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The present research work aims at the development of a systematic method to arbitrarily assign the zero dynamics of a nonlinear system by constructing the requisite synthetic output maps. The minimum-phase synthetic output maps constructed can be made statically equivalent to the original output maps, and therefore, they could be directly used for nonminimum-phase compensation purposes. Specifically,...
In this paper basic concepts on the passivity, i. e. passivity, state feedback passivity and output feedback passivity, are reviewed. We propose sufficient conditions on static and dynamic output feedback passification. For static output feedback passification, the class of output feedback passive systems is extended with the help of a slightly modified storage function. Dynamic output feedback passification...
In this paper, a sensor fault diagnosis and accommodation method is developed in nonlinear case. This method makes possible the sensor faults compensation. Its principle is based on the on-line detection, localization and estimation of a faulty element when a fault occurs on a nonlinear system. Then, a new control law is computed in order to compensate the fault effect on the system. The performances...
The problem of observer design for robust residual generation in nonlinear discrete-time systems is considered. The method is proposed to solve this problem involving nonlinear time-dependent transformation of state-space system model into strict feedback form. To make this transformation practicable, algebra of time-dependent functions is developed.
In this contribution, the problem of feedback stabilization of systems with delays is addressed. The systems under consideration are nonlinear and nonaffine in control. The origin of the open-loop system is supposed to be stable. By using the Lyapunov-Razumikhin approach, we deduce general conditions for stabilizing the closed-loop system and derive a particular class of stabilizing state feedback...
The concept of algebraic reachability refers to the property of a system that every state from a sufficiently big subset of a state-space can be reached from a given inital state by applying an admissible input to the system. In this paper we study algebraic reachability of rational systems. We provide necessary and sufficient conditions for a rational system to be algebraically reachable (from an...
A new approach to identification of Wiener models by using the least-squares method is presented. It is assumed that an inverse characteristic of the nonlinear element can be expanded to the power series of a finite and known order. A modified definition of the identification error is proposed and parameters of a modified serial-parallel Wiener model are estimated. A simulation example is included...
This paper studies the global asymptotic stability of the nonlinear systems described by the multiple model approach using the Takagi-Sugeno (T-S) fuzzy modelling. New sufficient conditions for the stability of such systems are given. Stability analysis is derived via Lyapunov technique and LMIs (Linear Matrix Inequalities) formulation obtained from BMIs (Bilinear Matrix Inequalities) linearisation...
In this Note, we give several new sufficient conditions for the Holder continuity of the minimal time to reach a closed set through trajectories of a given nonlinear system. When the closed set is reduced to a point this problem is equivalent to the local controllability around an equilibrium. In the case of a non singleton set, the problem is slightly different from the case of local controllability...
In this paper, we present a fuzzy observer based fuzzy control scheme for nonlinear processes. The observer and the controller are built by "fuzzily interconnecting" local linear Lu-enberger observers and linear controllers. The approach uses techniques of robust control along with piecewise quadratic lyapunov functions, to show the global stability of observer + controller + process. In...
An approach for the identification of single-input single-output dynamic errors-in-variables bilinear system models for the case of white input noise and coloured output noise is proposed. The algorithm is based on the extension of the bias compensation technique for bilinear systems that is applied to a set of overdetermined normal equations. The separable nonlinear least squares method is used,...
A new model class is proposed to use for identification purposes, which is able to approximate many nonlinear systems quite accurately. Conditions are given for the system to be representable by a linear-in-parameters equation, which allows to use effective linear methods to solve the identification problem. Finally an example is provided to illustrate the use of the proposed model class for identification...
The paper considers stability of periodic solutions in a class of periodically forced nonlinear systems depending on a scalar parameter and subject to disturbances. The stability analysis — based on a combined use of linearization techniques and frequency-domain stability criteria expressed via Integral Quadratic Constraints — can be efficiently performed in terms of Linear Matrix Inequalities. An...
In this note we extend the design tool presented in [6] for robust stabilization of nonminimum-phase nonlinear systems to the case of output regulation problems. As in [6] we take advantage from a design tool known in the linear literature as “vibrational feedback” to handle the presence of unstable zero dynamics in output regulation problems in presence of uncertainties. This work frames in a research...
This paper proposes an original solution for the observation of nonlinear uncertain systems. Features of this observer based on high order sliding modes are a finite and a priori known convergence time, robustness against unstructured (even unmatched) uncertainties and limited chattering. This is, as far as the authors known, the first observer structure which garantees an a priori known convergence...
Suppose a nonlinear plant is stabilized by a nonlinear controller, and further assume that the plant is unknown but the controller is known. Suppose also that the use of a new controller appears attractive. This paper extends our results for linear time-invariant systems and proposes novel nonlinear analysis results, utilizing the kernel representation of nonlinear systems, for ensuring that the introduction...
This paper tackles the problem of constructing semi-global state-feedback stabilizers that guarantee good transient closed-loop performance when applied to general nonlinear multi-input state-feedback stabilizable systems whose vector-fields are either known or totally unknown. In the case where the system vector-fields are known, a convex optimization design is proposed (which is based on the work...
In this paper, we address the problem of robust moving horizon observer for nonlinear discrete-time systems. The main contribution lies in the use of a robust moving horizon approach in a Luenberger structure observer. Thanks to this new design, a new nonrestrictive synthesis condition, expressed in term of Bilinear Matrix Inequality (BMI), is obtained. Indeed, the obtained BMI contains more degree...
Due to the improvements in computational speed and the development of effective solvers for nonlinear optimization problems, optimization-based state estimation has become an interesting alternative to common approaches such as the Extended Kalman Filter. Nevertheless the computational effort to solve the optimization problem may cause problems in the online application to chemical processes, especially...
Relaxed conditions for the stability study of nonlinear, continuous systems given by fuzzy models are presented. A theoretical analysis shows that the proposed method provides better or at least the same results of the methods presented in the literature. Digital simulations exemplify this fact. These results are also used for the fuzzy regulators and observers design. The nonlinear systems are represented...
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