Robust fault-tolerant controller design for linear time-invariant systems with actuator failures:an indirect adaptive method

In this paper,indirect adaptive state feedback control schemes are developed to solve the robust fault-tolerant control (FTC) design problem of actuator fault and perturbation compensations for linear time-invariant systems.A more general and practical model of actuator faults is presented.While both eventual faults on actuators and perturbations are unknown,the adaptive schemes are addressed to estimate the lower and upper bounds of actuator-stuck faults and perturbations online,as well as to estimate control effectiveness on actuators.Thus,on the basis of the information from adaptive schemes,an adaptive robust state feed-back controller is designed to compensate the effects of faults and perturbations automatically.According to Lyapunov stability theory,it is shown that the robust adaptive closed-loop systems can be ensured to be asymptotically stable under the influence of actuator faults and bounded perturbations.An example is provided to further illustrate the fault compensation effectiveness.

H-infinity performance optimization for networked control systems with limited communication channels

This paper studies the problems of H-infinity performance optimization and controller design for continuoustime NCSs with both sensor-to-controller and controller-to-actuator communication constraints(limited communication channels).By taking the derivative character of network-induced delay into full consideration and defining new Lyapunov functions,linear matrix inequalities(LMIs)-based H-infinity performance optimization and controller design are presented for NCSs with limited communication channels.If there do not exist any constraints on the communication channels,the proposed design methods are also applicable.The merit of the proposed methods lies in their less conservativeness,which is achieved by avoiding the utilization of bounding inequalities for cross products of vectors.The simulation results illustrate the merit and effectiveness of the proposed H-infinity controller design for NCSs with limited communication channels.

Robust stabilization of switched discrete-time systems with actuator saturation

This paper studies the robust stabilization problem of switched discrete-time linear systems subject to actuator saturation. New switched saturation-dependent Lyapunov functions are exploited to design a robust stabilizing state feedback controller that maximizes an estimation of the domain of attraction. The design problem of controller (coefficient matrices) is then reduced to an optimization problem with linear matrix inequality (LMI) constraints. A numerical example is given to show the effectiveness of the proposed method.

Adaptive fault-tolerant control of linear time-invariant systems in the presence of actuator saturation

This paper studies the problem of designing adaptive fault-tolerant controllers for linear time-invariant systems with actuator saturation. New methods for designing indirect adaptive fault-tolerant controllers via state feedback are presented for actuator fault compensations. Based on the on-line estimation of eventual faults, the adaptive fault-tolerant controller parameters are updating automatically to compensate the fault effects on systems. The designs are developed in the framework of linear matrix inequality (LMI) approach, which can enlarge the domain of attraction of closed-loop systems in the cases of actuator saturation and actuator failures. Two examples are given to illustrate the effectiveness of the design method.

Adaptive fault-tolerant control of linear systems with actuator saturation and L_2-disturbances

This paper studies the problem of designing adaptive fault-tolerant H-infinity controllers for linear timeinvariant systems with actuator saturation.The disturbance tolerance ability of the closed-loop system is measured by an optimal index.The notion of an adaptive H-infinity performance index is proposed to describe the disturbance attenuation performances of closed-loop systems.New methods for designing indirect adaptive fault-tolerant controllers via state feedback are presented for actuator fault compensations.Based on the on-line estimation of eventual faults,the adaptive fault-tolerant controller parameters are updated automatically to compensate for the fault effects on systems.The designs are developed in the framework of the linear matrix inequality(LMI) approach,which can guarantee the disturbance tolerance ability and adaptive H-infinity performances of closed-loop systems in the cases of actuator saturation and actuator failures.An example is given to illustrate the efficiency of the design method.

Observer-based H-infinity control in multiple channel networked control systems with random packet dropouts

This paper investigates the observer-based H-infinity control problem for networked control systems (NCSs) with random packet dropouts.A general packet dropout model with multiple independent stochastic variables in the multiple channels case is adopted to describe the data missing in the limited communication channels.With the consideration of the sensor-to-controller and controller-to-actuator packet dropouts at the same time,a new method is proposed based on a separation lemma to design an observer-based H-infinity controller,which exponentially stabilizes the closed-loop system in the sense of mean square and also achieves a prescribed H-infinity disturbance attenuation level.A numerical example is given to illustrate the effectiveness of the proposed control method.

Data Fusion about Serviceability Reliability Prediction for the Long-Span Bridge Girder Based on MBDLM and Gaussian Copula Technique

This article presented a new data fusion approach for reasonably predicting dynamic serviceability reliability of the long-span bridge girder.Firstly,multivariate Bayesian dynamic linear model(MBDLM)considering dynamic correlation among the multiple variables is provided to predict dynamic extreme deflections;secondly,with the proposed MBDLM,the dynamic correlation coefficients between any two performance functions can be predicted;finally,based on MBDLM and Gaussian copula technique,a new data fusion method is given to predict the serviceability reliability of the long-span bridge girder,and the monitoring extreme deflection data from an actual bridge is provided to illustrated the feasibility and application of the proposed method.

Robust H-infinity filtering for uncertain discrete-time systems using parameter-dependent Lyapunov functions

This paper deals with H-infinity filtering of discrete-time systems with polytopic uncertainties. The un- certain parameters are supposed to reside in a polytope. By using the parameter-dependent Lyapunov function approach and introducing some slack matrix variables, a new sufficient condition for the H-infinity filter design is presented in terms of solutions to a set of linear matrix inequalities (LMIs). In contrast to the existing results for H-infinity filter design, the main advantage of the proposed design method is the reduced conservativeness. An example is provided to demonstrate the effectiveness of the proposed method.

STABILITY ANALYSIS OF DECENTRALIZED ADAPTIVE BACKSTEPPING CONTROL SYSTEMS WITH ACTUATOR FAILURES

In this paper,the authors analyze the stability of a class of interconnected systems withsubsystem unmodeled dynamics and dynamic interactions employing decentralized adaptive controllersdesigned by Wen,Zhou,and Wang (2008) in the presence of actuator failures.It will be shown that theglobal stability of the remaining closed-loop system is still ensured and the outputs are also regulatedto zero when some subsystems break down.

A new stability analysis and controller design method for discrete-time linear systems with saturation nonlinearities

The problems of stability analysis and controllers design for discrete-time linear systems subject to state saturation nonlinearities are investigated in this paper. Both full state saturation and partial state saturation are considered. It is well known to all that the controller design problem under state saturation is very difficult and complex to deal with. In order to overcome the difficulty, a new and tractable system is constructed, and it can be proved that the constructed system is with the same domain of attraction as the original system. With the aid of this property, to estimate the domain of attraction of the original system, an LMI-based method is presented for estimating the domain of attraction of the origin for the new constructed system under state saturation. Further, two optimization algorithms are developed for constructing dynamic output-feedback controllers and state feedback controllers, respectively, which guarantee that the domain of attraction of the origin for the closed-loop system is as 'large' as possible. An example is provided to demonstrate the effectiveness of the new method.

Response and Assessment of the Effectiveness of the Countermeasures for a COVID-19 Outbreak—Guizhou Province,China,March 2022

Summary What is already known about this topic?Many regions in China have recently reported outbreaks of the coronavirus disease 2019(COVID-19)caused by the Omicron variant.What is added by this report?Wuchuan County,Guizhou Province reacted quickly and implemented accurate intervention measures to effectively control the outbreak.The susceptibleexposed-infectious-asymptomatic-removed(SEIAR)model was applied to evaluate the effectiveness of intervention measures.What are the implications for public health practice?Fast response measures should be taken to prevent the spread of outbreaks caused by the Omicron variant.