Search

An interval estimation method based on the reduced-order observer and peak-to-peak analysis is proposed for continuous-time linear time-invariant systems with disturbance and measurement noise. The proposed method consists of two steps. First, a reduced-order observer with L ∞ performance is designed to obtain point estimation. Second, interval estimation is achieved by integrating the obtained point estimation and the error interval estimation by peak-to-peak analysis. Steady-state gain optimisation in terms of linear matrix inequalities is used in both steps to improve the estimation accuracy of the proposed method. The superiority of the method over the reduced-order interval observer is illustrated through numerical simulations. [ABSTRACT FROM AUTHOR]

This article deals with the fault detection and isolation problems for a class of uncertain discrete-time Takagi-Sugeno (T-S) fuzzy system based on the combination of the H-infinity observer and the zonotope method (ZM). For fault detection (FD) purpose, first, a Luenberger-like H-infinity observer, which is robust to disturbance in a sense of H-infinity performance index is designed under the assumption of the feasibility of an linear matrix inequality. Second, the ZM is applied to the H-infinity observer error dynamic system such that the interval state estimation can be calculated iteratively if the system suffers from neither actuator nor sensor faults. Third, a residual is constructed and its interval estimation is also given, and furthermore, based on the residual interval estimation, an FD scheme is developed. After this, we discuss the fault isolation issue in the similar way to alarm the appearance of the exact type fault: actuator or sensor fault. It is the ZM is applied onto the Luenberger-like observer, the fault detection and isolation performances are improved greatly. Finally, a numerical simulation example is given and some comparisons are also made to the existing results to verify the effectiveness and to show the advantages of proposed method. [ABSTRACT FROM AUTHOR]

This paper deals with sensor fault detection (FD) for discrete-time switched systems subject to bounded disturbances. A novel approach is investigated to construct residual framers using interval observer with L ∞ performance. The proposed technique is used to provide more degrees of design freedom and to obtain accurate FD results. The design conditions of the FD observer are given in terms of Linear Matrix Inequalities (LMIs) adopting firstly a common quadratic Lyapunov function, under an arbitrary switching signal and secondly multiple quadratic Lyapunov functions, under an Average Dwell Time (ADT) switching signal. Furthermore, the FD decision is based on residual intervals generated by the proposed interval observer. The effectiveness of the proposed approach is highlighted through simulation results of an academic example. [ABSTRACT FROM AUTHOR]

Summary: This article investigates the problem of designing a distributed fault estimation observer (DFEO) for a given linear time invariant observed system with disturbances. The DFEO consists of a network of local fault estimation observers. The local observers at the network nodes are physically distributed and hence each of them has access to only part of the output of the observed system. Each local fault estimation observer communicates with its neighbors as prescribed by the given network graph. Both full order and reduced order DFEO's are presented in this article. A systematic design procedure for DFEO gains is addressed, enabling the estimation error dynamics to be robust against the effects of the external process disturbance and the derivative of the fault. The numerical design of our DFEO is amounts to solving an optimization problem with constraints of a bank of linear matrix inequalities. Finally, we illustrate the effectiveness of the proposed distributed fault estimation approach by means of a number of simulation results. [ABSTRACT FROM AUTHOR]

This paper investigates actuator fault detection and isolation for discrete-time linear descriptor systems. We propose a novel fault detection and isolation scheme based on a bank of H − / L ∞ fault detection observers (FDOs). Under the assumption that the disturbances are unknown but bounded, L ∞ analysis is used to attenuate the effects of disturbances. Meanwhile, the FDO is designed to be sensitive to the fault via considering the H − performance index in finite frequency domain. The design conditions of the proposed FDO are converted into solving a set of linear matrix inequalities. Furthermore, the residual evaluation based on a set-membership approach is proposed to reduce conservatism. Simulation results are provided to demonstrate the performance of the proposed method. [ABSTRACT FROM AUTHOR]

This paper considers robust consensus problem for Lur'e networks with incrementally nonlinearity and unknown disturbance, under a given directed communication topology. Both incrementally sector bounded nonlinearities and incrementally passive nonlinearities are investigated. A distributed protocol is proposed to achieve global consensus. In the design of consensus protocol, H∞ technique is used to attenuate the effect of disturbance. Moreover, the design conditions for robust H∞ consensus are formulated into linear matrix inequalities. Finally, numerical simulations are used to demonstrate the effectiveness and superiority of the proposed method. [ABSTRACT FROM AUTHOR]

Summary: This paper considers H−/L∞ fault detection for discrete‐time linear parameter‐varying (LPV) systems with parametric uncertainty. In H−/L∞ fault detection scheme, residual generation and threshold computation are simultaneously designed. With consideration of H−/L∞ performance indices, the generated residual is sensitive to faults while robust against unknown disturbances. Furthermore, the L∞ performance provides a time‐varying threshold for residual evaluation. This paper proposes a novel H−/L∞ fault detection observer design method to handle actuator fault detection for LPV systems with parametric uncertainty. Sufficient conditions of the fault detection observer design in the finite‐frequency domain are derived as linear matrix inequalities. Numerical simulations are used to illustrate the effectiveness and superiority of the proposed fault detection observer design approach. [ABSTRACT FROM AUTHOR]

This paper considers robust fault estimation in the finite frequency domain for linear continuous-time descriptor systems. Based on state augmentation, we propose a fault estimation observer with a non-singular structure. To attenuate the effect of unknown disturbance and fault variation on fault estimation, a fault estimation observer is designed in the finite frequency domain using H∞ optimisation technique. With the design conditions formulated as a set of linear matrix inequalities, the presented fault estimation observer can be efficiently designed. The applicability of the proposed method is verified by numerical simulations of a multi-machine infinite bus system. [ABSTRACT FROM AUTHOR]

In this paper, a distributed fault estimation observer (DFEO) is designed for multi-agent systems in the finite-frequency domain. The DFEO consists of a network of local fault estimation observers corresponding to each agent. Here communication topology is described as a graph with loops. By using the generalized Kalman–Yakubovich–Popov lemma, the proposed DFEO is designed to avoid the overdesign problem generated by the entire-frequency domain. Furthermore, the design conditions for DFEO are formulated as linear matrix inequalities. Finally, compared with the H ∞ approach in the entire-frequency domain, the proposed DFEO design approach shows better performance in numeral simulations of satellites attitude synchronization. [ABSTRACT FROM AUTHOR]

This paper proposes a novel interval observer design method for discrete-time Takagi–Sugeno fuzzy systems with parametric uncertainty, disturbances, and measurement noise. We present a new structure of interval observer with more design parameters, which can be used to broaden the application scope of interval observer design. For improving the accuracy of interval estimation, an $L_{\infty }$ norm-based approach is used in the design of interval observer to attenuate the effect of the unknown disturbances, noise, and parametric uncertainty. Furthermore, the design conditions are formulated into a set of linear matrix inequalities, which can be efficiently solved. Numerical simulations are given to illustrate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

This paper studies fault detection problem in the finite-frequency domain for linear systems with parameter uncertainties. We design an fault detection observer to generate residual that is robust against disturbance and sensitive to a fault. In the design, we use the finite-frequency performance index to measure fault sensitivity and introduce performance index to measure the effect of disturbance on residual. The obtained fault detection observer exhibits a peak-to-peak disturbance attenuation performance, which provides a time-varying threshold for residual evaluation. Therefore the proposed design method integrates residual generation and threshold calculation together. To facilitate the observer design process, sufficient conditions of the proposed fault detection observer are formulated as a set of linear matrix inequalities. Numerical simulations are given to verify the effectiveness of the proposed approach. [ABSTRACT FROM AUTHOR]

In this paper, an L∞ observer design method is proposed for linear system subject to parameter uncertainty and bounded disturbance. The proposed L∞ observer, which satisfies a peak‐to‐peak disturbances attenuation performance, is designed to overbound the estimation error. Moreover, sufficient conditions for the design of L∞ observer are derived and expressed in terms of linear matrix inequalities (LMIs). The novelty of the proposed method is that we develop an L∞ observer that not only can attenuate bounded disturbance but also provides an upper bound of estimation error norm. Simulation results are presented to illustrate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Sensor fault detection of discrete‐time descriptor systems with bounded disturbances is studied. The authors propose a new structure of a fault detection observer by augmenting the output, which can broaden the application scope. A H−/L∞ criterion is used to achieve the fault sensitivity and disturbance attenuation ability of the residual simultaneously. The residual generation and time‐varying threshold calculation are integrated together based on L∞ analysis. Furthermore, sufficient conditions for the H−/L∞ performance of the proposed observer are formulated in terms of linear matrix inequalities. Numerical simulations of a direct current motor and a flight vehicle are conducted to verify the applicability of the proposed fault detection observer design method. [ABSTRACT FROM AUTHOR]

This paper proposes a novel interval observer design method for discrete-time linear systems with unknown but bounded disturbance and measurement noise. The proposed interval observer has a new structure that provides more design degrees of freedom. A direct method based on H ∞ technique is used to improve the accuracy of interval estimation. The design conditions are formulated into linear matrix inequalities, which can be efficiently solved. Two numerical examples are given to illustrate the design and validate the performance of the interval observers. [ABSTRACT FROM AUTHOR]

This paper considers H − ∕ H ∞ fault detection observer design in the finite frequency domain for a class of linear parameter-varying (LPV) descriptor systems. We propose a novel fault detection observer with a non-singular structure. To make the residual sensitive to faults and robust against disturbances, we develop a finite frequency H − ∕ H ∞ design method based on a generalized Kalman–Yakubovich–Popov lemma for LPV descriptor systems. Design conditions for the proposed fault detection observer are derived and converted as linear matrix inequalities. Simulation studies are conducted to demonstrate the performance of the proposed method. [ABSTRACT FROM AUTHOR]

This study is about H−/H∞ fault detection observer design in finite‐frequency domain for Lipschitz non‐linear systems with actuator fault. To make the generated residual sensitive to fault while robust against disturbance, the authors derive design conditions for the fault detection observer to achieve H− fault sensitivity performance in finite‐frequency domain and H∞ disturbance attenuation performance. The authors further transform the design conditions as a set of linear matrix inequalities to facilitate the observer design. Besides, some extra design degrees of freedom parameters are provided in the proposed method to further reduce some conservatism. Numerical simulations of a single‐link flexible joint robot are conducted to verify the effectiveness of the proposed approach. [ABSTRACT FROM AUTHOR]

This paper proposes an actuator fault detection and isolation strategy based on a bank of unknown input observers with finite frequency specifications. In order to deal with actuator fault diagnosis problem, a bank of H−/ H ∞ unknown input observers are designed to generate residuals, which are insensitive to the corresponding faults but sensitive to the other actuators faults, and meanwhile robust against the unknown disturbances. In this paper, the actuator faults and unknown disturbances are considered to belong to finite frequency domains, and two finite frequency performance indices are used to measure the fault sensitivity and the disturbance robustness of the residuals. Furthermore, some parameters for extra design of freedom are introduced in the H−/ H ∞ unknown input observers design. Based on the generalised Kalman-Yakubovich-Popov (GKYP) lemma, the design conditions of the H−/ H ∞ unknown input observer are derived and formulated as linear matrix inequalities (LMIs). Finally, a VTOL aircraft model is used to demonstrate the performance of the proposed fault diagnosis scheme. [ABSTRACT FROM AUTHOR]

This study deals with actuator fault estimation for discrete‐time linear descriptor systems. The main contribution lies in the synthesis of a novel filter to estimate and isolate actuator faults for discrete linear descriptor systems. In this study, a restricted system equivalent (RSE) model is firstly obtained for the considered descriptor system, and then a fault estimation filter is designed based on the RSE representation. The gain matrix of the proposed filter has a special structure such that the residual vector will tend to the actuator fault with certain time delays which equal to the fault detectability indices. Moreover, this study proposes a robust filter design method to deal with the effect of the unknown disturbance. The proposed filter is able to detect and estimate the faults despite in the presence of disturbance. The design conditions for the proposed filter are formulated as a linear matrix inequality feasibility problem, which can be solved efficiently. Simulation results are given to illustrate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

This paper deals with actuator fault estimation for a class of discrete-time linear parameter-varying descriptor systems. By considering the fault as an auxiliary state vector, an augmented system is established. Then, a fault estimation observer is designed based on the augmented system. In this paper, the fault estimation observer design is formulated as a linear matrix inequality (LMI) feasibility problem. Therefore, all parameters of the observer can be simultaneously designed by solving a set of strict LMIs. In order to attenuate the effect of the unknown disturbance, fault variation, and measurement noise, we further propose a robust fault estimation observer design method, which is the main contribution of this paper. Finally, performance of the proposed robust fault estimation observer is shown through the application to a truck-trailer model. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This article proposes an actuator fault estimation approach for a class of nonlinear descriptor systems. The radial basis function (RBF) neural networks are utilised to model the actuator faults. The adaptive fault estimation observer is designed by exploiting the on-line learning ability of RBF neural networks to approximate the actuator fault. The adaptive algorithm of the RBF networks is established by the Lyapunov theory, and the design of the proposed observer is reformulated as a set of linear matrix inequalities (LMIs), which can be conveniently solved by standard LMI tools. Finally, two simulation examples are used to demonstrate the effectiveness of the proposed fault diagnosis method. [ABSTRACT FROM AUTHOR]

• Propose two prescribed time observers for LPV systems. • State estimation can be achieved in an arbitrarily prescribed time step. • The pole placement of observers only requires solving finite number of LMIs. This paper considers prescribed-time observer (PTO) designs for a class of linear parameter-varying (LPV) systems. Firstly, a full-order prescribed-time observer with time-varying gains is developed. The existence conditions are given in terms of linear matrix inequalities (LMIs). In addition, the reduced-order PTO is also considered in this paper. Moreover, it is shown that the existence conditions under which the full-order PTO exists can also guarantee the existence of a corresponding reduced-order PTO. The advantages of the full-order and the reduced-order PTOs over the existing asymptotic convergence observers are that (1) they can achieve exact estimations in almost any prescribed convergence time regardless of what the system initial values are. (2) the proposed time-varying gain PTOs can avoid the conservatism of the unknown input decoupling conditions brought about by the traditional polytopic LPV observer design methods. Finally, two examples are given to illustrate the effectiveness of the proposed methods. [ABSTRACT FROM AUTHOR]