Dual-finite distributed H∞ filtering in sensor networks

Generally, distributed H∞ filtering approach achieves a certain disturbance attenuation level in the full frequency range. However, the energy of system noise or reference input usually limits in a specified frequency range. To reduce such a design conservatism, this article develops a distributed filtering approach based on dual scale, that is, filtering over a finite-time interval from time scale and also on a specified finite-frequency region from the frequency scale. Our target is to make the filtering error under sensor networks monitoring be relaxed into an ellipsoid bound rather than asymptotically converging to zero for exogenous noise in a specified frequency range. Finally, two illustrative examples demonstrate the strength of the developed filtering approach.

Robust H ∞ Control for the Nonlinear Cascade Systems with Passive and Nonpassive Subsystems

In this paper, H ∞ control for the uncertain switched nonlinear cascade systems with passive and nonpassive subsystems is investigated. Based on the average dwell time method, for any given passivity rate, average dwell time, and disturbance attenuation level, the feedback controllers of the subsystems by predetermined constants are designed to solve the exponential stability and L 2 -gain problems of H ∞ control for switched nonlinear cascade systems. Two examples are provided to demonstrate the effectiveness of the proposed design method.

Finite frequency H∞ control for wind turbine systems in T-S form

In this work, we study H_∞ control wind turbine fuzzy model for finite frequency(FF) interval. Less conservative results are obtained by using Finsler’s lemma technique, generalized Kalman Yakubovich Popov (gKYP), linear matrix inequality (LMI) approach and added several separate parameters, these conditions are given in terms of LMI which can be efficiently solved numerically for the problem that such fuzzy systems are admissible with H∞ disturbance attenuation level. The FF H∞ performance approach allows the state feedback command in a specific interval, the simulation example is given to validate our results.

Robust stability and stabilization of networked control systems with stochastic time-varying network-induced delays

This paper investigates the robust stability analysis and state feedback controller design of networked control systems (NCSs). A stochastic network-induced delay in given interval with known lower and upper bounds is considered. Therefore, the NCS is modeled as linear system with probabilistic time-varying delay distribution. Then, the Lyapunov-Krasovskii functional (LKF) is formulated using probabilistic informations of both lower and upper bounds of the time-varying network-induced delay, and Wirtinger-based integral inequalities are used to estimate the accuracy of the resulting time derivatives and also to reduce conservatism by introducing some new cross terms. Afterwards, stability condition based on [Formula: see text] disturbance attenuation level is expressed in terms of a set of linear matrix inequalities (LMIs), and Finsler’s lemma is used to relax it by adding slack decision variables and decoupling the systems matrices from those of Lyapunov-Krasovskii. This procedure makes the state feedback controller design as simple as a variables change. Finally, a maximum allowable upper bound of the network-induced delay and state feedback controller gains are calculated by resolving the above relaxed LMIs’ convex optimization problem. Practical numerical examples are provided to validate the proposed approach; the results show that the negative effects of the unpredictable network-induced delays are compensated and the stability of NCSs with high disturbance attenuation level is guaranteed. A comparative study with other results in recent researches is also given and the superiority of the proposed method in terms of robustness and conservatism reduction is shown.

Event-based switching control for production inventory systems with time-varying delays

This paper investigates event-based switching control for production inventory systems with time-varying delays. The different subsystems are established to describe the fact that the different production rates are adjusted to meet the different customer needs, and the conditions of average dwelling time are used to constrain the switchings. The event-triggered scheme, where the event generates when the relative error between the current review-data and the last transmission review-data exceeds a certain threshold, depicts the transmission of raw materials (or finished products) in practice. Then, the sufficient conditions of exponentially stable with a prescribed disturbance attenuation level [Formula: see text] and controller synthesis are formulated as linear matrix inequalitiess for the production inventory switching systems. A numerical example is presented to illustrate the effectiveness of the proposed method.

H_/H∞ fault detection filter design for discrete-time stochastic systems with limited communication

This paper is concerned with the fault detection (FD) problem for discrete-time stochastic systems with limited communication. A filter structure is proposed to construct the residual model for fault detection. For the limited network resources, a novel event-triggered strategy is employed to decrease the amount of data that is transmitted from the sensor to the filter. With the consideration of stochastic model and limited network resources, a novel event-based method is designed to ensure the residual system is stochastically stable and satisfies the desired fault sensitivity level and disturbance attenuation level. Compared with the traditional FD method, the proposed design strategy can not only achieve the desired fault detection performance, but also save the limited network resources. The effectiveness of design strategy is verified by two simulation examples.

A New Hybrid Robust Fault Detection of Switching Systems by Combination of Observer and Bond Graph Method

<p>In this paper, the problem of robust Fault Detection (FD) for continuous time switched system is tackled using a hybrid approach by combination of a switching observer and Bond Graph (BG) method. The main criteria of an FD system including the fault sensitivity and disturbance attenuation level in the presence of parametric uncertainties are considered in the proposed FD system. In the first stage, an optimal switching observer based on state space representation of the BG model is designed in which simultaneous fault sensitivity and disturbance attenuation level are satisfied using H􀀀=H1 index. In the second stage, the Global Analytical Redundancy Relations (GARRs) of the switching system are derived based on the output estimation error of the observer, which is called Error-based Global Analytical Redundancy Relations (EGARRs). The parametric uncertainties are included in the EGARRs, which define the adaptive thresholds on the residuals. A constant term due to the effect of disturbance is also considered in the thresholds. In fact, a two-stage FD system is proposed wherein some criteria may be considered in each stage. The efficiency of the proposed method is shown for a two-tank system.</p>

Design of observer-based quantized control for nonlinear time-delay systems

This paper is concerned with the problem of observer design for a class of nonlinear systems with time-varying delay and bounded disturbances. For the stabilization problem, attention is focused on the design of a quantized observer that ensures stability of the closed-loop system. For the robust H∞ control problem, a quantized observer is designed such that, in addition to the requirement of the robust stability, a prescribed disturbance attenuation level also needs to be achieved. The nonlinearity is assumed to satisfy the local Lipschitz condition. A more general case is considered, differing from the previous results where the Lipschitz constant is fixed and predetermined. Finally, a numerical example is provided to show the effectiveness of our method.