,Jijel University | Chadli M.,CNRS Laboratory of Modelisation of Information and Systems | Labiod S.,Jijel University | Guerra T.M.,University of Valenciennes and HainautCambresis
International Journal of Control, Automation and Systems | Year: 2012

This paper proposes a method for designing robust H ∞ static output feedback stabilization of Takagi-Sugeno (T-S) fuzzy systems under actuator saturation. In this paper, the input saturation is represented by a polytopic model and the modeling error is assumed a norm-bounded uncertainty. A set invariance condition for robust H ∞ static output feedback system under actuator saturation is first established. Then, the estimation of the largest domain of attraction for the system is formulated and solved as a Linear Matrix Inequality (LMI) optimization problem. Two examples are used to demonstrate the effectiveness of the proposed design method. © ICROS, KIEE and Springer 2012;. Source


Aouaouda S.,Annaba University | Chadli M.,CNRS Laboratory of Modelisation of Information and Systems | Khadir M.T.,Annaba University | Bouarar T.,Annaba University
Journal of Process Control | Year: 2012

This work concerns the tracking problem of uncertain Takagi-Sugeno fuzzy continuous systems with unmeasurable premise variables and affected by unknown inputs. The aim is to synthesize a fault tolerant controller (FTC) ensuring trajectory tracking of a desired reference model. To emit the original plant system, a norm bounded parametric uncertainty is employed in building the T-S model. The control scheme is based on a fuzzy observer to estimate both faults and faulty system states; a proportional integer (PI) observer to estimate constant faults is then adopted. Using descriptor redundancy property and L 2 optimization to attenuate the unknown inputs effect, a solution is proposed in terms of bilinear matrix inequalities (BMIs). The performances of the proposed approach are pointed out by accentuating on a model of wastewater treatment plant (WWTP) through numerical results. © 2012 Elsevier Ltd. All rights reserved. Source

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