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This paper considers the problem of observer design for a class of nonlinear descriptor systems whose nonlinear terms are time-varying and satisfy a quadratic inequality. The error system is firstly represented by a Lur'e descriptor system (LDS). Then, motivated by the basic idea of absolute stability theory, both types of full-order and reduced-order observers are constructed by a unified approach...
We introduce an extension of the notion of homogeneous approximation to make it valid both at the origin and at infinity (homogeneity in the bi-limit). Exploiting this extension, we give several results concerning stability, robustness and uniform (in the initial condition) finite time convergence for a homogeneous in the bi-limit vector field. We then introduce a homogeneous in the bi-limit observer...
We consider the problem of observer design for systems with periodic disturbances in the system outputs. Assuming that the period T of the disturbance is known, we introduce the idea of mixing past and present output data to remove the disturbance, by defining a new output as the difference between the original output at time t and at time t-T .We determine the exact conditions under which the system...
An observer is designed for strongly detectable systems with unbounded unknown inputs. The design scheme is based on three steps. First, the system is extended taking the unknown inputs (and possibly some of their derivatives) as new states. Then, using a high-order sliding mode differentiator (HOSMD), a new output of the system is generated in order to fulfill the Hautus condition. Finally, the system...
A new observation procedure is proposed for a wide class of single output observable nonlinear systems written in lower triangular form. First, we give the n-th order time-varying differentiator that robustly estimates, in asymptotic manner, the higher derivatives of any model-free continuously differentiable signal. This n-th order differentiator is a generalization of the time-varying differentiator...
This paper addresses the exact transformation of nonlinear systems into a multiple model form with unmeasurable premise variables. The multiple model structure serves to treat the observability and the state estimation problem of nonlinear systems. Using a method with no information loss, a nonlinear system is transformed into a multiple model, depending on the choice of premise variables. It is a...
In this paper, the nonlinear observer based controller will be developed for PEM fuel cell system. Nonlinear model of PEM fuel cell system is introduced to study the design problems of observer. Sliding mode observer and nonlinear state observer are designed to estimate the system states such as supply manifold pressure, Oxygen pressure, Hydrogen pressure, return manifold pressure, etc. These states...
The asymptotic stable observer design for a class of nonlinear descriptor system is investigated in this paper. First, we further extend the LaSalle's invariance principle of index one nonlinear descriptor systems and put forward a sufficient condition for the asymptotically stability of the system. Then, we discuss the observer design of the nonlinear descriptor systems satisfying the Lipschitz condition...
This paper investigates the problem of simultaneous fault and state estimation of either bounded state or globally Lipschtiz nonlinear systems subject to time delay and unknown input. We assume that the system has a triangular structure and the fault is a scalar and polynomial time dependent function. Based on the Lyapunov analysis method, we show that the observer design is related to neither delay...
In this paper an approach for detecting impending rollover is proposed. The method includes an algorithm based on Takagi-Sugeno (TS) fuzzy observer to prevent rollover of the vehicle when road adhesion conditions change. To design such observer, we take into account that roll rate can be measured easily by sensor, but roll angle is not measured. The proposed method allows estimating the roll angle...
Continuous Petri nets (conPNs) are an approximation of (discrete) Petri nets (PNs) introduced to cope with the state explosion problem typical of discrete event systems. We consider a free-labeled Petri net model and assume that certain transitions, including all that model faulty behaviors are unobservable, i.e., they are labeled with the empty word. We show how to design a marking observer that...
This paper deals with necessary and sufficient conditions to transform a class of switched systems to a particular form dedicated to observer design with and without zeno phenomena. Meanwhile, sufficient observability conditions for switched system with or without zeno phenomena are given. In the last section, some observer structures are proposed upon two academical examples.
In this paper, a new fuzzy adaptive control approach is developed for a class of strict-feedback nonlinear systems with unknown time-delay. Using fuzzy logic systems to approximate the unknown nonlinear functions, a fuzzy adaptive observer is introduced for state estimation. Under the backstepping design, fuzzy adaptive output feedback control is constructed recursively. In addition, the number of...
In the synthesis of control systems, the stability is not only the main objective. But also robustness to the effect of the disturbance is required. In this paper, robust Hinfin control design based on fuzzy observer by linear matrix inequality is carried out in order to achieve a disturbance rejection. In addition, using fuzzy observer, the unmeasured states such as angle of attack can be estimated...
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