Scientific Publications

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Abstract

In this thesis, we presents in this thesis a new systematic controller design approach for disturbed nonlinear parameter varying systems subject to input and state constraints in discrete-time case. Nonlinear parameter varying formalism and parameter dependent Lyapunov framework are used to handle the varying parameters and control input saturation. Moreover, the proposed control method is based on L_2criterion which results in two different control design procedures. Both static output feedback control law and dynamic output feedback controller are proposed. To ensure the closed-loop system stability with respect to the given saturation constraints on the control input and estimation a largest domain of attraction, different optimization problem are formulated in terms of linear matrix inequality (LMI) conditions, which can be solved efficiently with available solvers.

Secondly, a state and fault estimation for nonlinear uncertain systems described by Quasi-LPV/T-S model with unmeasurable premise variables case is designed. Indeed robust observer based state feedback controllers, under input saturation are studied. By using the L_2 criterion and the pole placement method, certain performance requirements and good robustness are achieved. To achieve this end, a descriptor design approach is used by considering the fault as an auxiliary state variable. Then, stabilization conditions in the sense of Lyapunov method are derived and expressed as a linear matrix inequality formulation.

Furthermore, an Active Fault Tolerant tracking Control (AFTTC) for nonlinear system represented by NLPV under input saturation; actuator and sensor fault is studied. Based on the non quadratic Lyapunov function, design conditions of the controller/observer are formulated in terms of LMI. The obtained results are illustrated on industrial robot arm 2 degree of freedom model guarantying fault estimation and reconfiguration of the control law to maintain stability performance even in the presence of sensor/actuator faults, to maintain the stability performance.


BibTex

@phdthesis{uniusa3803,
    title={Commande Robuste des systémes nonlinéaires avec et sans contraintes},
    author={Ines RIGHI},
    year={2023},
    school={univ of souk ahras}
}