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In this paper, we present an observer-based partial integrated guidance and control (PIGC) scheme for missiles to achieve hit-to-kill attack at a given impact angle. This is particularly useful as the lethality of a missile can be maximized if collision occurs at a certain angle. A novel sliding mode observer is proposed to estimate all states of the system in finite time, from which the PIGC is designed to make all states converge to zero and achieve the objective. The observer parameters are automatically updated by adaptive laws, which removes the requirement of knowing the bound of disturbances and hence making the scheme more applicable to real missile systems. [ABSTRACT FROM AUTHOR]

This study is concerned with the state estimation and fault reconstruction problems for a class of discrete systems with integral measurements under partially decoupled disturbances. The considered integral measurements, as functions of the system states over a period of time, reflect the interval time between sample collections and real‐time signal processing. Moreover, the process disturbances are allowed to be partially decoupled in the observer design. An augmented state vector is constructed, which consists of the current system state, the delayed system state and the additive fault, and the resultant augmented system is described in a singular form. Then, an unknown input observer is obtained that decouples partial disturbances and attenuates the effect from the remaining undecouplable disturbances. The existence conditions of the desired observer are thoroughly investigated and an algorithm for designing the observer gains is also provided. Finally, a numerical example is presented to show the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

In this study, the estimation problem of periodically occurring faults is investigated for a class of non‐linear time‐varying systems. Unlike most existing results, the system subject to bounded disturbance and measurement noise is considered. A novel non‐linear iterative learning (IL) observer is constructed by using previous output estimation errors and inputs for the purpose of fault estimation (FE). The estimated fault is updated through a novel designed IL law. The recursive analysis and robust control technology are used to prove the condition under which the ultimate boundedness of the FE error can be guaranteed. Finally, a simulation study on a practical manipulator is provided to demonstrate the effectiveness and applicability of the proposed FE scheme. [ABSTRACT FROM AUTHOR]

This paper studies the problem of output tracking for networked control systems with network-induced delay, packet disorder, and packet dropout. The round-trip time (RTT) delay is redefined to describe these communication constraints in a unified way. By including the output tracking error as an additional state, the output tracking problem is converted into the stabilization problem of an augmented system. Based on the observer of the original state increment and the feedback of the output tracking error, a model-based networked predictive output tracking control (NPOTC) scheme is proposed to actively compensate for the random RTT delay. The closed-loop stability is proved to be independent of the RTT delay, and the separation principle for the design of the observer-based state feedback controller is still held in the NPOTC system. A two-stage controller design procedure is presented, which not only guarantees the stability of the closed-loop NPOTC system but also achieves the same output tracking performance as that of the local control system for time-varying reference signals. Both numerical simulations and practical experiments on an Internet-based servo motor system illustrate the effectiveness of the proposed method. [ABSTRACT FROM PUBLISHER]

This study investigates the problem of intermittent fault (IF) detection for a class of discrete‐time linear stochastic systems (LSSs) with time delay. The IF has the characteristics of intermittency, randomness and uncertainty, and the time delay is constant. By using the lifting method and a reduced‐order observer, the truncated residual over a sliding‐time window is presented for the IF detection of discrete‐time LSSs with time delay. Two hypothesis tests are proposed to set the thresholds for detecting the appearing (disappearing) time of IF. Moreover, the magnitude of IF is estimated and the detectability of IF is analysed based on the analysis of statistical characteristics of the truncated residual. The efficacy and practicality of the derived detection scheme are verified via a numerical simulation of the Williams–Otto process. [ABSTRACT FROM AUTHOR]

This study is concerned with the fault‐tolerant (FT) formation control problem with a guaranteed H∞ performance for non‐linear multi‐vehicle systems subject to actuator faults. The authors consider a practical situation: the information transferred between adjacent vehicles is disturbed and each vehicle is interfered by stochastic disturbance and measurement noise. For each vehicle, a decentralised state observer and an adaptive fault estimator are designed based on which a novel cooperative FT control (FTC) protocol is proposed to drive all the vehicles to the desired formation configuration. Taking the system noise into consideration, the error dynamics are modelled by Ito^ stochastic differential equations, whose properties are used for designing and analysing the Lyapunov function in the framework of Ito^ calculus. It is proved that the formation error system is mean‐square asymptotically stable with a prescribed attenuation level in an H∞ sense by the proposed FTC scheme. The observer, estimator and controller gains can be obtained by solving algebraic Riccati inequalities. Finally, the theoretical results are illustrated by simulations and real experiments. [ABSTRACT FROM AUTHOR]

This study deals with a fundamental issue of evaluating the performance of widely used fault detection and diagnosis (FDD) schemes within a closed‐loop framework. The focus is to examine how certain implemented controller would impact on the FDD performance and how such performance can be further improved. For this purpose, the authors consider the FDD problem for a class of linear discrete‐time systems (with and without unknown disturbances) under typical proportional–integral control using observer‐based methods. It is revealed that some existing observer‐based FDD approaches are no longer applicable in the closed‐loop situation due to the feedback control. To solve the problem, by appropriately modifying the structure and re‐designing the parameters of the observers, it is proven that the dynamics of closed‐loop residuals can be made identical with those of the residuals obtained with known control inputs at each time step. A numerical example is provided to show the effectiveness of the proposed algorithm. [ABSTRACT FROM AUTHOR]

Motivated by several accidents, attitude control of a spacecraft subject to faults/failures has gained considerable attention in a wider range of aerospace engineering and academic communities. This paper is concerned with industrial practices and theoretical approaches for fault tolerant control (FTC) and fault detection and diagnosis (FDD) in spacecraft attitude control system. An overview on recent development of spacecraft attitude FTC system design is presented. The basis of a FTC system is introduced. The existing engineering FTC techniques and theoretical methodologies, including their advantages and disadvantages, are discussed. Moreover, closely associated with the reliability-relevant issues, recent progress in attitude FTC design strategies is reviewed. A brief review of some open problems in the general area of spacecraft attitude control design subject to components faults/failures is further concluded. [ABSTRACT FROM PUBLISHER]